Stavropoulos G G, Samaras P, Sakellaropoulos G P
Chemical Engineering Department, Aristotle University of Thessaloniki, TEI campus, P.O. Box 1520, 54006 Thessaloniki, Greece.
J Hazard Mater. 2008 Mar 1;151(2-3):414-21. doi: 10.1016/j.jhazmat.2007.06.005. Epub 2007 Jun 7.
The primary objective of this work was the examination of modified activated carbons with tailored adsorption capacity properties. Production of activated carbons with desired properties was accomplished by modification of surface functional groups and introduction of acidic/basic properties. Modification of an activated carbon was performed using partial oxygen gasification, nitric acid treatment, urea impregnation followed by pyrolysis and pyrolysis in a urea saturated stream. The surface properties of the produced samples were estimated by the multibasic titration method of Boehm and by the CO/CO2 gas evolution profiles, while pore structure development was measured by the N2 and CO2 gas adsorption isotherms. Oxygen gasification resulted in samples with surface area slightly lower that the raw activated carbon; the introduction of surface functional groups depended upon the severity of the treatment: carbonylic and phenolic type groups were introduced in all partially gasified samples, while low temperatures and short reaction times enhanced the basic character of the carbon. However, nitric acid treatment resulted in the introduction of high nitrogen amounts in the samples, the reduction of surface area and the development of a surface containing carboxylic, lactonic, phenolic and carbonylic groups with negligible HCl neutralization capacity. Treatment of activated carbon by urea supported the formation of basic groups and carbonyls. The presence of surface functional groups affected the adsorption capacity of the produced samples for the removal of specific pollutants such as phenols. Urea treated samples with a basic character and high nitrogen content presented the highest phenol uptake capacity; nitric acid treated carbons and oxygen gasified samples presented an acidic surface functionality and a low phenol adsorption capacity. The beneficial role of nitrogen on phenol adsorption was attributed to adsorbate-adsorbent interactions.
这项工作的主要目标是研究具有定制吸附容量特性的改性活性炭。通过修饰表面官能团并引入酸性/碱性特性来制备具有所需特性的活性炭。使用部分氧气气化、硝酸处理、尿素浸渍后热解以及在尿素饱和气流中热解等方法对活性炭进行改性。通过Boehm多碱滴定法和CO/CO2气体逸出曲线评估所制备样品的表面性质，同时通过N2和CO2气体吸附等温线测量孔结构的发展。氧气气化导致样品的表面积略低于原始活性炭；表面官能团的引入取决于处理的强度：在所有部分气化的样品中都引入了羰基和酚类基团，而低温和短反应时间增强了碳的碱性。然而，硝酸处理导致样品中引入大量氮，表面积减小，并形成含有羧酸、内酯、酚和羰基基团且HCl中和能力可忽略不计的表面。用尿素处理活性炭有助于碱性基团和羰基的形成。表面官能团的存在影响了所制备样品对特定污染物（如酚类）的吸附能力。具有碱性特征和高氮含量的尿素处理样品表现出最高的苯酚吸附能力；硝酸处理的碳和氧气气化样品表现出酸性表面官能团和低苯酚吸附能力。氮对苯酚吸附的有益作用归因于吸附质与吸附剂之间的相互作用。
