Munyengabe Alexis, Zvinowanda Caliphs, Zvimba John Ngoni, Ramontja James
Department of Chemical Sciences, Faculty of Science, Doornfontein Campus, University of Johannesburg, Corner Beit and Nind Streets, P.O. Box: 17011, Johannesburg, 2028, South Africa.
Water Use and Waste Management, Water Research Commission, Bloukrans Building, Lynnwood Bridge Office Park, 4 Daventry Street, Lynnwood Manor, South Africa.
Heliyon. 2020 Oct 13;6(10):e05244. doi: 10.1016/j.heliyon.2020.e05244. eCollection 2020 Oct.
Mining activities are the main cause of generation of the voluminous sludge waste, loaded with metals precipitated from the treatment of acid mine drainage (AMD) and this is always disposed to the landfill. This study aimed at characterizing and suggesting the reusability potential of AMD sludge to reduce the environmental problem caused by its accumulation so that it could become a valuable material. The sludge was obtained after treating a synthetic AMD with a green oxidant sodium ferrate (VI) (NaFeO) that was prepared by a wet oxidation method. Chemical and physical characterization of a dried sludge generated after treatment was then performed using the Fourier Transform-Infrared and X-Ray powder Diffraction spectroscopy. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy also served to identify the surface morphology of the sludge. The sludge presented a high weight percentage of Fe and O and lower concentrations of other metals such as Al, Mn, Si, and Na. Nitrogen adsorption/desorption isotherms or Brunauer-Emmett-Teller (BET) was used to assess the surface area, pore volume and diameter of the sludge. The BET results showed that the surface area of the sludge obtained after treating the synthetic AMD using NaFeO was 31.50 ± 0.03 m/g with pore diameter and volume of 52.50 nm and 0.41 cm/g, respectively. However, the produced sludge could serve as an adsorbent to remove pollutants from water or to synthesize different magnetic nanocomposites due to its high surface area (>natural zeolite) and high composition of Fe and O.
采矿活动是产生大量污泥废弃物的主要原因，这些污泥含有从酸性矿山排水（AMD）处理过程中沉淀的金属，并且一直被处置到垃圾填埋场。本研究旨在表征并提出AMD污泥的再利用潜力，以减少其积累所造成的环境问题，使其成为一种有价值的材料。污泥是在用绿色氧化剂高铁酸钠（VI）（NaFeO）处理合成AMD后获得的，NaFeO是通过湿氧化法制备的。然后使用傅里叶变换红外光谱和X射线粉末衍射光谱对处理后产生的干燥污泥进行化学和物理表征。扫描电子显微镜-能量色散X射线光谱也用于识别污泥的表面形态。该污泥中Fe和O的重量百分比很高，而Al、Mn、Si和Na等其他金属的浓度较低。采用氮吸附/脱附等温线或布鲁诺尔-埃米特-特勒（BET）法评估污泥的表面积、孔体积和直径。BET结果表明，使用NaFeO处理合成AMD后获得的污泥表面积为31.50±0.03 m/g，孔径和孔体积分别为52.50 nm和0.41 cm/g。然而，由于其高表面积（>天然沸石）以及高含量的Fe和O，所产生的污泥可作为吸附剂用于去除水中的污染物或合成不同的磁性纳米复合材料。
