多孔二氧化硅的动态吸附特性研究

发布时间：2018-11-16 09:52

【摘要】：随着现代工业的发展,含有重金属及染料的废水排放造成严重的环境污染。吸附法是处理废水中重金属离子和染料的有效方法之一。本文采用比表面积大的多孔二氧化硅、负载在硅砂表面的多孔二氧化硅以及改性的多孔二氧化硅做为吸附剂来动态吸附水溶液中的六价铬离子、锌离子以及亚甲基蓝染料。实验所用介孔、微孔二氧化硅是由硅砂在强碱溶液中水热条件下部分溶出物做为硅源,十六烷基三甲基溴化铵(CTAB)为表面活性剂,调节不同的pH值而制得。用相同的方法,在未溶硅砂表面原位形成SiO_2-表面活性剂复合包覆层,然后经干燥煅烧后获得负载在硅砂上的多孔二氧化硅(以下简称负载SiO_2);负载SiO_2再利用3-氨丙基三乙氧基硅烷(KH550)修饰改性得到改性负载多孔二氧化硅(以下简称改性SiO_2)。实验研究了重金属离子和染料溶液的pH值、初始浓度、流量的大小以及吸附剂的量对动态吸附效果的影响。多孔二氧化硅对六价铬离子和锌离子的动态吸附过程用Thomas模型的非线性形式进行拟合,对亚甲基蓝动态吸附的过程用Thomas和Yoon-Nelson模型进行拟合,Thomas模型拟合的效果更好。通过实验确定对六价铬、锌离子动态吸附时的最佳条件。在最佳吸附条件下,当吸附剂分别为介孔SiO_2、微孔SiO_2、改性Si O_2、负载SiO_2、硅砂时,对六价铬吸附时,在5min的吸附率分别为58.02%、99.06%、99.9%、16.17%、3.37%;达到饱和的时间分别为255min、285min、185min、65min、15min;对锌离子吸附时,在5min的吸附率分别为92.3%、94.48%、98.49%、91.83%、72.44%;达到的饱和时间分别为250min、270min、240min、125min、65min。因此,微孔SiO_2相比介孔SiO_2对六价铬、锌离子的动态吸附效果好;改性SiO_2、负载SiO_2、硅砂对六价铬、锌离子动态吸附的效果依次变差。研究不同的多孔二氧化硅动态吸附水溶液中的亚甲基蓝。当吸附剂分别为介孔二氧化硅、微孔二氧化硅、负载SiO_2、硅砂时,动态吸附穿透时间分别为215min、375min、255min、7min;饱和时间分别为600min、840min、600min、45min。由结果可看出微孔SiO_2动态吸附水溶液中的亚甲基蓝比介孔SiO_2的吸附效果好,负载SiO_2的吸附效果比硅砂的较好。
[Abstract]:With the development of modern industry, the waste water containing heavy metals and dyes causes serious environmental pollution. Adsorption is one of the effective methods to treat heavy metal ions and dyes in wastewater. In this paper, porous silica with large surface area, porous silica loaded on silica sand surface and modified porous silica are used as adsorbents to dynamically adsorb hexavalent chromium ion, zinc ion and methylene blue dye in aqueous solution. The mesoporous silica used in the experiment was prepared by using silica sand as silicon source in hydrothermal solution and cetyltrimethylammonium bromide (CTAB) as surfactant to adjust different pH values. In the same way, the SiO_2- surfactant composite coating layer was formed on the surface of the undissolved silica sand in situ, and then the porous silica loaded on the silica sand (hereinafter referred to as SiO_2) was obtained after dry calcination. The modified porous silica (SiO_2) was prepared by modified SiO_2 with 3-aminopropyl triethoxy silane (KH550). The effects of pH value, initial concentration, flow rate and the amount of adsorbent on the dynamic adsorption of heavy metal ions and dye solutions were studied experimentally. The dynamic adsorption process of hexavalent chromium ion and zinc ion by porous silica is fitted by the nonlinear form of Thomas model, and the dynamic adsorption process of methylene blue is fitted by Thomas and Yoon-Nelson models. The effect of Thomas model is better. The optimum conditions for dynamic adsorption of hexavalent chromium and zinc ions were determined by experiments. Under the optimum adsorption conditions, when the adsorbents were mesoporous SiO_2, microporous SiO_2, modified Si O _ 2 and loaded SiO_2, silica sand, the adsorption rates of hexavalent chromium on 5min were 58.02% and 99.06%, respectively. 16.17 and 3.37; The saturation time was 255min ~ 285min ~ (185) min ~ (185) min ~ (65) min ~ (-1) ~ (15) min, and the adsorption rate of 5min was 92.3m ~ 94.48m ~ (98.49) and 91.833 ~ (3) ~ (th) ~ 72.44 ~ (4), respectively, when zinc ion was adsorbed to zinc ion. The saturation time was 250 min / 270 min ~ 240 min ~ (125) min ~ (65) min, respectively. Therefore, the dynamic adsorption of hexavalent chromium and zinc ions by microporous SiO_2 is better than that by mesoporous SiO_2, and the dynamic adsorption of hexavalent chromium and zinc ions by modified SiO_2, loaded SiO_2, silica sand is worse in turn. The dynamic adsorption of methylene blue in aqueous solution by different porous silica was studied. When the adsorbents are mesoporous silica, microporous silica and loaded SiO_2, silica sand, the dynamic adsorption penetration time is 215min / 375min / 255min / min, and the saturation time is 600min / 840min / 600min / 45min, respectively. The results show that the dynamic adsorption of methylene blue in aqueous solution by microporous SiO_2 is better than that of mesoporous SiO_2, and the adsorption effect of loaded SiO_2 is better than that of silica sand.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.33;X703

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