黄铁矿对六价铬还原作用的研究

Study on the reduction of Cr^(6+) by pyrite

研究了温度、pH和悬浮液中黄铁矿质量浓度等因素对黄铁矿还原Cr6+反应速率的影响。结果显示:随着温度、酸度和黄铁矿质量浓度的增加,黄铁矿对Cr6+的去除速率显著提高。25℃和pH 4.0时,在外加邻啡罗啉(消除Fe2+的作用)和未加邻啡罗啉下过量黄铁矿对Cr6+的去除率于20 h、40 h和60 h时依次分别为17%、27%、44%和32%、55%、86%,前者约为后者的一半。表明黄铁矿组成中Fe2+和S22-均能有效地还原Cr6+。黄铁矿在酸性溶液中溶解速率相对较快,并且容易达到溶解平衡。然而,由于反应形成的部分难溶物吸附沉积在矿物表面,导致剩余黄铁矿表面Fe2+的溶解速率要缓慢得多。

The effects of temperature, pH and concentration of pyrite in suspension on Cr^6＋ reduction by pyrite were studied. The results showed that rate of removal of Cr^6＋ by pyrite increased with temperature, acidic degree and concentration of pyrite. Both Fe^2＋ and S2^2- , consisted of pyrite, reduced Cr^6＋ to Cr^3＋ effectively. The percentage of removal of Cr^6＋ was reduced by about 50% when the role of Fe^2＋ in reducing Cr^6＋ was suppressed by 1,10-phenanthroline, a strong coordinating agent with Fe^2＋. The dissolution of pyrite in acidic solution was relatively fast and easily reached to dissolution equilibrium. But, residue of pyrite after the reaction dissolved rather slowly, partially resulting from the covering of the product of Crx Fe1-x （OH）3.