高碘酸盐光化学降解水中PFOA研究

Photo-chemical Decomposition of Perfluorooctanoic Acids in Aqueous Periodate

研究了反应气氛和TiO2对全氟辛酸(PFOA)的光化学降解行为的影响.结果表明,在254 nm紫外光照下,PFOA光解十分微弱,加入IO 4-显著增强PFOA光解.与氮气气氛相比,氧气气氛对PFOA光化学降解有抑制作用.PFOA在UV/TiO2/IO 4-体系中的降解效果低于在UV/IO 4-体系,反应120 min时,PFOA降解率为54%,降低了15%,这是由于均相反应和非均相反应发生竞争,光催化体系中产生的大量.OH消耗了IO 4-,使得IO 4-光解生成IO3.的反应受到抑制,从而抑制了PFOA的分解.HPLC/MS分析表明,PFOA光降解时逐级生成短链全氟羧酸(PFCAs).

The influence of reaction atmosphere and TiO2 on photochemical decomposition of perfluorooctanoic acid（PFOA） in aqueous periodate was investigated using a type of low-pressure mercury lamps emitted at 254 nm. PFOA photolysis was slight with 254nm light irradiation under nitrogen, whereas significant decomposition PFOA obtained with the addition of IO4- . In addition, oxygen restrained photochemical decomposition of PFOA. In UV/TiO2/IO4- system, PFOA degradation ratio was 54% , 15% lower than that for UV/IO4 system. ^＋OH radicals generated from UV/TiO2 system exhausted a lot of IO4^- , resulting in lower degree of IO3^- production. IO3^- was high reactive radical which great excitated PFOA decomposition. The accumulation of short-chain perfluorocarbonxylic acids （PFCAs） as products were identified with HPLC/MS. PFCAs bearing shorter perfluoroalkyl groups were formed in a stepwise way from PFCAs that bear longer perfluoroalkyl groups.