College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China; Research Center for Water Science and Environmental Engineering, Shenzhen University, 518055, China.
Chemosphere. 2020 Dec;261:127789. doi: 10.1016/j.chemosphere.2020.127789. Epub 2020 Jul 26.
Magnesium potassium phosphate cement (MKPC) is prepared from MgO and KHPO through an acid-base reaction and has been widely used in the rapid repairs of building structures and the solidification/stabilization (S/S) of heavy metals (HMs). The use of sludge incineration residue (SIR) rich in phosphorus resources to prepare SIR-based MKPC can achieve the reclamation of SIR and efficient HM S/S. Herein, based on the exploration of the optimal MKPC magnesia/phosphate ratio (M/P), the effects of SIR and HMs on the performance of the matrix and its interaction mechanism were comprehensively investigated. The results indicated that the compressive strength of the SIR-based MKPC increased first and then decreased with the gradual increase of SIR incorporation; the optimal was reached at 40.31 MPa when the SIR incorporation was 5 wt%. The peak signal and crystal lattice of Pb(PO) indicated that there is a mixed effect between HMs (in SIR) and KHPO. The Visual MINTEQ analysis results also indicated that HMs are precipitated as HM phosphates. The formation of HM phosphates not only increases the M/P (with 30 wt% SIR, M/P increased by 0.019), affecting the microstructure and changing the compressive strength of the matrix, but also promotes the transformation of HMs from the bioavailable to the more stable residual forms. The residual forms of the six HMs were all above 84% after S/S. Therefore, the SIR-based MKPC preparation significantly immobilized the HMs; particularly, the leaching toxicities of Cu (96.6%) and Zn (96.3%) were alleviated.
磷酸镁钾水泥（MKPC）由 MgO 和 KHPO 通过酸碱反应制备而成，广泛应用于建筑物结构的快速修复和重金属（HM）的固化/稳定化（S/S）。利用富含磷资源的污泥焚烧残渣（SIR）来制备基于 SIR 的 MKPC，可以实现 SIR 的回收利用和高效 HM 的 S/S。在此基础上，本文通过探索最佳 MKPC 氧化镁/磷酸盐比（M/P），综合研究了 SIR 和 HM 对基体性能的影响及其相互作用机制。结果表明，随着 SIR 掺入量的逐渐增加，基于 SIR 的 MKPC 的抗压强度先增加后降低；当 SIR 掺入量为 5wt%时，达到最大值 40.31MPa。Pb(PO)的峰值信号和晶格表明 HM（在 SIR 中）和 KHPO 之间存在混合效应。Visual MINTEQ 分析结果也表明 HM 被沉淀为 HM 磷酸盐。HM 磷酸盐的形成不仅增加了 M/P（掺入 30wt%的 SIR 时，M/P 增加了 0.019），影响了基体的微观结构并改变了其抗压强度，而且促进了 HM 从生物可利用态向更稳定的残留态的转化。S/S 后，六种 HM 的残留态均在 84%以上。因此，基于 SIR 的 MKPC 制备显著固定了 HM，特别是 Cu（96.6%）和 Zn（96.3%）的浸出毒性得到了缓解。
