Fabrication of visible light-excited photocatalytic TiO2 nanocomposite membranes for removal of organic pollutants and pathogenic microorganisms

虽然大多数加拿大人都可以获得处理过的水，但许多原住民和其他偏远和农村社区仍然面临获得清洁饮用水的挑战。这些水往往受到农用化学品和污水的污染，为微生物的生长提供了营养丰富的培养基，对人类健康构成巨大风险。鉴于全球的水处理需求，开发可在电网外部署的具有成本效益的水处理设备是非常可取的。膜技术在饮用水处理中得到了广泛的应用；然而，生物污垢和高运营成本仍然是实施的重大障碍。添加多种金属和非金属材料的TiO2纳米复合膜可以拓宽可见光光谱，用于驱动有机污染物和病原微生物的光催化降解；这种系统将是一种简单但经济有效的水处理方法。******目前，合成可见光激发的TiO2纳米材料有两种策略。第一种是将TiO2与其他可见光敏化纳米材料如CdS纳米粒子、贵金属纳米粒子（即AgNPs和AuNPs）和染料分子偶联，以缩小其带隙；然而，所有已发表的研究都是关于TiO2纳米粒子的，没有关于TiO2纳米线的研究。与传统的TiO2 NP方法相比，这些纳米线膜具有明显的优势，在传统的方法中，回收纳米颗粒需要消耗额外的能量，由于处理后去除的限制，纳米颗粒本身可能会污染最终处理的水。另一种策略是在合成TiO2纳米线的过程中掺杂金属元素（Fe, Mo, Ru, Os, Re， V，和Rh）或非金属元素（C， S， N， I），但这种方法的效率尚未得到证实。对于环境污染物或病原微生物的去除，仅对紫外线的抑菌和抗病毒衰减进行了初步评估。******我们期望开发一种高效、有效的“绿色”清洁技术（基于掺杂TiO2 NWs和TiO2复合材料与金、银纳米线、碳纳米材料、LDH），以太阳能为能源。我们进一步建议开发一种适用于城市和偏远低资源地区的单一家庭使用的综合水处理装置。迄今为止，我们的团队在制备和评估TiO2膜在紫外线下降解有机污染物的效率方面有相当多的经验。此外，对TiO2 NPs与生物分子（如DNA）相互作用的机理进行了研究，为TiO2如何与生物系统相互作用提供了新的见解。这些知识可以转移到制造DNA-TiO2纳米膜，用于污染物的浓度和去除。*****************

While most Canadians enjoy access to treated water, many First Nations and other remote and rural communities still face challenges with accessing clean drinking water. Frequently, such waters are contaminated with agrichemicals and sewage, providing a nutrient-rich medium for the growth of microorganisms posing a huge risk to human health. Development of cost-effective water treatment devices deployable off the electrical grid would, in light of water treatment needs globally, be highly desirable. Membrane technologies have been extensively ultilized in drinking water treatment; however, biofouling and high operating costs remain significant barriers for implementation. TiO2 nanocomposite membranes augmented with a variety of metallic and non-metallic materials can broaden the spectrum of visible light harnessed to drive photocatalytic degradation of organic contaminants and pathogenic microorganisms; such a system will be a simple but cost-effective means of treating water. ******Currently, there are two strategies for synthesis of visible light-excited TiO2 nanomaterials. The first is to couple TiO2 to other visible light sensitized nanomaterials such as CdS NPs, noble metal nanoparticles (i.e. AgNPs and AuNPs), and dye molecules, to narrow their band gap; however, all published work has been for TiO2 nanoparticles, with no work completed with TiO2 nanowires. These nanowire membranes demonstrated distinct advantages over traditional TiO2 NP approaches, where additional energy is consumed in recycling the nanoparticles, which due to post-treatment removal constraints, may themselves contaminate the final treated water. Another strategy is doping with metallic (Fe, Mo, Ru, Os, Re, V, and Rh) or non-metallic elements (C, S, N, I) during the synthesis of TiO2 nanowires, but the efficiency of this approach is yet to be proven. For the removal of environmental contaminants or pathogenic microorganisms, only initial forays were taken to evaluate anti-microbial and anti-viral attenuation with UV light.******We expect to develop an efficient and effective "green" clean technology (based on doped TiO2 NWs and TiO2 composites with gold and silver nanowires, carbon nanomaterials, LDH) using solar light as the energy source. We further propose the development of an integrated water treatment device, suitable for single family use, in both urban and remote low-resource areas. To date, our group has considerable experience fabricating and evaluating the efficacy of TiO2 membranes towards the degradation of organic contaminants under UV. In addition, a mechanistic study on TiO2 NPs interaction with biomolecules (such as DNA) has been performed, providing new insight into how TiO2 interacts with bio-systems. This knowledge can be transferred to fabricate DNA-TiO2 nanomembranes for pollutant concentration and removal. *****************