不同亲疏水性的天然有机物对铜和铬离子在钛酸纳米管表面的吸附行为及其形态影响

The adsorption technique using nano-materials is now a promising and high-profile method for the advanced treatment of the increasingly severe heavy metal pollution. Natural organic matter (NOM), which widely exists in natural water, can interact with both metal ions and adsorbents, thus impacts the adsorption behavior and mechanism. Moreover, due to the complex and heterogeneous composition of the NOM, the impact on adsorption by NOM with different origination and composition could be remarkably different. In this project, resin adsorption method is used to divide NOM into four components based on their hydrophilicity/hydrophobicity, i.e., hydrophobic base, hydrophobic acid, weak hydrophobic matter and hydropholic matter. Combined with the detection by ion selective electrode and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), the adsorption behavior of copper and chromium with free state and complex state onto titanate nanotubes (TNTs) will be studied. Specially, the following contents will be detailly investigated: (1) Influence of the four kinds of NOM components on adsorption of copper and chromium with free and complex state; (2) Influence of various NOM on changes of TNTs morphology and metal species; (3) The impact of added NOM on the achieved equilibrium. The project aims to further explore the role and mechanism of NOM with different chemical states on adsorption of metal ions by TNTs, thus establish the theoretical foundation on practical water treatment using TNTs.

纳米材料吸附技术是深度处理重金属污染的有效途径，水中天然有机物(NOM)能够与金属离子及吸附剂相互作用，进而影响吸附机理。然而，天然有机物化学组成复杂，且具有异质性，不同来源及化学组成的NOM对吸附过程的影响程度及机理差异显著。项目拟采用树脂极性分析，将水中天然有机物分为憎水碱性物、憎水酸性物、弱憎水性酸、亲水性物质四种组分，结合离子选择性电极与ICP-OES检测，研究四种NOM组分对铜和铬形态(自由态、络合态)的影响，以及其在钛酸纳米管(TNTs)上的吸附规律。具体研究内容包括：四种NOM组分影响TNTs对铜和铬的吸附行为及机理、NOM组分对TNTs表面结构的影响、NOM组分对铜和铬形态的影响、不同形态铜和铬在TNTs表面的吸附规律、外加NOM对已建立的吸附平衡的影响等。本项目旨在深入揭示不同化学形态的NOM对TNTs吸附铜和铬离子的影响规律及机理，为TNTs应用于实际水体处理奠定基础。

纳米材料吸附技术是深度处理重金属废水的有效途径，水体中的天然有机物(Natural Organic Matter, NOM)可通过与金属离子的络合影响其形态、迁移、转化及毒性，进而影响重金属污染废水的治理。然而，天然有机物化学组成复杂，且具有异质性，不同来源及化学组成的NOM对吸附过程的影响程度及机理差异显著。. 项目采用树脂极性分析法，分离获得了NOM组分憎水碱性物、憎水酸性物、亲水性物质，研究了NOM组分在铜和铬离子在钛酸纳米管(titanate nanotubes，TNTs)上的吸附规律。结果表明，HoB对Cu(II)吸附影响作用最强，其吸附等温线不再符合Langmiur模型，吸附的Cu(II)主要以TNTs-OCu（直接吸附）和TNTs-COOCu（静电桥接吸附）形式存在。pH 5时，柠檬酸和富里酸可显著促进Cr(III)的吸附，与其较好的金属络合能力有关。. 针对重金属与有机污染物共存的问题，研究了TNTs对Cu(II)和环丙沙星（CIP）的共同吸附及形态影响。等摩尔Cu(II)存在下，CIP吸附量可增加50%-200%，低Cu(II)存在下，由于Cu(CIP−·CIP±)+对CIP±的位阻作用，吸附量降低。不同形态CIP的吸附能力Cu(CIP±)2+>CIP+> CIP±> Cu(CIP−·CIP±)+>CIP-。. 采用0.1 M HNO3对吸附后的TNTs进行解吸，证实HoA、HoB和HiM组分存在下Cu(II)的解吸率均可达到98%以上，不影响TNTs的循环利用；此外，海藻酸钠（SA）包埋的TNTs具有较大的吸附量，在实际重金属污染废水的治理中有较好的应用前景。