小分子有机酸对纳米颗粒CNTs和SBA-15在多孔介质中迁移的影响  

Effect of small molecule organic acids on transport of CNTs and SBA-15 in porous media

作　　者：梁文[1] 秦睿[1] 黄辉[1] 李荣华[1] 张增强[1] 

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《西北农林科技大学学报（自然科学版）》2017年第4期140-148,共9页Journal of Northwest A&F University(Natural Science Edition)

基　　金：国家自然科学基金项目(41101288)

摘　　要：【目的】了解有机酸对硅酸盐纳米颗粒(SBA-15)和碳纳米管(CNTs)在多孔介质中迁移行为的影响差异。【方法】采用恒定流速柱迁移试验,探讨不同浓度(0,1,2.5和5 mmol/L)乙酸、酒石酸、柠檬酸对CNTs和SBA-15纳米颗粒在多孔介质(石英砂)中穿透曲线的影响。【结果】平衡对流-弥散方程能描述多孔介质中CNTs和SBA-15迁移过程的穿透曲线。在石英砂多孔介质中,CNTs的迁移能力强于SBA-15。体系不含有机酸时,CNTs、SBA-15流出液中的纳米颗粒浓度(C)与纳米悬液进入砂柱前的初始浓度(C_0)比值(C/C_0)的峰值分别为0.74和0.25,最远迁移距离L_(max)分别为221.2和45.1cm。3种有机酸对CNTs和SBA-15在多孔介质中的迁移具有类似的抑制作用,随着介质中3种有机酸浓度的增加,CNTs和SBA-15纳米颗粒的C/C_0减小,C/C_0平台峰值对应空隙体积(PV)倍数增大,迁移阻滞因子R和不可逆吸附系数μ增大,最远迁移距离L_(max)减小。柠檬酸对CNTs和SBA-15迁移的抑制作用强于乙酸和酒石酸。Zeta电位分析表明,当体系中引入有机酸后,随着有机酸浓度的增加,石英砂、CNTs和SBA-15纳米颗粒悬液的Zeta电位均逐渐增大。【结论】有机酸会改变多孔介质和CNTs、SBA-15这2种纳米颗粒的表面电荷特征,从而使得纳米颗粒悬液在多孔介质中的迁移行为更容易受团聚、滞留和沉积作用的影响。不管在何种有机酸中,CNTs的迁移能力均强于SBA-15。[Objective] This paper compared the effect of organic acids on transport of multiwall carbon nanotubes （CNTs） and silicate nanoparticles （SBA-15） in porous media. [Method] Column experiments with constant flow rate were conducted to explore the effects of citric acid, acetic acid, and tartaric acid with different concentrations （0,1,2.5 and 5 retool/L） on breakthrough curves and deposition profiles of CNTs and SBA-15 in porous media. [Result] The balanced convection-diffusion equation could be used to describe the breakthrough curves of CNTs and SBA-15 nanoparticles transport. The mobility of CNTs was higher than that of SBA-15 in sand porous media. Without organic acids in porous media,the peak C/Co values of CNTs and SBA-15 effluents were 0.74 and 0.25,and the farthest migration distances （Lmax） were 221.2 cm and 45.1 em,respectively. The presence of three organic acids inhibited the migration of CNTs and SBA-15 nanoparticles. With the increase of organic acids concentrations from 0 mmol/L to 5 mmol/L, the C/Co and Lmax decreased,while the porous volume multiple （PV） of peak C/Co ,the retardation factor （R） and the irreversible adsorption coefficient （μ） increased. Citric acid had stronger inhibition effect on transport of CNTs and SBA-15 nanoparticles than acetic acid and tartaric acid. Zeta potential analysis indicated that the presence of organic acids increased the surface charge of the sand porous media,CNTs and SBA-15 nanop-articles. [Conclusion] The presence of organic acids changed the surface charge characterization of sand porous media, CNTs and SBA-15 nanopartieles,resulting in agglomeration, retention and deposition effects. SBA-15 was easier to transport than CNTs in all organic acids.

关 键 词：小分子有机酸 多孔介质 纳米颗粒 迁移 滞留 

分 类 号：X703[环境科学与工程—环境工程]