磁性纳米氢氧化锆对硫酸根吸附特性研究

Study of Sulfate Adsorption onto Magnetic Nano-zirconium Hydroxide

以纳米四氧化三铁、氧氯化锆和氨水为原料,用溶胶凝胶法合成了磁性纳米氢氧化锆。通过静态吸附试验研究磁性纳米氢氧化锆对硫酸根的吸附性能。考察了溶液初始pH、吸附剂投加量、温度等因素对吸附效果的影响。结果表明：pH是影响吸附的重要因素,适宜的pH为1~2。吸附容量、去除率均随投加量增大而增大,之后去除率趋于平衡。磁性纳米氢氧化锆对硫酸根吸附过程符合Langmuir单分子层模型。对热力学参数ΔG0、ΔH0、ΔS0进行分析,表明磁性纳米氢氧化锆对硫酸根的吸附为吸热、熵值增加的自发过程。动力学分析表明,准二级动力学模型能更准确地拟合动力学过程。对吸附饱和的磁性纳米氢氧化锆进行脱附和再吸附,脱附率可达90%,再吸附容量为90 mg/g,表明磁性纳米氢氧化锆是一种磁分离性能良好的可以重复利用的硫酸根吸附剂。

Magnetic nano-zirconium hydroxide, prepared by sol-gel method using nano-Fe3O4, ZrOCl2 and NH4OH, was used as an adsorbent for sulfate adsorption experiment investigating the influencing factors of pH, dosage of the adsorbent and temperature. ＂ The experimental results showed the optimal range of pH, the main factor affected the adsorption, was between 1 and 2, and the adsorption isotherm fit well to Langmuir monolayer model. Analysis on thermodynamic parameters △G0, △H0 and △S0 indicated that the adsorption process featured endothermic and spontaneous with an increase of entropy, and the pseudo second-order model could better fit to the dynamic process during adsorption. As to the experiment on desorption of sulfate and regeneration of the saturated adsorbent using NaOH solution, the result showed just a slight decrease of adsorption capacity following a number of times of regeneration, which indicated magnetic nano-zirconium hydroxide as an adsorbent was of perfect characteristics.