Mg/Fe水滑石吸附水中磷的动力学及热力学研究  

Study on kinetic and thermodynamics for Mg/Fe layered double hydroxide adsorbing phosphate from aqueous solution

作　　者：商丹红[1] 王琦[1] 张志生[1] 

机构地区：[1]江苏科技大学环境与化学工程学院,江苏镇江212018

出　　处：《环境污染与防治》2015年第4期47-52,共6页Environmental Pollution & Control

摘　　要：以MgCl2和FeCl3为原料通过共沉淀法制备了Mg/Fe水滑石,并对其进行焙烧得到了焙烧态Mg/Fe水滑石。采用X射线衍射（XRD）和傅里叶红外光谱（FTIR）对所得产物进行了结构表征。利用焙烧前后的水滑石作吸附剂吸附处理含磷废水,比较了两者对磷的吸附能力,并在不同温度和pH条件下进行了吸附动力学实验。结果表明,焙烧前后的水滑石对磷都具有很好的吸附能力,但300℃焙烧后水滑石的吸附能力提高了约5%。动力学实验表明,水滑石对磷的吸附可很好地用准二级动力学方程进行描述,其线性相关系数达0.999以上。在15∽35℃下进行了等温吸附实验,结果发现水滑石对磷的吸附更符合Langmuir方程。经热力学研究发现,标准吸附焓变（ΔH0）〉0J/mol、标准吸附自由能（ΔG0）〈0J/mol和标准吸附熵变（ΔS0）〉0J/（mol·K）,说明水滑石对磷的吸附反应是自发的吸热反应,且是一个熵增加的过程。Mg/Fe layered double hydroxides（LDH）were synthesized via coprecipitation method with MgCl2 and FeCl3 as precursors,and Mg/Fe layered double oxides（LDO）was obtained when LDH was calcined.The products were characterized by X-ray diffraction（XRD）and FTIR.LDH and LDO,as adsorbents,were used to remove phosphate at different pH value and reaction temperature.The results showed that LDH and LDO were both particularly efficient in removing phosphorus,however,phosphate-uptake capacity of LDO-300 was improved by about 5%.The adsorption kinetic data was described by pseudo-second-order model very well,their linear correlations was above0.999.The adsorption isotherm test carried at 15-35 ℃ was well fitted with Langmuir equation.Thermodynamics studies showed that adsorption gibbs free energyΔG00J/mol,enthalpyΔH00J/mol and entropyΔS00J/（mol·K）,which indicated that the phosphate adsorption on LDH and LDO was an spontaneous endothermic process of entropy increase.

关 键 词：Mg/Fe水滑石 磷 吸附 动力学 热力学 

分 类 号：X52[环境科学与工程—环境工程]