The conversion of phosphogypsum waste (a waste product of phosphoric acid production in Richard Bay, South Africa), using sodium carbonate was tested. Response surface methodology (RSM) was used to investigate the combined effect of relevant process variables to maximize the production of calcium carbonate in a batch reactor. The process variables include time (0, 60, and 120 min); slurry content (5, 10, and 15%); agitation speed (100, 300, and 500 rpm); and sodium carbonate/gypsum molar ratio (0.8, 1.4, and 2). In the optimum conditions of the process (the slurry concentration of 5%, molar ratio sodium carbonate/gypsum of 2, stirring rate of 500 rpm) the conversion of waste gypsum to calcium carbonate after 105 minutes reaches over 98.5%. The calcium carbonate produced in this work compares favorably to the commercial calcium carbonate (laboratory grade) during Acid Mine Drainage (AMD) neutralisation.

written by Journal of Chemical Engineering and Process Technology

The rejection of nickel ions on water solutions was studied using aromatic polyamide nanofiltration membrane NF 90 by determination of solution chemistry as the concentration of solution, the pH and ionic strength at 27°C. The experimental results showed that the lower flow solution depends on concentration, solution pH and ionic strength. The solution concentrations showed greater decrease in flux and rejection. Flux decline conducted with a solution of nickel dropped for pH of the solution. At high pH, flux solutions showed higher flux decline than those of low solution pH, while the rejection of ions presented higher rejection. Increased ionic strength had a greater increase in flux decline. The rejection of nickel ions was found to be decreased with decreasing solution pH and increasing ionic strength. Flux and rejection decreased further to the higher ionic strength, which reduces the negative charge repulsion on the surface of the membrane, and thus a decrease of rejection. In addition, comparisons on the decline of flows to co-ions have also been studied in experiments filtration.

written by Journal of Chemical Engineering and Process Technology

In the present work porous poly (vinylidene fluoride) (PVDF) hollow fiber membranes were fabricated via thermally induced phase separation (TIPS) method for the application in gas-liquid membrane contactor. For this purpose long air gap distance was used (90 mm). Scanning electron microscopy (SEM) was used for membrane characterization. Gas permeation test was performed using carbon dioxide as test gas. It was observed that the effective surface porosity and membrane pore size increased with increased glycerol concentration. CO₂ absorption using the fabricated hollow fiber membranes were measured in a gas-liquid hollow fiber membrane contactor. The results of the CO₂ absorption rate of the tested fibers revealed that complete removal of CO₂ was achieved using 7% glycerol added to the casted solution at normal operating conditions for equal gas to liquid volumetric flow rates using sodium hydroxide as absorbent liquid.

written by Journal of Chemical Engineering and Process Technology