钙长石复相陶瓷的脱氮除磷功能化构筑及其调控机制

Anorthite is a common phase in the utilization of industrial solid wastes, such as paper processing residues, lime mud, waste gypsum mold. Research on anorthite is conducive to solve the solid wastes. The reported work was focused on finding suitable composite phases to increase the high temperature performance and strength. However, the function of anorthite ceramics is too single. It is necessary to design more function to expand its application field. The aim of this project is to prepare anorthite-gehlenite-glass phase composite ceramics with Ca2+ and OH- release performance from solid wastes (lime mud, fly ash) by sintering, which will complete the functionalization of nitrogen and phosphorus removal. The effects of preparation conditions on phase composition, crystal structure, morphology and physicochemical properties will be analyzed to reveal the synthesis mechanism of anorthite composite ceramics. On the basis of exploring the relationship between release performance and microcosmic composition, the internal regulation mechanism will be proposed and the releasing mechanism will be explained. In addition, the influence of dosage, leaching method and initial pH value on Ca2+ and OH- release efficiency will be analyzed to find out the external regulation mechanism. The application mechanism of nitrogen and phosphorus removal by anorthite composite ceramics will be clarified.

钙长石是废纸浆、造纸白泥、废石膏模等工业固废再利用过程中的常见晶相，探究钙长石的应用潜能对固废的资源化利用具有重要意义。目前，钙长石的研究多集中在寻找可提高陶瓷高温性能及强度的复合相上，陶瓷的功能单一，需要对其进行功能化构筑，扩大应用领域。本项目拟利用固体废弃物造纸白泥和粉煤灰为主要原料，通过高温烧结法，制备钙长石-钙铝黄长石-玻璃相复相陶瓷，使其获得供碱释钙性能，完成脱氮除磷功能化构筑。探究原料配比、煅烧温度等因素对陶瓷物相组成、晶体结构、微观形貌、物化性能的影响，揭示钙长石复相陶瓷的合成机制。考察陶瓷的供碱释钙能力与陶瓷微观构成的关系，揭示功能化的内部调控机制及缓释机理。考察投加量、浸出方式、初始pH值等因素对陶瓷供碱释钙能力的影响，揭示功能化的外部调控机制。探究陶瓷的供碱释钙性能在废水脱氮除磷中的作用机制。

本研究从固体废弃物资源化利用的角度出发，成功制备出系列钙长石复相陶瓷，通过引入钙铝黄长石晶体，实现该复相陶瓷供碱释钙功能的构筑，并将该陶瓷作为吸附剂或载体应用于水处理领域。结果表明，其堆积密度0.6-0.9 g/cm3，表观密度2.0 g/cm3左右，单颗强度1.44-8.30 MPa，24h吸水率19-42%，显气孔率35-50%，有效钙含量小于0.5%，耐碱性接近100%，释钙量30-582mg/L，浸出液pH在6.0-12.5，为绿色环保材料。其供碱释钙能力可控且持续时间长，主要取决于钙铝黄长石相或硅灰石相，而非钙长石相。造纸白泥掺量越高，钙铝黄长石和硅灰石的生成量越大，其供碱释钙能力越高。其利用多孔结构并结合供碱释钙作用，磷吸附容量可达4.15mg/g，铜吸附容量可达1.00mg/g，镉吸附容量可达1.68 mg/g，锰吸附容量可达2.54mg/g。其具有pH自调节能力，在处理实际废水时无需添加pH调节剂，可简化工艺过程，降低运行成本。氢氧化钠水热法改性可以在其表面生成氢氧化钙晶体，明显提升其对重金属离子的去除率和吸附速率。除磷后的复相陶瓷可进行不同方法再生，其中煅烧法恢复率高，循环使用性最好，其次是酸洗和碱洗法。其作为载体进行生物挂膜并用于废水脱氮除磷时，具有挂膜速度快，生物亲和性高，系统稳定高效的特点。本研究的成功实施为钙长石复相陶瓷的制备与应用奠定了技术基础，可加强我国多功能陶瓷的理论研究与工程应用，推动建筑、水处理等领域的技术进步。