Biochar supported CuO composites used as an efficient peroxymonosulfate activator for highly saline organic wastewater treatment.

Biochar supported copper oxide composite (BC-CuO) was synthesized and attempted to activate peroxymonosulfate (PMS) for treating highly saline (100-400 mM) wastewater. In the BC-CuO/PMS system, rapid removals of Methylene Blue (MB), Acid Orange 7, Rhodamine B, Atrazine and Ciprofloxacin from the highly saline system were observed within 30 min, attaining a high efficiency of 99.68%, 100%, 100%, 100% and 78.27%, respectively. Meanwhile, the BC-CuO/PMS can remove >88.61% of MB in other salt systems containing one or more salt components and 68.43% of COD from landfill leachate. Experimental results confirmed that sulfate radical (SO4▪-), hydroxyl radical (▪OH) and singlet oxygen (1O2) all contributed to the pollutants degradation, but 1O2 was dominated in highly saline systems. On the basis of the characterization and analysis data, possible activation mechanisms of the oxygenated functional groups of biochar and hydroxylation of CuO surface accelerating the generation of 1O2 were proposed. BC-CuO activating PMS is a promising technique for the removal of organic pollutants from highly saline wastewater or complex background.