赤泥质陶粒吸附模拟酸性废水中铜离子的行为

矿山酸性废水中重金属污染较普遍,利用赤泥陶粒对模拟酸性废水中的Cu2+进行净化处理。实验结果表明,当pH值为3、温度为30 ℃、Cu2+初始浓度为150 mg/L、陶粒添加量为20 g/L、吸附时间为4 h时,Cu2+的去除率达到95.06%。陶粒对Cu2+的吸附符合准二级动力学模型,相关系数为0.998 3,饱和吸附量为7.412 9 mg/g;等温吸附模型中更符合Langmuir等温吸附模型,相关系数为0.993 3。处理废水后的陶粒用硫酸-硝酸浸提,浸出液中重金属离子浓度均低于国家浸出毒性标准,表明陶粒是一种很好的酸性废水处理剂。吸附饱和的陶粒用1 mol/L的NaOH溶液再生效果好。实验结果表明,陶粒对Cu2+的吸附过程是物理吸附和化学吸附的共同作用。

Adsorption behavior of red mud ceramsite to Cu2+ from simulated acidic wastewater

Heavy metal pollution is relatively common in acidic mining wastewater. This study used red mud ceramsite to treat the copper (Cu2+) in the simulated acid wastewater. The results demonstrated that the removal rate of Cu2+ reached 95.06% at a pH of 3, a temperature of 30 ℃, an initial concentration of Cu2+ of 150 mg/L, a ceramsite quantity of 20 g/L, and an adsorption time of 4 h. Sorption kinetics of Cu2+ on ceramsite followed the quasi-second order kinetic model, the correlation coefficient was 0.998 3, and the value of maximum adsorption capacity was 7.412 9 mg/g. The adsorption of Cu2+ on ceramsite could be well described by the Langmuir adsorption isotherm model (R2=0.993 3). Ceramsite after the treatment of wastewater was leached with sulfuric and nitric acid and the concentration of heavy metals detected in the leaching liquid were below the national standards. The results indicated that ceramsite was useful as an absorbent to treat acid mine drainage. The regeneration effect for the adsorbent was optimized with 1 mol/L sodium hydroxide (NaOH) solution. The results showed that the process of adsorption of Cu2+ on ceramsite was a combination of physical and chemical adsorption.