Copper-doped ZIF-8 with high adsorption performance for removal of tetracycline from aqueous solution

Metal-organic frameworks (MOFs) with high porosity have attracted much attention in environment remediation. In this study, the copper-doped ZIF-8 (Cu-ZIF-8) was synthesized by an in-situ process of a zinc metal-organic framework (ZIF-8) in room temperature. The adsorption capacity of Cu-ZIF-8 towards tetracycline hydrochloride (TC) was 2.4 times higher than the pristine ZIF-8. The effects of adsorbent dosage, initial concentrations, solution pH values, coexisting ions and reaction temperature on adsorption capacity were investigated. The adsorption process of TC over Cu-ZIF-8 fitted well with pseudo-second-order and Langmuir models, which suggested that chemisorption was dominant in adsorption reaction and the Cu-ZIF-8 adsorbent had a homogenous surface for adsorption. Adsorption thermodynamic studies implied that the adsorption process was spontaneous and exothermic. In addition, the Cu-ZIF-8 adsorbent showed excellent adsorption performance towards TC in tap water, river water and pharmaceutical wastewater. This work provided a facile and efficient strategy to fabricate MOFs-based adsorbent for water purification.