Humic acid preparation, properties and interactions with metals lead and cadmium
Humic acid preparation, properties and interactions with metals lead and cadmium
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DOI：
10.1016/j.enggeo.2005.09.024
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发表时间：
2006-05-26
影响因子：
7.4
通讯作者：
Yong, RN
中科院分区：
文献类型：
--
作者：
Coles, CA;Yong, RN
研究了从土壤中提取的腐植酸(HA)的阳离子交换容量(CEC)、零电点(ZPC)、含氧官能团含量、扫描电子显微镜(SEM)图像和pH。干燥的HA的CEC约为水合HA的CEC的一半。在pH为4和6的条件下，通过对铅(Pb，As PbCl2)、镉(Cd，As Cd Cl2)和腐植酸，以及腐植酸、麦基纳威石和高岭石混合物进行24 h间歇平衡实验，研究了腐植酸对金属的保留作用。腐植酸与麦基纳威石和高岭石复配后，对铅、镉的反应活性降低。Mackinawite提高了pH并溶解了部分HA，直到金属和混合物之间充分的反应降低了pH，足以使溶解的HA固化并从溶液中去除更多的金属。HA与Mackinawite和高岭石的结合减少了可供吸收金属的HA位置。HA的官能团含量提供了HA的来源、腐殖化程度和存在较少分解组分的迹象。HA的CEC可以保守地预测金属摄取量。低pH条件有利于HA从溶液中去除金属，因为HA的ZPC低于pH 0.5，而当pH较高时，HA开始溶解。HA，特别是在水合阶段，可能是从含金属的水和废水中去除金属的一种重要材料。(C)2006爱思唯尔B.V.保留所有权利。
Humic acid (HA) extracted from soil is investigated in terms of its cation exchange capacity (CEC), zero point of charge (zpc), oxygen containing functional group content, scanning electron microscope (SEM) images, and pH. The CEC of HA that was dried was approximately half the CEC of hydrated HA. Metal retention by HA was studied by conducting 24 h batch equilibrium tests with lead (Pb, as PbCl2) and cadmium (Cd, as CdCl2) and HA at pH 4 and 6, and with a mixture of HA, mackinawite and kaolinite. The reactivity of the HA towards Pb and Cd was reduced when it was combined with the mackinawite and kaolinite. The mackinawite raised the pH and dissolved some of the HA, until sufficient reactions between the metals and mixture lowered the pH enough for the dissolved HA to solidify and remove more metal from solution. HA bonding with the mackinawite and kaolinite reduced the HA sites available for metal uptake. The functional group content of the HA provided indications regarding the origin of the HA, the extent of humification and the presence of less decomposed fractions. The CEC of the HA could conservatively predict the amount of metal uptake. Low pH conditions are favorable for metal removal from solution by HA because the zpc of the HA was below pH 0.5 and because at higher pHs HA begins to dissolve. HA, especially in the hydrated phase, may represent an important material for metal removal from waters and wastewaters containing metals. (C) 2006 Elsevier B.V. All rights reserved.