氧化镧改性硅酸盐矿物的表征及其除磷机理研究

发布时间：2018-08-31 18:36

【摘要】：磷是导致水体富营养化的限制因素,本研究选取斜发沸石、热液型海泡石、高岭土等3种典型硅酸盐矿物作为研究对象,采用响应面优化方法得到氧化镧改性三种硅酸盐矿物的最佳工艺条件。研究硅酸盐矿物物化特征变化与除磷性能之间的关系,分析硅酸盐矿物材料与氧化镧之间的促进及影响机制,揭示氧化镧改性硅酸盐矿物的作用机理及吸附磷酸根的机理。首先,以氧化镧作为改性剂,采用改进的水解沉淀法对硅酸盐矿物进行改性,改性工艺均可使用Quadratic模型进行模拟,pH值与焙烧温度间的交互作用最明显。斜发沸石、热液型海泡石及高岭土最佳改性pH值条件均为pH=8,改性溶液浓度分别为0.3%、0.4%、0.3%,焙烧温度为300℃C、200℃C、300℃C,此条件下最优改性矿物对5mg/L磷酸根的去除率分别为99.04%、99.62%、99.49%。氧化镧改性硅酸盐矿物在应用溶液pH=3-11的范围内,吸附磷酸根能力不受影响。改进的水解沉淀法制备的氧化镧改性斜发沸石的最大吸附容量可达到15.06mg/g,远高于普通的氯化镧改性工艺制备的改性斜发沸石的吸附容量(1.75mg/g)及文献中报道的镧改性矿物材料。其次,通过研究改性过程中硅酸盐矿物成分变化、晶体结构、分子基团及原子结合能的变化发现：斜发沸石、热液型海泡石改性机理主要包括阳离子交换作用和静电吸附作用,高岭土的改性机理以静电吸附作用为主。改性矿物表面的镧与硅酸盐矿物表面及溶液中的-OH基团结合,形成镧氢氧化物,焙烧作用下转化为镧氧化物。硅酸盐矿物吸附磷酸根的机制研究发现：改性斜发沸石对磷酸根的吸附主要是La-O化学键所引起的路易斯酸碱反应以及表面配合作用；改性热液型海泡石和改性高岭土对磷酸根的吸附以La-O化学键所引起的路易斯酸碱反应为主。最后,进行了三种改性硅酸盐矿物对实际市政污水的应用试验,发现它们对高碑店污水处理厂初沉池出水总磷的去除率可达到80%以上,出水总磷浓度低于1.00mg/L,达到城镇污水处理厂一级B出水标准。同时氧化镧改性硅酸盐矿物不会释放La元素进入水体,影响水质安全。优化得到的改进水解沉淀法工艺,是一项制备富营养化水体中磷污染物吸附材料的绿色、高效的应用技术,可推动硅酸盐矿物吸附材料的研发和应用。
[Abstract]:Phosphorus is the limiting factor of eutrophication in water body. Three typical silicate minerals, such as clinoptilolite, hydrothermal sepiolite and kaolin, are selected as the research objects. The optimum process conditions of three silicate minerals modified by lanthanum oxide were obtained by using the response surface optimization method. The relationship between physical and chemical characteristics of silicate minerals and phosphorus removal properties was studied. The promotion and influence mechanism between silicate mineral materials and lanthanum oxide were analyzed. The mechanism of lanthanum oxide modified silicate minerals and the mechanism of phosphate adsorption were revealed. Firstly, using lanthanum oxide as modifier, the modified hydrolysis precipitation method is used to modify silicate minerals. The Quadratic model can be used to simulate the interaction between pH value and calcination temperature. The optimum conditions of modified pH value of clinoptilolite, hydrothermal sepiolite and kaolin are as follows: the concentration of pH=8, modified solution is 0.30.40, the calcination temperature is 300 鈩，

本文编号：2215824