铝锆颗粒吸附材料去除水中氟、磷性能及机理研究

发布时间：2018-12-14 04:14

【摘要】：吸附法因其低廉、高效及操作方便等优点而被广泛用作深度净水工艺,该技术的关键在于选取合适的吸附材料。针对水体中氟(F)、磷(P)污染物超标的问题,本研究研发出一种新型高效的吸附材料——颗粒型铝锆复合金属氧化物(Aluminium Zirconium Granular Adsorbent,AZGA),通过热失重、抗压性实验、XRD、BET、Zeta电位分析等表征手段研究了AZGA的表面物化特性和结构特征;通过吸附动力学、吸附等温线、pH影响和共存离子影响实验来探讨了该吸附剂对F、P的吸附特性及水质因子影响规律;利用SEM-EDS、Mapping、FTIR、XPS、NMR、Raman等表征技术解释了AZGA对F、P的吸附机理;通过解吸-再生实验和动态小柱实验评价了吸附剂动态除F/P效果及再生性能,主要研究成果如下:1.通过对比不同比例的铝、铁、锆复合吸附剂对F、P的去除效果,确定了最佳吸附剂为Al:Zr=3:1的铝锆复合金属氧化物,以聚乙烯醇(PVA)为粘合剂采用挤压法制得粒径为2~2.5mm的AZGA颗粒,并用多项表征技术对其表面特性进行研究后发现:AZGA呈无晶型结构,最大机械载荷为34.21N,比表面积为29.55 m2/g,Zeta电位pHpzc=6.93,材料表面含有大量的羟基基团,主要元素有C、H、O、Al、Zr、S。2.AZGA除F、P的静态实验结果表明:AZGA除F的动力学特征符合拟二阶模型、除P动力学特征符合Power模型,这说明F/P的吸附都在异构表面发生,且以化学吸附为主;颗粒内扩散模型拟合结果表明AZGA对F、P的吸附速率受到不止一个反应过程的影响。同时,AZGA对F/P吸附等温线特征更符合Freundlich模型,这进一步验证了吸附以化学作用为主,AZGA对F和P的最大吸附量分别是65.07mg/g和20.76mg/g,高于大多数的其他颗粒型吸附剂。3.AZGA热力学参数分析表明其吸附为自发型吸热反应;AZGA除F的最佳pH值为6.93,除P的最佳pH值为3;阴离子对AZGA除F除P均起抑制作用,其中PO43-对除F抑制最大,SiO32-对除P抑制最大,其干扰作用主要归结于阴离子之间的竞争吸附作用;Ca、Mg等阳离子则均可通过架桥作用来促进F、P的吸附。4.AZGA除F的动态过柱及再生实验表明:最佳再生浓度为0.3mol/LNaOH,循环五次后吸附效果仍可达到首次吸附的71.34%;当过柱体积达到808BV时,出水F-浓度为0.997mg/L,且再生过柱体积可达704BV,相比初次吸附,过柱体积降低了12.87%,吸附容量下降了16.6%。5.AZGA除P的动态过柱及再生实验表明:最佳再生浓度为0.3mol/LNaOH,五次循环再生后吸附效果仍可达到首次吸附的77.8%;当过柱体积达到时,初次过柱吸附时出水P浓度超出国家一级A与一级B标准时的过柱体积分别为584BV、780BV,且动态再生后的过柱体积分别为504BV、636BV,对比再生过柱前后,过柱体积降低了18.5%,吸附容量下降了23.7%。6.对AZGA吸附F、P前后的样品进行SEM-EDS、Mapping、FTIR、XPS、NMR、Raman等表征分析后发现,AZGA主要通过表面丰富的羟基与F、P发生结合,少部分F、P还可与AZGA表面嵌入的SO42-发生离子交换反应。
[Abstract]:Adsorption method is widely used in deep water purification process because of its advantages of low cost, high efficiency and convenient operation. The key of this technology is to select suitable adsorption materials. Aiming at the problem of exceeding the standard of fluorine (F), phosphorus (P) pollutants in water, a new and high efficient adsorbent material, granular aluminum zirconium composite metal oxide (Aluminium Zirconium Granular Adsorbent,AZGA), was developed in this study. Through the experiments of thermogravimetric, compressive resistance, XRD,, The surface physicochemical and structural characteristics of AZGA were studied by means of BET,Zeta potential analysis. Adsorption kinetics, adsorption isotherm, influence of pH and coexisting ions were studied to study the adsorption characteristics and water quality factors of the adsorbent. The adsorption mechanism of AZGA on FNP was explained by means of SEM-EDS,Mapping,FTIR,XPS,NMR,Raman and other characterization techniques. Through desorption and regeneration experiments and dynamic column experiments, the dynamic removal of F / P and regeneration performance of adsorbent were evaluated. The main results are as follows: 1. By comparing the removal efficiency of aluminum, iron and zirconium composite adsorbents with different ratios, it was determined that the best adsorbent was the aluminum zirconium composite metal oxide with Al:Zr=3:1. AZGA particles with diameter of 2~2.5mm were prepared by extruding polyvinyl alcohol (PVA) as binder. The surface properties of AZGA particles were studied by multiple characterization techniques. It was found that AZGA had amorphous structure and the maximum mechanical load was 34.21N. There are many hydroxyl groups on the surface of pHpzc=6.93, material with a specific surface area of 29.55 m2 / g ~ (-1) G ~ (2 +). The static experimental results of P show that the kinetic characteristics of AZGA and P are in accordance with the quasi second order model and the Power model respectively, which indicates that the adsorption of F / P occurs on the isomerization surface and is mainly chemisorption. The fitting results of intraparticle diffusion model show that the adsorption rate of FNP by AZGA is affected by more than one reaction process. At the same time, the isotherm characteristics of F / P adsorption by AZGA are more in line with the Freundlich model, which further verifies that the adsorption is mainly chemical. The maximum adsorption capacity of F and P by AZGA is 65.07mg/g and 20.76 mg / g, respectively. Higher than most other granular adsorbents. 3.AZGA thermodynamic parameters analysis showed that the adsorption was self-generated endothermic reaction. The optimum pH value of AZGA divided by F was 6.93, and the best pH value of P was 3. The anion inhibited the removal of F and P by AZGA, especially by PO43- and SiO32-, which was mainly attributed to the competitive adsorption between anions. Ca,Mg and other cations can promote the adsorption of FNP by bridging. The dynamic column and regeneration experiments of 4.AZGA for removing F indicate that the optimum regeneration concentration is 0.3mol / L NaOH, and the optimum regeneration concentration is 0.3mol / L NaOH, and the optimum regeneration concentration is 0.3mol / L NaOH. After five cycles, the adsorption effect can still reach 71.34 of the first adsorption. When the column volume reaches 808BV, the effluent F- concentration is 0.997mg / L, and the regenerated column volume can reach 704BV, which is 12.87% lower than the initial adsorption. The adsorption capacity of 16.6%.5.AZGA decreased the dynamic column and regeneration experiments showed that the optimum regeneration concentration was 0.3 mol / L NaOH, and the adsorption effect was still 77.8% of the first adsorption after the fifth cycle regeneration. When the column volume is reached, when the effluent P concentration exceeds the national first class A and B standards, the column volume is 584 BV or 780 BV respectively, and the dynamic regenerated column volume is 504 BV or 636 BV, compared with that before and after regeneration. The volume of the column decreased by 18.5and the adsorption capacity decreased by 23.70.6. The samples before and after AZGA adsorption were characterized by SEM-EDS,Mapping,FTIR,XPS,NMR,Raman. It was found that AZGA binds to FNP mainly through the abundant hydroxyl groups on the surface. P can also exchange ions with SO42- embedded on the surface of AZGA.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;X52;O647.3

【相似文献】