Selective photodegradation of tetracycline by molecularly imprinted ZnO@NH2-UiO-66 composites

A simple and recyclable imprinted catalytic composite (ZnO@NH2-UiO-66, ZUM) was synthesized by postsynthetic modification method with tetracycline (TC) as molecular template. A series of ZUM-n composites with different NH2-UiO-66 dopants from 0.1 to 0.7 g had been prepared and compared. The characterization results showed that ZUM-1 possessed the advantages of uniform size, high surface area and wide absorption spectrum. Further research results indicated that ZUM-1 composite has the ability of selective adsorption and the higher photocatalytic degradation efficiency to TC without secondary pollution. Under visible light irradiation, the ZUM-1 could degrade 61.9% of TC within 30 min, which may relate to the inhibition effect of composite materials on electron-hole recombination. The degradation selectivity of ZUM-1 was investigated by comparing the degradation efficiency of TC, tetracycline hydrochloride and ciprofloxacin. The high degradation efficiency and selectivity of ZUM-1 were also confirmed in real samples. The stability experiments showed that the ZUM-1 possessed excellent recyclability and stability in the photocatalytic degradation process, and the recycled process was environmentally friendly. The mechanism of TC photodegradation by ZUM-1 was investigated by UV-vis spectra, photoelectrochemical and radical scavenger experiment. And the possible degradation products were analyzed by HPLC-MS. All in all, this method provided a simple and promising perspective for preparing visible-light-responsive molecular imprinting composites with high specificity and photocatalytic activity.