Ujjal Ghosh

Synthesis and characterization of porous polyurethaneurea membranes for pervaporative separation of 4-nitrophenol from aqueous solution

Hydroxyterminated polybutadiene (HTPB) based porous polyurethaneurea (PUU) membranes were prepared. The porosity was developed by incorporation of lithium chloride into polymer matrix with subsequent leaching of the same in hot water. Scanning electron microscopic analysis of the prepared membrane surfaces was performed. The pervaporation performance of the synthesized membrane was studied with aqueous 4-nitrophenol solution as feed. The effects of various parameters on 4-nitrophenol separation factor and total as well as 4-nitrophenol flux were studied. Polyurethaneurea membrane was found to permeate 4-nitrophenol selectively with high separation factors for the organic component. Pore size and number of pores on the surface of the membrane were calculated from SEM image of the membranes. Effects of pore size and porosity on pervaporation flux were also investigated.

Review of Membranes for Helium Separation and Purification

Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

Fish (Labeo rohita) Scales as Potential Low-Cost Biosorbent for Removal of Malachite Green from Aqueous Solutions

ABSTRACT The feasibility of using fish (Labeo rohita) scales as low-cost biosorbent for the removal of hazardous Malachite Green (MG) dye from aqueous solutions was investigated. Employing a batch experimental setup, the effect of operational parameters such as biosorbent dose, initial solution pH, contact time, and temperature on the dye removal process was studied. The equilibrium biosorption data followed both Langmuir and Freundlich isotherm models, whereas the experimental kinetic data fitted well to the pseudo-second-order kinetic model. Thermodynamic study indicated spontaneous and endothermic nature of the biosorption process. The results suggest that fish scales could be used as an effective biosorbent for removal of MG dye from aqueous solutions.

Solar hydrogen production via erbium oxide based thermochemical water splitting cycle

The erbium oxide based water splitting (Eb-WS) cycle was thermodynamically studied by using the HSC Chemistry software and databases. The first step of the Eb-WS cycle involves thermal reduction of Er2O3, whereas the second step corresponds to the production of H2 via water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined by performing HSC simulations. Influence of partial pressure of oxygen ( PO2) in the inert purge gas on thermal reduction temperature ( TH) and equilibrium compositions associated with the solar thermal dissociation of Er2O3 was identified. Furthermore, energy and exergy analysis of the Eb-WS cycle was carried out to estimate the cycle ( ηcycle) and solar-to-fuel conversion efficiency ( ηsolar−to−fuel). Simulation results indicate that the ηcycle and ηsolar−to−fuel of Eb-WS cycle increase with the decrease in TH. Also, the ηcycle and ηsolar−to−fuel can be increased further via the recuperation of the heat release...

Modelling and simulation of reaction kinetics of carbon dioxide absorption into aqueous ammonia in a wetted wall column

Carbon dioxide accounts for about 80% of all greenhouse gases (GHG) and thus becomes the major source responsible for global warming which is considered as the greatest environmental challenge the world is facing. The post-combustion capture is the main way to lower the emission of existing power plants and future power plants where CO2 is produced during the combustion. Solvent-based CO2 capture technology a proven technology for CO2 capture. Carbon dioxide absorption process using an ammonia solution provides many advantages including higher absorption capacity, no degradation and lower regeneration energy requirement. In this paper, a mathematical model for the reaction kinetics of carbon dioxide absorption into aqueous ammonia in a wetted wall column is developed. Simulation of the mathematical model is performed and the simulated results are compared with literature data.