Zheng-Yi Choong, Mohamed Faisal Gasim, Tao Zhou, Tuan Sherwyn Hamidon, M. Hazwan Hussin, Fitri Khoerunnisa, Wen-Da Oh
N, B-co-doped biochars with varying boric acid (BA):urea mass ratio were prepared by two-step calcination of sawdust (NB-BC-x, where x = 1, 2, and 3 corresponds to the BA:urea mass ratio of 0.025:1, 0.05:1, and 0.1:1, respectively) and characterized. Generally, B doping prior to N doping can improve N doping because the presence of oxidized B during N doping can interact with NH3, facilitating N doping. The performance of NB-BCs in PMS activation for ciprofloxacin (CIP) removal was evaluated and it was found that the kapp increased in the order of: N-BC (0.010 min−1) < B-BC (0.016 min−1) < NB-BC-2 (0.031 min−1) < NB-BC-3 (0.039 min−1) < NB-BC-1 (0.053 min−1). Due to its large specific surface area and synergistic interaction between N and B moieties, NB-BC-1 presented the best PMS activator, achieving CIP removal of ∼45 and ∼80 % by adsorption and degradation in 60 min, respectively. Further performance study using NB-BC-1 revealed that the kapp increased with increasing catalyst loading and PMS dosage. Meanwhile, higher pH can reduce the CIP removal efficiency due to the electrostatic repulsion between NB-BC-1 and PMS. It was also demonstrated that NB-BC-1 can be reused and regenerated after deactivation using thermal treatment at 500 °C. From the chemical scavengers and electrochemical studies, it can be deduced that NB-BC-1 activates PMS through both radical and nonradical pathways. Lastly, the degradation pathway of CIP was also proposed by identifying the degradation intermediates and their toxicity were accessed. Overall, this study showed that NB-BC-1 can potentially be used as a PMS activator for wastewater treatment. © 2022
School of Chemical Sciences, Universiti Sains Malaysia, Penang, 11800, Malaysia; School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China; Department of Chemistry, Indonesia University of Education, Setiabudhi 229, Bandung, 40154, Indonesia
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