SYNTHESIS OF CARBOXYMETHYL CELLULOSE (CMC) BASED COMPOSITE MEMBRANE AND TESTING ITS PERFORMANCE FOR SALINE WATER TREATMENT

Abstract

Along with natural causes, anthropogenic activities have intensified the water scarcity issue. Apart from conservation techniques solution to water scarcity is recovery of clean water that could be done by desalination of inland brackish water or sea water by reverse osmosis membrane technology. When it comes to membrane technology polymer composite membranes are most efficient & inexpensive. The aim of the current study was to develop a composite membrane using carboxymethyl cellulose (CMC) as a basic component. For the purpose, carboxymethyl cellulose was prepared from already isolated cellulose by alkalization and etherification of cellulose. CMC along with polyvinylpyrrolidone (PVA) and polyvinyl alcohol (PVP) was then used to prepare composite membrane in order to treat (0.1, 0.3, 1, 3%) synthetic saline water. PEG was used as a pore forming agent. Furthermore characterization was done using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Thermo-Gravimetric Analysis and Universal Testing Machine. SEM indicates that addition of PVP resulted in smoother surface as compared to the membrane fabricated without PVP and the membrane formed lies in microfiltration (0.1 - 10 micron) range. FT-IR spectroscope images gave the bands that are attributed to the dispersion of PVA and PVP in substrate matrix. Weight loss started at 270°C which was 210°C in the absence of PVP, hence TGA results showed that PVP effectively enhanced the thermal stability of membrane. The trend of increase in salt rejection in selected salts i.e. NaCl < KCl < CaCl2 was due to the increase in molecular mass respectively and overall efficiency ranges from 27 to 37%. The removal was highest for CaCl2 followed by KCl and NaCl (i.e. 37> 29 > 27%) respectively. It was concluded that PVP shows positive effect on thermal stability, surface morphology and mechanical properties of membrane. The fabricated membrane can be used for pre-treatment to Reverse Osmosis (RO) in order to improve efficiency and the life of RO membranes.