过渡金属辅酶催化降解全氟己磺酸的仿生体系优化

Catalytic degradation of perfluorohexanesulfonate by transition-metal coenzymes:Optimization of the biomimetic systems

优化了过渡金属辅酶仿生降解体系以实现直链(L-PFHxS)和支链全氟己磺酸(Br-PFHxS)的仿生降解和脱氟.结果表明,维生素B_(12)(VB_(12))可同时仿生催化降解L-PFHxS和Br-PFHxS,辅助因子430(F430)仅可仿生降解Br-PFHxS,且降解效能远低于VB_(12),而羟高铁血红素无法仿生降解PFHxS.VB_(12)和F430仿生降解PFHxS过程可采用指数衰减模型进行拟合,表明投加的PFHxS可分为两类,即可降解部分和不可降解部分.VB_(12)轴向配体可影响其仿生催化降解PFHxS效能,其中腺苷钴胺仿生催化PFHxS脱氟的效能最高.nZn0最适宜作为仿生降解体系的电子供体,在60℃和pH=9.0的条件下PFHxS去除率和脱氟率分别高达57.1%±2.9%和8.19%±0.65%,且可降解PFHxS去除速率系数高达1.01d^(-1).

Biomimetic systems containing transition-metal coenzymes as catalyst have been optimized for simultaneous degradation and defluorination of both linear-(L-PFHxS)and branched-perfluorohexanesulfonate(Br-PFHxS).Vitamin B_(12)(VB_(12))catalyzed the reductive degradation and defluorination of both L-PFHxS and Br-PFHxS,whereas hematin did not.For cofactor 430(F430),biomimetic degradation and defluorination was only found for Br-PFOS but not for L-PFHxS.However,the removal rate and defluorination rate of technical PFHxS catalyzed by VB_(12)were both much higher than that catalyzed by F430.Biomimetic degradation of technical PFHxS catalyzed by VB_(12)as well as F430 could well be described by a first-order exponential decay model,indicating that the spiked PFHxS could initially distribute between two completely separate pools with independent degradability,i.e.non-degradable and degradable fractions.The axial ligands of VB_(12)could impact their catalytic defluorination of PFHxS,and the highest defluorination rate was achieved by adenosylcobalamin.Nanoscale zero-valent zinc(nZn0)is the best electron-donor for the biomimetic system under the experimental conditions.At 60℃and pH=9.0,the removal rate and defluorination rate of technical PFHxS were as high as 57.1%±2.9%and 8.19%±0.65%,respectively,with cyanocobalamin as biomimetic catalyst and nZn0as electron-donor,and then the degradable fraction accounted for about 54.6%and its depletion rate was 1.01d-1.