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研究了25℃下,不同pH时磷酸盐(KH2PO4)对黄铁矿(FeS2)氧化的影响。流动态中,黄铁矿氧化服从假零级反应规律。经0.1mol/LH2O2+0.01mol/LKH2PO4混合液(pH分别为3,5和7)淋洗480min后,再经相应pH的0.1mol/LH2O2溶液淋洗400min,黄铁矿剩余百分率分别从对照的94.92%,97.52%和99.38%提高到98.15%,99.52%和99.48%,分别增加了3.23%,2.00%和0.10%。pH5和pH7时的对照和处理样品,换用pH3的0.1mol/LH2O2淋洗400min后,则对照组的剩余百分率分别为96.17%和98.16%,下降了1.35%和1.22%。而经磷酸盐处理的变化较小,分别为99.32%和98.95%,仅下降了0.20%和0.53%。随溶液pH提高,黄铁矿氧化速度下降,这与pH升高,导致H2O2氧化能力下降有关。pH7时,OH-和Fe3+反应强烈,生成Fe(OH)3被吸附沉积在黄铁矿表面,抑制黄铁矿氧化,但Fe(OH)3膜不够稳定,对H+浓度较敏感。
The effects of phosphate (KH2PO4) on the oxidation of pyrite (FeS2) at 25 ℃ were investigated. In the fluid state, the pyrite oxidizes obey the rules of fake zero-order reaction. After the rinsing with 0.1 mol / L H2O2 + 0.01 mol / L KH2PO4 (pH 3, 5 and 7 respectively) for 480 min and then with the corresponding pH 0.1 mol / LH2O2 solution for 400 min, the remaining percentage of pyrite was 94.92%, 97.52% and 99.38% increased to 98.15%, 99.52% and 99.48%, increased by 3.23%, 2.00% and 0.10% respectively. Control and treatment samples at pH 5 and pH 7, after switching to pH 3 0.1 mol / LH 2 O 2 for 400 min, the remaining percentage of the control group was 96.17% and 98.16% respectively, down 1.35% and 1 .22%. However, the change of phosphate treatment was smaller, which was 99.32% and 98.95% respectively, only decreased by 0.20% and 0.53% respectively. With the increase of solution pH, the rate of pyrite oxidation decreased, which was related to the increase of pH and the decrease of oxidative capacity of H2O2. At pH7, Fe (OH) 3 was adsorbed and deposited on the surface of pyrite, which inhibited the oxidation of pyrite, but the Fe (OH) 3 film was not stable enough and sensitive to H + concentration.