碳纳米管催化臭氧降解PFOS动力学与过程控制

Kinetic and process control of CNT-induced catalytic ozonation of PFOS

针对全氟化合物难降解问题通过碳纳米管(CNT)诱导臭氧高级氧化路径研究非均相催化体系对高稳性全氟辛烷磺酸(PFOS)的降解效能与机制。结果表明:CNT介质可催化臭氧通过C-F断键对PFOS强制氧化分解,其准一级降解常数(A=0.O_37 min^(-1),5 mg·L^(-1)CNT)均高于碱式臭氧处理(A:=0.009 min^(-1),pH=11)以及高负荷活性炭颗粒(A:=0.013 min^(-1)3 g·L^(-1)GAC);溶液pH是控制催化过程的重要因素酸性或碱性环境由于PFOS吸附阻隔均不利于CNT表面与溶解O_3的接触催化反应;结合羟基自由基淬灭实验,推测CNT通过表面石墨层促成·OH大量生成并在固/液界面原位降解PFOS。研究结果可为开发利用CNT介质强化臭氧水处理过程提供科学依据。

Carbon nanotube（CNT） was utilized aiming to intensify advanced-oxidation pathway for ozonation of highly-persistent perfluorochemicals.The effectiveness on degradation of perfluorooctane sulfonate（PFOS） as model compound has been investigated in this work.Results show that CNT media can induce an intensified decomposition of PFOS through oxidative cleavage of C-F bond,of which the pseudo-first-order rate constant（k=0.037 min^-1,5 mg·L^-1 CNT） is substantially higher than that of alkaline-ozonation（k=0.009 min^-1,pH=11） or highly-loaded activated carbon particles（k=0.013 min^-1,5 g·L^-1GAC）.Solution pH was abstracted as a controlling factor,since either acidic or basic environment was adverse to the catalytic reaction because of adsorptive hindrance of PFOS on-catalyst surface.Numerous·OH species were speculated to generate on surface of CNT referring to·OH scavenging experiments,and in situ interact with PFOS at solid/liquid interface.Research outcome can make referential significance for heterogeneous catalytic ozonation by virtue of CNT.