Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW, 2007, Australia.
Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW, 2007, Australia.
Chemosphere. 2019 Jul;226:431-438. doi: 10.1016/j.chemosphere.2019.03.142. Epub 2019 Mar 26.
Arsenic (As) contamination of drinking water is a major cause of As toxicity in many parts of the world. A study was conducted to evaluate As removal from water containing 100-700 μg/L of As and As to Fe concentration ratios of 1:5-1:1000 using the coprecipitation process with and without As/Fe adsorption onto granular activated carbon (GAC). Fe concentration required to reduce As concentrations in order to achieve the WHO standard level of 10 μg/L increased exponentially with the increase in initial As concentration. When small amounts of GAC were added to the As/Fe solutions the Fe required to remove these As concentrations reduced drastically. This decline was due to the GAC adsorption of Fe and As, enhancing the removal of these metals through coprecipitation. Predictive regression equations were developed relating the GAC dose requirement to the initial As and Fe concentrations. Zeta potential data revealed that As was adsorbed on the GAC by outer-sphere complexation whereas Fe was adsorbed by inner-sphere complexation reversing the negative charge on GAC to positive values. X-ray diffraction of the GAC samples in the presence of Fe had an additional peak characteristic of ferrihydrite (Fe oxide) compared to that of the GAC sample without Fe. The study showed that incorporating an adsorbent into the coprecipitation process has the advantage of removing As from waters at all concentrations of Fe and As compared to coprecipitation alone which does not remove As to the required levels if Fe concentration is low.
饮用水中的砷（As）污染是世界许多地区砷毒性的主要原因。本研究采用共沉淀法，研究了在含 100-700μg/L 的 As 和 As/Fe 浓度比为 1:5-1:1000 的水中，通过共沉淀过程以及是否通过颗粒活性炭（GAC）吸附砷和铁来去除水中的砷。为了达到世界卫生组织（WHO）规定的 10μg/L 的标准水平，将砷浓度降低到所需的铁浓度与初始砷浓度呈指数级增加。当向砷/铁溶液中添加少量 GAC 时，去除这些砷浓度所需的铁量会急剧减少。这种下降是由于 GAC 对铁和砷的吸附，通过共沉淀增强了这些金属的去除。建立了与初始砷和铁浓度相关的 GAC 剂量需求的预测回归方程。动电电位数据表明，砷通过外层络合吸附在 GAC 上，而铁通过内圈络合吸附，使 GAC 的负电荷转变为正值。与没有铁的 GAC 样品相比，在 GAC 样品中存在铁时，X 射线衍射有一个额外的特征峰，属于水铁矿（Fe 氧化物）。研究表明，与单独的共沉淀相比，将吸附剂纳入共沉淀过程具有从所有铁和砷浓度的水中去除砷的优势，如果铁浓度低，共沉淀本身无法将砷去除到所需的水平。
