Experimental and modeling of fluoride removal using aluminum fumarate (AlFu) metal organic framework incorporated cellulose acetate phthalate mixed matrix membrane

Abstract

Selective adsorption of small sized contaminant by inorganic component incorporated in a polymeric membrane in addition to separation of total solids, iron, alkalinity and hardness makes mixed matrix membrane (MMM) a unique filtration medium. Significant separation of tiny pollutants along with high throughput at low operating pressure is the remarkable feature of MMM. Aluminum fumarate metal oxide framework (MOF), a super adsorbent for fluoride was included in cellulose acetate phthalate as base polymer to prepare a novel MMM for removal of fluoride from contaminated groundwater. The membranes were characterized by porosity, permeability, molecular weight cut off and contact angle. The morphology and the surface roughness were studied by scanning electron and atomic force microscope. The adsorption capacity of the membranes for fluoride varied from 107 to 179 mg g^-1 for MOF concentration of 2 to 10 wt%. The fluoride rejection was more than 99% for 10% AlFu concentration. The life of the membrane was determined using a continuous cross flow setup with membrane area of 0.01 m² and it was found to be 17 h for a feed concentration of 10 mgL^-1 of fluoride in synthetic solution. Regeneration study and performance of the MMM in real life ground water samples were also investigated. The study provides a promising, scalable technology using MMM for fluoride mitigation by combining high throughput, selective separation of fluoride and general filtration including removal of total dissolved solids, hardness, alkalinity and iron.