Zeolitic imidazolate framework biocomposite as a visible light-assisted photocatalyst: Synthesis (in-situ and blending), regeneration, and decolorization of Malachite Green

To overcome the limitations of current water treatment technologies, it is essential to develop non-toxic materials with high removal capabilities. Herein, novel green biocomposite beads, CS/ZIF-8/TiO2 (CZT), based on chitosan modified with zeolitic imidazolate framework (ZIF-8) and titania (TiO2) was introduced. The interesting and noteworthy features of this new biocomposite are its green synthesis, biocompatibility, and easy separation ability. The composite beads effectively decolorize Malachite Green (MG) dye solution using visible LED light. In the present study, the efficiency of three components of CZT biocomposite, which were synthesized by two different methods (in situ and blending), was compared to investigate the effect of the synthesis method, as well as the synthesis with two different amounts of TiO2 (0.2 g, and 0.4 g) to investigate the effect of TiO2. The prepared materials through the XRD, SEM, EDS, FTIR, DRS, TGA, and RAMAN analyses were characterized. The synergistic effect of ZIF-8, TiO2, and chitosan in the biocomposite increased the photo-decolorization ability of the MG dye under visible-light irradiation. The decolorization at the optimum pH (pH = 6.5) after 180 min reached 94.5% and at the natural pH (pH = 3.93) after 300 min reached 98.2%. The photocatalytic decolorization reaction of the biocomposite followed zero-order kinetics.