Yang Kun, Xing Baoshan
Department of Environmental Science, Zhejiang University, Hangzhou 310028, China.
Environ Sci Technol. 2009 Mar 15;43(6):1845-51. doi: 10.1021/es802880m.
Phenanthrene sorption by nano-TiO2 and nano-ZnO particles was enhanced significantly by coated humic acids (HAs), implying that additional toxicity can be potentially given to these nanooxides by adsorbed HOCs once released to the environment. Phenanthrene isotherms of adsorbed HA on nano-TiO2 and nano-ZnO were more nonlinear than that of their respective bulk HA. Both HA conformation changes and fractionation were observed upon HA adsorption on nano-TiO2 and nano-ZnO, which further affected phenanthrene sorption. Nano-TiO2 and nano-ZnO interacted with differentfunctional groups of HA (i.e., phenolic OH with nano-TiO2, while COOH with nano-ZnO), leading to different conformations of adsorbed HA. Interaction of HA phenolic OH with nano-TiO2 increased the pi-polarity/polarizability of adsorbed HA and, consequently, its phenanthrene adsorption affinity and isotherm nonlinearity. Interactions of COOH groups on HA aromatic rings with nano-ZnO would also increase the pi-polarity/polarizability of adsorbed HA and its phenanthrene adsorption affinity, whereas interactions of COOH groups on HA aliphatic chains with nano-ZnO would make the adsorbed HA be in a more condensed state with lower partitioning affinity. Increase in adsorption and decrease in partitioning were responsible for the more nonlinear phenanthrene isotherms of adsorbed HA than bulk HA.
纳米二氧化钛（nano-TiO₂）和纳米氧化锌（nano-ZnO）颗粒对菲的吸附作用通过包覆腐殖酸（HAs）得到显著增强，这意味着一旦这些纳米氧化物释放到环境中，吸附的疏水性有机化合物（HOCs）可能会给它们带来额外的毒性。吸附在nano-TiO₂和nano-ZnO上的HA的菲等温线比各自的本体HA的等温线更非线性。在HA吸附到nano-TiO₂和nano-ZnO上时，观察到了HA构象变化和分馏现象，这进一步影响了菲的吸附。nano-TiO₂和nano-ZnO与HA的不同官能团相互作用（即nano-TiO₂与酚羟基相互作用，而nano-ZnO与羧基相互作用），导致吸附的HA构象不同。HA酚羟基与nano-TiO₂的相互作用增加了吸附HA的π-极性/极化率，因此增加了其对菲的吸附亲和力和等温线非线性。HA芳香环上的羧基与nano-ZnO的相互作用也会增加吸附HA的π-极性/极化率及其对菲的吸附亲和力，而HA脂肪链上的羧基与nano-ZnO的相互作用会使吸附的HA处于更凝聚的状态，分配亲和力较低。吸附增加和分配减少导致吸附的HA的菲等温线比本体HA的等温线更非线性。
