Adsorption characteristics of Direct Red 23 from aqueous solution by biochar
Adsorption characteristics of Direct Red 23 from aqueous solution by biochar
复制标题
生物炭对水溶液中直接红23的吸附特性
DOI：
10.1016/j.molliq.2016.08.061
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发表时间：
2016-11-01
影响因子：
6
通讯作者：
Ma, Huiqiang
中科院分区：
文献类型：
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作者：
Liu, Na;Zhu, Meiling;Ma, Huiqiang
以800℃热解猪粪制备的生物炭被作为一种吸附剂用于去除水溶液中的直接红23，并对其进行了表征和研究。吸附动力学用改进的弗罗因德利希模型和颗粒内扩散模型能得到最好的描述。当生物炭的量从1克/升增加到8克/升时，表观吸附常数k（改进的弗罗因德利希模型）的值从0.133降至0.076升/(克·分钟^(1/m))。计算了有效颗粒扩散系数（D - p）和液膜扩散系数（D - f）以进一步确定吸附过程的限速步骤。活化能的值为5.558千卡/摩尔，表明吸附是一个由膜扩散控制的物理过程，且吸附过程是吸热的。当pH＜pHₚₑₑ（8.71）时，生物炭表面带正电；正电荷通过静电力促进阴离子染料吸附到生物炭上，并且与活性位点上质子化的 - OH官能团形成氢键。吸附平衡研究表明，吸附呈多层模式，在pH为2.20和温度为25℃时，最大吸附容量为2.19×10⁻⁵摩尔/克。考虑到其广泛的可获取性和较高的去除效率，生物炭在去除更多有害物质方面的应用值得进一步研究。（C）2016年由爱思唯尔B.V.出版
Biochar, produced by the pyrolysis of pig manure at 800 degrees C, was characterized and investigated as an adsorbent for the removal of Direct Red 23 from aqueous solution. The adsorption kinetics was best described by a modified Freundlich model and intra-particle diffusion models. The value of the apparent adsorption constant k (modified Freundlich model) decreased from 0.133 to.0.076 L/(g.min(1/m)), when the amount of biochar increased from 1 to 8 g/L. Values of effective particle diffusion coefficient (D-p) and liquid film diffusion coefficient (D-f) were calculated to further determine the rate-limiting step of the adsorption process. The value of activation energy 5.558 kcal/mol indicates that the adsorption is a physical process controlled by film diffusion and the adsorption process is endothermic. When pH < pH(zpc) (8.71),the surface of biochar is positively charged; the positive charge promoted the anionic dyes attracted onto the biochar by electrostatic force; and a hydrogen band was formed with the protonated -OH functional groups on the active sites. The adsorption equilibrium study indicates that the adsorption was in a multilayer mode, and the maximum adsorption capacity was 2.19 x 10(-5) mol/g, at pH 2.20 and temperature 25 degrees C. Considering the widely availability and high removal efficiency, biochar is deserved further investigations for applications in more hazardous substances removal. (C) 2016 Published by Elsevier B.V.