摘要
采用La3+、Fe^(2+)、Fe3+和粉末状天然沸石制备了一种镧-Fe_3O_4-沸石复合材料,通过批量吸附实验考察了该复合材料对水中磷酸盐和铵的吸附作用.结果表明,镧-Fe_3O_4-沸石复合材料对水中磷酸盐和铵的单位吸附量随吸附剂投加量的增加而降低,对磷酸盐和铵的去除率随吸附剂投加量的增加而增加.当溶液pH值由6逐渐增加到11时,镧-Fe_3O_4-沸石复合材料对水中磷酸盐和铵的吸附能力逐渐下降.镧-Fe_3O_4-沸石复合材料对水中磷酸盐的吸附平衡数据可以采用Langmuir、Freundlich和Dubinin-Redushkevich(D-R)等温吸附模型加以拟合,对铵的吸附平衡数据可以采用Langmuir和D-R等温吸附模型加以拟合.根据Langmuir模型计算得到的镧-Fe_3O_4-沸石复合材料对水中磷酸盐和铵的最大单位吸附量分别为12.9 mg·g^(-1)(以磷计)和6.99 mg·g^(-1)(以铵计).镧-Fe_3O_4-沸石复合材料对水中磷酸盐和铵的吸附动力学过程可以采用准二级动力学方程加以描述.升高反应温度增强了镧-Fe_3O_4-沸石复合材料对水中磷酸盐和铵的吸附.溶液存在的氯离子、硫酸根离子和碳酸氢根离子对镧-Fe_3O_4-沸石复合材料吸附磷无负面影响.溶液存在的钾离子对镧-Fe_3O_4-沸石复合材料吸附铵的负面影响最大,其次为钠离子,钙离子的负面影响最小.1 mol·L^(-1)NaOH溶液可以使50%左右吸附到吸附剂上的磷酸盐解吸下来.1 mol·L^(-1)NaCl溶液可以使98%左右吸附到吸附剂上的铵解吸下来.当溶液pH值为7时,镧-Fe_3O_4-沸石复合材料对磷酸盐的吸附机制主要是配位体交换作用.镧-Fe_3O_4-沸石复合材料对铵的吸附机制主要是阳离子交换作用.
A novel lanthanum / magnetite / zeolite（ La / Fe_3O_4/ Zeo） composite was prepared,characterized and used as an adsorbent to remove phosphate and ammonium from aqueous solution.The adsorption characteristics of phosphate and ammonium from aqueous solution onto the La / Fe_3O_4/ Zeo composite were investigated using batch experiments. The phosphate and ammonium removal efficiencies increased with adsorbent dosage,while the amount of phosphate or ammonium adsorbed on the La / Fe_3O_4/ Zeo composite decreased with adsorbent dosage. The phosphate and ammonium adsorption capacity decreased with solution p H from 6 to 11. The equilibrium adsorption process of phosphate on the composite could be described by the Langmuir,Freundlich and Dubinin-Redushkevich（ D-R） isotherm models. The equilibrium adsorption process of ammonium could be described by the Langmuir and D-R isotherm models. The maximum phosphate and ammonium adsorption capacities were determined to be 12.9（ mg P）·g^（-1） and 6.99（ mg NH＋4）·g^（-1）,respectively（ pH 7 and 298 K）. The phosphate and ammonium adsorption capacities for the La /Fe_3O_4/ Zeo composite increased with increasing reaction temperature. The adsorption kinetic of phosphate and ammonium can be well described by the pseudo-second-order kinetic equation. The presence of chloride,sulfate or bicarbonate in solution had no effect on the adsorption of phosphate on the La / Fe_3O_4/ Zeo composite. The presence of potassium or sodium ion in solution had a great negative effect on the adsorption of ammonium on the La / Fe_3O_4/ Zeo composite,while the presence of calcium ion had a slight negative effect on the adsorption of ammonium. The desorption studies showed that 50% phosphate and 98% ammonium desorbed in 1 mol·L^（-1）NaOH solution and1 mol·L^（-1）NaCl solution,respectively. The main mechanism for phosphate adsorption onto the La / Fe_3O_4/ Zeo composite at pH 7 was ligand exchange interaction,and the main mechanism for ammonium adsorption was cation exchang
出处
《环境化学》
CAS
CSCD
北大核心
2015年第12期2287-2297,共11页
Environmental Chemistry
基金
国家自然科学基金(50908142
51408354)
上海市科学技术委员会科研项目(10230502900)
上海市自然科学基金(15ZR1420700)资助
