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为揭示赤泥类钝化剂对Cd2+的吸附规律和动力学特性,研究了纳米化和酸洗处理,以及不同Cd2+添加质量浓度对赤泥类钝化剂吸附Cd2+动力学的影响。结果表明:准二级动力学方程和指数(Ⅱ)型方程可用于描述赤泥对Cd2+的吸附动力学特征。溶液中Cd2+的质量浓度从50mg/L增加到100mg/L,其平衡吸附量相应增加1倍,平衡时间也相应延长。纳米化赤泥、酸洗赤泥、酸洗纳米化赤泥的准二级动力学方程拟合参数K值(反应速率常数)与原状赤泥的比值分别为2.34、0.15、0.63,而指数(Ⅱ)型方程拟合参数-B(吸附量达到平衡吸附量36.8%时所需的时间)与原状赤泥的比值分别为0.53、2.09、0.85。赤泥类钝化剂既作用于Cd2+的吸附离子交换反应,又作用于表面络合反应,吸附速率受膜扩散和颗粒间扩散的联合控制。纳米化增大了赤泥的比表面积,提高了赤泥的吸附性能;酸洗处理也增大了赤泥的比表面积,但同时降低了赤泥的pH值,从而降低了赤泥的吸附性能。
In order to reveal the adsorption and kinetics of Cd2 + by the red mud passivating agent, the effects of nanocrystallization and pickling treatment and the kinetics of Cd2 + adsorption by red mud-based passivating agent were studied. The results show that quasi - second order kinetic equation and exponential type (Ⅱ) equation can be used to describe the adsorption kinetics of red mud on Cd2 +. The mass concentration of Cd2 + in the solution increased from 50mg / L to 100mg / L, the equilibrium adsorption capacity increased by 1 time, and the equilibrium time extended accordingly. The ratio of the K value (reaction rate constant) to the original red mud of quasi-second-order kinetic equation of nano-sized red mud, pickled red mud and pickling nanometerized red mud were 2.34,0.15,0.63 respectively, while the index ( Ⅱ) equation fitting parameters-B (adsorption capacity reaches equilibrium adsorption 36.8% of the time required) with the original red mud ratio were 0.53,2.09,0.85. The red mud passivating agent acts not only on the adsorption ion exchange reaction of Cd2 + but also on the surface complexation reaction, and the adsorption rate is controlled by the combination of membrane diffusion and interparticle diffusion. Nanometer increased the specific surface area of red mud and increased the adsorption capacity of red mud; pickling also increased the specific surface area of red mud, but at the same time decreased the pH of red mud, which reduced the adsorption capacity of red mud .