A novel post coordination modulation method to synthesize N/S functionalized ZIF-8 for removal of trace heavy metals from drinking water

The functionalization of metal-organic frameworks (MOFs) has been considered an effective strategy for pro-moting heavy metals removal from water. Therefore, a novel post coordination modulation method was sys-tematically studied to synthesize ZIF-8 functionalized by 2,5-Dimercapto-1,3,4-thiadiazole (Post-ZIF-8-DMTD) for trace heavy metals removal from drinking water. The effects of addition time and addition amount of DMTD on the structure and adsorption performance of Post-ZIF-8-DMTD were investigated. It was found that addition time of DMTD had minor impact, while addition amount of DMTD had great impact, appropriate DMTD addition amount (375 mg) could not only provide sufficient active sites but also avoid self-polymerization of DMTD. Post-ZIF-8-DMTD exhibited a more regular structure than Before-ZIF-8-DMTD synthesized by direct coordination of mim and DMTD with Zn2+, and had faster adsorption rate and deeper purification capability for trace Pb(II). Post-ZIF-8-DMTD also exhibited good stability, wide suitable pH range, high maximum adsorption capacity (4.34 mg/g) that met WHO effluent Pb(II) concentration standard and excellent capture capacity for many trace heavy metals in tap water, and could be regenerated effectively with thiourea solution. The post coordination modulation method provides a novel and efficient strategy for the functionalization of MOFs, and Post-ZIF-8-DMTD has excellent application prospects in drinking water purification.