Removal of arsenic from water by porous charred granulated attapulgite-supported hydrated iron oxide in bath and column modes
Removal of arsenic from water by porous charred granulated attapulgite-supported hydrated iron oxide in bath and column modes
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DOI：
10.1016/j.jclepro.2017.08.026
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发表时间：
2017-11
影响因子：
11.1
通讯作者：
Hongbin Yin;M. Kong;Guan Xiaohong;Huiui Chen
中科院分区：
文献类型：
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作者：
Hongbin Yin;M. Kong;Guan Xiaohong;Huiui Chen
粘土越来越多地被用作承载材料，以开发成本效益高的吸附剂来去除水中的污染物。这对农村和欠发达地区的砷净化尤为迫切。然而，由于分离困难，改性粘土的细粉形式不能直接用于水处理。本文采用一种简单易行的方法，将水合氧化铁负载到多孔的炭化凹凸棒石颗粒中，制备了一种低成本的砷吸附剂。结果表明，铁浸渍能够提高炭化凹凸棒石的Brunauer-Emmett-Teller比表面积和微孔体积，这可能是由于炭化凹凸棒石孔道中生成了纳米级的铁所致。批量研究表明，As(Ⅲ)(亚砷酸盐)和As(Ⅴ)(砷酸盐)在所制备的吸附剂上的最大吸附容量分别为3.25g/g和5.09g/g，符合朗缪尔方程，均高于已报道的低成本砷吸附剂。浸铁吸附剂对砷的吸附速率随初始砷浓度的不同而不同，但均可用准二级模型描述。铁改性炭化凹凸棒石具有较宽的pH值范围(5~9)。但共存离子SO42-−、HCO3-−和PO43-−对砷吸附的抑制作用随其浓度的增加而增强。其中，PO43−的作用最大。吸附后的砷在0.5mol/L氢氧化钠溶液中可再生4次，对As(Ⅴ)和As(Ⅲ)的脱附率分别为11.3%和25.6%。固定床柱实验表明，铁改性炭化凹凸棒石对10μg/L以下砷污染水中As(V)的处理能力为397BV，对As(III)的处理能力为175BV，表明铁改性炭化凹凸棒石作为一种低成本的炭化凹凸棒石用于农村和经济欠发达地区的砷污染水净化具有很好的应用前景。
Clays are increasingly used as hosting materials to develop cost-effective adsorbents for pollutant removal from water. This is especially urgent for arsenic purification in rural and undeveloped areas. However, the fine powder form of modified clay cannot be used directly in water treatment due to the separation difficulty. Herein, a simple and easy method was used to prepare a low-cost arsenic adsorbent through loading hydrated iron oxide into porous charred granulated attapulgite. The results show that iron impregnation can increase the Brunauer-Emmett-Teller surface area and micropore volume of charred granulated attapulgite, which was possibly caused by the nano-sized iron formed in the channel of charred granulated attapulgite. Batch studies indicate that As(Ⅲ) (arsenite) and As(Ⅴ) (arsenate) sorption on the prepared adsorbent fit well with the Langmuir equation as the maximum sorption capacities were 3.25 and 5.09 mg/g, respectively, which were higher than the reported low-cost arsenic adsorbent. The arsenic sorption rate on the iron impregnated sorbents varied with initial arsenic concentrations, but all can be described by a pseudo-second-order model. The iron modified charred granulated attapulgite performed well with a wider pH value (5–9). However, inhibition effects of arsenic sorption by coexisting ions SO42−, HCO3−and PO43−increased with the increase of their concentrations. Of these, PO43−exerted the largest effect. The arsenic adsorbed sorbent can be regenerated by 0.5 mol/L NaOH four times with an approximate 11.3% and 25.6% sorption capacity lost for As (Ⅴ) and As (Ⅲ), respectively. A fixed bed column experiment showed that iron-modified charred granulated attapulgite can treat 397 BV for As (V) and 175 BV for As (III) of arsenic contaminated water below 10 μg/L. These results indicated that the first reported low-cost iron modified charred granulated attapulgite is very promising for arsenic contaminated water purification in rural and developing area.