Activation of persulfate by CuOx@Co-LDH: A novel heterogeneous system for contaminant degradation with broad pH window and controlled leaching

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2018-03, Vol.335, p.548-559
• Main Authors: Jawad, Ali, Lang, Jie, Liao, Zhuwei, Khan, Aimal, Ifthikar, Jerosha, Lv, Zhanao, Long, Sijie, Chen, Zhulei, Chen, Zhuqi
• Format: Article
• Language: English
• Subjects: Broad pH window; Diverse free radicals; Phenol degradation; PS activation; Scavenging effect
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2017.10.097

[Display omitted] •CuOx@Co-LDH/PS system presented consistent performance over a wide pH range.•CuOx@Co-LDH/PS system offered minimum scavenging for inorganic anions.•LDH structure and diverse free radicals were responsible for consistent performance.•Components of Cu and Co showed synergetic effect. To meet the current challenges of waste water, an efficient, environment friendly and economical treatment process is always desirable for the degradation of toxic organic compounds. Herein, we reported a stable and active bimetallic CuOx@Co-LDH catalyst for the degradation of phenol using persulfate (PS) under mild conditions. The system of PS/CuOx@Co-LDH completely degraded 0.1 mM of phenol in less than 40 min while at the same time, all the other tested catalysts including catalyst precursors remained sluggish. In view of the practical application, CuOx@Co-LDH/PS system demonstrated consistent performance over a broad pH range (pH 5.0–12.0), during which minimum leaching could be detected. Moreover, good resistance to various inorganic anions was demonstrated in CuOx@Co-LDH/PS system. The consistent performance of CuOx@Co-LDH/PS system may originate from the constant buffer pH of catalyst (9.5 ± 0.8), minimum leaching and the generation of diverse free radicals (SO4−, OH or −O2) under different pH conditions. Additionally, LDH structure offered strong synergetic interactions among active components which might also help in minimum leaching and good reactivity of CuOx@Co-LDH catalyst. The results of radical scavengers, EPR and XPS studies collectively proved the mechanism of diverse free radicals, which was accounted to the redox cyclic reactions of active sites (Cu(III)–Cu(II)–Cu(III) and Co(III)–Co(II)–Co(III)) during degradation of phenol.