School of Environment, Tsinghua University, Beijing, 100084, China.
College of Architecture and Civil Engineering, Wenzhou University, Wenzhou, 325035, China.
Environ Sci Pollut Res Int. 2018 Aug;25(22):21483-21497. doi: 10.1007/s11356-018-2143-7. Epub 2018 Jun 14.
Due to high pollution associated with traditional Portland cement and bio-carbonate cement, a new generation of cementitious material needs to be developed. Bio-barium phosphate, magnesium phosphate, and ferric phosphate are synthesized by bio-mineralization. Firstly, the substrate is hydrolyzed by alkaline phosphatase secreted via phosphate-mineralization microbes, obtaining phosphate ions. Micro- and nano-scale phosphate minerals are prepared by phosphate ions reacting with different types of metal cation. The setting time of bio-BaHPO has a greater effect on the strength of sand columns when a mixing precipitation process is innovatively adopted. The strength of the sand columns increases as bio-BaHPO content (1050%) increases. The optimum content of bio-BaHPO is 60%. Porosity and permeability of the sand columns decrease as bio-BaHPO content (1060%) increases. Ammonium and ammonia can effectively be synthesized to magnesium ammonium phosphate by adding KHPO·3HO to Sporosarcina pasteurii liquid. Permeability, porosity, and compressive strength of the sand columns are close to CJ1, CJ1.5, and CJ2 cementation. However, the fixation ammonia ratio of CJ2 is bigger than CJ1 and CJ1.5 (The mixture solutions of Sporosarcina pasteurii and KHPO·3HO (1, 1.5, and 2 mol/L) are named as CJ1, CJ1.5, and CJ2) cementation. The results show that the Sporosarcina pasteurii liquid containing KHPO·3HO (2 mol/L) and the mixture solution of MgCl and urea (3 mol/L) cemented loose sand particles best. Two types of bio-cement are environmentally friendly and can partially or completely replace bio-carbonate cement.
由于传统的波特兰水泥和生物碳酸盐水泥存在高污染问题，因此需要开发新一代的胶凝材料。生物磷灰石、磷酸镁和磷酸铁是通过生物矿化合成的。首先，通过磷酸盐矿化微生物分泌的碱性磷酸酶将基质水解，得到磷酸离子。然后，通过磷酸离子与不同类型的金属阳离子反应，制备出微纳米级的磷酸盐矿物。在创新采用混合沉淀工艺时，生物-BaHPO 的凝固时间对砂柱强度的影响较大。随着生物-BaHPO 含量（10%50%）的增加，砂柱的强度增加。当生物-BaHPO 的含量为 60%时，强度最佳。随着生物-BaHPO 含量（10%60%）的增加，砂柱的孔隙度和渗透率降低。通过向巴氏芽孢杆菌液体中添加 KHPO·3HO，可以有效地将铵和氨合成到磷酸镁铵中。砂柱的渗透率、孔隙度和抗压强度与 CJ1、CJ1.5 和 CJ2 胶结剂相近。然而，与 CJ1 和 CJ1.5 相比，CJ2 的固定氨比更大（巴氏芽孢杆菌液体和 KHPO·3HO（1、1.5 和 2 mol/L）的混合物溶液分别命名为 CJ1、CJ1.5 和 CJ2）胶结剂。结果表明，含有 KHPO·3HO（2 mol/L）的巴氏芽孢杆菌液体和含有 MgCl 和尿素（3 mol/L）的混合物溶液对松散砂粒的胶结效果最好。这两种生物水泥环保且可部分或完全替代生物碳酸盐水泥。
