Surface induced growth of ZIF-67 at Co-layered double hydroxide: Removal of methylene blue and methyl orange from water

Abstract Industrial waste water containing organic pollutants is a universal issue due to its hazardous chemical nature. Fabrication of hybrid mixed-matrix is a typical and powerful approach to create new functionalities that cannot be represented by single-phase materials. In present study, we have reported the in-situ growth of zeolite imidazolate frameworks (ZIF-67) on layered double hydroxides (LDH) to form porous composites to develop materials for removal of methylene blue (MB) and methyl orange (MO). Scanning electron spectroscopy showed a sandwich like structure of composite decorated with polyhedrons of ZIF-67. For comparative studies, ZIF-67 and CoAl-LDH were also synthesized and used for adsorptive removal of MB and MO dyes. Results showed that ZIF-67@CoAl-LDH has good adsorption capacity (qm, 57.24 mg g−1) for methylene blue as compared to LDH (15.04 mg g−1) and ZIF-67 (57.14 mg g−1). Furthermore, ZIF-67@CoAl-LDH also showed good adsorption capacity (qm 180.5 mg g−1) for methyl orange than LDH (32.27 mg g−1) and ZIF-67 (75.58 mg g−1). Also, with 100 min contact time 79.9% MB and with 90 min contact time 72.3% MO was adsorbed by ZIF-67 and it's composite. The equilibrium adsorption data were well fitted by Langmuir model and relatively high correlation coefficient of Langmuir model (R2 = 0.9953 ZIF-67 and 0.9889 ZIF-67@CoAl-LDH) for MB and (R2 = 0.9917 ZIF-67 and 0.9737 ZIF-67@CoAl-LDH) for MO suggesting a mono-layer adsorption of MB and MO on the ZIF-67 and its composite. Further, the ZIF-67 and its composite (ZIF-67@CoAl-LDH) exhibited no obvious loss in MB and MO removal after recycling for four times. The overall results indicate that the as-prepared ZIF-67 and its composite are efficient for removal of dye pollutants containing methylene blue and methyl orange form water.