改性剂在蒙脱石层间的负载特性及其对改性蒙脱石结构的影响研究

发布时间：2018-06-10 20:11

本文选题：烷基铵 + 络合剂　；参考：《广西大学》2017年硕士论文

【摘要】：膨润土由于其独特的层状结构和较大的比表面积,常被用作吸附剂应用于废水处理中,其中烷基铵和络合剂复合改性膨润土是具有重要应用前景的新型废水吸附材料。本文采用烷基铵与络合剂半胱胺盐酸(CSH)作为改性剂对钠化蒙脱石进行复合改性,系统研究了烷基铵的结构和制备工艺条件对改性剂在蒙脱石层间的负载量、赋存形式以及复合改性膨润土结构的影响,并对改性剂在蒙脱石上的吸附机理进行了研究。研究结果表明:1.半胱胺盐酸盐/十六烷基三甲基氯化铵(CSH/CTAC)用量配比中CTAC的用量对改性剂在蒙脱石层间的负载量、赋存形式及其层间距有着决定性的影响。随着CTAC用量的增加,CTAC在蒙脱石上的负载量增加,CSH的负载量减少,其复合改性蒙脱石的层间距增大,并出现混层结构,层间CTAC阳离子由一种“近液态”的构型状态转变为“近固态”,而CSH用量的增加对改性剂在蒙脱石层间的负载量及其层间距的影响不明显。2.烷基铵碳链长度和苄基结构对改性剂在蒙脱石层间的负载量、赋存形式,以及复合改性蒙脱石的结构影响显著。随着烷基铵碳链长度的增加,复合改性蒙脱石的层间距和失重率增大,且在2850 cm-1附近的C-H对称伸缩振动吸收带强度越大;烷基铵存在苄基时,改性剂在蒙脱石层间的负载量减少,但其复合改性蒙脱石的层间距和失重率均增大。3.对于不同改性剂添加顺序条件下制备的复合改性蒙脱石,CTAC和CSH在蒙脱石层间的负载量及复合改性蒙脱石的层间距均变化不大,但CTAC的负载量均远大于CSH的,说明CTAC比CSH更易于被蒙脱石吸附,提前进入蒙脱石层间的CSH会被CTAC置换出来。4.反应时间对CTAC和CSH在钠化蒙脱石上的负载过程影响显著。随着改性时间的延长,改性剂在蒙脱石上的负载量呈先快速增加后缓慢增加的趋势,在l0min时达到平衡;CTAC和CSH在钠化蒙脱石上的插层负载过程符合准二级动力学模型,且CTAC比CSH能更快地进入蒙脱石层间。5.反应温度对CTAC和CSH在钠化蒙脱石上的负载量影响较小,随着改性温度的升高,CTAC和CSH在蒙脱石上的负载量变化不大;Redlich-Peterson等温线模型能更好地模拟CTAC和CSH在钠化蒙脱石上的插层负载过程,说明CTAC和CSH在钠化蒙脱石上的吸附可能主要在蒙脱石的非均匀孔隙或表面上。
[Abstract]:Bentonite is often used as an adsorbent in wastewater treatment because of its unique layered structure and large specific surface area. The composite modification of bentonite with alkyl ammonium and complex agent is a new type of wastewater adsorption material with important application prospects. In this paper, montmorillonite sodium montmorillonite was modified with alkylammonium and cysteamine hydrochloride as modifier. The structure and preparation conditions of alkylammonium montmorillonite on the loading amount of modifier between montmorillonite layers were studied systematically. The influence of the existing form and the structure of modified bentonite on the adsorption mechanism of modifier on montmorillonite was studied. The results of the study show that 1: 1. The amount of CTAC in the ratio of cysteamine hydrochloride / cetyltrimethylammonium chloride (CSH / CTAC) has a decisive effect on the loading amount, the existing form and the interlayer spacing of the modifier. With the increase of the amount of CTAC, the loading amount of CTAC on montmorillonite decreases, and the interlayer spacing of composite modified montmorillonite increases, and the mixed layer structure appears. The interlayer CTAC cations changed from a "near-liquid" configuration to a "near-solid" state, but the increase of CSH content had no significant effect on the loading amount and interlayer spacing of the modifier between montmorillonite layers. The carbon chain length and benzyl structure of alkyl ammonium have significant effects on the loading amount of modifier between montmorillonite layers, the existing form and the structure of composite modified montmorillonite. With the increase of alkyl ammonium carbon chain length, the interlaminar spacing and weight loss rate of composite modified montmorillonite increase, and the strength of C-H symmetrical stretching vibration absorption band near 2850 cm-1 increases. The loading amount of the modifier between montmorillonite layers was reduced, but the interlayer spacing and weight loss rate of the modified montmorillonite increased by 0.3. The loading amount of CTAC and CSH between montmorillonite layers and the interlayer spacing of composite modified montmorillonite prepared with different modifiers have little change, but the loading amount of CTAC is much larger than that of CSH. The results show that CTAC is easier to be adsorbed by montmorillonite than CSH, and CSH which enters the interlayer of montmorillonite in advance will be replaced by CTAC. 4. The effect of reaction time on the loading process of CTAC and CSH on sodium montmorillonite was significant. With the prolongation of modification time, the loading amount of modifier on montmorillonite increased rapidly at first and then increased slowly. The intercalation loading process of CTAC and CSH on sodium montmorillonite at l0min reached the equilibrium of quasi-second-order kinetic model. Moreover, CTAC can enter the interlayer of montmorillonite faster than CSH. The reaction temperature had little effect on the loading amount of CTAC and CSH on sodium montmorillonite. With the increase of modification temperature, the loading of CTAC and CSH on montmorillonite is not changed much. The Redlich-Peterson isotherm model can better simulate the intercalation loading process of CTAC and CSH on sodium montmorillonite. It is suggested that the adsorption of CTAC and CSH on sodium montmorillonite may be mainly on the heterogeneous pores or surfaces of montmorillonite.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3;X703

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