Porous Cu-Bi loaded bamboo charcoal prepared by the citric acid complexation method for efficient photo-assisted peroxymonosulfate activation to remove antibiotic pollution

Developing inexpensive and highly active biochar for advanced oxidation processes is crucial for addressing water pollution problems. Here, Bi2O3/CuBi2O4/CuxO multi-active sites loaded bamboo charcoal (Cu/Bi-BC) was fabricated by pyrolysis of a citric acid/Cu2+/Bi3+ complex modified bamboo powder. Firstly, the chemical structure, morphology, and adsorption properties of Cu/Bi-BC were studied. Then, the catalytic performance of Cu/Bi-BC was evaluated through H2O2 activation, photo-H2O2 activation, peroxymonosulfate (PMS) activation, and photo-PMS activation. Our results revealed that 98.9% of tetracycline (TC) could be removed within 10 min in the Cu/Bi-BC-500/PMS/Visible-light catalytic system with a rate constant (k) of 0.4509 min− 1. This rate constant is 2.50 times that in the Cu/Bi-BC-500/PMS system (k = 0.1796 min− 1). In the presence of Cu/Bi-BC, visible-light could significantly improve the activation efficiency of both PMS and H2O2, and the activation of PMS was more efficient than that of H2O2. The photoassisted activation mechanism was investigated through a comprehensive approach encompassing electrochemical analysis, quenching experiments, and density functional theory calculations. The redox cycle of Cu(I)/Cu(II) and the formation of metastable Cu/Bi-BC-PMS complexes accelerate the transfer of electrons to PMS, generating a series of reactive oxygen species. The degradation of TC in the Cu/Bi-BC-500/PMS system mainly depends upon the non-radical process of 1O2, while ·OH and ·O2− are the main active radicals in the Cu/Bi-BC-500/H2O2 system. Degradation pathways, ecotoxicity assessments, and wheat germination toxicity were also investigated.