草酸铁光化学体系在自然界中广泛存在,此体系可以内源生成过氧化氢,构成Fenton体系,产生羟基自由基(·OH),用于降解有机污染物.通过测定赤铁矿(α-Fe2O3)和针铁矿(α-FeOOH)两种铁氧化物-草酸体系在光降解五氯酚(PCP)过程中草酸和pH的变化,计算反应过程中各种Fe(Ⅲ)和Fe(Ⅱ)物种的分配情况,分析影响体系活性的关键因素.研究表明,体系中的铁物种分配和pH通过影响体系的铁循环直接影响体系的反应活性.相同初始pH,不同草酸初始浓度下,高活性的Fe(Ⅱ)物种分配具有较大差异从而影响体系的铁循环速率和反应活性.不同初始pH,达到饱和吸附的相同草酸初始浓度下,高活性的Fe(Ⅱ)和Fe(Ⅲ)物种均为体系控制物种,而pH通过影响Fe(Ⅲ)的还原速率从而影响体系的铁循环速率和反应活性.
The photochemistry system of Fe-oxalic acid is ubiquitous in nature,in which H2O2,Fenton reaction and ·OH can be formed in situ.In this paper,during the photodegradation of pentachlorophenol (PCP) in hematite (α-Fe2O3) and goethite (oα-FeOOH) system with oxalic acid,the variation of oxalic acid and pH were determined,the distribution of various Fe species were calculated and the critical factors of system were explored.The results showed that the distribution of Fe species and pH greatly influenced the activity of system by regulating the iron redox cycling.At the same initial pH and different initial concentrations of oxalic acid,the proportion of high activity Fe (Ⅱ) was different which greatly influenced the efficiency of the iron cycling and the activity of system.At different initial pH and same initial concentration of oxalic acid approaching the maximum amount of adsorption,the dominant species of Fe (Ⅱ) and Fe (Ⅲ) were all high activity,pH influenced the efficiency of the iron cycling and the activity of system by influencing the reduction rate of Fe (Ⅲ).
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