Adsorptive removal of heavy metal ions (HMIs) using L-Glutamic acid treated UIO-66(COOH)2 MOF

Heavy metal ions (HMIs) are produced as a result of fast industrial and agricultural expansion. They are exceedingly hazardous to both humans and the environment, and the necessity to eliminate them from aqueous systems prompted the development of novel materials. Metal-Organic Frameworks (MOFs), a novel class of organic-inorganic hybrid materials, have generated interest in the field of adsorption of HMIs due to the facts of the high material's porous structure, wide surface area, availability of exposed adsorptive sites, and post-synthetic modification capability. In the present study, UIO-66(COOH)2 MOF which contains free carboxylic acid groups was postsynthetically modified with L-Glutamic acid (GA) to produce an analogue of UIO-66(COOH)2 having both amide and free carboxylic acid groups. Pristine and GA treated MOF materials were well characterized with several physico-chemical techniques. The single and diverse ion batch adsorption studies of Cu2+, Pb2+, Hg2+ and Cd2+ ions were carried out using pristine as well as GA treated MOFs. The parameters influencing the removal efficiency such as effect of initial concentration, contact time, adsorbent dosage and cyclic sorption studies were examined.