Adsorption of dyes on activated carbons: influence of surface chemical groups

被引:481
作者
Pereira, MFR [1 ]
Soares, SF [1 ]
Orfao, JJM [1 ]
Figueiredo, JL [1 ]
机构
[1] Univ Porto, Lab Catalise & Mat, Dept Engn Quim, Fac Engn, P-4200465 Oporto, Portugal
关键词
activated carbon; chemical treatment; heat treatment; temperature programmed desorption; adsorption properties;
D O I
10.1016/S0008-6223(02)00406-2
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The surface chemistry of a commercial activated carbon has been selectively modified, without changing significantly its textural properties. by means of chemical treatments. using HNO3. H2O2. NH3. and thermal treatments under a flow of H-2 or N-2. The resultant samples were characterized in terms of their surface chemistry and textural proper-ties. and subsequently tested in the removal of different classes of dyes. It was shown that the surface chemistry of the activated carbon plays a key role in dye adsorption performance. The basic sample obtained by thermal treatment under H-2 flow at 700 degreesC is the best material for the adsorption of most of the dyes tested. For anionic dyes (reactive, direct and acid) a close relationship between the surface basicity of the adsorbents and dye adsorption was shown. the interaction between the oxygen-free Lewis basic sites and the free electrons of the dye molecule being the main adsorption mechanism. For cationic dyes (basic) the acid oxygen-containing surface groups show a positive effect but thermally treated samples still present good performances, showing the existence of two parallel adsorption mechanisms involving electrostatic and dispersive interactions. The conclusions obtained for each dye individually were confirmed in the colour removal from a real textile process effluent. (C) 2002 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:811 / 821
页数:11
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