UV强化草酸络合Fe3+活化过硫酸盐氧化降解苯胺

采用UV-草酸络合Fe~(3+)UV-Fe(C_2O_4)3-3]活化过硫酸钠(PS)氧化降解苯胺,研究了Fe(C_2O_4)3-3浓度,PS浓度,pH对PS活化效率及苯胺氧化降解效果的影响机制.结果表明,Fe(C_2O_4)3-3浓度和pH决定了UV-Fe(C_2O_4)3-3体系中Fe~(3+)向Fe2+的转化过程,并对活化PS氧化降解苯胺产生显著影响.随着Fe(C_2O_4)3-3浓度增加,PS的分解率不断提高,但当浓度高于0.75 mmol·L~(-1)时,草酸根离子(C2O_2-4)对硫酸根自由基(SO·-4)的竞争以及SO·-4之间的相互淬灭作用降低了苯胺的降解效果,降解速率大小顺序为5 mmol·L~(-1)0.25 mmol·L~(-1)0.5 mmol·L~(-1)1 mmol·L~(-1)0.75 mmol·L~(-1);中性和碱性条件不利于Fe(C_2O_4)3-3发生光化学反应生成Fe2+,但当初始pH为7和9时,由于PS活化分解过程降低反应体系pH,反应300min时PS的活化率可分别达到74%和67%,苯胺去除率分别高达91%和97%,均高于初始pH为酸性条件下的结果;苯胺降解率随初始PS浓度增加而增大,当PS浓度大于10 mmol·L~(-1)时,苯胺降解过程由二级反应变为准一级反应,但此时过量的PS因与SO·-4发生反应而显著降低PS用于氧化降解苯胺的利用率.

Enhanced Degradation of Aniline by PS Oxidation in the Presence of UV and Ferric Oxalate

Oxidative degradation of aniline by Sodium Persulfate (PS) activated with UV-ferric oxalateUV-Fe(C₂O₄)₃^3-] was studied. The effects of Fe(C₂O₄)₃^3- concentration, PS concentration, and pH on PS activation and aniline degradation were investigated. Results showed that Fe(C₂O₄)₃^3- concentration and pH determined the reduction process of Fe³⁺ into Fe²⁺, which had significant effects on the oxidative degradation of aniline by PS. With an increase in Fe(C₂O₄)₃^3- concentration, PS decomposition increased; however, when concentrations were>0.75 mmol·L^-1, aniline degradation efficiency decreased due to competition with oxalate ions (C₂O₄^2-) for SO₄^·-. Aniline degradation efficiency in processes with different initial Fe(C₂O₄)₃^3- concentrations followed the sequence:5 mmol·L^-1 < 0.25 mmol·L^-1 < 0.5 mmol·L^-1 < 1 mmol·L^-1 < 0.75 mmol·L^-1. Neutral and alkaline conditions were not conducive to Fe²⁺ formation via photochemical reaction. However, with initial pH values of 7 and 9, PS activation efficiency reached 74% and 67% respectively after 300 min due to pH decline during the reaction; aniline removal efficiency was as high as 91% and 97%, respectively, higher than under initial acidic conditions. Furthermore, increased PS concentration was conducive to improvement of aniline degradation efficiency, but when PS concentration was>10 mmol·L^-1, the aniline degradation process followed the pseudo first-order reaction kinetics model instead of the second-order reaction kinetics model. PS efficiency for aniline degradation decreased significantly due to the reaction between excessive PS and sulfate radicals.