Aluminium terephthalate (Al-BDC) based metal organic framework decorated carboxymethylated filter cloth for defluoridation application

Abstract

Current work adopts a novel approach for deposition of aluminium terephthalate-based metal organic framework (MOF) on carboxymethylated filter paper for defluoridation purpose. Aluminium terephthalate-based MOF was prepared using an optimized technique and showed a fluoride uptake capacity of 665 mg/g. However, due to its low yield, synthesized MOF was immobilized on carboxymethylated filter paper, using hydrothermal method. MOF immobilized filter paper (MOF cloth) showed a fluoride uptake capacity of 88 mg/g. Different surface-based characterization for MOF and MOF cloth were performed. Synthesized MOF was quasi-spherical in shape, forming flower like structures, when coalesced together and it showed crystalline property, having lattice fringes of 0.2 nm. Uniform and dense distribution was observed during its deposition process on filter paper. Both functional groups and mineralogical phases present in the MOF were also imparted to the immobilized filter paper. Uptake of fluoride by MOF cloth was governed by monolayer adsorption, as evident from Langmuir isotherm analysis. Uptake capacity increased with temperature and the highest one was recorded at 318 K. Prepared MOF cloth was subjected to dynamic studies via glass-funnel based filtration, where, effects of pH, coexisting ions including an organic pollutant and real-life feed were carried out. Regeneration of the MOF cloth was also studied for four cycles. Leaching study was performed at different time intervals. Finally, comparison was made with different conventional MOF based adsorbents and it was observed that this cloth can be an adaptable and pollution free medium for defluoridation applications.