改性生物炭活化过硫酸盐降解盐酸四环素

Modified biochar activated persulfate for degradation of tetracycline

以双氧水改性磁性生物炭(H_(2)O_(2)Modified Biochar,HMB)为过二硫酸盐(PDS)的活化剂降解盐酸四环素(TC),考察初始pH值对TC降解的影响.通过淬灭试验和电子顺磁共振(EPR)鉴定活性物种,结合XPS分析、密度泛函理论(DFT)计算和液质联用仪(LC-MS)检测,探究HMB活化PDS降解TC的反应机理和降解路径.结果表明,经双氧水改性后,在TC浓度20mg/L,PDS浓度1mmol/L,HMB投加量为0.5g/L的条件下,TC去除率83.9%,显著高于单独PDS或生物炭体系,且去除率随pH值增大而减小.猝灭试验和EPR分析表明TC降解存在自由基路径和非自由基路径,活性物种主要包括SO_(4)^(-)、·OH、O_(2)^(-).和^(1)O_(2).XPS表明羰基(C=O)是HMB/PDS体系降解TC的主要活性位点.DFT计算进一步定量分析C=O对HMB催化PDS的贡献.结合LC-MS和理论计算提出了TC的2条降解路径,降解方式包括脱酰胺、羟基化、去甲基化、脱水开环等.

Tetracycline hydrochloride(TC)degradation was investigated utilizing hydrogen peroxide modified magnetic biochar(H_(2)O_(2)modified biochar,HMB)as an activator of peroxydisulfate(PDS),with a focus on assessing the impact of initial pH on TC degradation kinetics.The underlying reaction mechanisms and degradation pathways of HMB-activated PDS for TC degradation were elucidated through a series of experimental techniques,including quenching tests,electron paramagnetic resonance(EPR)spectroscopy for identifying active species,X-ray photoelectron spectroscopy(XPS)analysis,density functional theory(DFT)calculations,and liquid-liquid mass spectrometry(LC-MS)detection.Hydrogen peroxide modification significantly enhanced TC removal,achieving a removal rate of 83.9%under the specified conditions of TC concentration(20mg/L),PDS concentration(1mmol/L),and HMB dosage(0.5g/L).This efficacy surpassed that of PDS alone or the unmodified biochar system,albeit exhibiting a decrease in removal efficiency with rising pH levels.Quenching tests and EPR analyses unveiled both radical and non-radical pathways contributing to TC degradation,the active species mainly includes:SO_(4)^(-)、·OH、O_(2)and^(1)O_(2).XPS analysis identified carbonyl(C=O)functionalities as the primary active sites responsible for TC degradation within the HMB/PDS system.Complementary DFT calculations were employed to quantitatively assess the contribution of C=O moieties to the HMB/PDS-mediated degradation process.Furthermore,LC-MS analyses coupled with DFT calculations delineated two distinct degradation pathways for TC,involving mechanisms such as deamidation,hydroxylation,demethylation,and dehydration ring opening.