Lorenc-Grabowska Ewa, Gryglewicz Grazyna
Institute of Chemistry and Technology of Petroleum and Coal, Wrocław University of Technology, ul. Gdańska 7/9, 50-344 Wrocław, Poland.
J Colloid Interface Sci. 2005 Apr 15;284(2):416-23. doi: 10.1016/j.jcis.2004.10.031.
The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore volume, mesopore size distribution, and chemical properties of the surface. The kinetics of adsorption of HAs have been discussed using three kinetic models, i.e., the first-order Lagergren model, the pseudo-second-order model, and the intraparticle diffusion model. It was found that the adsorption of HAs from alkaline solution on mesoporous activated carbon proceeds according to the pseudo-second-order model. The correlation coefficients were close to 1. The intraparticle diffusion of HA molecules within the carbon particle was identified to be the rate-limiting step. Comparing the two activated carbons, the carbon with a higher volume of pores with widths of 10-50 nm showed a greater removal efficiency of HA. An increase in the Freundlich adsorption capacity with decreasing carbon content of HA was observed. Among the HAs studied, S-HA shows characteristics indicating the highest contribution of small-size fraction. The S-HA was removed by both activated carbons to the highest extent. The effect of pH solution on the adsorption of HA was examined over the range pH 5.4-12.2. It was found that the extent of adsorption decreased with decreasing pH of the solution.
研究了煤基介孔活性炭对从两种波兰褐煤中分离出的腐殖酸（HAs）的吸附作用。为作比较，本研究还纳入了一种市售的Aldrich腐殖酸。通过元素分析和红外光谱漫反射（DRIFT）确定了腐殖酸化学结构和官能团的差异。所使用的两种活性炭在介孔体积、介孔尺寸分布和表面化学性质方面存在差异。使用三种动力学模型，即一级Lagergren模型、准二级模型和颗粒内扩散模型，讨论了腐殖酸的吸附动力学。结果发现，碱性溶液中腐殖酸在介孔活性炭上的吸附遵循准二级模型。相关系数接近1。已确定腐殖酸分子在碳颗粒内的颗粒内扩散是限速步骤。比较这两种活性炭，孔径在10 - 50 nm之间且孔体积较大的活性炭对腐殖酸的去除效率更高。观察到随着腐殖酸碳含量的降低，Freundlich吸附容量增加。在所研究的腐殖酸中，S - HA显示出小尺寸部分贡献最大的特征。两种活性炭对S - HA 的去除程度最高。在pH值5.4 - 12.2范围内研究了溶液pH值对腐殖酸吸附的影响。结果发现，吸附程度随溶液pH值的降低而降低。
