改性活性炭的制备及其对气态汞的吸附研究

采用高温热处理法去除活性炭表面含氧官能团,并通过化学浸泡法分别将酚羟基和羧基添加到活性炭表面。利用氮气吸附-脱附、X射线衍射分析、X射线光电子能谱法对改性前后活性炭进行表征。研究发现：经高温热处理的活性炭比表面积增大为1139m2／g,孔径集中分布于1nm以下;热处理后活性炭内部晶格结构更加完整。经过化学改性后,酚羟基和羧基均可以一定比例负载到活性炭表面,且比表面积随着负载量增多而下降。对气态汞的吸附实验表明：经高温热处理的样品对气态汞的吸附能力与原始活性炭相比有所下降：当达到吸附饱和时,原始活性炭的吸附量为306．55μg／g,而经热处理的样品的吸附量是243．5μg／g;负载羧基的活性炭样品,其吸附容量高达865．3μg／g;负载酚羟基样品的吸附容量为133．1μg／g。由此得出结论：活性炭表面的含氧官能团对其吸附气态汞有重要影响,其中羧基的存在有利于对气态汞的吸附,而酚羟基的存在对气态汞的吸附不起促进作用。     

活性炭表面性质对其吸附及氧化氢醌的影响

研究了活性炭表面性质对活性炭吸附及氧化氢醌的影响。考察了3种材质活性炭在不同初始pH下吸附和氧化氢醌的性能以及氢醌吸附率、表观转化率与活性炭材质及用量的关系。实验结果表明：活性炭可以吸附及氧化氢醌,木屑材质活性炭对氢醌的吸附及转化效果好于其他两种,在未调节初始pH,反应时间3 h,反应温度25℃,木屑质活性炭用量为0.5 g·L^-1时,对氢醌的吸附率可达95.5%;木屑质活性炭用量为0.1 g·L^-1,其对氢醌的表观转化率为32.1%。木屑质活性炭微孔面积更大,表面的酚羟基、羧基和羰基官能团更丰富,故其吸附及转化氢醌的效果更好。在此基础上,提出了活性炭吸附及氧化氢醌的机理,为活性炭作为吸附剂或催化剂载体处理废水中酚类有机污染物提供理论依据。     

表面改性对活性炭吸附性能的影响

采用浓硝酸对活性炭进行表面氧化处理,将得到的样品分别浸渍在银氨、硫酸铜及咪唑溶液中进一步改性,然后采用Boehm滴定法对改性活性炭表面酸性基团的含量进行测定,研究改性对活性炭吸附性能的影响。结果表明：通过上述改性,活性炭表面酸性基团发生了显著变化,特别是羧基含量增加较多,从而活性诙的吸附性能发生了相应的变化。     

活性炭孔结构和表面官能团对吸附甲醛性能影响

通过对不同比表面积和孔结构的活性炭进行甲醛吸附的研究，以重量法精确测量活性炭对甲醛气体的饱和吸附量，比较各种活性炭和改性活性炭的吸附效果。实验表明，活性炭对甲醛分子的吸附与其孔结构和表面官能团密切相关，微孔比表面积大吸附效果明显，中孔比表面积大达到吸附平衡的时间短。此外，通过对活性炭浸渍改性的研究表明，强氧化性的HNO，和H202处理的样品均有利于对甲醛分子的吸附，而氨基改性过的样品吸附效果减弱，主要原因是HNO3改性增加了活性炭表面的C=O、O-C=O等含氧官能团的量，从而改善了对甲醛的吸附效果。     

含氮活性炭对Cu~(2+)的吸附性能研究

采用未改性的和氨化处理后的活性炭进行Cu2+的吸附平衡实验。考察了溶液p H、吸附温度对两种活性炭的吸附性能的影响。分别采用伪一次方动力学方程、伪二次方动力学方程考察了活性炭的吸附动力学行为。结果表明:经过氨化处理的活性炭能显著提高活性炭对Cu2+的吸附性能,这可能是由于活性炭表面的含氮官能团提高了活性炭的碱性造成的。     

表面功能化活性炭对水溶液中汞离子的吸附

利用硝酸氧化改性和氨还原改性实现活性炭表面功能化,并通过静态吸附实验研究了改性前后活性炭对水溶液中汞离子的吸附性能。硝酸改性使得活性炭表面含氧官能团数量增多,氨改性后成功在活性炭上引入含氮官能团。实验结果表明在pH值为4～7的范围内有较好的吸附效果。吸附等温线和吸附动力学结果表明活性炭表面功能化可以提高对水溶液中汞离子的吸附性能。活性炭表面含氧官能团和含氮官能团与汞离子发生离子交换和配位络合作用。     

活性炭孔径分布和表面化学性质对吸附影响的研究进展

介绍了活性炭孔径分布及表面官能团的种类,分析了近年来国内外在活性炭孔径分布和表面官能团对吸附性能影响的研究进展情况,对以活性炭孔隙结构和表面官能团为出发点的研究提出了一些建议。     

酸预处理对活性炭吸附有机物的影响

无论是在工业用水还是生活饮用水的处理中,活性炭都是一种常规的去除有机物的方法.但活性炭在使用前如何进行预处理却无相关的研究资料,作者将水处理中常用的5种活性炭,包括果壳炭、椰壳炭、煤质炭进行酸预处理对比,试验证实,酸预处理后可以提高活性炭对水中有机物的吸附性能.     

过氧化氢氧化-活性炭吸附法回收碘的研究

采用过氧化氢氧化-活性炭吸附法回收高浓度含碘废水中的碘,考察了pH值、H2O2与I-摩尔比、反应时间对I-转化率的影响以及活性炭加量对I2提取率的影响,并对其机理进行了探讨。结果表明,在pH值为2、H2O2与I-摩尔比为1.00∶1、反应时间为2.0h、活性炭加量为2.2g.L-1的最优条件下,碘回收率为95.3%,纯度大于98.7%。     

活性炭表面氧化改性技术及其对吸附质量的影响

近年来,活性炭被广泛应用于吸附、催化、分离等多个领域,加强其吸附能力的探究意义重大,本文就活性炭表面氧化改性技术展开论述,首先介绍了活性炭表面氧化改性技术及基本原理,指出了改性之后活性炭的相关变化,最后阐述了活性炭表面氧化改性之后,对其吸附质量的影响,旨在为有效提高活性炭的吸附能力提供参考。     

活性炭表面改性及其对Cr(Ⅵ)吸附性能的研究

分别用HNO3、H2SO4以及HNO3加乙酸铜溶液对活性炭进行了表面改性处理,测定了它们的表面化学性能,研究了改性活性炭对Cr(VI)吸附性能的影响。实验结果表明：通过上述改性,活性炭表面官能团数量发生了显著改变,特别是羧基增加较多;通过改性后的活性炭对Cr(Ⅵ)吸附性能有所提高。     

Adsorption of Phenol and Basic Dye on Carbon Nanotubes/Carbon Fabric Composites from Aqueous Solution

The liquid-phase adsorption of phenol and dye (basic violet 10) onto carbon nanotube (CNT)-activated carbon fabric (ACF) composites, prepared by a catalytic chemical vapor deposition (CCVD) approach, has been investigated. The CCVD technique enables the decoration of CNTs on microscaled ACFs, creating a hierarchy CNT-ACF composite. The as-grown nanotubes were found to have a tortuous shape and to be several micrometers in length. The deposition of CNTs efficiently shifts the micropore size distribution of ACFs to mesoporosity. The adsorption isotherms for phenol and BV10 on ACF and CNT-ACF adsorbents are well characterized by the Dubinin-Radushkevich and Langmuir models. The surface accessibility, the equilibrium rate constant, and the adsorption energy are significantly enhanced due to the deposition of CNTs, as analyzed by these models. Accordingly, the existence of CNTs on ACF adsorbent plays a positive role in facilitating pore accessibility to adsorbate and providing more adsorptive sites for the liquid-phase adsorption.     

N-butyl Mercaptan Adsorption on Activated Carbon in Aqueous Phase

Adsorption of aqueous n-butyl mercaptan on Granular/Powder Activated Carbon is studied at pH 5-12.4 and 301 K/313 K. In GAC mercaptan blocks micropores and mesopores, whereas in PAC the broader mesopores remain intact providing access to micropores. Mercaptan is transformed into isomer disulfides and non-extractable sulfur forms following acid-base or oxidation-reduction reaction depending on carbon surface groups and iron, and dissolved oxygen. Adsorption obeys a Langmuir isotherm, with oxygen competing with mercaptan (<100 mg mercaptan/L), followed by a Dubinin-Raduschkevich isotherm. Mercaptan uptake increases with temperature. Free energy values suggest that the Langmuir part represents hydrogen bonds whereas the Dubinin-Raduschkevic part the van der Waals ones.     

Peanut Shell Activated Carbon： Characterization,Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

H_2O_2/O_3催化氧化改性活性炭研究

采用H2O2/O3催化氧化改性活性炭。以含氧官能团总量为主要指标、比表面积和碘吸附值为辅助指标评价改性效果。在活性炭质量和H2O2体积一定的条件下,考察了H2O2质量分数、O3浓度、反应时间及反应温度等因素对活性炭性能的影响。在H2O2质量分数为10%、O3浓度为4.32 mg.L-1、反应时间为2.5 h、反应温度为50℃的最优改性条件下,活性炭的含氧官能团总量为1.525 mmol.g-1,比改性前提高61.38%。     

Removal of Acid Dyes from Aqueous Solutions using Chemically Activated Carbon

Abstract

Textile dyes (Acid Yellow 17 and Acid Orange 7) were removed from its aqueous solution in batch and continuous packed bed adsorption systems by using thermally activated Euphorbia macroclada carbon with respect to contact time, initial dye concentration, and temperature. The activated carbon was prepared using a cheap plant-based material called Euphorbia macroclada, which was chemically modified with K₂CO₃. Lagergren-first-order and second-order kinetic models were used to fit the experimental data. Equilibrium isotherms were analyzed by Langmuir and Freundlich isotherms. Equilibrium data fitted well the Langmuir model in the studied temperature (25–55°C) ranges. The maximum adsorption capacity of AY17 and AO7 onto activated carbon was found to be 161.29 and 455 mgg^?1, respectively by Langmuir isotherm at 55°C. Breakthrough curves for column adsorption have also been studied. The desorption of dyes has been experimentally investigated using NaOH solution of pH 11.     

花生壳活性炭的表征,表面改性及吸附脱除水中Pb2+离子

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell (PAC) was used for the removal of Pb2 from aqueous solution. The impacts of the Pb2 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Boehm titration. The textural properties (surface area, total pore volume) were evaluated from the nitrogen adsorption isotherm at 77K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon (GAC) showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% (by mass)] modified PAC has larger adsorption capacity of Pb2 from aqueous solution (as much as 35.5mg.g1). The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.