Wet Chemical Colorimetric Estimation of CO: An Update on the Reduced Silver Sol Spectral and Kinetic Transformations to Silver nanoparticle

Abstract

Measurements of ppm (v/v) level CO g concentration is conveniently performed by its preconcentration in alkaline absorber solution of Ag + -(4)-HCO 2 -C 6 H 4 -SO 2 NH 2 complex, followed by a spectral measurement of the reduced silver sol. In this study, the transitory nature of this latter species and its subsequent real-time transformation to silver nanoparticle are presented. These results were based on spectral measurements made under varying concentrations of alkali, (4)-HCO 2 -C 6 H 4 -SO 2 NH 2 , and Ag + in the absorber solution, and in the presence of a wide range of sampled CO g concentration. The initially created light yellow colored sol with its broad absorption profile peaking at 380 nm and absorption coefficient 3500± 300 cm −1 M −1 (related to the amount of sampled [CO g ] as standardized by gas chromatographic analysis) changed into the characteristic yellow orange nanoparticle with its plasmon band peak absorption at 425 nm and absorption coefficient 6350 ± 300 cm −1 M −1 . Under different sampling conditions, the respective first-order conversion rates varied between 0.03 and 0.15 h −1 , whereas simultaneous dynamic light scattering measurements revealed steady growth of the averaged particle size ranging from 60 to 300 nm.

Dielectric Barrier Discharge Initiated Gas-Phase Decomposition of CO2 to CO and C6–C9 Alkanes to C1–C3 Hydrocarbons on Glass, Molecular Sieve 10X and TiO2/ZnO Surfaces

“…As reported earlier [2], the CO yield increased continuously with the applied electrical field strength, and its production efficiency remained high near the reduced electric field value of 75-100 Td (1 Td = 10 À17 V cm 2 ), corresponding to the experimentally maintained electric field strength of 1800-2400 V mm À1 . Table 1 summarizes typical CO yields obtained with uncoated and coated central electrode under identical discharge and gas flow conditions.…”

“…Amongst various past practice to chemically reduce CO 2 to a number of products, free radical chemistry initiated by Atmospheric Pressure Dielectric Barrier Discharge (AP-DBD) have been found promising for its specific reduction to CO. Additionally, for further selective generation of other partially hydrogenated products like methanol and formaldehyde, H 2 and also hydrocarbon type H-atom donors have been selectively used as reactants [1][2][3][4][5][6][7][8][9][10]. In regards to the latter methodology, in our previous study we employed various types of gaseous C 6 -C 12 hydrocarbons as well as solid polypropylene granules for obtaining the necessary H-atoms in a restrictive manner, and thus achieve the reduction up to the HCHO production stage as was desired [1].…”

Transformation of Carbon Dioxide to Useable Products through Free Radical‐Induced Reactions

“…Chemical reduction of CO 2 with different energy inputs such as light energy through photochemical reactions using semiconductor photocatalysts [26][27][28][29][30][31][32], high-energy ionizing radiation (radiolysis) [33][34][35][36][37], electrochemical reactions (electrolysis) [38][39][40][41][42] (discussed below), sonolysis [43][44][45], and dielectric barrier discharge [46][47][48][49][50], etc. has been studied by researchers all over the world in the last decades.…”