Isotherm Studies for Performance Evaluation of Functionalized Carbon Nanotubes (CNT) Based Polymer Composite Nanofiltration Membranes for Desalination

Composite Nanofiltration membranes were fabricated by incorporating Carbon Nanotubes (CNT) and Polyvinylidene Fluoride (PVDF) membranes. A suspension was prepared by dispersing CNT (30 minutes of sonication) in Dimethyl Sulfoxide (DMSO) solvent for 0.5 mg/ml. This suspension after vacuum filtration dispersed over PVDF membrane of pore size 0.22μm. Excess DMSO was removed by washing using Ethanol followed by Deionized water. Normal and various functionalized (Hydroxyl (-OH), Carboxylic (-COOH), Amine (-NH2)) SWCNTs and MWCNTs were purchased and the CNT based polymer composite nanofiltration membranes were fabricated by vacuum filtration method at a uniform loading of 10mg/cm 2 . The experimental results were used to evaluate the TDS removal efficiency of the fabricated membrane modules, which are normal and functionalized (4 composites in both SW and MW combinations) CNT. The TDS removal efficiency of all the 8 composite membranes were observed under varied operating conditions viz., varying flow rate (100,150,200 and 250 ml/hr) and influent TDS (2500, 3000, 4000 and 5000 mg/l). The flux of the membrane is varied 200 to 500 lit/m 2 .hr. The Isotherm studies using the experimental data on Langmuir and Freundlich isotherm models validated the results of the experiment and are indicative of the role of adsorption of the functionalized CNT based polymer composite nanofiltration membranes which removing the TDS. The results showed that the amino functionalized SWCNTs based polymer composite (PVDF/SWCNTs) nanofiltration membranes can be used as an effective adsorbent for desalination due to their high adsorption capacity.