响应面法优化制备复合金属氧化物及其对硫酸根离子吸附效果研究

Optimization of preparation of composite metal oxide by response surface method and its study on adsorption of sulfate ions

使用水稻秸秆作为生物模板,通过共沉淀法制备了一种含锆、铁和锌的复合金属氧化物(RS-Zr-Fe-Zn),并以煅烧温度、秸秆投加量、晶化时间为影响因素,硫酸根离子为响应值,采用响应曲面法对RS-Zr-Fe-Zn吸附剂的制备工艺进行优化,还通过吸附实验研究了p H值、温度、初始硫酸根浓度及吸附剂投加量对硫酸根吸附效果的影响。结果表明:煅烧温度为648℃,秸秆投加量为6.44 g,晶化时间为6.32 h时,其对硫酸根离子的吸附量最大,为161.46 mg/g,且在pH值低于7时具有更好的吸附性能;Freundlich模型对本过程的拟合效果更好,表明硫酸根离子发生多层吸附;RS-Zr-Fe-Zn对硫酸根离子的吸附速率较快,符合准二阶动力学方程。

A composite metal oxide(RS-Zr-Fe-Zn)containing zirconium,iron and zinc was prepared by co-precipitation method using rice straw as a biological template.The preparation process of RS-Zr-Fe-Zn adsorbent was optimized by response surface method with calcination temperature,straw dosage and crystallization time as influencing factors and sulfate ion as response value.The effects of pH value,temperature,initial sulfate concentration and adsorbent dosage on sulfate adsorption were also studied by adsorption experiments.The results showed that the maximum adsorption capacity of sulfate ion was 161.46 mg/g when the calcination temperature was 648°C,the straw dosage was 6.44 g,and the crystallization time was 6.32 h,and it had better adsorption performance when the pH value was lower than 7.Thermodynamic analysis indicated that the Freundlich model provided a better fitting effect on the adsorption process,suggesting that sulfate ion adsorption occurred in multiple layers.Kinetic experiments showed that the adsorption rate of sulfate ions by RS-Zr-Fe-Zn was faster,which was consistent with the quasi-second-order kinetic equation.