海泡石结构中镁的浸出和赋存形式调控与废水中磷的矿化回收研究

The cost of external magnesium source is the main factor, which influences the applications in phosphorus recovery as struvite. In this proposal, sepiolite, a low-cost and rich magnesium silicate clay, is selected as object material, and a combination of acid-activation of clay and nanomineral synthesis will be adopted to control the Mg forms after the leach from sepiolite, and then Mg-containing nanocomposite will be prepared based on sepiolite mineral. Furthermore, the effects of different Mg forms on the nucleation, growth and morphogenesis of struvite will be investigated by batch experiments to reveal the mechanism in the removal and recovery of phosphorus by Mg-containing nanocomposite. On this basis, the effects of probable calcium, ferrous and aluminum ions in sepiolite, and common inorganic and organic matters in wastewater on struvite mineralization will be also studied. The feasibility of modified sepiolite as external magnesium source for struvite mineralization will be evaluated. The successful implementation of the proposed project can not only expand the applications of rich magnesium clay, enrich environmental mineralogy, but also promote the development of new struvite recovery route and techniques involved the effective recycling reuse of the non-renewable resource.

外加镁源的成本是影响鸟粪石结晶工艺在废水中磷资源回收应用的主要因素。本项目拟以廉价的富镁硅酸盐粘土矿物海泡石为研究对象，试图采用粘土矿物酸化和纳米矿物制备相结合的实验方法，调控海泡石结构中镁浸出后的赋存形式，进而基于海泡石制备含镁纳米复合材料。通过批量实验法，系统研究镁的不同赋存形式对鸟粪石成核、生长和形貌的影响，揭示含镁纳米复合材料对废水中磷的去除、回收机制。在此基础上，研究海泡石中可能具有的外来钙、铁、铝离子和废水中常见的有机、无机物质对鸟粪石矿化的影响，评估富镁粘土矿物改性后作为鸟粪石矿化的镁源，应用于废水中磷资源回收的可行性。实验成果的取得不仅能够拓展富镁粘土矿物在环境中的应用范围，丰富环境矿物学，而且有助于促进鸟粪石结晶工艺和不可再生资源回收再利用技术的发展。

外加镁源的成本是影响鸟粪石结晶工艺在废水中磷资源回收应用的重要限制性因素。本项目以富镁硅酸盐纳米棒状海泡石为研究对象，通过对海泡石进行酸碱调控、热处理和多种纳米材料制备手段，开展了不同改性条件下对海泡石结构中镁的浸出和转化研究，成功调控了海泡石结构中镁离子的赋存形态，制备出SiO2–Mg(OH)2和SiO2–MgO系列纳米复合材料，并研究了海泡石酸碱化处理制备SiO2–Mg(OH)2纳米复合材料对重金属去除能力与机制；系统阐明了以海泡石粘土矿物为基本材料所制备的含镁纳米复合材料及其对水体中磷的去除回收机制。在此研究基础上，以富镁石棉尾矿蛇纹岩为原材料，通过酸碱改性石棉尾矿，其对水体中的磷的去除性能大幅度提高，可潜在应用于废水中磷的去除与回收，拓展了本研究方法在石棉尾矿资源化中的应用。