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可以获得经过处理的水，但许多原住民和其他偏远和农村社区在获得清洁饮用水方面仍然面临挑战。这些水经常被农用化学品和污水污染，为微生物的生长提供了营养丰富的媒介，对人类健康构成了巨大风险。鉴于全球的水处理需求，开发可脱离电网部署的具有成本效益的水处理设备将是非常可取的。膜技术已被广泛应用于饮用水处理，然而，生物污染和高昂的运行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二氧化钛纳米复合膜可以拓宽可见光的光谱，以驱动有机污染物和病原微生物的光催化降解；这样的系统将是一种简单但具有成本效益的水处理方法。 目前，可见光激发的二氧化钛纳米材料的合成方法主要有两种。第一种是将二氧化钛与其他可见光敏化纳米材料，如镉纳米颗粒、贵金属纳米颗粒(即银纳米颗粒和金纳米颗粒)和染料分子偶联，以缩小它们的带隙；然而，所有已发表的工作都是针对二氧化钛纳米颗粒，还没有完成关于二氧化钛纳米线的工作。与传统的二氧化钛纳米颗粒方法相比，这些纳米线膜显示出明显的优势，在传统方法中，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后的水。另一种策略是在合成二氧化钛纳米线的过程中掺杂金属元素(Fe，Mo，Ru，Os，Re，V，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。对于去除环境污染物或致病微生物，只采取了初步尝试，以评估抗微生物和抗病毒衰减的紫外线。 我们期望开发一种高效、有效的绿色清洁技术(基于掺杂的TiO2NWS及其与金银纳米线、碳纳米材料、LDH的复合材料)，以太阳能为能源。我们还建议开发一种综合水处理设备，适用于城市和偏远低资源地区的单户使用。到目前为止，我们团队在制备和评估二氧化钛膜在紫外光下降解有机污染物的有效性方面拥有丰富的经验。此外，还对纳米二氧化钛与生物分子(如DNA)相互作用的机理进行了研究，为理解纳米二氧化钛与生物系统的相互作用提供了新的视角。这些知识可以被转移到制备用于污染物浓缩和去除的DNA-二氧化钛纳米膜。

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.