Effect of molar ration of Ti/Ligand on the synthesis of MIL-125(Ti) and its adsorption and photocatalytic properties

Abstract

In this study, a pristine MIL-125(Ti) was synthesized via a modified solvothermal method. The effect of titanium metal ion to organic ligand ratio on surface and structural properties of material was investigated. With changing the Ti/Ligand ratios, the surface charge of catalyst changed, that was explained by Zeta potential. Moreover, surface area significantly dropped as Ti/Ligand molar ratio was increased or decreased from 2:3, respectively. Furthermore, effect of these surface changes on physicochemical (adsorption and photocatalysis) properties of material was investigated. Electrostatic potential and strong oxo and metal cluster peaks, mesoporosity, and good crystallinity were the reasons for enhanced adsorption and photocatalytic properties of material. Isotherm studies of adsorption illustrated a monolayer adsorption with good favorability. In addition, photocatalysis followed first order kinetics with good sustainability that was explained by reusability results. Further, LC/MS analysis identified Rhodamine, benzoic acid, cyclohexanes, succinic acid, cyclohexylammonium, dimethylamine, and acetate as photocatalytic degradation intermediates. Moreover, Quantitative evaluation of material revealed MIL-2 (Ti/Ligand ratio = 2:3) as the best performing candidate among prepared MIL's. Therefore, we propose a molar ratio of 2:3 of Titanium metal ion to organic ligand for synthesis of pristine MIL-125(Ti).