Multicomponent transport model-based scaling up of long-term adsorptive filtration of MOF incorporated mixed matrix hollow fiber membrane: Treatment of textile effluent

Abstract

The present work describes the preparation and detailed characterization of porous chromium terephthalate metal–organic framework (MOF) impregnated polyacrylonitrile based hollow fiber membrane. The hollow fibers were characterized by their surface morphology, zeta potential, permeability, average pore diameter, molecular weight cut off (MWCO) and contact angle. Variation of MOF concentration upto 10 wt% resulted in 43% reduction in membrane permeability. The corresponding change in MWCO was from 140 kDa to 70 kDa. The addition of MOF made the membrane more hydrophilic and at 10 wt% MOF, the contact angle was reduced to 52° from 86°. The Fourier Transform Infrared Spectra (FTIR) of mixed matrix membrane (MMM) showed that there existed strong chemical interaction between MOF particles and polymer backbone, precluding the leaching of MOF from the membrane matrix over long term use. The MOF incorporated MMM exhibited tremendous adsorption capacity (197–260 mg/g for 10 wt% MOF doped fiber) towards reactive dyes commonly used in the textile industry. As the dye removal by MMM hollow fiber was based on the adsorption mechanism, the breakthrough behavior of the membrane was important to estimate the membrane life and onset of membrane regeneration. In the present work, a detailed two-dimensional transient transport model was developed for a multi-component real-life textile effluent from the first principles using the equation of continuity, momentum balance, species balance based on convective-diffusive-adsorptive solute transport in the hollow fiber. The model results were validated with the experimental data of a textile effluent having four reactive dyes. The multicomponent model was used for scaling up the actual hollow fiber based filtration system and the performance curve was generated relating the breakthrough volume, number and length of fibers.