离子电荷对碳纳米管悬浮液的化学絮凝作用研究

发布时间：2019-05-28 17:05

【摘要】：随着纳米材料的广泛使用,纳米材料不可避免进入到天然水体。研究表明,纳米材料具有生态毒性,威胁生物体健康。然而,目前的水质标准未对纳米颗粒进行限定,因此,需要对饮用水中纳米颗粒的去除效果及影响因素进行深入研究。本文选用MWCNTs为目标污染物,分别以十二烷基苯磺酸钠(SDBS)、十六烷基三甲基溴化铵(CTAB)和辛基酚聚氧乙烯醚(TX-100)三种分散剂制备分散MWCNTs s悬浮液。并研究了pH、NaCl浓度、阳离子,如Na+、Ca2+、Mg2+,阴离子如SO42-、HPO42-、HCOO-和(OOCCHOHCHOHCOO)2-对三种MWCNTs悬浮液絮凝脱稳效果及絮凝剂有效脱稳区间(ECR)的影响,并对结果进行了分析。pH值对三种MWCNTs悬浮液的絮凝脱稳有重要影响。对于SDBS-MWCNTs和TX100-MWCNTs体系,pH=4.0和pH=7.0时,MWCNT的去除率随聚合氯化铝(PAC)投量呈现倒“U”型;pH=11.0时,无再稳现象。ECR随着pH升高而变宽。对于CTAB-MWCNTs体系,随着pH的变化,逐渐升高,未发现ECR出现。NaCl对于SDBS-MWCNTs、CTAB-MWCNTs、TX-100MWCNTs的临界聚沉浓度(CCCs)大约为70.0、29.0、20.0 mmol/L。电解质NaCl的加入,能有效的改变MWCNTs悬浮液的絮凝区间。NaCl对三种MWCNTs悬浮液絮凝的影响符合DLVO理论,基本都随着其浓度升高,压缩双电层能力增强,使MWCNTs去除率升高,ECR变宽。Ca2+和Mg2+的加入,使得三种MWCNTs的稳定性下降,粒径增大。对于SDBS-MWCNTs和CTAB-MWCNTs,Ca2+和Mg2+的加入,MWCNTs去除率下降,ECR变窄。但使TX100-MWCNTs悬浮液的去除率升高,ECR变宽。对于SDBS-MWCNTs和TX100-MWCNTs,HPO42-使MWCNTs的Zeta电位下降最多,其他阴离子使MWCNTs的Zeta电位下降不大。HCOO-的加入使ECR变窄,其余三种多价阴离子均能使MWCNTs的絮凝脱稳区间明显变宽,无倒“U”型曲线出现,但是HPO42-水样的去除率下降。对于CTAB-MWCNTs,高价阴离子使CTAB-MWNCTs的粒径增加最多,由300nm增大到5000nm左右,除HCOO-外,其余阴离子均能使CTAB-MWCNTs絮凝去除率明显变大,未见ECR。
[Abstract]:With the wide use of nanomaterials, nanomaterials inevitably enter the natural water body. Studies have shown that nanomaterials are ecotoxic and threaten the health of organisms. However, the current water quality standards do not limit the nanoparticles, so it is necessary to study the removal efficiency and influencing factors of nanoparticles in drinking water. In this paper, MWCNTs was used as the target pollutant to prepare dispersed MWCNTs s suspensions with sodium dodecylbenzene sulfonate (SDBS), cetyltrimethyl ammonium bromide (CTAB) and octyl phenol polyoxylene ether (TX-100) respectively. The effects of pH,NaCl concentration, cations, such as Na, Ca2, Mg2, anions such as SO42-,HPO42-,HCOO- and (OOCCHOHCHOHCOO) 2-on the flocculation and instability of three kinds of MWCNTs suspensions and the effective instability range (ECR) of flocculants were also studied. The results were analyzed. Ph value has an important effect on the flocculation and instability of three kinds of MWCNTs suspensions. For SDBS-MWCNTs and TX100-MWCNTs systems, the removal rate of MWCNT was inverted "U" with the dosage of polyaluminum chloride (PAC) in pH=4.0 and pH=7.0, and there was no restability in pH=11.0. ECR widened with the increase of pH. For CTAB-MWCNTs system, with the change of pH, no ECR was found. The critical concentration of (CCCs) for SDBS-MWCNTs,CTAB-MWCNTs,TX-100MWCNTs was about 70.0, 29.0 and 20.0 mmol/L.. The addition of electrolyte NaCl can effectively change the flocculation range of MWCNTs suspensions. The effect of NaCl on the flocculation of three kinds of MWCNTs suspensions accords with DLVO theory. With the increase of DLVO concentration, the ability of compression double layer increases, and the removal rate of MWCNTs increases. With the addition of Ca2 and Mg2, the stability of the three kinds of MWCNTs decreased and the particle size increased. For the addition of SDBS-MWCNTs, CTAB-MWCNTs,Ca2 and Mg2, the removal rate of MWCNTs decreased and ECR narrowed. However, the removal rate of TX100-MWCNTs suspension increased and ECR widened. For SDBS-MWCNTs and TX100-MWCNTs,HPO42-, the Zeta potential of MWCNTs decreased the most, while other anions did not decrease the Zeta potential of MWCNTs. The addition of HCOO-narrowed ECR, and the other three polyvalent anions significantly widened the flocculation and instability range of MWCNTs. No inverted "U" curve appeared, but the removal rate of HPO42- water sample decreased. For CTAB-MWCNTs, high valence anions, the particle size of CTAB-MWNCTs increased the most, from 300nm to 5000nm. Except HCOO-, the other anions could obviously increase the flocculation removal rate of CTAB-MWCNTs, but no ECR. was found.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.1

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