Synthesis of novel benzoic acid modified metal organic framework for adsorptive removal of arsenate

Abstract

Researchers worldwide have extensively studied metal organic framework (MOF) for its adsorption capabilities. Despite its potential, challenges such as particle agglomeration, low porosity and low surface area persist. This study aims to enhance the performance of MIL-100(Fe) for As(V) adsorption using a feasible and straightforward technique. To achieve this, benzoic acid was introduced as a modulator for ligand exchange, creating vacancy defects within the MIL-100(Fe) structure, resulting in defective MIL-100(Fe)-BA1. Through TEM imaging, visible deformations were observed on the surface of the adsorbent, with an average particle size of approximately 200 nm. XRD spectrum analysis revealed a reduction in peak intensity at 2–5°, indicating reduced crystallinity in the MIL-100(Fe) due to the presence of defects. Meanwhile, BET analysis demonstrated a significantly larger surface area for defective MIL-100(Fe) at 1081.09 m2/g, compared to the pristine MIL-100(Fe) with a surface area of 844.00 m2/g. Regarding adsorptive performance, the defective MIL-100(Fe) exhibited higher As(V) adsorption capacity (173.82 mg/g at pH8) than the pristine form (70 mg/g). This improvement can be attributed to the larger pore size of the particles and the exceptional affinity of As(V) anions towards the bulk Lewis Acid sites present on the surface of defective MIL-100(Fe). However, it is important to note that for effective As(V) adsorption by defective MIL-100(Fe)-BA1, it is crucial to eliminate competing compounds such as carbonate and phosphate anions from the water sources. Addressing these challenges will further enhance the efficacy of the adsorption process