Research Projects

This project aims to investigate the efficiency of functionalized membranes in separating nitrate ions from water, a crucial component in the production of salt from process plants. Fluctuations in market demands make the plants vulnerable to the accumulation of effluents, and the presence of contaminants like fluorides, sulphates, and oxalates adds to the challenges in disposing of treated water/solids. The project aims to develop an ultrafiltration membrane-based micro reactor system for separating nitrate from other anions like oxalate, sulphate, and fluoride from wastewater, generating cleaner water with nitrate concentration below 50 ppm for safe disposal or reuse. Four different simulated feed streams were considered: sodium nitrate (2-4 M), ammonium nitrate (1-9 M) with ammonium fluoride (1-2 M), ammonium nitrate (1 M) with ammonium oxalate (0.5M oxalate), and ammonium fluoride (0.5 to 2 M) with ammonium sulphate (2-7 M). The streams were treated with pyrophellite to remove fluoride completely, and the stream containing ammonium oxalate and ammonium nitrate was refluxed with calcium carbonate to precipitate out oxalate. UF/NF membrane separation technology was used to concentrate sodium nitrate solution. Two membrane systems were adopted: selective adsorption and rejection through ion exchange using Zr hydroxide, 3-(trimethoxysilyl) propyl dimethyl octadecyl ammonium chloride and PVDF ultrafiltration membrane materials, and formation of positive charge on the membrane surface due to the protonation of amine groups of chitosan nanoparticles on PES through functionalized membrane materials. The project aims to convert the recovered 85-90% concentrated nitrate into a commercially viable product, such as a ternary eutectic mixture for heat transfer media.