Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China.
Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China.
Sci Total Environ. 2018 Mar 15;618:1677-1684. doi: 10.1016/j.scitotenv.2017.10.018. Epub 2017 Oct 18.
Knowledge of adsorption mechanism and behavior of organic compounds by KOH-activated carbons (KOH-ACs) from wastewater is crucial to its environmental application in wastewater treatment as adsorbent. A superior adsorbent, KOH-activated carbon (KOH-AC), with large surface area (3143m/g), total pore volume of 2.03cm/g, relatively low micropore fraction of 53.2%, and having adsorption capacities of organic compounds up to >1000mg/g, was prepared. It is an adsorbent significantly different with common ACs because the molecular sieving effect, widely observed for common ACs, is insignificant for KOH-AC. This difference could be attributed to the lower micropore fraction of KOH-AC than common ACs. A negative relationship of adsorption capacity of 25 aromatic compounds (including phenols, anilines, nitrobenzenes and polycyclic aromatic hydrocarbons) with chemical melting point was observed, suggesting that adsorption is dependent on the packing efficiency and stacking density of molecules on KOH-AC. A linear solvation energy relationships of adsorption affinity of 25 aromatic compounds with solute solvatochromic parameters was also observed, that can be used to quantify the contributions of π-π interaction, hydrogen-bonding interaction and hydrophobic effect to adsorption on KOH-AC. Combined with the reported results of adsorption of organic compounds on carbon nanotubes and biochars, it was also observed that external surface area of adsorbents is controlling the packing efficiency and stacking density of molecules on adsorbents and thus affecting adsorption capacity of organic compounds. Moreover, micropore surface area and the fraction of micropores are the adsorbent properties mainly affecting adsorption affinity of organic compounds. The observations and the developed correlations in this study would be helpful in the application of KOH-AC as superior adsorbent by enhancing the understanding of adsorption mechanisms of organic compounds on KOH-AC and by giving a method to predict the adsorption behaviors.
了解 KOH 活化碳（KOH-AC）从废水中对有机化合物的吸附机制和行为对于其作为吸附剂在废水处理中的环境应用至关重要。制备了一种具有大表面积（3143m/g）、总孔体积为 2.03cm/g、相对较低的微孔分数为 53.2%、对有机化合物的吸附容量高达>1000mg/g 的优良吸附剂 KOH 活化碳（KOH-AC）。它与普通活性炭显著不同，因为普通活性炭广泛存在的分子筛效应对于 KOH-AC 来说并不重要。这种差异可以归因于 KOH-AC 的微孔分数低于普通活性炭。观察到 25 种芳香族化合物（包括酚类、苯胺类、硝基苯和多环芳烃）的吸附容量与化学熔点呈负相关，表明吸附取决于分子在 KOH-AC 上的堆积效率和堆积密度。还观察到 25 种芳香族化合物与溶质溶剂化参数之间吸附亲和力的线性溶剂化能量关系，可用于量化π-π 相互作用、氢键相互作用和疏水效应对 KOH-AC 吸附的贡献。结合文献中关于碳纳米管和生物炭对有机化合物的吸附结果，还观察到吸附剂的外比表面积控制分子在吸附剂上的堆积效率和堆积密度，从而影响有机化合物的吸附容量。此外，微孔表面积和微孔分数是吸附剂性质，主要影响有机化合物的吸附亲和力。本研究中的观察结果和开发的相关性将有助于通过增强对 KOH-AC 上有机化合物吸附机制的理解和提供预测吸附行为的方法，将 KOH-AC 作为优良吸附剂进行应用。
