Influence of surface properties on the mechanism of H2S removal by alkaline activated carbons.
Influence of surface properties on the mechanism of H2S removal by alkaline activated carbons.
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DOI：
10.1021/es0303992
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发表时间：
2004
影响因子：
11.4
通讯作者：
R. Yan;Terence Chin;Y. Ng;H. Duan;D. T. Liang;J. Tay
中科院分区：
文献类型：
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作者：
R. Yan;Terence Chin;Y. Ng;H. Duan;D. T. Liang;J. Tay
碱性活性炭广泛用作硫化氢 (H2S) 的吸附剂，硫化氢是污水处理设施中产生的主要恶臭化合物之一。尽管许多研究探讨了各种参数的影响，但碱性碳吸附 H2S 的机制尚未完全了解。主要困难似乎在于，人们对碳表面发生的主要反应知之甚少。在本研究中，系统地研究了碱性活性炭的表面性质，以进一步探索和更好地理解碱性活性炭吸附H2S的机制。研究了两种市售碱性活性炭及其代表性的废样品（H2S 突破测试后在柱的不同高度收集的 8 个样品）。用8份排出的碳来代表H2S/碳反应过程。使用氮吸附（BET 测试）、表面 pH 值、Boehm 滴定、热分析和 FTIR 分析来表征原始碳和废碳的表面特性。孔隙率和表面积提供了有关反应程度的废碳孔隙结构的详细信息，有助于了解潜在的孔隙堵塞。 Boehm 滴定和 FTIR 的结果均证明了表面官能团的显着影响，氧化产物的鉴定证实了两种碳所涉及的不同机制。从热分析的DTG曲线来看，从8个耗尽部分观察到代表两种表面反应产物（即硫和硫酸）的两个明确的峰，其图案逐渐变化，与反应程度一致。耗尽的碳的表面 pH 值显示出随着反应范围 pH 值下降的明显趋势，而床底部的 pH 值在 2 左右，表明硫酸是主要产物。虽然这两种碳都是煤基且是 KOH 浸渍型，但不同碳的性能差异很大。已经建立了将反应程度与各种表面特性联系起来的相关性。总之，不仅均匀的碱浸渍和物理孔隙率，而且碳表面化学也是影响碱性活性炭作为 H2S 吸附剂性能的重要因素。
Alkaline activated carbons are widely used as adsorbents of hydrogen sulfide (H2S), one of the major odorous compounds arising from sewage treatment facilities. Although a number of studies have explored the effects of various parameters, mechanisms of H2S adsorption by alkaline carbons are not yet fully understood. The major difficulty seems to lie in the fact that little is known with certainty about the predominant reactions occurring on the carbon surface. In this study, the surface properties of alkaline activated carbons were systematically investigated to further exploit and better understand the mechanisms of H2S adsorption by alkaline activated carbons. Two commercially available alkaline activated carbons and their representative exhausted samples (8 samples collected at different height of the column after H2S breakthrough tests) were studied. The 8 portions of the exhausted carbon were used to represent the H2S/carbon reaction process. The surface properties of both the original and the exhausted carbons were characterized using the sorption of nitrogen (BET test), surface pH, Boehm titration, thermal and FTIR analysis. Porosity and surface area provide detailed information about the pore structure of the exhausted carbons with respect to the reaction extent facilitating the understanding of potential pore blockages. Results of Boehm titration and FTIR both demonstrate the significant effects of surface functional groups, and identification of oxidation products confirmed the different mechanisms involved with the two carbons. From the DTG curves of thermal analysis, two well-defined peaks representing two products of surface reactions (i.e., sulfur and sulfuric acid) were observed from the 8 exhausted portions with gradually changing patterns coinciding with the extent of the reaction. Surface pH values of the exhausted carbons show a clear trend of pH drop along the reaction extent, while pH around 2 was observed for the bottom of the bed indicating sulfuric acid as the predominant products. Although both carbons are coal-based and of KOH impregnated type, performances of different carbons differ significantly. A correlation is well established to link the reaction extent with various surface properties. In summary, not only the homogeneous alkali impregnation and physical porosity but also the carbon surface chemistry are significant factors influencing the performances of alkaline activated carbons as H2S adsorbents.