无机阴离子及有机物对过硫酸盐去除废水中苯胺的影响

突发排放废水中可能含有大量阴离子和有机物,其会淬灭自由基和限制基于过硫酸盐的高级氧化技术的应用。考察了过硫酸钠投加量、Fe²⁺投加量、pH、Cl⁻、${rm{HCO}}_3^ - $、${rm{NO}}_3^ - $和其他有机物对过硫酸盐降解苯胺的影响。结果表明：随着过硫酸盐和Fe²⁺浓度的升高,苯胺的去除率也随之增加,但过量投加反而会导致苯胺的去除率下降,活化过硫酸盐氧化去除苯胺的过程符合一级降解动力学;酸性条件有利于Fe²⁺活化过硫酸盐降解苯胺,但在不投加Fe²⁺时碱性条件可以活化过硫酸盐;${rm{HCO}}_3^ - $和硝基苯的存在会抑制苯胺的去除,而${rm{NO}}_3^ - $对苯胺的去除基本没有影响;酚的加入会促进苯胺的去除;Cl⁻的存在可以促进Fe²⁺活化过硫酸盐对苯胺的去除,但其中间产物可能会造成潜在的生态风险,后续需进一步研究。同时,在不投加Fe²⁺时,Cl⁻也可以活化过硫酸盐去除苯胺。通过对自由基的识别,发现${rm{SO}}_4^ - cdot $在降解过程中起主要作用。此外,提出了1种计算Fe²⁺/过硫酸盐体系中${rm{SO}}_4^ - cdot $和·OH稳态浓度的简单方法。该计算方法可用于估算降解过程中产生的${rm{SO}}_4^ - cdot $和·OH的量,并评价不同活化体系下${rm{SO}}_4^ - cdot $和·OH的产率,为氧化机理的研究提供参考。

Impacts of inorganic anions and organic matters on aniline removal in wastewater by ferrous ions activated persulfate

Emergency wastewater contains a large amounts of anions and organics which can scavenge reactive radicals and limit the application of sulfate radical-based advanced oxidation processes. Here, the effects of sodium PS dosage, Fe2+ dosage, solution pH, Cl−, ${rm{HCO}}_3^ - $, ${rm{NO}}_3^ - $, and other organic matter on aniline degradation by persulfate (PS) were studied. The results showed that the aniline removal rate increased with the increase of the concentrations of PS and Fe2+, but their excessive dosages could lead to the decrease of aniline removal, the aniline degradation by Fe2+-activated PS followed a first-order kinetic equation. Acidic conditions were conducive to aniline removal rate by Fe2+-activated PS, while the PS could be activated under alkaline conditions without Fe2+ addition. The addition of bicarbonate ions and nitrobenzene could inhibit aniline removal, while the addition of nitrate ions had slight inhibition effect on aniline removal. The addition of pheon could promote aniline removal. The addition of chloride ions could promote aniline degradation by Fe2+-activated PS, but the intermediates may pose potential risks which need to the further study. In addition, the degradation of aniline could be promoted by chloride ions without ferrous ions addition. By recognizing and analyzing free radicals, we concluded that ${rm{SO}}_4^ - cdot $ plays a major role in aniline degradation. A simple method to calculate the normalized steady-state concentrations of ${rm{SO}}_4^ - cdot $ and •OH in the Fe2+/PS system was proposed. The proposed method for calculating ${rm{SO}}_4^ - cdot $ and •OH could be used to estimate the amounts of ${rm{SO}}_4^ - cdot $ and •OH produced in the process of aniline degradation and evaluate the production rates of ${rm{SO}}_4^ - cdot $ and •OH in different activated systems, providing reference for the study of oxidation mechanism.