VUV/HPW/BMMs体系对全氟辛酸（PFOA）的脱氟研究

采用真空紫外灯(VUV)和双模型介孔材料(BMMs)负载磷钨酸(HPW)催化剂构建光催化体系,探究该体系对水中全氟辛酸(PFOA)的脱氟效果.研究了PFOA初始浓度、HPW/BMMs投加量、初始p H值对体系脱氟的影响,并采用响应曲面法(Response Surface Method,RSM)分析了最佳边界反应条件.结果表明,体系对PFOA具有明显的脱氟效果:脱氟效率随PFOA初始浓度的增大而减小;催化剂投加量为0.2 g·L~(-1),脱氟效率最高达50.2%;体系p H为3~4时,体系脱氟效果显著.基于Box-Behnken响应曲面法,各影响因子对脱氟效率的显著性排序为:p HPFOA初始浓度HPW/BMMs投加量.p H值与HPW/BMMs投加量及初始PFOA浓度交互作用显著,模型回归性良好,最佳运行条件为:p H=3.82,HPW/BMMs投加量为0.3 g·L~(-1),PFOA初始浓度为20 mg·L~(-1),反应4 h的脱氟率达到52.6%,与预测值相比偏差为1.2%.本研究为高效降解全氟化合物提供了新思路.

Defluorination of aqueous perfluorooctanoic acid by combination of vacuum ultraviolet and bimodal mesoporous materials supported phosphotungstic acid catalyst

A combined process of vacuum ultraviolet (VUV) and the catalyst prepared by supporting phosphotungstic acid (HPW) on bimodal mesoporous SiO₂ (BMMs) was built to explore the defluorination of aqueous perfluorooctanoic acid (PFOA). The effect of PFOA concentration, HPW/BMMs dosage and solution pH on the defluorination of the photocatalytic system were discussed, and the response surface orthogonal test (RSM) was used to optimize and analyze the optimal reaction conditions. The results indicate that the degradation of PFOA improved significantly in the system under low PFOA concentration, dosage of the catalyst (0.2 g·L^-1) and pH 3~4. Based on the Box-Behnken response surface method, the significance of each influencing factor was pH > PFOA initial concentration > HPW/BMMs dosage. The synergetic effect of pH with HPW/BMMs dosage and PFOA concentration on defluorination were all significant. The optimum operating conditions are pH 3.82, HPW/BMMs dosage of 0.3 g·L^-1 and initial PFOA concentration of 20 mg·L^-1, and the defluorination rate of the reaction was up to 52.6% after 4 h radiation. The predicted values agreed well with the experimental values with only 1.2% deviation.