Clay minerals can hinder the transport of various contaminants in soil and aquifer, but how clay minerals affect the transport of nanoparticles in aquifers has not been investigated in depth. In this paper, the transp...Clay minerals can hinder the transport of various contaminants in soil and aquifer, but how clay minerals affect the transport of nanoparticles in aquifers has not been investigated in depth. In this paper, the transport of surfactants dispersed multi-walled carbon nanotubes（MWCNTs） in welldefined quartz sand and mixtures of quartz sand and clay minerals（kaolinite and montmorillonite） with varying ionic strengths was studied. Sodium dodecyl benzenesulfonate（SDBS） and octyl-phenolethoxylate（TX100） MWCNT suspensions can migrate through quartz sand easily, but the presence of less than 2% w/w clay minerals in quartz sand can significantly hinder the transport of MWCNT suspensions, especially at high ion strength（0.6 m M CaCl2）. The inhibition mechanism of clay minerals for surfactant-dispersed MWCNTs in porous media is the interception of MWCNTs. Kaolinite has stronger inhibition effect for MWCNTs transport than montmorillonite because more kaolinite can be retained in the quartz sand. Adsorption of surfactants by clay minerals does not affect the transport of MWCNTs significantly. This finding is important for the environmental assessment of MWCNT transport risks in soils and aquifers.展开更多
Sonication is a powerful technique to promote the dispersion of carbon nanotubes(CNTs) and enhance their solubility;this is necessary for CNT applications,especially in the biochemical and biomedical fields.In this st...Sonication is a powerful technique to promote the dispersion of carbon nanotubes(CNTs) and enhance their solubility;this is necessary for CNT applications,especially in the biochemical and biomedical fields.In this study,batch experiments were conducted to evaluate the role of sonication energy on the dispersion of CNTs in the presence of a widely used anionic surfactant,sodium dodecylbenzene sulfonate(SDBS).It was observed that the concentration of dispersed CNTs in the SDBS solution depended on the sonication energy,but not the sonication time or output power of the sonicator alone.The amount of dispersed CNTs was positively correlated with the concentrations of SDBS and CNTs,and the length of the CNTs.The promotion of oxygen-containing functional groups on the dispersed CNTs was observed at relatively low sonication energies.The optimal energy,i.e.the minimum energy supplied by sonication to achieve a saturated suspension of dispersed CNTs in the SDBS solution,was CNT diameter-dependent,because of the larger vdW forces between tubes of smaller diameter.An exponential decay curve was constructed for the optimal energy values as a function of the outer CNT diameter,to assist in determining the energy needed to disperse CNTs.展开更多
基金supported by National Natural Science Foundation of China (41002088)Fundamental Research Project (SK201002,SK201502) of the Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences
文摘Clay minerals can hinder the transport of various contaminants in soil and aquifer, but how clay minerals affect the transport of nanoparticles in aquifers has not been investigated in depth. In this paper, the transport of surfactants dispersed multi-walled carbon nanotubes（MWCNTs） in welldefined quartz sand and mixtures of quartz sand and clay minerals（kaolinite and montmorillonite） with varying ionic strengths was studied. Sodium dodecyl benzenesulfonate（SDBS） and octyl-phenolethoxylate（TX100） MWCNT suspensions can migrate through quartz sand easily, but the presence of less than 2% w/w clay minerals in quartz sand can significantly hinder the transport of MWCNT suspensions, especially at high ion strength（0.6 m M CaCl2）. The inhibition mechanism of clay minerals for surfactant-dispersed MWCNTs in porous media is the interception of MWCNTs. Kaolinite has stronger inhibition effect for MWCNTs transport than montmorillonite because more kaolinite can be retained in the quartz sand. Adsorption of surfactants by clay minerals does not affect the transport of MWCNTs significantly. This finding is important for the environmental assessment of MWCNT transport risks in soils and aquifers.
基金supported by the Zhejiang Provincial Natural Science Foundation of China (R5110004)the National Natural Science Foundation of China (21137003 and 40973065)+3 种基金the National Science & Technology Pillar Program of China (2013BAC01B01)the Scholarship Award for Excellent Doctoral Student Granted by Ministry of Educationthe Fundamental Research Funds for the Central Universitiesthe Key Innovation Team for Science and Technology of Zhejiang Province (2009R50047)
文摘Sonication is a powerful technique to promote the dispersion of carbon nanotubes(CNTs) and enhance their solubility;this is necessary for CNT applications,especially in the biochemical and biomedical fields.In this study,batch experiments were conducted to evaluate the role of sonication energy on the dispersion of CNTs in the presence of a widely used anionic surfactant,sodium dodecylbenzene sulfonate(SDBS).It was observed that the concentration of dispersed CNTs in the SDBS solution depended on the sonication energy,but not the sonication time or output power of the sonicator alone.The amount of dispersed CNTs was positively correlated with the concentrations of SDBS and CNTs,and the length of the CNTs.The promotion of oxygen-containing functional groups on the dispersed CNTs was observed at relatively low sonication energies.The optimal energy,i.e.the minimum energy supplied by sonication to achieve a saturated suspension of dispersed CNTs in the SDBS solution,was CNT diameter-dependent,because of the larger vdW forces between tubes of smaller diameter.An exponential decay curve was constructed for the optimal energy values as a function of the outer CNT diameter,to assist in determining the energy needed to disperse CNTs.
