Effective degradation of tetracycline via recyclable free-standing three-dimensional copper-based graphene as a persulfate catalyst.

Water pollution by antibiotics is a serious and growing problem. Given this challenge, a free-standing three-dimensional (3D) reduced graphene oxide foam supported copper oxide nanoparticles (3D-rGO-CuO) was synthesized using GO as a precursor and applied as an efficient persulfate activator for tetracycline (TC) degradation. The influences of CuO mass, solution pH, persulfate dosage, and common anions on the TC degradation were investigated in detail. Analytical techniques indicated that the 3D-rGO-CuO showed a cross-linking three-dimensional network structure, and CuO particles with irregular shapes were uniformly loaded on graphene pore walls. The XPS and Auger spectra of Cu confirmed that CuO was the main component in solid copper compounds. The addition of CuO was vitally important for the activation of the oxidation system, and the removal rate reached 98% with a CuO load of 7:1. The pH showed little influence on the activation effect on TC degradation. For common anions, Cl and CO had little influence on the system, while humic acid had a great inhibitory effect. The EPR test and quenching experiment revealed that the active substances in the oxidative degradation process mainly include SO·, ·OH, O, and reactive Cu(III). Additionally, the 3D-rGO-CuO material proved highly stable according to the replicated test results and was promising for the remediation of antibiotic-contaminated water.