摘要
nTiO2进入水环境后,其存在形态及环境行为主要受水环境因素影响.以P25 nTiO2为研究对象,通过改变nTiO2悬浊液的pH值、电解质和表面活性剂种类,分析了nTiO2的分散、团聚及沉降行为.结果表明,pH通过改变nTiO2颗粒的Zeta电位影响nTiO2在水中的稳定性,等电点附近nTiO2发生显著聚沉.nTiO2颗粒选择性吸附AlCl3、CaCl2、NaCl及Na2SO4电离产生的荷电离子,阳离子的吸附中和了TiO2颗粒表面的负电荷,导致颗粒急速聚沉;阴离子的吸附使颗粒间静电斥力增强,颗粒稳定存在于水中.不同类型的表面活性剂通过改变nTiO2颗粒表面性质,增强nTiO2颗粒在水中的稳定性.运用DLVO理论建立了nTiO2的势能方程,势能曲线拟合结果表明,水环境条件通过影响颗粒间势能大小影响nTiO2在水中的分散沉降行为.
The existing form and environmental behavior of nTiO2 in aquatic system are mainly affected by environmental factors. The dispension and deposition behavior of nTiO2 was investigated by changing pH values of the suspension liquid and adding electrolytes and surfactants using P25 nano-TiO2 as the research object. The results indicated that the pH value obviously affected the stability of nTiO2 by changing the charge distribution on the nTiO2 particles. TiO2 nanopartieles were highly aggregated to deposit when the pH value was close to the isoeleetric point. The characteristic adsorption ion of AlCl3 , CaCl2 , NaCI and Na2SO4 after ionization on the surface of nTiO2 particles varied from each other. The adsorption of cations neutralized the negative charge on the surface of nTiO2 particles which led to the quick aggregation and deposition of nTiO2 particles. The adsorption of anions improved the stability of nTiO2 particles in water by increasing electrostatic repulsion between TiO~ particles. Surfactants would adsorb onto the surface of nTiO2 particles and enhance the stability of nTiO2 by changing the surface properties of the nanoparticles. The potential energy of nTiO2 particles were simulated by the DLVO theory. The simulative potential energy curve confirmed that the change of relevant water environment conditions led to the change of potential energy of nTiO2 particles, which determined the dispension and deposition behavior of nTiO2 particles.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2013年第10期3933-3939,共7页
Environmental Science
基金
国家自然科学基金项目(20877070
21177114)
