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Solubility of CO2 in distilled water (in ppm) as a function of temperature and the vol.% C02 in the gas bubbled through at 1 bar pressure 

Solubility of CO2 in distilled water (in ppm) as a function of temperature and the vol.% C02 in the gas bubbled through at 1 bar pressure 

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Article
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Fiber-optic sensors were developed for monitoring dissolved carbon dioxide in water samples in the 0 to 900 ppm concentration range. A pH-sensitive fluorescent dye (HPTS) was reacted with a cationic quaternary ammonium salt to form an ion pair which was electrostatically bound to the surface of particles of aminocellulose which then were dispersed...

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Context 1
... values for higher 1202 concentrations can be extrapolated from the air-saturated system. Table 2 gives the solubility data for carbon dioxide in water (in ppm) depending on the temperature and the vol.% of the carbon dioxide bubbled through the solution. ...
Context 2
... change a -60 -56. 5 -47 -49 -86 -87 -85 Forward response time b 7 3 4 4.5 2 2 2.5 Reverse response time b'c 12 7 8 8 6.5 5.5 8 Detection limit d 1 0.5 2 2 0.05 0.05 0.05 Dynamic range a 1-50 1-80 2-100 2-100 0.05-50 0.05-50 0.05-50 ...
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... a result, more of the strongly fluorescent phenolate form of The difference between the signals measured at different temperatures is smaller at higher CO2 levels, the calibration curves from an average curve when plotting the counts vs. ppm. This can be explained by the highly temperature-dependent solu- bility of CO2 (Table 2), the saturation concentration at 5 ~ being about two times higher than at 25 ~ This experiment showed that the stability and reproducibility of the signal at a given CO2 concen- tration is acceptably good with the M-4 membrane which was in operation for more than 40h during measurement of temperature effects. No change in the response characteristics was observed after this test period and upon returning to 25 ~ ...

Citations

... Carbon dioxide (CO 2 ) monitoring sees application in a broad range of fields, including waste water treatment (Park and Craggs, 2010), environmental monitoring (Wolfbeis et al., 1998), food science (Neethirajan et al., 2009), and biopharmaceutical production (Ge et al., 2005). In biomanufacturing, cell culture is a cornerstone upstream method for the generation of a wide variety of therapeutic products (Bielser et al., 2018;Bort et al., 2012). ...
... More recently developed CO 2 sensors rely upon optical detection due to their more straightforward design and use (Wolfbeis et al., 1998;Ge et al., 2005;Mills and Chang, 1994a;Malins and Maccraith, 1998;Chu and Lo, 2008;Dansby-Sparks et al., 2010;Chatterjee and Ayusman, 2015). To couple CO 2 monitoring with optical detection, a sensing material with spectral behavior in the visible range that changes in the presence of CO 2 must be chosen. ...
... Thus, HPTS must be in an aqueous environment to detect the acidification of water from dissolved CO 2 . To date, most sensors prepared with HPTS involve complicated ion-pairing loading techniques (Wolfbeis et al., 1998;Mills and Chang, 1993), or sol-gel fabrication (Malins and Maccraith, 1998;Dansbysparks et al., 2010) to immobilize HPTS in an aqueous environment within a hydrophobic matrix. Such sensors are thus difficult to fabricate, requiring complex chemistry steps, limiting their use to research labs where intricate fabrication processes are tolerable. ...
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Monitoring and measurement of carbon dioxide (CO 2 ) is critical for many fields. The gold standard CO 2 sensor, the Severinghaus electrode, has remained unchanged for decades. In recent years, many other CO 2 sensor formats, such as detection based upon pH-sensitive dyes, have been demonstrated, opening the door for relatively simple optical detection schemes. However, a majority of these optochemical sensors require complex sensor preparation steps and are difficult to control and repeatably execute. Here, we report a facile CO 2 sensor generation method that suffers from none of the typical fabrication issues. The method described here utilizes polydimethylsiloxane (PDMS) as the flexible sensor matrix and 1-hydroxypyrene-3,6,8-trisulfonate (HPTS), a pH-sensitive dye, as the sensing material. HPTS, a base (NaOH), and glycerol are loaded as dense droplets into a thin PDMS layer which is subsequently cured around the droplet. The fabrication process does not require prior knowledge in chemistry or device fabrication and can be completed as quickly as PDMS cures (∼2 h). We demonstrate the application of this thin-patch sensor for in-line CO 2 quantification in cell culture media. To this end, we optimized the sensing composition and quantified CO 2 in the range of 0–20 kPa. A standard curve was generated with high fidelity ( R ² = 0.998) along with an analytical resolution of 0.5 kPa (3.7 mm Hg). Additionally, the sensor is fully autoclavable for applications requiring sterility and has a long working lifetime. This flexible, simple-to-manufacture sensor has a myriad of potential applications and represents a new, straightforward means for optical carbon dioxide measurement.
... Optical transcutaneous CO 2 sensors based on luminescent materials may offer several advantages, such as accurate detection of CO 2 levels, as well as great potential for miniaturization [15]. Such sensors have traditionally employed a pH indicator that exhibits different fluorescent intensities upon exposure to different CO 2 concentrations [16][17][18]. The pH-sensitive fluorescent dye 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) is one of the most widely used in optical CO 2 sensors [19,20]. ...
... For skin-worn devices, it can be important to create sensors whose response will not be altered by changes in humidity [21,22], which can vary widely depending on climate or body location [23]. In order to make HPTS molecules compatible with hydrophobic matrices, a lipophilic hydrated ion pair is usually formed by converting the dye into its anion form with a quaternary ammonium cation [16,17,19]. In addition, a phase transfer reagent (quaternary ammonium hydroxide) co-embedded along with the dye within a support matrix is necessary to facilitate the tuning of the materials' sensitivity and enhanced stability. ...
... The most common principle for optical CO 2 sensors is based on fluorescence changes of pH indicators upon their protonation or deprotonation at different pH values [17,18]. In HPTS, it has been widely reported that the pH sensitivity of HPTS arises from the OH group [19]. ...
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Continuously monitoring transcutaneous CO2 partial pressure is of crucial importance in the diagnosis and treatment of respiratory and cardiac diseases. Despite significant progress in the development of CO2 sensors, their implementation as portable or wearable devices for real-time monitoring remains under-explored. Here, we report on the creation of a wearable prototype device for transcutaneous CO2 monitoring based on quantifying the fluorescence of a highly breathable CO2-sensing film. The developed materials are based on a fluorescent pH indicator (8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt or HPTS) embedded into hydrophobic polymer matrices. The film’s fluorescence is highly sensitive to changes in CO2 partial pressure in the physiological range, as well as photostable and insensitive to humidity. The device and medical-grade films are based on our prior work on transcutaneous oxygen-sensing technology, which has been extensively validated clinically.
... values. 62 CO 2 gas was subsequently bubbled with a constant rate (2 mL s −1 , CO 2 solubility is about 350 ppm in 1 L of water in standard conditions 63,64 ) for a distinct period, the pH of the medium was measured, and the fluorescence spectra were collected by fluorescence spectroscopy, and the resulting calibration curve is shown in Figure S9. The medium was changed to acidic by CO 2 bubbling, and the tertiary amine groups of PDMAEMA were switched from neutral to cationic states. ...
... The most basic sensors use a single wavelength for illumination-in case of absorbance measurements-or a pair of excitation-emission wavelengths-in case of luminescence measurement. Photobleaching may be compensated for, using more wavelengths and ratiometric methods similar to that driving pulse oximetry [90][91][92][93][94][95][96][97], while variations in the emitted light intensities or sensitivities toward received light can be addressed by using referencing-i.e., taking a measurement in pure di-nitrogen (N 2 ) and/or pure CO 2 prior to CO 2 measurement for sensor calibration purposes [98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114]. ...
... 2. Polymer: hydroxy propyl methylcellulose (HPMC) may be a better choice than ethyl cellulose for being more hydrophilic than the latter, allowing water molecules to be entrapped with the dye and favoring the hydration of CO 2 into bicarbonate ions [121]. 3. Plasticiser: several plasticizers were compared in the literature, tributyl phosphate (TPB) and Tween 20 appear to be the most efficient ones in terms of sensor response time [105,121]. 4. Phase transfer agent: cetyltrimethyl ammonium hydroxide (CTAH) tends to lead to shorter response times [125] although tetramethyl ammonium hydroxide (TMAH) may be more stable since it is less susceptible to Hofmann elimination [121]. 5. Covering membrane: Hyflon or even Cytop if a minimal response time is not mandatory may be used to limit the sensor poisoning and humidity loss [128]. ...
Article
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Carbon dioxide (CO2) monitoring in human subjects is of crucial importance in medical practice. Transcutaneous monitors based on the Stow-Severinghaus electrode make a good alternative to the painful and risky arterial “blood gases” sampling. Yet, such monitors are not only expensive, but also bulky and continuously drifting, requiring frequent recalibrations by trained medical staff. Aiming at finding alternatives, the full panel of CO2 measurement techniques is thoroughly reviewed. The physicochemical working principle of each sensing technique is given, as well as some typical merit criteria, advantages, and drawbacks. An overview of the main CO2 monitoring methods and sites routinely used in clinical practice is also provided, revealing their constraints and specificities. The reviewed CO2 sensing techniques are then evaluated in view of the latter clinical constraints and transcutaneous sensing coupled to a dye-based fluorescence CO2 sensing seems to offer the best potential for the development of a future non-invasive clinical CO2 monitor.
... HPTS has distinct emission and absorption bands in the visible light area (6). Fluorescent HPTS dye, which is pH sensitive, has previously been used in many carbon dioxide sensor studies (11)(12)(13)(14)(15). pHsensitive and fluorescence-based HPTS dye embedded in an organically modified silica (ORMOSIL) glass matrix were utilized for CO2 gas monitoring (16). ...
Article
Semiconductor metal oxide materials have gained huge attention in gas sensors owing to their high sensitivity to many target gases. Herein, ZnO/CuO core-shell and ZnO/CuO hybrid, which were synthesized by different sol-gel methods and formed in two different crystal structures, were used as an additive material to enhance the response range of 8-hydroxypyrene-1, 3, 6-trisulfonic acid (HPTS) for the sensing of gaseous carbon dioxide. Metal oxide materials were characterized by using XPS, XRD, FTIR, SEM, UV–Vis, and PL spectroscopy. The HPTS dye along with the ZnO/CuO hybrid material displayed a higher CO2 gas sensitivity as 94% ratio (I0/I100=16.90) and Stern-Volmer constant (KSV) value and extended linear response range compared to the HPTS-based sensing thin films along with ZnO/CuO core-shell material and additive-free form. ZnO/CuO core-shell and hybrid structures were used for enhancing of carbon dioxide sensitivity of the HPTS dye.
... Values of pH obtained for the supporting electrolyte saturated by CO 2 and Ar amount to 7.4 � 0.1 and 8.9 � 0.1, respectively. The former value is in a perfect agreement with the theoretical prediction (7.50) obtained for 0.5 M KHCO 3 additionally containing 35 mM CO 2 (the solubility limit at 298 K and 1 atm, see [73] ) employing PeakMaster program. A more pronounced deviation is noticed for the Ar saturated electrolyte (theoretical prediction 8.34, obtained for 0.5 M KHCO 3 with no CO 2 added). ...
... For the total electrolyte concentration of 500 mM this fraction translates to 1.4 mM, which represents 4 % of CO 2 present in its saturated aqueous solution (35 mM at 298 K and 1 atm). [73] Taking the limiting HCOO À concentration of 1.0 mM found for CO 2 saturated electrolytes ( Figure 4B) one obtains that up to 0.040 mM of this product may be generated under the same conditions by reducing CO 2 formed by the hydrolysis. The above-mentioned experimentally obtained range of c HCOO À ð Þ values represents 45 to 63 % of this limit. ...
Article
Rising levels of atmospheric carbon dioxide (CO2) intensify global warming. Electrochemical reduction of CO2 allows its conversion into value‐added chemicals. This work presents the first application of 3D printing to manufacture catalysts for this process. Carbon nanotube‐based electrodes printed by fused deposition modeling were functionalized by copper electroplating. The combination of scanning electron microscopy and electrochemical characterization revealed that the electroplating leads to randomly positioned hemispherical copper microparticles with charge transfer characteristics approaching those of planar interfaces. The activity of catalysts was inspected in the saturated solution of CO2 in aqueous KHCO3 electrolyte by monitoring the concentration of formate HCOO‐ as one of reaction products. The Faradaic efficiency vs. electrode potential dependence found in this work is comparable to characteristics reported for conventionally prepared micro‐structured copper catalysts. Procedures devised and implemented in this work pave the way for the development of 3D printed electrocatalysts with controlled micro‐architecture, activity and product selectivity.
... With the development of global industrialization, a great amount of carbon dioxide (CO 2 ) has been discharged in the past decades, which is one of the most critical parts of the greenhouse effect to cause climate change. 1 At this moment, reliable and simple analysis methods for rapidly detecting and precisely quantifying CO 2 are vital to face this severe challenge. 2 Several methods have already been developed to detect CO 2 with a low detection limit, which are used in biotechnology, 3 healthcare or medical diagnosis, 4,5 food industry, 6−8 environmental monitoring, 9 and so on. Common techniques include the Severinghaus electrode, 10 nondispersive infrared spectroscopy, 11 electrochemical measurements, 12,13 and gas chromatography−mass spectrometry (GC−MS). ...
... Saturated aqueous solution of CO 2 was prepared by bubbling sublimated dry ice through water for at least one hour while continuously monitoring the gas pressure and the solution temperature. The concentration of CO 2 in its saturated solution (denoted as c 0, CO 2 ) was calculated employing Henry's law and solubilitytemperature profiles reported for CO 2 at standard pressure [63] . The pressure of 1.01 bar and temperature ranging from 294 to 297 K were applied. ...
Article
The combination of computer assisted design and 3D printing has recently enabled fast and inexpensive manufacture of customized ‘reactionware’ for broad range of electrochemical applications. In this work bi-material fused deposition modeling 3D printing is utilized to construct an integrated platform based on a polyamide electrochemical cell and electrodes manufactured from a polylactic acid-carbon nanotube conductive composite. The cell contains separated compartments for the reference and counter electrode and enables reactants to be introduced and inspected under oxygen-free conditions. The developed platform was employed in an electrochemical study investigating the electrochemical oxidation of aqueous hydrazine coupled to its bulk reaction with carbon dioxide. The analysis of cyclic voltammograms obtained in reaction mixtures with systematically varied composition confirmed that the reaction between hydrazine and carbon dioxide follows 1/1 stoichiometry and the corresponding equilibrium constant amounts to (2.8 ± 0.6) × 10³. Experimental characteristics were verified by results of numerical simulations based on the finite-element-method.
... CO 2 -absorbing MOFs have been studied for CO 2 monitoring and demonstrated quick and reversible responses [117,170,171]. Because dissolved CO 2 can reduce the solution pH, CO 2 sensors also employ pH indicators (colorimetric or fluorescent dyes) within various sensing layers such as silica gel coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H 2 S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO 2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. ...
... Table 2 lists some examples of OFS chemical sensing layers for corrosivity monitoring. coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H2S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. ...
... Table 2 lists some examples of OFS chemical sensing layers for corrosivity monitoring. Al [191] 0.05 mol/L NaOH uW increase in light transmission in 5 min coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H2S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. ...
Article
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Corrosion has been a great concern in the oil and natural gas industry costing billions of dollars annually in the U.S. The ability to monitor corrosion online before structural integrity is compromised can have a significant impact on preventing catastrophic events resulting from corrosion. This article critically reviews conventional corrosion sensors and emerging sensor technologies in terms of sensing principles, sensor designs, advantages, and limitations. Conventional corrosion sensors encompass corrosion coupons, electrical resistance probes, electrochemical sensors, ultrasonic testing sensors, magnetic flux leakage sensors, electromagnetic sensors, and in-line inspection tools. Emerging sensor technologies highlight optical fiber sensors (point, quasi-distributed, distributed) and passive wireless sensors such as passive radio-frequency identification sensors and surface acoustic wave sensors. Emerging sensors show great potential in continuous real-time in-situ monitoring of oil and natural gas infrastructure. Distributed chemical sensing is emphasized based on recent studies as a promising method to detect early corrosion onset and monitor corrosive environments for corrosion mitigation management. Additionally, challenges are discussed including durability and stability in extreme and harsh conditions such as high temperature high pressure in subsurface wellbores.
... Various fiber-optic sensor configurations have been exploited for monitoring CO 2 concentration, including long period grating [16], Bragg grating [17], evanescent filed [18], and fluorescent based [19,20]. Fiber fluorescence sensor has also been employed to demonstrate monitoring of environmental CO 2 [21]. Use of fluorescent dyes, nanoparticle coatings, or extensive etching of the fibers in the reported studies are likely to affect the aging behavior and robustness of the sensors. ...
... Various fiber-optic sensor configurations have been exploited for monitoring CO2 concentration, including long period grating [16], Bragg grating [17], evanescent filed [18], and fluorescent based [19,20]. Fiber fluorescence sensor has also been employed to demonstrate monitoring of environmental CO2 [21]. Use of fluorescent dyes, nanoparticle coatings, or extensive etching of the fibers in the reported studies are likely to affect the aging behavior and robustness of the sensors. ...
Article
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Monitoring of greenhouse gases is essential to understand the present state and predict the future behavior of greenhouse gas emissions. Carbon dioxide (CO2) is the greenhouse gas of most immediate concern, because of its high atmospheric concentration and long lifetime. A fiber-optic Mach–Zehnder interferometer (MZI) is proposed and demonstrated for the laboratory-scale monitoring of carbon dioxide concentration. The interferometric sensor was constructed using a small stub of hollow-core photonic crystal fiber between a lead-in and lead-out standard single mode fiber, with air-gaps at both interfaces. At room temperature and atmospheric pressure, the sensor shows the sensitivity of 4.3 pm/% CO2. The device was packaged to demonstrate the laboratory-scale leakage detection and measurement of CO2 concentration in both subsurface and aqueous environments. The experimental study of this work reveals the great potential of the fiber-optic approach for environmental monitoring of CO2.