Multicomponent Steady State Modeling of Concentration Polarization Including Adsorption during Nanofiltration of a Textile Effluent

Abstract

Steady state modeling of nanofiltration of a textile effluent was carried out. The model comprised of three distinct parts. Film theory was used to account for the solute transport outside the membrane surface within the mass transfer boundary layer. An osmotic pressure model and a solution-diffusion model were used to quantify the solvent and solute flux through the porous membrane. The osmotic pressure model was modified by incorporating adsorption of dyes onto the membrane surface. The system had three components, namely, Cibacron Black and Cibacron Red and the salt as sodium chloride. The model had three parameters, namely, solute permeability of two dyes and sodium chloride through the membrane. These parameters were estimated by comparing the calculated and experimental data of permeate flux and permeate concentration. It was observed that membrane hydraulic resistance and the resistance due to concentration boundary layer were more significant. The calculated permeate flux was within ±20% of the experimental data. Values of resistance due to adsorption of dyes onto the membrane surface were calculated to be about 2 to 3% of total resistance and of those due to concentration boundary layer were about 47%.