地下水化学组成对Fe^(2+)氧化产生羟自由基的影响

Effect of Groundwater Components on Hydroxyl Radical Production by Fe(Ⅱ) Oxygenation

羟自由基(·OH)是自然环境中氧化活性最强的物种,对物质转化具有重要影响.前期研究发现地下水接触O2可产生·OH,其中Fe^(2+)氧化起主导作用,但地下水化学组成对Fe^(2+)氧化产生·OH的影响尚不清楚.通过室内模拟实验,探究了地下水中常见组分(Ca^(2+)、Mg^(2+)、腐殖酸(HA)和磷酸根)对Fe^(2+)氧化产生·OH的影响.结果表明,pH 6.5时0.357mM Fe^(2+)在5h内氧化完全,产生约1.8μM的·OH;Ca^(2+)(1~6mM)、Mg^(2+)(1~4mM)对Fe^(2+)氧化和·OH产生无明显影响;HA(10~30mg/L)促进Fe^(2+)氧化和·OH产生,促进效果随pH降低而增强;磷酸根(0.01~0.03mM)抑制Fe^(2+)氧化,对·OH产生的影响为先抑制后促进.

Hydroxyl radical（·OH）is the most reactive oxidant in nature,which significantly impacts the transformation of substance and contaminants.Previous studies have substantiated that exposure of groundwater to O2 can produce · OH through Fe（2＋）oxygenation.However,the effect of groundwater compositions on Fe（2＋）oxygenation and·OH production remainsis unclear.Therefore,this study evaluates the influence of groundwater components（Ca（2＋）,Mg（2＋）,humic acid（HA）and phosphate）on Fe（2＋）oxygenation and resultant·OH production.Results show that at pH 6.5,0.357 mM Fe（2＋）was completely oxidized within 5hwith production of 1.8μM·OH.Ca（2＋）（1-6mM）and Mg（2＋）（1-4mM）had no obvious influence on Fe（2＋）oxidation and ·OH production.HA（10-30mg/L）promoted Fe（2＋）oxidation and ·OH production,and the promotion increased with the decrease in pH.Phosphate（0.01-0.03mM）inhibited Fe（2＋）oxidation and ·OH production in initial stage while promoted Fe（2＋）oxidation and ·OH production later on.