Influência da modificação química de superfície de óxidos de ferro na adsorção de cádmio e chumbo

• Ano de defesa: 2009
• Autor(a) principal: Marques, Márcio da Silva
• Orientador(a): Reis, César
• Banca de defesa: Neves, Antônio Augusto , Okumura, Leonardo Luiz
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Adsorção; Metais tóxicos; Óxidos de ferro
• Palavras-chave em Inglês: Adsorption; Toxic metals; Iron oxides
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2081

The treatment of wastewater from industrial processes is of paramount importance to avoid contamination of ecosystems. The development of methods of low cost sewage treatment aims to help companies to adapt to new times. Given that this study sought to produce a new adsorbent of low cost, by modifying a surface of iron oxide and assess whether it had potential for removal of toxic metal ions from aqueous solutions. The oxide was modified by the addition of citric acid molecules on the surface of it. The change was made to increase the number of oxygen atoms per unit area and therefore also increase the capacity of adsorption. The modified material was compared with the material in natura by the testing adsorptive, where metals were used as lead and cadmium contaminants and evaluated the influences of initial pH of the solution, initial concentration of metal, the time of contact and the percentage of removal in fixed bed. Were also adjusted to the experimental data reported in the literature models such as the Langmuir and Freundlich isotherms, and kinetic models of Lagergreen of pseudo-first- order and pseudo-second-order. Based on the analysis of experimental data obtained and the starting parameters of the models that best fit, it was found that the modified material showed better results that the source material, and the values of maximum adsorption capacity (Qm) obtained from Langmuir isotherm of where to lead the Qm was 2.4 mg / g and 4.1 mg / g for the material of origin and for the modified respectively, for cadmium the Qm was 1.8 mg / g for the material origin and 2.1 mg / g for the modified material in kinetic tests was also observed the fact that the modified material into balance with values always above the adsorbed amount of material in nature, with an increase of about 30.7 % for lead and 32.6% for cadmium. Assays were performed in fixed bed using a factorial design using the material of origin and it was thus more favorable conditions for obtaining the highest percentage of removal of lead. In such conditions were tested for comparison between the material and changed in nature, resulting in the removal of 98.3% and 51.6% respectively. Based on adsorptive test results could conclude that the modification was carried out successfully and that caused a relatively high increase of the adsorptive capacity of the material, it was concluded that the said material has a potential to be applied as adsorbent of toxic metals in processes of decontamination of effluents.