碳酸镧除磷剂的制备及其吸附性能的研究

发布时间：2018-05-30 05:50

  本文选题：除磷 + 碳酸镧　； 参考：《浙江大学》2017年硕士论文

【摘要】：磷是水体中的主要污染物,水中过多的磷将导致水体富营养化,所以有效去除废水中的磷是亟待解决的问题。目前吸附法除磷效果易受pH影响,难以在中性条件下达到较高的去除效率,本文通过对含镧吸附剂的研究,扩大了除磷剂的pH适用范围,提高了其在中性及弱碱性条件下的除磷效果,降低了除磷成本。本文首先从不同金属离子中筛选出了除磷效果最好的镧离子,接着研究了不同镧化合物对磷的去除率,得到除磷效果最好为碳酸镧,在此基础上,研究了制备条件对碳酸镧、金属掺杂碳酸镧以及镧改性膨润土除磷效果的影响,最终得到了吸附速率快、能在中性条件下高效除磷的铁-镧改性膨润土(B-FeLa),本文的概括如下:首先,研究了铁、钙、镁、镧四种金属离子对不同浓度KH2PO4的去除效果,筛选出最有效的除磷元素为镧;接着对比了氢氧化镧(C-La(OH)3)、氧化镧(C-La2O3)和碳酸镧(C-La2(CO3)3)三种镧化合物在不同时间和pH条件下对磷的去除率。结果表明:C-La(OH)3、C-La2O3和C-La2(CO3)3的除磷实验中,C-La2(CO3)3是除磷效率更高的镧化合物,在pH=7.5温度为25 ℃的条件下符合Langmuir等温吸附曲线,饱和吸附量达到了 66.23 mg/g。其次,探究制备条件对制得的La2(CO3)3组成、结构和除磷效率的影响,最后研究了除磷效率最高的碳酸镧在不同条件下对磷的吸附。结果表明:除磷效率最高的仍为La2(CO3)3;最优制备的条件是:沉淀剂为Na2CO3,沉淀pH为8,沉淀温度为45℃,干燥温度为35℃ 在除磷实验中,La2(CO3)3达到平衡时间缩短至12h,饱和吸附量增加到了 112.36 mg/g。然后,采用共沉淀的方法合成了不同金属掺杂的碳酸镧除磷剂,以除磷效率最高的铁-镧除磷剂(Fe-La)为对象,继续研究了铁镧掺杂比例、沉淀pH和金属离子浓度对铁镧复合物组成及除磷效率的影响,确定最佳的制备条件是:总金属离子浓度为20 mmol/L,沉淀pH = 8,n(Fe):n(La)= 0.3:1。研究结果表明,Fe-La比表面积增大,等电点升高,除磷效果受pH影响减小;饱和吸附量达到了 101.09 mg/g。最后,研究了不同方法制得的镧改性膨润土的除磷效果,以B-FeLa为对象系统地讨论了 B-FeLa的除磷效果。结果表明B-FeLa除磷速率提高,平衡反应时间缩短到了 4 h;饱和吸附量达到了 27.86mg/g,除磷效果受pH的影响小。
[Abstract]:Phosphorus is the main pollutant in water, and excessive phosphorus in water will lead to eutrophication, so it is an urgent problem to remove phosphorus from wastewater effectively. At present, the removal effect of phosphorus by adsorption method is easily affected by pH, and it is difficult to achieve a higher removal efficiency under neutral conditions. Through the study of lanthanum adsorbent, the pH range of phosphorus removal agent has been expanded in this paper. The efficiency of phosphorus removal under neutral and weak alkaline conditions was improved, and the cost of phosphorus removal was reduced. In this paper, the best phosphorus removal efficiency was obtained from different metal ions, and then the phosphorus removal efficiency of different lanthanum compounds was studied. It was found that the best phosphorus removal effect was lanthanum carbonate. On this basis, the preparation conditions of lanthanum carbonate were studied. The effect of metal doped lanthanum carbonate and lanthanum modified bentonite on the removal of phosphorus was studied. Finally, the Fe-La modified bentonite with fast adsorption rate and high efficiency phosphorus removal under neutral conditions was obtained. The summary of this paper is as follows: firstly, iron, calcium, magnesium, iron and lanthanum modified bentonite were obtained. The removal effect of lanthanum ions on KH2PO4 with different concentrations was screened out as the most effective phosphorus removal element, and the phosphorus removal efficiency of three lanthanum compounds (lanthanum hydroxide C-LaHH _ 3, lanthanum oxide C-La _ 2O _ 3) and lanthanum carbonate C-La _ 2o _ 3CO _ 3C _ 2O _ 3 were compared at different time and pH. The results show that in the experiment of phosphorus removal by C-La2(CO3)3 and the ratio of C-LaH3O _ 2O _ 3 and C-La2(CO3)3, the lanthanum compounds with higher phosphorus removal efficiency are found to be the lanthanum compounds with higher phosphorus removal efficiency. Under the condition of pH=7.5 temperature of 25 鈩，

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