Search

Abstract: Active carbon, grade 80 CTC, of surface area 1199m2/g, 12×30 BSS particle size and coconut shell origin was impregnated (5%, W/W) with various impregnants such as Cu(II) 1,1,1,5,5,5-hexafluoroacetylacetonate, Cu(II) 1,1,1-trifluoroacetylacetonate, 1-phenylbute-1,3-dione-2-oxime plus Cu(II) using incipient wetness technique. These impregnated carbons along with active carbon (Grade 80 CTC) and whetlerite were studied for the adsorption of dimethyl methylphosphonate (DMMP) at 33±1°C under static conditions. Cu(II) 1,1,1,5,5,5-hexafluoroacetylacetonate impregnated carbon system showed highest uptake (68.5%, W/W) of DMMP amongst all the carbon systems, however, active carbon with higher surface area could adsorb 61.5% (W/W) of DMMP under same conditions. It indicated that the adsorption by Cu(II) 1,1,1,5,5,5-hexafluoroacetylacetonate impregnated carbon was not only due to physisorption but chemisorption as well. Kinetics of adsorption was also studied and various parameters such as equilibration time, equilibration capacity, rate constant (k), diffusional exponent (n) and constant (K) were determined. Carbons with and without DMMP exposure were also studied using IR and TGA techniques. Reaction products were analyzed using gas chromatography coupled with mass spectrometry (GC/MS) and found to be methyl methylphosphonic acid (MMPA) and methylphosphonic acid (MPA) for Cu(II) 1,1,1,5,5,5-hexafluoroacetylacetonate impregnated carbon. [Copyright &y& Elsevier]

Abstract: Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different carbon systems such as 11-molybdo-1-vanadophosphoric acid impregnated carbon (V1/C), ruthenium chloride impregnated carbon (Ru/C) and combination of these two (V1/Ru/C) were prepared. These carbons were characterized for cumulative micropore volume and surface area by N2 BET. The kinetics of the in situ degradation of HD and its simulants were studied and found to be following the first order kinetics. Kinetic rate constants and t 1/2 values were determined. Products were characterized using NMR, IR and GC–MS. Reaction products were found to be sulphoxide and sulphone. The combined system, i.e., 11-molybdo-1-vanadophosphoric acid plus ruthenium chloride (V1/Ru/C) was found to be best for in-situ degradation of HD and its simulants. In-situ degradation by polyoxometalate based system was found to be stoichiometry based while Ru/C oxidized HD in presence of chemisorbed oxygen. In combined system of V1/Ru/C ruthenium worked as a catalyst and polyoxometalate acted as a source of oxygen. Effect of moisture was also studied in combined system. Rate of degradation of HD was found to be increasing with increased percentage of moisture content. [Copyright &y& Elsevier]

Abstract: Whetlerite carbon, which is in use in nuclear, biological and chemical filtration systems can degrade highly volatile chemical warfare gases such as phosgene, cyanogen chloride, hydrogen cyanide, etc. Degradation of vesicants such as sulphur mustard (HD) over whetlerite has not been extensively studied, except that the probability of some hydrolysis has been reported. In order to investigate the latter and incorporate HD degradation capability to the filter adsorbent, indigenous whetlerite carbon containing sodium hydroxide was further impregnated with various in situ degradation capable impregnants. The prepared adsorbent materials (impregnated modified whetlerite systems) were studied for in situ degradation of HD at ambient temperature. Degradation kinetics monitored by GC/FID was found to be pseudo-first-order. Kinetic rate constant and half-life values of degradation were calculated. Hemimustard, thiodiglycol, 1,4-oxathiane, sulphoxide and vinyl-2-chloroethyl sulphide were found to be the degradation products with modified whetlerite (MWh) and modified whetlerite impregnated with 11-molybdo-1-vanadophosphoric acid (MWh/V1) systems indicating that oxidative, hydrolytic and dehydrohalogenation decompositions are responsible for HD degradation. Effect of moisture on HD degradation was also studied on MWh and MWh/V1 systems, indicating that the rate of degradation increases with increasing moisture content. [Copyright &y& Elsevier]

A significant quantity of hydrocarbons remains in the reservoir after production using primary and secondary techniques. Traditional recovery techniques produce about 33 % of the original oil in place. However, the utilization of chemicals such as surfactants and polymers facilitate the additional recovery of one‐third of this oil. Researchers are currently aiming at mixing surfactant and nanoparticles for their potential applications in petroleum industry. In this work, authors claimed to be the first to study usage of synthesized Mesoporous Silica Nanoparticles (MSN) with Sodium Dodecyl Sulphate (SDS) surfactant to understand its applicability in Chemical Enhanced Oil Recovery through evaluation of the surface tension & Interfacial tension, surfactant adsorption, contact angle, and core flooding experiments. Surface tension studies revealed a synergistic interaction between MSN and anionic surfactant molecules. With the introduction of 2500 ppm of anionic surfactant, the surface tension of deionized water reduces to 34.5 mN/m from 72.4 mN/m. The surface tension of the mixture was further lowered by ∼9.8 % with the addition of 300 ppm MSN. The Interfacial Tension results also showed the same trend. When 300 ppm of MSN was introduced, then IFT values decreases from 8.13 mN/m to 3.91 mN/m at 2500 ppm of anionic surfactant. Contact angle measurements after MSN injection went from 77.98° for SDS (2500 ppm) to 73.36°, 66.54°, and 41.95° for 100, 200, and 300 ppm of MSN, respectively. This demonstrates that the shift toward water‐wet behavior increased along with the MSN concentration. Additionally, adding 300 ppm of MSN lowered surfactant adsorption by ∼80 % at a surfactant concentration of 2500 ppm. Up to 72.27 % of the OOIP could be recovered using the chemical slug made of SDS surfactant, polymer, and MSN. The research data suggests that the MSN can increase the effectiveness of the chemical injection approach, which can be used to recover more oil. [ABSTRACT FROM AUTHOR]

Surfactant flooding is a prolific enhanced oil recovery technique. It alters the rock fluid interfacial interactions between reservoir fluids and rocks. However, a pair of impeding factors often limit the economic viability of the process and need to be optimized. The first is the surfactant loss on the adsorbent surface due to adsorption making it a potential environmental problem. The second is the Critical Micelle Concentration (CMC) which governs the amount of surfactant pumped. This study aimed to minimize the surfactant loss and the CMC, thereby optimizing the flooding efficiency and reducing the environmental concerns for nanoparticle applications. To achieve this, Silicon Carbide nanoparticles (SCN) were employed as additives to the surfactant solution. It was observed that the use of SCN reduces the surfactant adsorption by as much as 44 % and the critical micelle concentration by 14 %. The studies also observed that the concentration of SCN required to get these results is dramatically (more than 25 times) lower than previously reported literature on other nanoparticles. To adsorption isotherm studies provide an insight into the type of adsorption taking place. The adsorption isotherm follows the Langmuir model. [ABSTRACT FROM AUTHOR]