Abstract
Recently, persulfate (PS) activation system has grown up as a primary branch of advanced oxidation processes, and biochar has been recognized as a potential nonmetal material in this field. However, few studies have focused on the corresponding relationship between actives sites on biochar and active species in AOPs. To pave this way, similar biochar (obtained from different pyrolysis temperature) with different functional structures were involved. In this study, biochar derived from swine bone (BBC) was applied in PS activation system to degrade acetaminophen (ACT). The results showed that both radical and non-radical pathway worked in the PS/BBCs systems, and the degradation rate (from 0.1042 to 0.4364 min−1) climbed with the increase of pyrolysis temperature (from 700 to 900 °C). To probe into the corresponding relationship between functional structure and active species, the effect of pyrolysis temperature on functional structure was analyzed. It came out that 1) defects could act as active sites for various active species; 2) persistent free radicals could do favor to the generation of 1O2 and O2−; 3) hydroxyapatite in swine bone only served as hard templet for the porous structure. ACT degradation process was measured by Liquid chromatograph-mass spectrometer, and Scendesmus obliquus was applied to investigate the toxicity of PS/BBCs system. It illustrated that the existence of SO4− mainly contributed to the generation of high toxic intermediates (such as biphenyl and diphenyl ether) in the PS/BBCs system. Furthermore, the enhancement of adsorption capacity would mitigate the toxicity of PS/BBCs systems to some extent.
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•Hydroxyapatite in bone acts as hard template in persulfate activation system.•Defects might do favor to the generation of SO4− and OH.•Persistent free radicals on biochar can induce the generation of O2−.•SO4− is the main cause for the generation of biphenyls and diphenyl ethers.•Higher adsorption capacity mitigates the toxicity of persulfate activation system.