改性滤料强化过滤去除水中典型工程纳米颗粒的研究

Based on the safety issues of drinking water quality caused by the engineering nanoparticles (ENPs) due to their toxicity and environmental effects as well as the limited removal of ENPs by filtration using regular media. The principal objective of this study is to use microwave-assisted preparation of iron oxides coated sand to enhanced removal of ENPs by filtration from aqueous solution. Specific objectives include: 1)to prepare modified sand and to characterize its physical and chemical characteristics ,to discuss the influence of praparation conditions on the surface properties of modified sand, 2) to investigate the influence of praparation conditions on ENPs removal, then to optimize the preparation conditions,to disucss the relationship between the surface properties of modified sand and the removal efficiency, 3)to evaluate the removal efficiency of ENPs by filtration under different influence factors such as filter parameters and water quality, then to determine the main factors affecting the removal efficiency of ENPs, to optimize the filtration parameters, 4) to calculate the DLVO forces and collector surface coverage as well as attachment ffficiency, to analyze the stability of ENPs in water, the to discuss the removal mechanism of ENPs by filtration. This objective will be developed to provide a theoretical and technical support to solve the threat of ENPs on the safety of drinking water quality.

基于工程纳米颗粒（ENPs）的毒性效应和环境效应所带来的饮用水水质安全问题，以及常规滤料过滤去除ENPs的有限性，本项目拟采用微波辅助制备载铁石英砂强化过滤去除水中ENPs。具体内容包括：1）制备改性滤料并对其表面特性进行表征，探讨不同制备条件对改性滤料表面特性的影响；2）考察制备条件对改性滤料去除ENPs的影响，确定最佳制备条件，并分析ENPs去除效率与滤料表面特性之间的关系；3）研究过滤参数和水化学条件对改性滤料过滤去除ENPs的影响，揭示影响ENPs去除的关键因素，优化过滤工艺参数；4）通过DLVO理论、滤料表面覆盖度以及吸附效率计算，并结合水中ENPs的稳定性，阐明过滤去除ENPs的机理。本项目的研究可以为有效地控制工程纳米颗粒，保障饮用水水质安全提供理论依据和技术指导。

针对纳米TiO2颗粒的毒性效应和环境效应所带来的饮用水水质安全问题，以及常规工艺混凝-沉淀-过滤去除纳米TiO2颗粒的有限性，本项目研究了微波辅助制备载铁石英砂强化过滤去除水中纳米TiO2颗粒的效能。具体内容包括：采用微波辅助的方法制备了载铁石英砂，并对其制备条件进行了优化，表征分析了其表面的物理化学性能；确定了改性滤料过滤去除纳米TiO2颗粒的运行参数，揭示了影响纳米TiO2颗粒去除的关键因素；考察了水体中纳米TiO2颗粒的稳定性及水质条件对纳米TiO2颗粒稳定性的影响；研究了不同水质条件下混凝过滤联合工艺对水中纳米TiO2颗粒的去除效能并探讨其影响机制。为有效地控制纳米TiO2颗粒，保障饮用水水质安全提供了理论依据和技术指导。.研究结果表明：采用微波辅助制备载铁石英砂的最佳制备条件为改性剂Fe(NO3)3浓度为2mol/L，pH=1，煅烧温度500℃，煅烧时间2h，微波辐照强度低中档，辐照时间5min。改性后的石英砂物理化学稳定性良好，覆铁量为20.6mg/g，比表面积是天然石英砂的3.64倍，改性石英砂的等电点为7.8，其对纳米TiO2颗粒的去除效果优于天然石英砂；再生滤料比一次滤料处理效果有所下降，但仍优于天然石英砂；纳米TiO2颗粒的去除效果随着过滤速度的增大而降低。在考察范围内，纳米TiO2颗粒的平均有效粒径为220.6nm，零点电位为6.2。纳米TiO2的稳定性随溶液pH偏离其等电点的程度而增加；离子强度的增加使得纳米TiO2的稳定性变差；腐殖酸的加入提高了纳米TiO2的稳定性。通过考察混凝过滤联合工艺去除纳米TiO2颗粒，结果表明混凝过程对纳米TiO2颗粒的去除作用较大，混凝过滤联合工艺可显著降低水中纳米TiO2颗粒的浓度；腐殖酸的存在可降低混凝过滤联合工艺去除纳米TiO2颗粒的效率，且天然有机物浓度越高，处理效果越差；Ca2+的存在可提高混凝过滤联合工艺去除纳米TiO2颗粒的效率。