2,4-二氯苯酚的矿物表面化学行为研究

矿物质是土壤中的重要组成成分，本实验采用动态反应和平衡反应研究氧化物矿物表面2,4 二氯苯酚（2,4-DCP）的化学行为.结果表明，无定形铁氧化物、针铁矿、α-MnO₂、δ-MnO₂对自然的或外源的有机化合物有较强的氧化能力，其中对2,4-二氯苯酚的氧化能力是：δ-MnO₂α-MnO₂＞无定形铁氧化物、针铁矿.采用分段法估算反应系统的速率，发现氧化锰氧化2,4-二氯苯酚的反应速率是氧化铁的3～50倍，δ-MnO₂氧化2,4-二氯苯酚的速率是α-MnO₂的1.5～3.2倍.根系分泌物由于参与氧化物表面化学反应，对系统2,4-二氯苯酚的氧化过程产生一定影响，α-MnO₂加入根系分泌物后，2,4-二氯苯酚在溶液中的消减速率明显减慢，δ-MnO₂则相反，在根系分泌物共存下溶液中的2,4-二氯苯酚的转化率增加.Cu复合共存可能影响2,4-二氯苯酚在矿物表面的键合氧化过程，其中δ-MnO₂对铜吸附能力大于α-MnO₂， Cu复合共存对δ-MnO₂表面2,4-二氯苯酚的氧化影响较大.

Surface chemical behavior of 2,4-dichlorophenol in presence of metal oxides

To understand the surface chemistry of phenolic pollutants in the presence of metal oxides, this paper studied the reactions of 2,4-dichlorophenol with metal oxides in a kinetic and batch experiment. The results showed that amorphous ferric oxyhydroxide, goethite, delta-MnO2 and alpha-MnO2 were the potential oxidizing agents of natural and xenobiotic organic compounds. The oxidation rate of 2,4-DCP on the surface of these metal oxides was in order of delta-MnO2 > alpha-MnO2 > iron oxides. It was observed from the pseudo-first-order kinetics that the reaction rates of manganese oxides were 3-50 times higher than those of iron oxides, and delta-MnO2 had a 1.5-3.2 times higher reaction rate than alpha-MnO2. Root exudates had a significant effect on the oxidation ability of metal oxides through changing the surface characteristics or involving in the reaction process. Upon the addition of ryegrass root exudates, the oxidation of 2,4-DCP was decreased in the suspension of alpha-MnO2 while increased in that of delta-MnO2. The coexistence of Cu probably influenced the oxidation process of 2,4-DCP on the surface of metal oxides. A greater negative effect of Cu on the oxidation of 2,4-DCP was also observed in the suspension of delta-MnO2 due to its strong adsorption toward Cu, as compared with that of alpha-MnO2.