Thiol/nitrogen functionalized Fe3O4@ZIF-8-DMTD by one-pot post coordination modulation for efficient and rapid removal of trace heavy metals from drinking water

The deep purification of trace heavy metals in drinking water is of great significance and has received consid-erable attention worldwide. 2,5-dimercapto-1,3,4-thiadiazole (DMTD) functionalized magnetic ZIF-8 adsorbent (Fe3O4@ZIF-8-DMTD) using a novel one-pot post coordination modulation method at room temperature could effectively adsorb trace heavy metals from drinking water through cooperating with the abundant functional groups and surface charges. The negative surface charges promoted the rapid accumulation of trace heavy metals on the surface of the adsorbent, meanwhile, the abundant thiol/nitrogen sites contributed to their adsorption, thus the adsorption rate and adsorption capacity of trace heavy metals were greatly improved. For trace Pb(II) (150 ppb), the effluent concentration could meet the World Health Organization (WHO) standard (<= 10 ppb) within 10 s after adsorption by Fe3O4@ZIF-8-DMTD, and the cumulative adsorption capacity that met WHO standard was 12.11 mg/g. Fe3O4@ZIF-8-DMTD also showed high stability in a broad pH range and excellent adsorption performance in a wide low concentration range. The effluent concentration still could meet the WHO standard when the initial Pb(II) concentration was 11.70 ppm, and the corresponding adsorption capacity reached 35.00 mg/g. Moreover, the capture experiments for multiple heavy metals that coexisted in tap water showed that the effluent concentrations of Hg(II), Pb(II), Cu(II), Cd(II), and Cr(III) could be lower than the allowable limits in a few minutes. The adsorbent could also be easily recovered using magnets and regenerated by thiourea solution, which showed great application potential for the purification of trace heavy metals in drinking water.

Automated summary

Fe3O4@ZIF-8-DMTD adsorbent prepared using a novel method showed effective adsorption of trace heavy metals from drinking water. The adsorbent's negative surface charges and abundant thiol/nitrogen sites greatly improved the adsorption rate and capacity. It also exhibited high stability and adsorption performance in a wide pH and concentration range. Additionally, the adsorbent could be easily recovered and regenerated, showing great potential for purification of trace heavy metals in drinking water.