废水中Cr(VI)快速光-电协同催化还原与Cr(III)资源回收研究

This project will be carried out for cleaning up the technical bottleneck of suffering excess use of reductants and production of massive Chromium residue during the treatment of Cr(VI)-contaminated water. Three-dimensional Ti and W meshes are selected as the substrates for being anodized. TiO2 and WO3 nanotubes are grown from the Ti and W substrates. After that, calcination will be performed to change the crystalline of the as-prepared TiO2 and WO3, making them stable in acid or alkaline medium. Two dimensional superconductive materials of MoS2xSe2(1-x)(x=0~1) nanosheet or composite crystals based on the nanosheets are in-suit grown on the TiO2 and WO3 nanotubes. The resulted MoS2xSe2(1-x)/Ti(W) nets are with unique physic/chem properties and abundant yield of photo-electricity triggered electrons, which can be applied in fast reduction of Cr(VI). After that, a fixed-bed filled with sulfonated mesoporous carbon is combined. The resulting Cr(III) can be immobilized on the mesoporous carbon based on ion exchange. Then, sulfate acid as eluant is employed to regenerate the mesoporous carbon and produce Cr2(SO4)3 which will be served as raw materials in printing, electroplating and leathermaking, realizing the recovery of Cr(III). As both the 3D Ti and 3D W meshes are solid, soft and conductive substrates, They can be conveniently incorporated as a system core in an apparatus, suggesting a promising application future. The combined techonology can realize the cleaning treatment of Cr(VI) contaminated water with no toxic residue produced.

针对目前Cr(VI) 废水处理工艺中还原剂使用多、铬渣排放多的技术瓶颈，对比性选取耐酸耐碱的柔性三维网格钛（Ti）网、钨（W）网为基底电极，经阳极氧化-煅烧处理，应用异相水热晶体制备技术、在Ti、W网格表面原位生长富电子二维MoS2xSe2(1-x)(x=0~1)超导层。在太阳光激发与外加偏压（<2V）共同驱动下，使其具备高电子产量特性，快速还原水体中的Cr(VI)。以大比表面积磺酸化介孔碳微球组装流动床，基于离子交换原理吸附固定生成的Cr(III)，随后经硫酸酸洗再生；洗脱液经蒸发-结晶生成Cr2(SO4)3，实现Cr(III)元素资源回收。三维Ti、W网兼具柔韧性与导电性，能便捷组装入电路，构建光电化学反应器件，与介孔碳流动床联合应用，避免了常规Cr(VI)处理中铬渣的生产与存放弊端。本研究将为光-电催化技术在Cr污染水体的清洁处理提供基础研究数据，为实际应用提供理论指导。

项目针对传统工艺去除废水中六价铬时化学还原剂使用多、无选择性、产生铬渣成分复杂难回收的技术难题，另针对复杂废水中污染物在氧化还原转化中存在的电子转移无序自耗、有效作用率低、环境生态风险消除难的技术瓶颈，突破以传统还原剂/氧化剂为活性物质的传统思路，设计全固态、自支撑纳米光/电极，通过界面结构及电子通道调控光/电纳米催化系统电子的有序迁移与流动，以电子为“清洁还原剂”还原高毒六价铬为三价铬，并通过吸附固定Cr(III)-酸洗再生电极-回收硫酸铬工艺流程，实现水体中总铬的去除、回收；以光激发诱导产生的氧自由基为“清洁氧化剂”与典型水体内分泌干扰污染物的深度脱毒。主要成果包括：（1）设计制备以柔性导电固态金属钛、钨、镍等为基底，具有光电催化、电催化活性的功能电极：MoSe2/TiO2，TiO2/C，Ti3+/TiO2、WO3、MoS2/WO3、Cu2WS4、MoS2/Ni2S3、Pd/UiO-66、Fe/Ni-MIL(53)；（2） 阐明了界面电子通道形成的物化原理，促进光生电对有效分离，导流电子有序定向传输，提升电子还原六价铬、自由基深度去除内分泌干扰污染物的效能；（3）优化了反应催化界面电子和活性自由基浓度、寿命、迁移速率，明析了电荷可控调制传递的作用原理，揭示了光/电催化体系高效除水体污染物的电子还原规律、自由基氧化机制，阐释了活性物种脱除污染物环境毒性的微观机理。共发表学术论文9篇，其中SCI1区论文4篇；授权发明专利3项，实用新型专利1项，培养硕士研究生8人。相关研究为低能耗、高效率水处理纳米技术的发展提供理论数据与技术参考。