Pb(II) and Cd(II) Removal from Aqueous Solutions Using Activated Carbon Developed from Coffee Residue Activated with Phosphoric Acid and Zinc Chloride
Pb(II) and Cd(II) Removal from Aqueous Solutions Using Activated Carbon Developed from Coffee Residue Activated with Phosphoric Acid and Zinc Chloride
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DOI：
10.1021/je1009569
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发表时间：
2011-05-01
期刊：
影响因子：
--
通讯作者：
Aissani-Benissad, F.
中科院分区：
文献类型：
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作者：
Boudrahem, F.;Soualah, A.;Aissani-Benissad, F.
咖啡渣是一种低成本的农业副产品，在使用磷酸和氯化锌的化学方案中作为生产多孔碳的前体进行了测试。将原材料以从(0至100)96增加的浸渍比(ZnCl2或H3PO4的质量/咖啡渣的质量)进行浸渍，然后在600℃下热解1小时。该产品通过在77K下对N-2的吸附进行表征，并被证明具有高微孔和高比表面积。浸渍比对这些活性炭的孔结构有很大影响，这可以通过简单地改变活化中使用的活化剂的比例来容易地控制。因此，低浸渍比产生基本上微孔的活性炭。在中等和高浸渍比下，获得了具有更宽孔径分布（从微孔到中孔）和高表面积的活性炭。这些用 ZnCl2 和 H3PO4 开发的低成本吸附剂用于去除铅（II）和镉（II），并且它们显示出从水溶液中吸附铅（II）和镉（II）离子的强大能力。吸附动力学和平衡吸附程度取决于吸附剂、吸附物的物理和化学特性以及实验参数。通过批量实验研究了接触时间和吸附物初始浓度对铅和镉吸收的影响。动力学数据符合伪一级和伪二级模型，并严格遵循伪二级模型。采用Langmuir和Freundlich等温线模型分析了Pb(II)和Cd(II)的平衡吸附等温线。 Langmuir 模型比 Freundlich 模型拟合得更好。
Coffee residue, a low-cost agricultural byproduct, was tested as a precursor for the production of porous carbons in a chemical scheme using phosphoric acid and zinc chloride. The raw material was impregnated with increasing impregnation ratio (mass of ZnCl2 or H3PO4/mass of coffee residue) from (0 to 100) 96 followed by pyrolysis at 600 degrees C for 1 h. The products were characterized by adsorption of N-2 at 77K and proved to be highly microporous with high surface area. The impregnation ratio had a strong influence on the pore structure of these activated carbons, which could be easily controlled by simply varying the proportion of activating agents used in the activation. Thus, a low impregnation ratio led to essentially microporous activated carbons. At intermediate and high impregnation ratios, activated carbons with a wider pore size distribution (from micropores to mesopores) were obtained with high surface area. These low-cost adsorbents developed with ZnCl2 and H3PO4 were used for the removal of lead(II) and cadmium(II), and they showed a substantial capability to adsorb lead(II) and cadmium(II) ions from aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium were dependent on the physical and chemical characteristics of the adsorbent, adsorbate, and experimental parameters. The effect of contact time and initial concentrations of adsorbate on the uptake of lead and cadmium was studied in batch experiments. The kinetic data were fitted to pseudofirst-order and pseudosecond-order models and follow closely the pseudosecond-order model. Equilibrium adsorption isotherms of Pb(II) and Cd(II) were analyzed by the Langmuir and Freundlich isotherm models. The Langmuir model gives a better fit than the Freundlich model.