Soil Department, Universidade Federal de Viçosa, PH Rolfs Avenue, Viçosa, MG, Brazil.
National Institute of Science and Technology, INCT Acqua, Belo Horizonte, Brazil.
Environ Sci Pollut Res Int. 2018 May;25(13):12967-12980. doi: 10.1007/s11356-018-1458-8. Epub 2018 Feb 24.
Several methods to remove arsenic from water have been considered, including co-precipitation with Fe and Al (hydr)oxides. Such compounds are considered very effective to remove As from contaminated water due to strong bindings between them. Three Fe:Al molar ratios (100:0, 80:20, and 60:40) were used to synthesize aluminum, ferrous, and ferric (hydr)oxides by precipitation in water highly contaminated with arsenite (50 and 500 mg L). The method was very efficient for all treatments (> 93%) at the beginning of the incubation period, excepted the one with 60:40 Fe(II):Al molar ratio at the higher As concentration (500 mg L) in which gibbsite was identified in precipitated phases. In spite of the high efficiency, however, the threshold for drinking water was not attained, mainly to the higher As concentration, even 84 days after precipitation. At this high concentration of arsenite, even the required threshold for effluent discharge was not attained in some treatments. The sludge resulting from treatments with higher As concentration were considered hazardous according to results from leaching test and corroborated by BCR extractions. Arsenic associated with Al and adsorbed phases were also assessed by extractions with NHF and KHPO, respectively. In general, the presence of Al increased the efficiency as well as the stability of the sludge resulting from Fe (II) treatments, but did not affect Fe (III) treatments, which were more efficient for As removal.
已经考虑了几种从水中去除砷的方法，包括与 Fe 和 Al（氢）氧化物共沉淀。由于它们之间的强结合，这些化合物被认为是非常有效地从受污染的水中去除 As。使用三种 Fe:Al 摩尔比（100:0、80:20 和 60:40）通过沉淀在高度受亚砷酸盐污染的水中合成铝、亚铁和铁（氢）氧化物（50 和 500 mg L）。在孵育期开始时，除了在较高 As 浓度（500 mg L）下用 60:40 Fe(II):Al 摩尔比处理的情况外，该方法对所有处理（>93%）都非常有效，在沉淀相中鉴定出了水铝石。尽管效率很高，但仍未达到饮用水的阈值，主要是由于 As 浓度较高，即使在沉淀 84 天后也是如此。在如此高的亚砷酸盐浓度下，即使在一些处理中也未达到排放标准的要求。根据浸出试验的结果和 BCR 提取的结果，认为高 As 浓度处理产生的污泥是危险的。还通过分别用 NHF 和 KHPO 进行提取来评估与 Al 和吸附相结合的砷。一般来说，Al 的存在提高了 Fe(II)处理产生的污泥的效率和稳定性，但不影响 Fe(III)处理，Fe(III)处理对 As 的去除更有效。
