水合氧化物多孔材料的制备表征及吸附机理研究

发布时间：2018-11-04 21:44

【摘要】：重金属钒污染已经严重威胁到了当下环境以及生物系的健康发展,未经达标处理而排放的含钒废水,会对水体、土壤、植被乃至整个生态系统造成严重的影响。此外,我国的铬盐生产约占世界总产量的35%,是铬盐生产大国,在以绿色环保的无钙焙烧工艺为主导的形势下,铬酸盐浸出液中的钒浓度常高达560 mg·L~(-1)(以V~(5+)计),为满足后续铬盐产品的制备需求,必须进行除钒处理。针对溶液中钒离子的去除,研究出一种高效便捷的分离方法是当下势在必行的一项课题。本文首先以K_2CrO_4为原料,经氢气还原制备出了γ-CrOOH;以CrCl_3·6H_2O作为铬源,通过添加强碱制备出了介孔Cr(OH)_3。随后,细致研究了两种材料对溶液中五价钒离子的静态与动态吸附性能。最后,结合实际水质情况配制了模拟溶液,初步探讨了两种材料实际应用的可行性。主要创新性结果如下:1)系统研究并确定了γ-CrOOH对V~(5+)的最佳吸附条件:溶液pH为2.0、吸附剂用量为60:1(nCr:nV)、适宜的吸附温度为30℃。在此条件下,经过10.0 h的吸附,钒离子出水浓度可由300 mg·L~(-1)降低至0.75 mg·L~(-1)。在有常见离子的存在下,γ-CrOOH的除钒率依然维持在97%以上;钒铬共存模拟液(150~250 g·L~(-1)的Na2Cr2O7·2H_2O中V~(5+)的浓度为500 mg·L~(-1)),除钒后钒离子浓度可降低至45 mg·L~(-1)以下。γ-CrOOH可实现很好的解吸并且解吸液中的钒离子可实现富集与回收再利用。2)制得的Cr(OH)_3其比表面积高达312.70 m2·g-1、孔体积为0.48 cm3·g-1。该吸附剂在溶液pH处于2.0~9.0的范围内,均可表现出较高的除钒率;经过14.0 h吸附,钒离子出水浓度可由500 mg·L~(-1)降低至0.81 mg·L~(-1)。该吸附过程同样符合拟二级动力学方程与Langmuir等温吸附方程。当溶液中存在常见的阴离子与阳离子时,Cr(OH)_3的除钒效率仍高达99.6%以上;钒铬共存模拟液中可有效地将钒离子完全去除。以钠化焙烧-水浸-酸性铵盐沉钒工艺所产生的含钒废水作为参考,配制出的具有相同组分的含钒废水模拟液,经静态吸附处理,溶液中钒离子的去除率可达99.88%。Cr(OH)_3同样可实现很好的解吸。3)对γ-CrOOH与Cr(OH)_3进行装柱处理,以单床降流式对其动态吸附性能进行了研究。结果表明,较慢的流速、较高的装填高度与低浓度的钒溶液,能够适当的提高动态吸附效率。γ-CrOOH与Cr(OH)_3作为新型的介孔吸附材料对V~(5+)具有很好的去除能力,同时具有操作简便,性能优良的特性,为水处理领域的进一步研究提供了很好的参考价值。
[Abstract]:Vanadium pollution has seriously threatened the current environment and the healthy development of biological systems. Vanadium wastewater discharged without standard treatment will have a serious impact on water, soil, vegetation and even the whole ecosystem. In addition, the production of chromium salt in China accounts for about 35% of the world's total output. It is a big country in the production of chromium salt. Under the situation of taking the green environment free calcium roasting process as the leading factor, The vanadium concentration in chromate leachate is as high as 560 mg L ~ (-1) (V ~ (5). In order to meet the needs of the preparation of subsequent chromate products, vanadium removal must be carried out. For vanadium ion removal in solution, it is imperative to develop an efficient and convenient separation method. In this paper, firstly, 纬-CrOOH; was prepared by hydrogen reduction using K_2CrO_4 as raw material and CrCl_3 6H_2O as chromium source. Mesoporous Cr (OH) _ 3 was prepared by adding strong alkali. Then, the static and dynamic adsorption properties of the two materials for pentavalent vanadium ions in solution were studied in detail. Finally, the simulated solution was prepared in combination with the actual water quality, and the feasibility of the two materials in practical application was preliminarily discussed. The main innovative results are as follows: 1) the optimal adsorption conditions for V ~ (5) by 纬-CrOOH were studied and determined: pH of solution was 2.0, amount of adsorbent was 60:1 (nCr:nV), and the optimum adsorption temperature was 30 鈩，

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