Rathore Vineet Kumar, Mondal Prasenjit
Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
J Environ Manage. 2017 Sep 15;200:160-169. doi: 10.1016/j.jenvman.2017.05.081. Epub 2017 May 31.
The presence of arsenic and fluoride in groundwater has been observed throughout the world. Many technologies have been developed by various research groups in order to tackle this problem. Adsorption has emerged as one of the best possible technique for the removal of arsenic, fluoride and many other pollutants from drinking water. Although a considerable amount of work has been published on the adsorptive removal of arsenic and fluoride, the area related to the management of spent adsorbent is not well explored. Present paper deals with the adsorptive removal of arsenic and fluoride from aqueous solution by three different types of adsorbents, namely, thermally treated laterite (TTL), acid-base treated laterite (ABTL) and aluminum oxide/hydroxide nanoparticles (AHNP). Under the experimental conditions in batch operation, the adsorption capacities of TTL, ABLT and AHNP for arsenic are found to be 6.43 μg/g, 9.25 μg/g and 48.5 μg/g respectively, whereas for fluoride, these values are found as 0.21 mg/g, 0.85 mg/g and 4.65 mg/g respectively. After adsorption, the spent adsorbents have been stabilized in the form of clay bricks. The effects of spent adsorbent concentration on the properties of bricks and their leaching properties are investigated. The bricks have been tested for various properties like density, percentage water absorption, shrinkage, compressive strength and efflorescence. The maximum values of density and shrinkage of the bricks formed are found as 2.3 g/cm and 10.2%, whereas the percentage water absorption and compressive strength of the bricks are found between 11 and 14% and 35 to 150 kgf/cm respectively. All the test results are in accordance with the criteria set by Indian Standards. The leaching test of arsenic and fluoride from the bricks reveals that their maximum values in leachate are 510 μg/L and 2.1 mg/L respectively, which are below the permissible limits of USEPA standards.
世界各地的地下水中均检测到了砷和氟化物的存在。各个研究团队已开发出多种技术来解决这一问题。吸附法已成为从饮用水中去除砷、氟化物及许多其他污染物的最佳可行技术之一。尽管已有大量关于吸附法去除砷和氟化物的研究报道，但与废吸附剂管理相关的领域尚未得到充分探索。本文研究了三种不同类型的吸附剂，即热处理红土（TTL）、酸碱处理红土（ABTL）和氧化铝/氢氧化铝纳米颗粒（AHNP）对水溶液中砷和氟化物的吸附去除效果。在间歇操作的实验条件下，TTL、ABLT和AHNP对砷的吸附容量分别为6.43μg/g、9.25μg/g和48.5μg/g，而对氟化物的吸附容量分别为0.21mg/g、0.85mg/g和4.65mg/g。吸附后，废吸附剂被制成粘土砖进行稳定化处理。研究了废吸附剂浓度对砖性能及其浸出特性的影响。对砖的密度、吸水率、收缩率、抗压强度和泛霜等各种性能进行了测试。所制砖的密度和收缩率最大值分别为2.3g/cm³和10.2%，而砖的吸水率和抗压强度分别在11%至14%和35至150kgf/cm²之间。所有测试结果均符合印度标准规定的标准。砖中砷和氟化物的浸出试验表明，浸出液中它们的最大值分别为510μg/L和2.1mg/L，均低于美国环保署标准的允许限值。
