多孔水化硅酸钙的制备及其磷回收特性

为实现磷资源的可持续利用,以环境废弃物电石渣为钙质材料,以白碳黑为硅质材料合成CSH(水化硅酸钙),以该材料为晶种,以结晶形成羟基磷灰石的形式从含磷废水中回收磷,重点研究了不同钙硅比〔c(CaO)/c(SiO₂)〕条件下制备的CSH对含磷废水中磷的回收特性. 结果表明,钙硅比为1.8∶1时所得的CSH结构更疏松、表面分布有较多的孔隙, 较大的比表面积使其具有较好的溶钙能力. 钙硅比为1.8∶1的CSH最佳磷回收工艺条件:反应时间为60min,CSH投加量为4g/L,搅拌强度为40r/min. 在该条件下重复除磷15次以后,回收产物中w(P)达到17.56%,说明CSH具有良好的磷回收性能. 对回收磷前后的CSH进行了XRD图谱分析和FTIR分析发现,溶液中的磷主要生成了羟基磷灰石并嵌入到CSH中. 基于回收磷的目的,CSH可以用于处理ρ(P)较高的工业废水,或者是生物除磷系统中的污泥厌氧释磷液中,回收磷后的产品可作为含磷矿石或者磷肥加以利用. 

Preparation and Phosphorus Recovery Properties of Porous Calcium Silicate Hydrate

In order to sustainably utilize phosphorus, Carbide residue (as calcium material) and white carbon black (as silica material) was used to synthesize calcium silicate hydrate (CSH). As a crystal seed, CSH was used to recover phosphorus from wastewater by producing hydroxyapatite (HAP). The effect of Ca/Si molar ratio on the phosphorus recovery properties of CSH was studied. It was found that there were effects of Ca/Si molar ratio on the structure of CSH. When the Ca/Si molar ratio was 1.8∶1, the surface of prepared CSH presented porous structure. A good solubility of Ca2+ was obtained when the large area was used. The best operating condition to recover phosphorus by CSH were CSH dosage of 4g/L, reaction time of 60minutes, stirring intensity of 40r/min. Under the optimum condition, the phosphorus content of regenerated products reached 17.56% after 15times of circulation of phosphorus removal. This result indicated that the CSH material possessed good phosphorus recovery properties. According to X-ray diffraction and FTIR analysis, HAP has been formed on the surface of CSH during the phosphorus recovery process. In order to recover phosphorus, the CSH can be used to deal with the high phosphorus-contenting wastewater, including industrial wastewater and anaerobic rich phosphate supernatant. In addition, the regenerated phosphorus-containing products (HAP), instead of precious and depleting phosphorus resource, can be reused as phosphorus rock and phosphorus fertilizer.