红土镍矿制备的花状Mg(OH)_(2)对Cu^(2+)、Ni^(2+)的吸附性能

Preparation of flower-like Mg(OH)_(2)from nickel laterite and its adsorption ability for Cu^(2+)and Ni^(2+)

以红土镍矿湿法提镍后的废液(含(NH4)_(2)SO_(4)的MgSO_(4)溶液)为原料、氨水为沉淀剂、在无分散剂条件下采用水热法制备了片状颗粒组成的六方晶系花状Mg(OH)_(2),并研究了花状Mg(OH)_(2)对Cu^(2+)、Ni^(2+)吸附性能的影响。结果表明:在Mg^(2+)浓度2.0 mol/L、Mg^(2+)与NH4OH摩尔比1:0.5、水热温度120℃、反应时间2 h的条件下合成了形貌完美的花状Mg(OH)_(2)。花状Mg(OH)_(2)去除重金属离子Cu^(2+)、Ni^(2+)的能力良好。在50 mL、Cu^(2+)和Ni^(2+)浓度200 mg/L的溶液中分别添加200和300 mg花状Mg(OH)_(2),吸附时间6 min后,Cu^(2+)和Ni^(2+)的去除率即可达到94.10%和95.46%。表明花状氢氧化镁是重金属离子的高效去除剂。吸附机理研究表明,吸附过程为单分子层吸附,符合Langmuir模型,吸附动力学遵从拟二阶动力学模型。

Employing waste solution after precipitating nickel from nickel laterite hydrometallurgy(MgSO_(4) solution containing(NH4)_(2)SO_(4))using raw material and ammonia water as precipitant,hexagonal flower-like Mg(OH)_(2)was successfully prepared by hydrothermal process without dispersant,which is composed of many ultra-thin sheets.Flower-like Mg(OH)_(2)with perfect morphology can be obtained under the conditions of Mg^(2+)concentration 2.0 mol/L,molar ratio of Mg^(2+)and NH4OH 1:0.5,hydrothermal temperature 120℃,reaction time 2 h.Flower-like Mg(OH)_(2)exhibits good adsorption ability for Cu^(2+)and Ni^(2+).The removal rate of Cu^(2+)and Ni^(2+)reach 94.10%and 95.46%in 6 min by adding 200 and 300 mg of flower-like Mg(OH)_(2),respectively,into 50 mL solution with Cu^(2+)and Ni^(2+)concentrations of 200 mg/L,indicating flower-like Mg(OH)_(2)is a highly effective remover for heavy metal ions.Further studies on adsorption mechanism show that the adsorption characteristic as monolayer was well fitted by the Langmuir model.The adsorption of heavy metal ions was adjusted by the pseudo-second-order kinetic model.