Xu Wenbin, Yang Hailang, Mao Qiming, Luo Lin, Deng Ying
College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha 410128, China.
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Polymers (Basel). 2022 Dec 7;14(24):5355. doi: 10.3390/polym14245355.
Various metal ions in acid mine drainage (AMD) cause environmental pollution. Due to the unique advantages of heavy metal treatment and gelling properties, previous concretes incorporating red mud have attracted extensive attention in AMD passive treatment, which utilises naturally occurring chemicals to cleanse contaminated mine waters with low operating costs. This study aims to develop red mud-based geopolymer pervious concrete as an eco-friendly method to remove heavy metals in AMD. Compared with raw pervious concrete, red mud-based geopolymer pervious concrete improves the purification efficiency of heavy metals. The high rate of acid reduction and metal removal by the geopolymer is attributed to the dissolution of portlandite in red mud. Precipitation of metal hydroxides seems to be the dominant metal removal mechanism. Under optimal conditions (influent pH = 4.0 and the hydraulic retention time = 24 h), red mud-based geopolymer pervious concrete could completely remove Cu(II), Mn(II), Cd(II) and Zn(II) by up to 10 mg/L, 10 mg/L, 1.6 mg/L and 16 mg/L, respectively. When the influent pH is 2.5, the hydrolysis of Fe(III) released from red mud increases the consumption of OH. Moreover, when the influent pH is 4.0, the precipitation of CaSO promotes the dissolution of portlandite and metal removal. Therefore, red mud has demonstrated feasibility in the manufacturing of geopolymer-based pervious concrete for purification AMD.
酸性矿山排水（AMD）中的各种金属离子会造成环境污染。由于在重金属处理和胶凝性能方面具有独特优势，先前掺入赤泥的混凝土在AMD被动处理中引起了广泛关注，AMD被动处理利用天然化学物质以低成本净化受污染的矿井水。本研究旨在开发基于赤泥的地质聚合物透水混凝土，作为一种去除AMD中重金属的环保方法。与原始透水混凝土相比，基于赤泥的地质聚合物透水混凝土提高了重金属的净化效率。地质聚合物对酸的高还原率和金属去除率归因于赤泥中氢氧化钙的溶解。金属氢氧化物的沉淀似乎是主要的金属去除机制。在最佳条件下（进水pH = 4.0，水力停留时间 = 24 h），基于赤泥的地质聚合物透水混凝土可以分别完全去除高达10 mg/L的Cu(II)、10 mg/L的Mn(II)、1.6 mg/L的Cd(II)和16 mg/L的Zn(II)。当进水pH为2.5时，赤泥释放的Fe(III)水解会增加OH的消耗。此外，当进水pH为4.0时，CaSO的沉淀会促进氢氧化钙的溶解和金属去除。因此，赤泥已证明在制造用于净化AMD的基于地质聚合物的透水混凝土方面具有可行性。
