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Abstract(s)
Grape bagasse generated in wine production can be used as a potential biosorbent for colour removal. Batch experiments were carried out for kinetic studies of textile dyes Acid Orange 7 (AO7) and Direct Red 80 (DR80) onto dried grape bagasse, at pH of 7-7.5. For dye AO7 the influence of initial dye concentration (from 20 to 100 mg/), temperature (20, 37 and 50ºC) and contact time was evaluated. A maximum efficiency rate (ca. 89%) was found for 2.5g of biosorbent in tests with a 20 ml solution /g biosorbent. Kinetic studies show that, at 50ºC, experimental data are well described by a pseudo second order model. However, the rate-limiting step of the process at 37ºC appears to be the internal diffusion. At 20ºC both processes are determinant. The equilibrium data were fitted to the Langmuir, Freundlich and Langmuir-Freundlich isotherms. Langmuir and Langmuir-Freundlich were considered as those that better describe the equilibrium results. The adsorption capacities ranged from 2,7 a 3,5 mg de AO7/g biosorbent. Dye DR80 displayed a lower efficient colour removal rate (ca. 43%) than AO7 in similar test conditions, which could be due to the type of solute-sorbent interactions, since DR80 is a linear molecule with a higher hydrophilic character. Results show that grape bagasse could be employed as a low-cost adsorbent on colour removal.
Description
Entre as tecnologias orientadas para o tratamento de efluentes contendo corantes, principalmente do grupo azo, destaca-se o processo de adsorção utilizando como adsorvente o bagaço de uva que é um subproduto originado nas indústrias vitivínicolas. O presente trabalho tem como objectivo primeiro a aplicação deste material de baixo custo na remoção de corantes em efluentes industriais.
Keywords
Bagaço de uva - Absorvente de corantes Cinética Adsorção Biosorção - Corantes Azo
Pedagogical Context
Citation
Publisher
Universidade da Beira Interior