Carbon Dioxide Sensing E-Book

• Herausgeber: Wiley-VCH Verlag GmbH & Co. KGaA
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 782

Veröffentlichungsjahr: 2019

Beschreibung

The book provides the reader with a profound knowledge of basic principles, properties and preferred applications of diverse kinds of CO2 measurement. It shows the advantages, disadvantages and limitations of several methods and gives a comprehensive overview of both possible applications and corresponding boundary conditions. Applications reach from environmental monitoring to safety control to biotechnology and food control and finally to medicine.

Leseprobe

Table of Contents

Cover

Scientific Biographies of the Authors

Scientific Biographies of the Co-Authors to Chapter 16

Preface

Reference

Part I: General

1 Introduction

Reference

2 Carbon Dioxide in General

2.1 Chemical and Physical Properties of Carbon Dioxide

2.2 The Carbon Cycle

2.3 Anthropogenic CO

2

References

Part II: Principles of Carbon Dioxide Sensors and Measuring Methods

3 Analytical Methods for the Detection of Gaseous CO

2

3.1 Spectroscopy

3.2 Gas Chromatography

3.3 Analytical Determination of CO

2

in Liquids

References

4 Electrochemical CO

2

Sensors with Liquid or Pasty Electrolyte

4.1 Severinghaus‐Type Membrane‐Covered Carbon Dioxide Sensors

4.2 Coulometric and Amperometric CO

2

Sensors

4.3 Conductometric CO

2

Sensors

4.4 Quinhydrone CO

2

Electrode

References

5 Potentiometric CO

2

Sensors with Solid Electrolyte

5.1 Indirect Measurement of CO

2

in Hot Water Gas

5.2 Direct CO

2

Measurement with Solid Electrolyte Cells

5.3 Solid‐State Sensors Based on Changes in Capacity and Resistivity

References

6 Opto‐Chemical CO

2

Sensors

6.1 Liquid Reagent‐Based Opto‐Chemical CO

2

Sensors

6.2 CO

2

Detector Tubes

6.3 Fibre‐Optic Fluorescence CO

2

Sensors

References

7 Non‐dispersive Infrared Sensors

7.1 Basic Principle and General Set‐Up

7.2 NDIR Components

7.3 NDIR Sensors

7.4 IR Spectrometers

7.5 IR Imaging for CO

2

Detection

References

8 Photoacoustic Detection of CO

2

8.1 Photoacoustic Effect and Photoacoustic Gas Detection

8.2 Photoacoustic Signal Generation

8.3 Photoacoustic Gas Analysis with Thermal Sources

8.4 Laser‐Based Photoacoustic Trace Gas Detection

References

9 Acoustic CO

2

Sensors

9.1 Basic Principles of Resonant Sensors

9.2 Quartz Crystal Microbalance Sensors

9.3 Surface Acoustic Wave Sensors

9.4 Ultrasonic CO

2

Sensors

References

10 Miscellaneous Approaches

10.1 Hydrogel‐Based CO

2

Sensors with Pressure Transducer

10.2 Miniaturized and ISFET‐Based CO

2

Sensors

10.3 Thermal Conductivity CO

2

Detectors

10.4 Membrane‐Based CO

2

Sensors with Pressure Measurement

References

11 Survey and Comparison of Methods

Part II: Applications

12 Environmental CO

2

Monitoring

12.1 CO

2

and Climate Change

12.2 Atmospheric CO

2

12.3 Oceanic and Water CO

2

and Carbonate Content

References

13 CO

2

Safety Control

13.1 Limit Values for CO

2

Concentrations at Workplaces

13.2 CO

2

in Buildings and Workplaces

13.3 CO

2

Warning Devices

References

14 CO

2

Measurement in Biotechnology and Industrial Processes

14.1 Beverage and Food Industry

14.2 Bioreactors

14.3 Biogas Plants

References

15 CO

2

Measurements in Biology

15.1 Aquatic Animals

15.2 Insects

15.3 Plants

References

16 CO

2

Sensing in Medicine

16.1 Introduction

16.2 Physiological Background of CO

2

Sensing

16.3 Measuring Principles

16.4 Clinical Applications

16.5 Comparison of Methods and Conclusions

16.6 CO

2

Analysis in Human Breath

16.7 CO

2

Measurements on Baby Mattresses

References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Conversion factors for CO

2

concentrations.

Table 1.2 Conversion factors for CO

2

partial pressures.

Chapter 2

Table 2.1 Industrial use of carbon dioxide ( [9] ; the author points out the la...

Table 2.2 Specific heats and phase change enthalpies of carbon dioxide at specif...

Table 2.3 Reservoir distribution (in 10

19

 g element, resp. water); after [36], i...

Table 2.4 Degassing of gases from heated rocks ([46] and citations therein).

Table 2.5 Evolution of the Earth's atmosphere.

Table 2.6 Main composition of the atmospheres of the inner terrestrial planets (...

Table 2.7 Global estimates of

NPP

and biomass (standing crop).

Table 2.8 Loss of

NPP.

Table 2.9 Global biomass use as of the year 2000.

Table 2.10 Global estimates of burned biomass and released carbon into the atmos...

Table 2.11 Biomass burning emissions in Tg C a

−1

(related to the late 1990s...

Chapter 3

Table 3.1 Fundamental oscillations of CO

2

and H

2

O.

Table 3.2 Interaction of atoms and molecules with electromagnetic radiation.

Table 3.3 Isotopologues of CO

2

.

Table 3.4 Typical requirements for lasers suitable for gas spectroscopy.

Table 3.5 Commercially available single‐mode semiconductor lasers for the differ...

Table 3.6 Classification of gas and fluid chromatographic methods.

Table 3.7 Detectors for gas chromatography.

Table 3.8 Analytical determination of

K

a

and

K

b

and

m

‐value and

p

‐value.

Table 3.9 Estimation of the main components of the sample from the

m

‐ and

p

‐value...

Chapter 4

Table 4.1 ln Δ

C

/

εC

2

(

ε

 = 0.01) versus analyte concentration change ref...

Chapter 5

Table 5.1 Conditions for the ion exchange process in layered β″‐alumina.

Chapter 6

Table 6.1 Influence of temperature on CO

2

detector tubes.

Table 6.2 Commercially available CO

2

detector tubes for short‐term CO

2

measuremen...

Table 6.3 Specification of

p

CO

2

sensors (PreSens Precision Sensing GmbH, Regensbur...

Table 6.4 Specification of the VisiSens system to image CO

2

concentration distrib...

Chapter 7

Table 7.1 Structural components of NDIR gas sensors.

Table 7.2 Preferably used wavelengths for gas detection [1] .

Table 7.3 Comparison of the sensor properties for NDIR CO

2

detectors. See also [...

Table 7.4 IR radiation sources [ 22 36 –38].

Table 7.5 Optimal optopairs of radiation source and detector for CO

2

detection (4...

Table 7.6 Characteristic properties of commercial NDIR CO

2

sensors (selection; v...

Table 7.7 Structural components of IR spectrometers.

Table 7.8 Infrared cameras for gas detection (GasFindIR cameras; FLIR).

Chapter 8

Table 8.1 Noise and background characteristics for the B&K 1306 gas analyser.

Table 8.2 System and performance data of different laser‐photoacoustic gas analy...

Chapter 9

Table 9.1 Comparison of parameters of piezoelectric microelectromechanical reson...

Table 9.2 Properties of QCM quartz crystals.

Table 9.3 Some widespread SAW sensor materials.

Table 9.4 SAW sensors for the detection of CO

2

.

Table 9.5 Velocity of sound in selected gases.

Chapter 10

Table 10.1 Thermal conductivity

λ

of selected gases (in mW m

−1

 K

−1

...

Table 10.2 Technical data of the carbon dioxide analyser TC1 for the measurement...

Chapter 11

Table 11.1 Principles of carbon dioxide sensors.

Table 11.2 Characteristics of some CO

2

measurement methods.

Table 11.3 Decision support for the choice of analysis method.

Table 11.4 Examples for CO

2

measurements on different fields of application.

Chapter 12

Table 12.1 Global carbon budgets in 10

15

 g C a

−1

.

Table 12.2 Characteristics of two periods of Montsouris Observatory monitoring.

Table 12.3 Historic CO

2

measurements (mixing ratio in ppm).

Table 12.4 Mean CO

2

mixing ratios (1981–1992 annual average) for different remote...

Table 12.5 Growth rates of CO

2

increase (ppm CO

2

a

−1

) at Mauna Loa station...

Table 12.6 Carbon dioxide offset in cities compared with the rural environment (...

Table 12.7 Equilibrium constants in the aqueous CO

2

–carbonate system.

Table 12.8 Mean data sets from the deepwater Station ALOHA (A Long‐Term Oligotro...

Table 12.9 Some selected examples of CO

2

sensors for marine and freshwater appli...

Table 12.10 Performance parameters of the SAMI‐CO

2

ocean CO

2

sensor (Sunburst Sen...

Table 12.11 Typical CO

2

concentrations in different water sources measured in Se...

Chapter 13

Table 13.1 Limit values for CO

2

concentrations at workplaces.

Table 13.2 Critical values, effects, and symptoms of CO

2

exposure.

Table 13.3 Composition of the room air after introduction of 5% CO

2

to the room'...

Chapter 14

Table 14.1 Changes in CO

2

concentration and pH value of some liquid and paste‐li...

Chapter 15

Table 15.1 Results of RQ measurements in summer and winter on different sampling...

List of Illustrations

Chapter 2

Figure 2.1 Phase diagram for carbon dioxide.

Figure 2.2 Solubility of carbon dioxide in water at different temperatures and ...

Figure 2.3 Scheme of the inorganic carbon cycle (inorganic carbon burial).

Figure 2.4 Scheme of the carbon cycle and reservoirs; fluxes in 10

15

 g a

−1

...

Figure 2.5 (a, b) World production of fossil fuels in Mt oil equivalent (toe). ...

Figure 2.6 Carbon release due to land‐use change.

Figure 2.7 Global CO

2

emission trend; fossil fuel data from [114], land‐use cha...

Figure 2.8 Per capita CO

2

emission for selected countries; data from [115] .

Chapter 3

Figure 3.1 CO

2

molecule as simple mechanical spring–mass resonator. The bonds b...

Figure 3.2 Potential energy

E

(

v

) of a diatomic molecule with (a) linear and (b)...

Figure 3.3 Line strengths

S

for ro‐vibrational transitions of the most abundant...

Figure 3.4 Line strengths of CO

2

transitions for different CO

2

isotopomers arou...

Figure 3.5 Line strengths of CO

2

and H

2

O at higher resolution between 4.243 and...

Figure 3.6 CO

2

linewidth reduction by pressure reduction in a sample cell of a ...

Figure 3.7 Transmission of CO

2

with different concentrations. Absorption length...

Figure 3.8 (a) Basic laser spectroscopy set‐up. (b) Observed detector signal wh...

Figure 3.9 Intrapulse technique. (a) Fast frequency tuning of a QCL during a 20...

Figure 3.10 Example of a laser scan across the CO

2

P36e absorption line (dash‐d...

Figure 3.11 Principle of 2

f

WMS. (a) Modulation with frequency

f

is added to th...

Figure 3.12 Principle of cavity ring‐down spectroscopy (CRDS).

Figure 3.13 Functional principle of gas chromatography.

Figure 3.14 (a) Separation of a composition containing the components A and B i...

Figure 3.15 Chromatograms of a greenhouse gas sample. CO

2

is methanized and mea...

Figure 3.16 pH dependence of the carbonate system.

Figure 3.17 General titration curve of carbonic acid at 10 °C according to [74...

Figure 3.18 Percentage

Q

c

of free carbonic acid from total carbonic acid versus...

Figure 3.19 Dependence of the CO

2

concentration on pH value and alkalinity of t...

Figure 3.20 Determination of CO

2

concentrations in various samples of diluted m...

Chapter 4

Figure 4.1 Top of Stow's

p

CO

2

cell according to [2] . A, Beckman glass elect...

Figure 4.2 Schematic drawing of the Severinghaus CO

2

electrode. A, glass electr...

Figure 4.3 Main components and mode of operation of the Severinghaus carbon dio...

Figure 4.4 Dependence of the sensitivity of the Severinghaus carbon dioxide sen...

Figure 4.5 Shape, dimensions, and internal structure of a Severinghaus‐type ele...

Figure 4.6 Calibration curve of the Severinghaus carbon dioxide sensor as shown...

Figure 4.7 Steady‐state model of the electrode response of the CO

2

electrode ac...

Figure 4.8 Scheme of the cell design used for coulometric CO

2

sensors without f...

Figure 4.9 Course of the pH value during two measuring cycles for the measuring...

Figure 4.10 Current response of the RuO

2

electrode on pure N

2

, air, and air wit...

Figure 4.11 CO

2

and O

2

monitoring of human breath with a pulsed titration senso...

Figure 4.12 Schematic drawing of the cross section of a planar conductivity‐typ...

Figure 4.13 Response of the planar CO

2

sensor from Figure 4.12 to fast chang...

Figure 4.14 Simulated concentration profile in the diffusion channel at the pos...

Figure 4.15 Comparison between experimental and simulation results of the senso...

Chapter 5

Figure 5.1 Potentiometric sensors: (a) basic principle of thermodynamically co...

Figure 5.2 Basic principles of solid electrolyte CO

2

sensors. (a) Sodium carbon...

Figure 5.3 Response behaviour of a solid electrolyte CO

2

sensor during a pressu...

Figure 5.4 Schematic cross section of a CO

2

sensor using the pellet design. 1, ...

Figure 5.5 Cross section of a thick‐film sensor using β‐alumina layer on an alu...

Figure 5.6 Measurement in breath gas. Due to the fast response of the thick‐fil...

Figure 5.7 SEM images of layered alumina substrates. (a) Na

+

‐β′‐alumina, (b...

Figure 5.8 Arrhenius plots for the temperature dependence of ion‐exchanged β″‐a...

Figure 5.9 Influence of the firing temperature of NASICON on the CO

2

signal.

Figure 5.10 Temperature dependence of the cell voltage of (a) Na

2

CO

3

and (b) Li

Figure 5.11 Influence of the electrolyte on cell voltage at 598 °C (a) and 423 ...

Figure 5.12 Influence of water vapour on (a) impedance and (b) cell voltage

U

.

Figure 5.13 Influence of combustibles on (a) 2‐propanol and (b) acetone. The do...

Chapter 6

Figure 6.1 Sensor set‐up of the YSI 8500 CO

2

monitor. (YSI Inc., USA, accordin...

Figure 6.2 SAMI‐CO

2

sensor (Sunburst Sensors, Missoula MT, USA) based on a memb...

Figure 6.3 Instrument layout of the SAMI‐CO

2

sensor from Figure 6.2 .

Figure 6.4 Drawings of the invented gas detector tube [17] . A, glass tube; B...

Figure 6.5 Detector tube before and after measurement.

Figure 6.6 Measuring ranges of the CO

2

detector tubes from Table 6.2 .

Figure 6.7 General set‐up of a fibre‐optic sensor [26].

Figure 6.8 Schematic of an optical fibre.

Figure 6.9 Fibre Bragg grating;

I

I

,

I

T

,

I

R

light intensity of incident; transmi...

Figure 6.10 (a) Intrinsic and (b) extrinsic fibre‐optic sensors.

Figure 6.11 Techniques providing interaction between light guided in an optical...

Figure 6.12 Fibre‐optic CO

2

sensor based on the Severinghaus effect.

Figure 6.13 Fibre‐optic sensor tip based on a CO

2

‐permeable Teflon membrane , O...

Figure 6.14 Fluorescence with excitation and emission wavelength [34] .

Figure 6.15 Emission spectra versus CO

2

concentration for a fibre‐optic fluores...

Figure 6.16 Structure of the CO

2

‐gas sensor with a CO

2

‐sensitive capillary arra...

Figure 6.17 Fluorescence spectra of the sensor from Figure 6.16 at different...

Figure 6.18 CO

2

response curve of the sensor from Figure 6.16 in different C...

Figure 6.19 Measurement set‐up with sensor spots fixed to the inner surface of ...

Figure 6.20 VisiSens system to image CO

2

concentration distributions (PreSens P...

Chapter 7

Figure 7.1 Schematic set‐up of (a) an absorption spectrometer and (b) a multis...

Figure 7.2 (a) Simplified thermal model and (b) equivalent electrical circuit f...

Figure 7.3 (a) Electric small‐signal model of the responsive element of a pyroe...

Figure 7.4 Basic circuit of a pyroelectric sensor element (a) in current mode a...

Figure 7.5 Frequency dependence of signal voltage

U

S

and responsivity

R

V

of pyr...

Figure 7.6 Compensated pyroelectric sensors in (a) parallel circuit and (b) ser...

Figure 7.7 Pyroelectric sensors. (a) Temperature‐compensated sensor in current ...

Figure 7.8 (a) Thermoelectric effect, (b) principle of a thermocouple, and (c) ...

Figure 7.9 (a) Electronic model of a thermopile and (b) typical integrated eval...

Figure 7.10 Miniaturized thermopile modules: (a) sensor and (b) sensor with int...

Figure 7.11 Characteristic wavelength‐dependent responsivity (sensitivity) of a...

Figure 7.12 Temperature shift of NBP filters.

Figure 7.13 Beam splitting of the incident radiation in a 4‐channel NDIR module...

Figure 7.14 Fabry–Pérot interferometer filter.

Figure 7.15 Transmittance spectrum of a Fabry–Pérot interferometer filter.

Figure 7.16 Relative spectral response of the FPF detector type LFP‐3041L‐337 a...

Figure 7.17 Variable colour detector with integrated Fabry–Pérot interferometer...

Figure 7.18 Spectral transmittance of a micro‐Fabry–Pérot interferometer filter...

Figure 7.19 Planck's radiation law in double‐logarithmic representation. Parame...

Figure 7.20 Novel thermal IR emitter with nanostructured surface made from NiCr...

Figure 7.21 Optimization for the optical design of NDIR sensors: (a) illuminati...

Figure 7.22 Long‐term test of a single‐beam NDIR sensor.

Figure 7.23 Schematic drawing of a membrane‐covered gas transfer probe for the ...

Figure 7.24 Functional principles of infrared spectrometers.

Figure 7.25 Main components and of IR spectrometers and illustration of Fourier...

Figure 7.26 Schematic set‐up of a thermal imaging camera.

Figure 7.27 CO

2

content in breathing air while exhaling through the nose; IR ca...

Figure 7.28 Images of CO

2

flows with flow rates from 5 to 1000 ml/min; IR camer...

Chapter 8

Figure 8.1 Alexander Graham Bell's photophone – technical drawing by Bell. (a,...

Figure 8.2 Basic set‐up for transmission‐based gas analysis.

Figure 8.3 Radiation detector based on the photoacoustic effect. (a) No target ...

Figure 8.4 Single‐channel photoacoustic set‐up developed by Veingerov.

Figure 8.5 Basic photoacoustic sensor set‐up with detection in the sample chamb...

Figure 8.6 Relaxation processes after excitation: (a) radiative relaxation, (b)...

Figure 8.7 Vibrational relaxation channels for CO

2

/N

2

after excitation of the 2

Figure 8.8 Basic set‐up of the URAS concept of Lehrer and Luft [15] . A capac...

Figure 8.9 Typical transmission spectrum of a process gas containing CO, CO

2

, a...

Figure 8.10 CO

2

PA detection chamber with MEMS microphone.

Figure 8.11 MEMS microphone SMM310 (Infineon) on a TO socket without cap and wi...

Figure 8.12 Compact single‐path PA sensor for CO

2

measurements. Left side: MEMS...

Figure 8.13 Laboratory measurement of a CO

2

concentration series (250–20 000 pp...

Figure 8.14 Basic scheme of the Brüel & Kjaer PA system with thermal IR source.

Figure 8.15 Modes of an acoustic resonator: (a) radial, (b) azimuthal, and (c) ...

Figure 8.16 Cross section of a resonant PA cell with buffer volumes for the sup...

Figure 8.17 Shape and dimensions of a standard quartz tuning fork.

Figure 8.18 QEPAS spectral scan across a CO

2

absorption line at 2311.515 cm

−1

...

Figure 8.19 Configuration for QEPAS with micro‐resonator tubes for signal enhan...

Figure 8.20 Set‐up for a QEPAS system with acoustic micro‐resonator tubes.

Figure 8.21 PAS with interferometer for the cantilever read‐out (a) schematic s...

Figure 8.22 Noise spectrum of the cantilever with dominating Brownian noise. Th...

Chapter 9

Figure 9.1 Steps in an acoustic process.

Figure 9.2 General set‐up of a resonance sensor.

Figure 9.3 Simplified model of a mass–spring–damper resonator of resonance sens...

Figure 9.4 Resonance peak of a mass–spring–damper resonator at resonance freque...

Figure 9.5 Electromechanical model of a piezoelectric resonator. (a) With elect...

Figure 9.6 General frequency dependence of the absolute value of impedance

Z

fo...

Figure 9.7 Frequency dependence of absolute value

Z

and phase

φ

of impedan...

Figure 9.8 Quartz crystal. (a) Assignment of axes to the quartz crystal. (b) AT...

Figure 9.9 Vibration modes in piezoelectric plates.

Figure 9.10 Ideal thickness shear vibration of a quartz plate;

x

,

y

,

z

coordina...

Figure 9.11 Frequency change of a QCM coated with THEED during a series of five...

Figure 9.12 Absorption of CO

2

in polymers: TEF, Teflon AF‐1600; TPX, poly 4‐met...

Figure 9.13 Uniform interdigital transducer with period

p

and constant electrod...

Figure 9.14 Surface acoustic wave generated by an interdigital transducer.

Figure 9.15 Delay line‐based SAW sensor as part of an oscillator circuit.

Figure 9.16 Wave propagation in SAW devices. (a) Rayleigh wave, (b) acoustic pl...

Figure 9.17 Cross view showing the particle displacement in a cubic lattice cau...

Figure 9.18 Dual‐delay‐line configuration of the SAW‐based gas sensor.

Figure 9.19 Schematic diagram of a passive, i.e. remotely operated, SAW sensor.

Figure 9.20 Operation principle of a passive SAW sensor where the output signal...

Figure 9.21 Velocity of sound

v

in CO

2

versus frequency

f

of the sound wave at ...

Figure 9.22 Ratio

v

anisentropic

/

v

isentropic

of the velocity of sound for anisen...

Figure 9.23 (a) Operational principle. (b) Instrumentation of an ultrasonic gas...

Figure 9.24 (a) Time of flight TOF. (b) Velocity of sound at 22 °C versus CO

2

g...

Figure 9.25 Real‐time human respiration process analysis based on CO

2

output pa...

Chapter 10

Figure 10.1 Block diagram of the main components and the working principle of ...

Figure 10.2 Set‐up of a hydrogel‐based CO

2

sensor [3] .

Figure 10.3 Plot of a CO

2

measurement cycle with a hydrogel‐based Severinghaus‐...

Figure 10.4 Partial CO

2

pressure

p

CO

2

versus pressure

P

for the measured equili...

Figure 10.5 Schematic drawing of a needle-type CO

2

microelectrode.

Figure 10.6 Cross section of an ISFET with an Ag/AgCl, Cl

−

electrode plac...

Figure 10.7 Cross section of an ISFET with screen‐printed hydrogel and siloxane...

Figure 10.8 Thermal conductivity detector with Wheatstone bridge configuration....

Figure 10.9 Thermal conductivity detector module (Henze‐Hauck Prozessmesstechni...

Figure 10.10 Principle of a linear CO

2

sensor, based on the permeation of gases...

Figure 10.11 Basic set‐up for measuring pressure changes Δ

p

as a result of chan...

Chapter 12

Figure 12.1 Cumulative anthropogenic CO

2

emission () versus atmospheric CO

2

mi...

Figure 12.2 Historical CO

2

records derived from Law Dome ice core, Antarctica, ...

Figure 12.3 Keeling curve: monthly mean of the atmospheric CO

2

content (ppm) be...

Figure 12.4 Annual mean rate of growth of CO

2

at Mauna Loa [68] and relative...

Figure 12.5 Seasonal variation of CO

2

at Mauna Loa (for data source see Figure ...

Figure 12.6 Scheme of the multiphase CO

2

–carbonate system.

Figure 12.7 Solubility of CO

2

(ratio between volume of dissolved CO

2

and volume...

Figure 12.8 Relationship between atmospheric CO

2

mixing ratio and seawater pH a...

Figure 12.9 Trend of dissolved inorganic carbon (DIC) at Station ALOHA (see Tab...

Figure 12.10 Measuring principles for oceanic CO

2

sensors. (a) Membrane equilib...

Figure 12.11 SAMI‐CO

2

ocean CO

2

sensor (Sunburst Sensors, Missoula, MT, USA). (...

Figure 12.12 Schematic drawing of an electrochemical carbon dioxide sensor with...

Figure 12.13 Hydro Bottom Station for deep‐sea research [155] .

Figure 12.14 Temperature dependence of the CO

2

concentration in water at the to...

Figure 12.15 Comparison of calculated and measured CO

2

concentrations during th...

Figure 12.16 Comparison of calculated and measured CO

2

concentrations during sp...

Figure 12.17 CO

2

probe with unscrewed protective cap (KSI Meinsberg) for measur...

Figure 12.18 Temporal course of the CO

2

concentration in a mineral water spring...

Chapter 13

Figure 13.1 CO

2

concentrations in a laboratory and in the outdoor air measured ...

Figure 13.2 Portable CO

2

warning device with electrochemical CO

2

sensor.

Figure 13.3 Stationary CO

2

warning device with electrochemical CO

2

sensor for a...

Figure 13.4 Single CO

2

gas detector Pac 7000. Source: © Drägerwerk AG & Co. KGa...

Figure 13.5 Gasmessgerät Polytector III G999 (GfG Gesellschaft für Gerätebau, D...

Figure 13.6 Determination of the NDIR sensor drift according to [47] .

Figure 13.7 CO

2

concentrations (a) in laboratory air and (b) in atmosphere of u...

Chapter 14

Figure 14.1 Results of measurement (performed at KSI Meinsberg Kurt Schwabe Re...

Figure 14.2 Two litres stirred bioreactor (VSF 2000, Bioengineering AG, CH) wit...

Figure 14.3 Comparison of simulated and measured dissolved CO

2

concentrations i...

Figure 14.4 Schematic construction of the biogas laboratory plant: (1) two glas...

Figure 14.5 Course of the development of the gases H

2

, CO

2

, and CH

4

during the ...

Figure 14.6 Courses of CO

2

and CH

4

concentrations during feeding events of cows...

Figure 14.7 Multi‐gas monitor SSM 6000 from Pronova Analysentechnik GmbH & Co. ...

Chapter 15

Figure 15.1 Photograph of the aquarium with sections of different CO

2

concentr...

Figure 15.2 Electrochemical carbon dioxide sensor and handheld CO

2

metre [5] ...

Figure 15.3 Variations in the respiratory quotient of the mussel between April ...

Figure 15.4 Schematic drawing of the measurement set‐up for mussels with insert...

Figure 15.5 Measuring chamber with Atlas moth pupa, length 4.5 cm.

Figure 15.6

In vivo

measured respiratory cycles of an Atlas moth pupa, (a) carb...

Figure 15.7 Measurement of carbon dioxide concentrations in two beehives.

Figure 15.8 Electrochemical carbon dioxide sensor (EMCO2, KSI Meinsberg) in a h...

Figure 15.9 CO

2

concentration in a beehive over a period of five days. SR, sunr...

Figure 15.10 Carbon dioxide measurement on plants using a miniaturized electroc...

Figure 15.11 Typical course of the CO

2

concentration on a room fern.

Chapter 16

Figure 16.1 Set‐up of a Severinghaus electrode showing the important chemical ...

Figure 16.2 Sensor set‐up for the transcutaneous measurement of

p

CO

2

and

p

O

2

. T...

Figure 16.3 Set-up of an extracorporeal sensor system measuring

p

CO

2

,

p

O

2

, pH, ...

Figure 16.4 Photograph of an

ex vivo

optical CO

2

sensor (Terumo CDI Blood Param...

Figure 16.5 Colorimetric sensor for CO

2

analysis in breath (Nellcor™ adult/pedi...

Figure 16.6 Schematic of a miniaturized CO

2

mainstream sensor based on infrared...

Figure 16.7 Capnograph with one compact module for respiratory monitoring of O

2

Figure 16.8 Phases of a capnogram.

Figure 16.9 Schematic representation of the mechanical model.

Figure 16.10 Experimental set‐up for investigation of CO

2

diffusion through mat...

Figure 16.11 Course of the CO

2

concentration in the opened measuring chamber wi...

Guide

Cover

Table of Contents

Begin Reading

Pages

iii

vi

xiii

xiv

xv

xvi

xvii

xviii

xix

1

3

4

5

6

7

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

45

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

114

117

117

118

119

120

121

122

123

124

125

126

127

128

129

130

132

133

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

273

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

320

321

322

323

324

325

326

327

328

329

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

E1

Carbon Dioxide Sensing

Fundamentals, Principles, and Applications

Edited by

Gerald Gerlach

Ulrich Guth

WolframOelßner

Copyright

Editors

Prof. Dr. Gerald Gerlach

Technische Universität Dresden

Faculty of Electrical and Computer

Engineering

Institute of Solid-State Electronics

01062 Dresden

Germany

Prof. Dr. Ulrich Guth

Technische Universität Dresden

Faculty of Chemistry and Food

Chemistry

01062 Dresden

Germany

Priv.-Doz. Dr. Wolfram Oelßner

Kurt-Schwabe-Institut für Mess- und

Sensortechnik e.V. Meinsberg

Kurt-Schwabe-Straße 4

04736 Waldheim

Germany

Cover

Background image: Creativ Collection

All books published by Wiley‐VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.

Library of Congress Card No.:

applied for

British Library Cataloguing‐in‐Publication Data

A catalogue record for this book is available from the British Library.

Bibliographic information published by the Deutsche Nationalbibliothek

The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d‐nb.de>.

© 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Boschstr. 12, 69469 Weinheim, Germany

All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.

Print ISBN: 978‐3‐527‐41182‐5

ePDF ISBN: 978‐3‐527‐68829‐6

ePub ISBN: 978‐3‐527‐68827‐2

oBook ISBN: 978‐3‐527‐68830‐2

Cover Design SCHULZ Grafik‐Design, Fußgönheim, Germany

Scientific Biographies of the Authors

Manfred Decker studied organic and analytical chemistry at the University of Münster, Germany. He gained industrial experience in the field of medical and environmental sensors before he started his employment at Kurt‐Schwabe‐Institut in 2007. His research topics cover amperometric, coulometric, and potentiometric sensors and their applications in environmental, biotechnological, and medical needs. This involved R&D of Clark‐type biosensors for the determination of glucose and lactate in blood and of probes for the H2O2 analysis in exhaled breath. Further research covered the development of pH measuring devices for agricultural needs and the application of Severinghaus‐type CO2 sensors for bioprocess control and medical purposes.

Gerald Gerlach is a professor and the head of the Solid‐State Electronics Laboratory at the Technische Universität Dresden (TUD), Germany. After obtaining his MSc and PhD degrees in electrical engineering from TUD in 1983 and 1987, respectively, he spent almost ten years in sensor industry before taking up his present appointment at TUD. Professor Gerlach has authored over 400 scientific publications and was granted more than 50 patents. He is author or co‐author of nine monographs and textbooks. From 2007 to 2010, Prof. Gerlach was President of the German Society for Measurement and Automatic Control (GMA). From 2007 to 2008, he served as Vice President and President of EUREL (The Convention of National Associations of Electrical Engineers of Europe), respectively. He is Associate Editor‐in‐Chief for the IEEE Sensors Journal and Founding Chief Editor for the Journal of Sensors and Sensor Systems (JSSS).

Ulrich Guth received his PhD in Physical Chemistry from the University of Greifswald, Germany, in 1975. From 1989 to 1993, he worked in the industry and at Battelle Institute, Frankfurt am Main. In 1993, he became a professor of solid-state chemistry at the University of Greifswald. From 1999 until his retirement in 2010 he was Director of the Kurt-Schwabe-Institut für Mess- und Sensortechnik e.V. Meinsberg and Professor for Physical Chemistry, especially Sensor and Measuring Technology at Technische Universität Dresden. He is now Professor emeritus. His principal research interests include solid electrolyte sensors, fuel cells, and new materials for high temperature sensors and high temperature fuel cells. He authored more than 230 scientific publications including 5 book contributions and more than 40 patents.

Frank Kühnemann received his MSc (Diplom‐Physiker) and PhD degrees in physics from Humboldt University in Berlin in 1987 and 1991, respectively, and his habilitation in experimental physics from Bonn University in 2000.

After several research and teaching positions at universities in Germany and Egypt, he has been working at the Fraunhofer Institute for Physical Measurement Technologies IPM (since 2011) and teaches at the Institute of Physics, Freiburg University (since 2017).

His research activities include high‐sensitivity laser spectroscopic methods for both trace gas analysis and residual absorption in optical materials and nonlinear optical frequency conversion for tunable light sources and infrared detection. He is (co‐) author of more than 30 papers and co‐owner of five patents in these areas.

Armin Lambrecht has received his PhD in Physics from the University of Karlsruhe in 1985. Since 1986 he has been working at the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg, Germany. Starting with R&D projects on molecular beam epitaxy for mid-infrared lasers and thermoelectric devices, he later focussed on infrared sensors systems for gas and liquid analysis. His main research interests are directed towards laser spectroscopy applications for process analytics. He has 15 years of experience as department head at Fraunhofer IPM and has acquired and managed several industrial and public funded R&D projects. He is author of more than 100 publications and several patents. He is a member of DPG, VDI, and GDCh focussing on process analytics (www.arbeitskreis‐prozessanalytik.de).

Detlev Möller was born in 1947 in Berlin. He studied chemistry at Humboldt University in Berlin (HUB) from 1965 to 1970. He gained his PhD from HUB on electrochemical kinetics in 1972. Since 1974 he has been working on air chemistry in different institutes of the former Academy of Sciences of GDR (until 1991); his habilitation on the atmospheric chemistry he obtained in 1982. In 1992 he became the head of a branch of the Fraunhofer Society in Berlin in atmospheric environmental research. In 1994 he became a full professor for atmospheric chemistry and air pollution control at Brandenburg University of Technology Cottbus-Senftenberg. In 2012 he retired but still works as guest professor. He is/was member of many editorial boards, national and international committees, and three academies of sciences; he authored more than 200 scientific publications including 25 book contributions and 3 monographs. His principal research interest were all aspects of chemical climatology such as rain and cloud chemistry, ozone formation, and sulphur and nitrogen cycling by means of modelling, monitoring, and field experiments.

Wolfram Oelßner studied nuclear physics at the Technische Universität Dresden from 1956 to 1962, where he received his PhD in Electrochemical Measuring Technology in 1968. Since 1963 he has been working at the Meinsberg Kurt‐Schwabe Research Institute, currently still as a scientific consultant. Furthermore, he is appointed at the Technische Universität Dresden as a private lecturer for electrochemical measuring technique as well as for environmental measuring technology and corrosion research. His diverse research and development activities have been focussed on pH measurement, encapsulation and application of ISFET pH sensors, corrosion measurement technique, and electrochemical carbon dioxide sensors and measuring devices.

Gerald Urban was born in Vienna, Austria, and studied physics at the Technical University (TU) Vienna. Afterwards he was employed at the neurosurgical department of University Hospital Vienna. In 1985 he received his PhD in electrical engineering at the TU Vienna. He was co‐founder of the venture company OSC in Cleveland. In 1994 he received the Venia Legendi for Sensor Technology and in 1995 he became scientific director of the Ludwig Boltzmann Institute for Biomedical Microengineering in Vienna, Austria. In 1997 he became a full professor of sensors at the faculty of engineering at the University of Freiburg/Germany. He was dean of the faculty and speaker of the academic senate from 2009 to 2011. From the year 2002 till now he is member of the directorate of the Freiburg Material Research Center. He is co-founder of the company Jobst Technologies which was sold to the Endress group in the year 2015.

His research interests are the development of miniaturized and integrated sensor systems and complete miniaturized analysis systems for biomedical applications. Additionally, he is interested in the development of microbiosensor arrays for measuring RNA and protein markers by highly sensitive microcapillary immunoassays in body fluids.

He published more than 100 journal papers and received four awards; he currently holds 70 patents, and is a series editor of the Springer series on chemical sensors and biosensors and is corresponding member of the Austrian Academy of Sciences.

Jens Zosel received his diploma in physics from the University of Greifswald in 1990 and his PhD from the Freiberg University of Mining and Technology in 1997. Since 1992 he has been working at the Meinsberg Kurt‐Schwabe Research Institute. His basic research interests are directed towards the behaviour of electrochemical sensors in liquid and gaseous flows and the development of electrochemical sensors, based on solid and liquid electrolytes for different applications. Especially the development of materials, designs and measuring methods for solid electrolyte devices like gas sensors, fuel cells, and electrolyzers as well as the exploitation of new applications for those are the focus of his research activities.

Scientific Biographies of the Co-Authors to Chapter 16

Josef Guttmann studied Applied Precision Engineering at the FH Furtwangen in 1971–1975 and Biology/Biophysics at the Universität Freiburg in 1975–1981 where he received in 1986 his PhD on Biophysics. In 1994 he habilitated in Biomedical Engineering at the University of Basel. In 2001 he was appointed as an APL Professor of Biomedical Engineering at the University of Freiburg. In 1994–2014 he was the head of the working group “Clinical Respiratory Physiology” at the Department of Anesthesiology and Critical Care, Medical Centre – University of Freiburg, with the following main research areas: biomechanics of the lung, control of ventilators, and respiratory monitoring; in 2008–2012 he was Director of the course “MasterOnline Technical Medicine (TM)”.

Prof. Josef Guttmann contributed to Section 16.6.

Jochen Kieninger received his diploma in microsystems engineering from the University of Freiburg in 2003. Afterwards, he worked in the Laboratory for Sensors at the Department of Microsystems Engineering (IMTEK) and in the School of Soft Matter Research at the Freiburg Institute for Advanced Studies (FRIAS). In 2011, he completed his PhD on “Electrochemical microsensor system for cell culture monitoring”. In 2012, he was nominated as a lecturer and has since been working as a senior scientist in the Laboratory for Sensors. His research interests are electrochemical sensors, biosensors, microsensors for neurotechnology, cell culture monitoring, electrochemical methods, and microfabrication.

Dr.‐Ing. Jochen Kieninger contributed to Sections 16.1–16.4.

Andreas Weltin received his diploma and doctoral degrees in microsystems engineering from the University of Freiburg. Since 2015, he has been a group leader at the Laboratory for Sensors. In 2016, he received the 2nd Klee prize from DGBMT for his dissertation on microfabricated, electrochemical in vivo sensors. Among his research interests are (bio‐)analytical microsystems, bio‐ and chemo‐sensors, electrochemistry, microfluidics, and biomedical applications. Current activities include the development of novel electrochemical sensor principles and platforms, organs‐on‐chip in cancer research, and sensors at neural interfaces.

Dr.‐Ing Andreas Weltin contributed to Sections 16.2–16.4.

Jürgen Wöllenstein received his degree in electrical engineering from the University of Kassel in 1994. In 1994 he joined the chemical sensors group at the Fraunhofer Institute for Physical Measurement Techniques in Freiburg. He is head of a department at Fraunhofer‐IPM. In 2009, he became a full professor at the Department of Microsystems Engineering of the University of Freiburg. He is author and co‐author of more than 50 publications and holds several patents.

Prof. Jürgen Wöllenstein contributed to Section 16.5.

Preface

Carbon dioxide (CO2) is one of the key components of life. Without any doubt, it is the most important chemical substance in the global climate system. For instance, it is considered as one of the crucial sources of the dangerous greenhouse effect and the corresponding global warming. On the other side, it governs photosynthesis and, hence, is – beside oxygen and carbon – the basis for the existence of life on Earth.

Sensing and monitoring of carbon dioxide is fundamental to get knowledge on CO2‐affected mechanisms and to control them. Observation of CO2 in the atmosphere and in the oceans yields important data for long‐term predictions of the world's climate. Monitoring of CO2 in industrial processes is a decisive tool to control their efficiency. Carbon dioxide in higher concentration can be lethal for human beings, so warning detectors for dangerous CO2 concentrations are needed. This short listing gives proof for the general importance to sense CO2 both in gases and in liquids over a wide range of concentrations from the ppm level up to the pure carbon dioxide.

The manifold application fields as well as the huge range of CO2 concentration to be measured make CO2 sensing a challenging task. This was the reason that a part of the author team of this book decided in 2011 to write a review paper The measurement of dissolved and gaseous carbon dioxide concentration[1]. The intention was to give an overview of the state of the art and the new developments to measure CO2 and of the different fields where CO2 monitoring and detection is of interest and which methods are used there. Shortly after being published we were heavily surprised by the large download numbers of this paper. At this point we came to the conclusion that it might make a lot of sense to give researchers and scientists, confronted with the detection of CO2 in the most diverse application fields, a guide to support them in their decision which method should be used for which application‐related demands and requirements. We are convinced that this goal could only be achieved by a much broader approach, i.e. by a monography instead of a review article.

The present book is the result of our efforts with respect to these objectives. It is organized in three parts. After a general consideration in Part I on the properties of CO2 and the CO2 cycle, Part II gives an overview of the different chemical and physical measuring methods and sensors for the determination of carbon dioxide in liquids and gases (Chapters 3–11). Afterwards, Part III describes the most important application fields of CO2 sensing – from environmental monitoring and safety control via biotechnology and industrial processes to the measurement in biology and medicine (Chapters 12–16). In view of the great diversity of CO2 measurement tasks, it is not intended and not possible at all to present a solution for each individual measurement problem. Rather, it is about showing by means of a great number of typical and also somewhat exceptional examples where everywhere and how CO2 is measured.

However, the heart of the book is Chapter 11 ‘Survey and Comparison of Methods’. It gives a concise overview of the characteristics of all these CO2 measurement methods including their advantages and disadvantages and provides a decision support for choosing the most suitable analysis method for a certain measurement task.

The editors of this book hope that the contents depict both the state of the art and the most recent progress in sensing and monitoring CO2 in the many fields of application. We are convinced that this book can fill the gap between scientific research in measurement technology and its application in practice. Let the book be an inspiration to all the colleagues involved in this area!

Most of the authors of this book are scientists from the Meinsberg Kurt‐Schwabe‐Institut and the Technische Universität Dresden having been involved in the ‘sensor business’ for many years. However, to achieve our goal, we had to form a team far beyond these two institutions to become capable to deal with all aspects of such a complex matter. We found this expertise in our colleagues from the Universities of Freiburg and of Cottbus‐Senftenberg as well as of the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg. We are deeply indebted to them and would like to thank them for contributing their comprehensive knowledge and particular competence to this book. We would also like to thank those companies and institutions that allowed us to use figures and material and which are named in the captures of the individual figures. Furthermore, we would very much like to thank VCH‐Wiley and in particular Mrs. Nina Stadthaus and Mrs. Abisheka Santhoshini for the cordial cooperation, but also for the patience when faced with repetitive delays due to the authors' workload. We are deeply grateful to the VCH‐Wiley staff for their support during the entire process from the first idea all the way through to the final book.

Dresden, July 2018

Gerald Gerlach

Ulrich Guth

Wolfram Oelßner

Reference

1 Zosel, J., Oelßner, W., Decker, M. et al. (2011). The measurement of dissolved and gaseous carbon dioxide concentration.

Meas. Sci. Technol.

22: 072001.

https://doi.org/10.1088/0957‐0233/22/7/072001

.

Part IGeneral

1Introduction

Wolfram Oelßner

Kurt‐Schwabe‐Institut für Mess‐ und Sensortechnik e.V. Meinsberg, Kurt‐Schwabe‐Straße 4, 04736 Waldheim, Germany

Carbon dioxide (CO2) is one of the key components in our life and without any doubt the most important chemical substance in the global climate system. It presents the feedstock for plant assimilation and for the growth of plants and phyto cells in the biological carbon cycle as well as buffer system in the blood of humans and animals, and hence, it is important for total life on Earth. On the other hand, CO2 is the “waste” produced by the metabolism of most of the living creatures on our Earth and by combustion of fossil fuels using carbon stocks or biomass, and it is widely understood to be one of the crucial sources of the dangerous greenhouse effect. Observation of CO2 in the atmosphere and in the oceans yields important signals for long‐term predictions of the world's climate. Furthermore, in process technology, CO2 is an important reagent for the manufacture of a variety of products. Monitoring of CO2 in chemical as well as in biotechnological processes is a valuable tool to control the efficiency of the production processes. Since carbon dioxide in higher concentration can be lethal for human beings, CO2 warning devices are needed. This short listing indicates the general importance of CO2 and the need to determine it in gases as well as in liquids over a wide range of concentrations from ppm level up to 100% [1].

In publications and regulations the CO2 concentration is indicated in different units. The general formula for converting the units vol ppm to mg m−3 and vice versa is:

1.1

with M being the molar mass in g mol−1 (e.g. for CO2M = 44 g mol−1) and Vm being the molar volume in l mol−1 (e.g. for ideal gases at 25 °C Vm = 24.5 l mol−1).

Table 1.1 is intended to simplify the conversion.

Table 1.1 Conversion factors for CO2 concentrations.

To

To convert from the units on the left to the units on top, multiply by

vol%

vol ppm

mg m

−3

From

vol%

1

10

4

1.8 × 10

4

vol ppm

10

−4

1

1.8

mg m

−3

5.56 × 10

−5

0.56

1

In medicine, the carbon dioxide partial pressure pCO2 is usually indicated in the unit mm Hg instead of in the SI unit Pa. The conversion is done according to Table 1.2.

Table 1.2 Conversion factors for CO2 partial pressures.

To

To convert from the units on the left to the units on top, multiply by

mm Hg

Pa

bar

From

mm Hg

1

133.32

1.33 × 10

−3

Pa

7.50 × 10

−3

1

10

−5

bar

750.06

10

5

1

This means that typical CO2 partial pressures in the range pCO2 =35–45 mm Hg correspond to 4.6–6.0 kPa.

Depending on the medium in which CO2 needs to be measured and the requirements for measuring range, accuracy, long‐term stability, selectivity, and maintenance, different methods can be applied [1] :

Standard test methods for the analytical determination of total and dissolved carbon dioxide in water require the titration of test samples.

CO

2

sensors that are based on various chemical or physical measuring methods are more user‐friendly and therefore preferably applied:

Because of their simple set‐up and the resulting low costs, membrane‐covered electrochemical CO

2

sensors according to the Severinghaus principle have been manufactured and widely applied already for a long time. Unlike other types of CO

2

sensors, Severinghaus sensors can be applied not only in gases but also for direct measurements in liquid media.

In comparison with these sensors with aqueous electrolytes, solid electrolyte CO

2

sensors operating at high temperatures have the advantages of a short response time and maintenance‐free operation without calibration. They are used successfully in all cases of long‐term measurements in air, in breath gas analysis, and in the process monitoring especially at higher temperatures.

As an economic alternative to the electrochemical CO

2

sensors, detector tubes have been used in a broad range of applications, in particular for control of the concentration at the workplace.

Nowadays IR, NDIR, opto‐chemical, and acoustic CO

2

sensors, which use physical measuring methods, are being used increasingly.

In several fields of application, a variety of other CO

2

sensor principles, based on conductometric, thermal conductivity, hydrogel expansion, and mass spectrometric measurements, have been tested and partly commercially applied.

Compared to spectrometric (FTIR, UV‐VIS), mass spectrometric (MS) and chromatographic techniques (GC, HPLC), electrochemical sensors (Severinghaus and solid electrolyte sensors) are simple in their set‐up as well as in the electronic equipment necessary for operation and for data acquisition. The effort for maintenance and calibration is low. Since sensor signals are obtained directly (in situ), real‐time information for process control is delivered. Therefore, they are preferred tools for screenings in field application. On the other hand, electrochemical sensors cannot completely replace the standard methods in laboratories in terms of precision, detection limit, etc.

The current development activities in CO2 sensor technology and application are focused on [1] :

Miniaturization of electrochemical sensors based on the Severinghaus principle, e.g. for measurement in liquid biological systems, cell cultures, cell tissues, and living organisms;

Development of sterilizable and even CIP (

c

leaning

i

n

p

rocess)‐resistant sensors for measurement of dissolved CO

2

in biotechnological processes and foodstuff production;

Extension of the measuring ranges to higher or lower concentrations, as required;

Extension of the sensor service lifetime and the calibration intervals;

Application of thin‐film and thick‐film manufacturing technologies for the mass production of low‐cost sensors;

Development of solid electrolyte CO

2

sensors with short response time for

in situ

breath analysis;

Miniaturization and improvement of selectivity and sensitivity of IR sensors; and

Utilization of ultrasonic sensors for breath gas analysis in medical and sportive applications.

Depending on the special field of application and the goals of the investigation, the measuring conditions and technical requirements on the sensors can be very different. Each application has its own scientific background without which the results of measurement cannot be interpreted. A detailed knowledge of the basic detection principles and the frames for their applications is necessary to find an appropriate decision on the technology to be applied for measuring dissolved CO2. Especially the pH value and the composition of the analyte matrix may exert important influence on the results of the measurements, and sampling of liquids in which CO2 is dissolved is often a source of errors. Sensors for safety control should be mechanically robust and long‐term stable and have low maintenance, whereas for measurements in boreholes or in the deep sea, challenging demands on pressure resistance and compensation of rapid temperature changes have to be fulfilled. In biology and medicine often small dimensions and short response times are required. In biotechnology precise, real‐time data on CO2 concentration fosters the understanding of critical fermentation and cell culture processes and can help in gaining insight into cell metabolism, cell culture productivity, and other processes within bioreactors. But in this case the sensor must be sterilizable. When being applied online in food industry, it is required that the sensor is non‐breakable and even survives the rigorous CIP cleaning procedures [1] .

After a general consideration on the CO2 cycle, the book gives an overview of the different chemical and physical measuring methods and sensors for the determination of CO2 in liquids and gases and their manifold applications in environmental control, biotechnology, biology, food industry, and medicine to a certain extent without claiming to cover completely the whole phenomenon. The wide variety of applications is illustrated by some typical and also somewhat original examples ranging from measurements in the higher atmosphere to the depth of the ocean. The advantages and drawbacks of the different sensor principles will be outlined with the main focus directed on electrochemical sensors, which means on devices that can be applied directly (in situ) without sampling. There is no CO2 sensor available to date that meets these partly contrary requirements all at the same time. For this reason, the book should not only be a source of information about CO2 measurement, but it is also intended to be an invitation to the reader to accept the challenge to continue developing and improving CO2 sensors and to be a motivation to open up new areas for their application.

Reference

1 Zosel, J., Oelßner, W., Decker, M. et al. (2011). The measurement of dissolved and gaseous carbon dioxide concentration.

Meas. Sci. Technol

. 22: 072001.

https://doi.org/10.1088/0957‐0233/22/7/072001

.

2Carbon Dioxide in General

Detlev Möller1Manfred Decker2Jens Zosel2 and Wolfram Oelßner2

1Brandenburgische Technische Universität Cottbus und Senftenberg, Fakultät für Umwelt, Verfahrenstechnik, Biotechnologie und Chemie, Institut für Umweltwissenschaften, Platz der Deutschen Einheit 1, 03046 Cottbus, Germany

2Kurt‐Schwabe‐Institut für Mess‐ und Sensortechnik e.V. Meinsberg, Kurt‐Schwabe‐Straße 4, 04736 Waldheim, Germany

2.1 Chemical and Physical Properties of Carbon Dioxide

2.1.1 Chemical Properties of Carbon Dioxide

2.1.1.1 Chemical Properties

Carbon dioxide (CO2) is a linear molecule with the oxygen atoms placed opposite to the carbon centre. The carbon atom itself is sp‐hybridized with each of the sp orbitals forming a σ‐bond to an oxygen atom. The py orbital of the carbon is establishing a π‐bond with the available p orbital of one O atom, whereas the pz orbital completes the second double bond with the other oxygen partner. This results in the high stability of the gaseous CO2 molecule with a standard formation enthalpy ΔHr° of −393.522 kJ mol−1 at 298.15 K [1]. This high value causes remarkable dissociation reactions of pure carbon dioxide to C, CO, and O2 only at temperatures far above 1000 K [2,3].

The two π‐bonds of CO2 show a length of 116.2 pm [4]. The two p orbitals connecting the oxygen atoms are oriented perpendicular to each other. Although each CO bond is polarized caused by the differences of electronegativity of carbon and oxygen, the linear symmetry of the CO2 molecule results in a net dipole moment of zero. However, the polarization of the carbon–oxygen bond is essential for the explanation of the CO2 reactivity. The pull of π‐electrons to the oxygen atoms causes an electron deficiency at the carbon atom and enables the attack of nucleophiles and electron donors to the carbon centre of the molecule. This step is essential for the formation of carbonic acid and hydrogen carbonate in water [5]. This nucleophilic addition changes the sp hybridization of the C atom to a sp2 state. Otherwise the partial negative polarization of the oxygen can be targeted for the coordination of electron deficient metals. An intensive overview of the reaction paths for catalysed chemical transformations of CO2 is comprehended in detailed publications [6–8]. The use of carbon dioxide in industrial syntheses is mainly concentrated on applications where CO2 is produced as waste product or by‐product of other chemical transformations, mainly by combustion processes for energy generation.

2.1.1.2 Industrial Use of Carbon Dioxide

The industrial consumption of carbon dioxide can roughly be estimated as up to 100 Mt a−1. Table 2.1 presents the dominating products as has been listed in the IPCC Special Report on Carbon Dioxide Capture and Storage (2005) [9].

Table 2.1 Industrial use of carbon dioxide ( [9] ; the author points out the large uncertainty of the data).

Product class or utilization

Yearly demand (Mt yr

−1

)

Applied carbon dioxide (Mt yr

−1

)

Urea

90

65

Methanol (addition to CO)

24

<8

Inorganic carbonates

8

3

Organic carbonates

2.6

0.2

Polyurethanes

10

<10

Technological uses

10

10

Food applications

8

8