Kinetic and thermodynamic evaluation of effective combined promoters for CO₂ hydrate formation

The increase in carbon dioxide (CO2) concentration in the atmosphere raises earth's temperature. CO2 emissions are closely related to human induced activities such as burning of fossil fuels and deforestation. So, to make the environment sustainable, carbon capture and storage (CCS) is required to reduce CO2 emissions. In this study, CO2 hydrate (CO2:6H2O) formation has been explored as an approach to capture CO2 in the integrated gasification combined cycle (IGCC) conditions. The formation of hydrate was experimentally investigated in an isochoric system with high-pressure volumetric analyzer (HPVA). The solubility of CO2 in water using experimental pressure–time (P-t) curves were analyzed to determine the formation of hydrate. Additionally, the effect of newly synthesized combined promoters and various driving forces were evaluated. The experimental results demonstrated that the CO2 uptake expanded as ΔP expanded and designated combined promoters type T1-5 and type T3-2 were the two best, acquiring a uptake of 5.95 and 5.57 mmol of CO2 per g of H2O separately. Ethylene glycol mono-ethyl ether (EGME) was demonstrated to be a good option to THF when linked with SDS, with a CO2 uptake of 5.45 mmol for the designated combined promoters T1A-2. Additionally, the total sum of CO2 devoured through hydrate development maximize as the measure of water inside mesoporous silica increased. All results of the studied parameters confirmed the reliability of experiments and successful implementation

Experimental investigation of tar arresting techniques and their evaluation for product syngas cleaning from bubbling fluidized bed gasifier

© 2019 Elsevier Ltd Hazardous waste products along with the syngas produced from biomass gasification are one of the major problems of today world. Tar and other solid contaminants removal from syngas are necessary as it is widely used for the production of energy in thermal and power sectors. The raw syngas can be clean up by directly controlling the operating parameters and applying cleaning units. This study aimed to analyze bubbling fluidized bed gasifier and focuses on investigating the novel tar reducing techniques. Different cleaning units; char bed, woodchip bed and mop fan were used to arrest tar directly from producer gas. For the first time, a novel strategical technique of mop fan based on water spray was evaluated. Results showed that tar arrest with bio-char is unsuccessful due to the burning of bed while the average concentration of tar captured by woodchips and mop fan with or without water spray was 0.459 mg/L, 0.987 mg/L and 0.617 mg/L respectively. Furthermore, the concentration of naphthalene and phenanthrene reduced significantly by 96.46% and 99.27% with water spray based mop fan. Overall tar arresting percentage efficiency with small woodchip, large woodchip, mop fan without water and mop fan with water spray was 22.5% < 29.4% < 60.54% < 89.61% respectively. Hence, these investigations lead to the important findings that mop fan with water spray can be deployed directly to capture contaminants, to prevent the production of waste and to increase the efficiencies of clean syngas for the safer use in the power sector

Formulation of zeolite supported nano-metallic catalyst and applications in textile effluent treatment

Textile industry is one of the major industries worldwide and produces a huge amount of coloured effluents. The presence of coloured compounds (dyes) in water change its aesthetic value and cause serious health and environmental consequences. However, the present investigation was carried out to minimize and reduce the colour compounds discharged by the textile industries through a nano-scaled catalyst. This study is mainly focused on the explanation of nanoparticles aggregation by deposition on natural zeolite, and utilization of this natural zeolite as supported material to nano zerovalent iron (NZ-nZVI) in the form of liquid slurry with sodium percarbonate acting as an oxidant in a Fenton like system for the removal of synthetic CI acid orange 52 (AO52) azo dye, in textile effluent. The nano-scaled zerovalent irons were synthesized by borohydride method in ethanolic medium. UV–vis spectrophotometry, FTIR, EDX, SEM, and XRD (powdered) analysis were used for the investigations of surface morphology, composition, and properties of natural zeolite supported nZVI and study the dye removal mechanism. The XRD spectrum revealed that clinoptilolite is the major component of natural zeolite used, while EDX found that the iron content of NZ-nZVI was about 9.5 %. The introduction of natural zeolite as supporting material in the formation of iron nanoparticle resulted in the partial reduction of aggregation of zerovalent iron nanoparticles. The findings revealed that the 94.86 % removal of CI acid orange 52 dye was obtained after 180 min treatment at 15 mg/L initial dye concentration. The highest rapid dye removal of about 60 % was achieved within the first 10 min of treatment at the same dye concentration. Furthermore, the actual dyeing effluent including green, magenta, and the blended colour was successfully decolourized by natural zeolite-supported nZVI/SPC Fenton process. It is concluded that the acceleration of corrosion of NZ-nZVI, breaking of azo bond, and consumption of Fe2+ were the possible mechanisms behind the removal of AO52 dye. It is also recommended that NZ-nZVI/SPC Fenton process could be a viable option for effluent and groundwater remediation