Department of Civil and Environmental Engineering, University of Delaware, Newark, DE, 19716, United States.
Department of Environmental Engineering, University of Seoul, Seoul, 02504, South Korea.
Chemosphere. 2021 Sep;278:130239. doi: 10.1016/j.chemosphere.2021.130239. Epub 2021 Mar 23.
Red mud (RM), an industrial waste of bauxite refinery, shows great potential in adsorptive phosphate immobilization but granulation of RM enables the ease for field application. Red-mud-based ceramsites with 12 compositions that blended Korean red mud, American red mud, ocher, and bentonite were synthesized through firing process (600-1000 °C). The porosity, bulk density, mechanical strength, mineralogical composition, and phosphate adsorption capacity of granulated RM were characterized and analyzed. The crystallization of plagioclases, nepheline and gehlenite was observed in the ceramsites with high alkali flux content, which enhanced both porosity and phosphate adsorption capacity. The characteristics of the ceramsites without phase transition were highly correlated with porosity. The mechanical strength of ceramsites was governed by crack population, describable by the Weibull distribution model, and thus the maximal tensile stress correlated negatively with porosity. Results showed that 32 wt % of KRREM and USREM treated at 1000 and 900 °C, respectively, yielded the best performing ceramites in terms of mechanical strength and phosphate adsorption capacity. Ultimately, the phosphate adsorption capacity, as affected by initial phosphate concentration, contact time, and temperature, of the optimized ceramsites was studied.
赤泥（RM）是铝土矿精炼的工业废料，在吸附固定磷酸盐方面具有很大的潜力，但 RM 的颗粒化使其易于现场应用。通过烧制过程（600-1000°C）合成了 12 种成分的基于赤泥的陶粒，这些成分混合了韩国赤泥、美国赤泥、赭石和膨润土。对粒状 RM 的孔隙率、堆积密度、机械强度、矿物成分和磷酸盐吸附能力进行了表征和分析。在碱通量含量高的陶粒中观察到斜长石、霞石和钙长石的结晶，这提高了孔隙率和磷酸盐吸附能力。没有相变的陶粒特性与孔隙率高度相关。陶粒的机械强度由裂纹群控制，可用威布尔分布模型来描述，因此最大拉伸应力与孔隙率呈负相关。结果表明，分别在 1000°C 和 900°C 下处理 32wt%的 KRREM 和 USREM，得到的陶粒在机械强度和磷酸盐吸附能力方面表现最佳。最终，研究了优化后的陶粒对初始磷酸盐浓度、接触时间和温度对磷酸盐吸附能力的影响。
