In this work, it was studied the caffeine removal through the adsorption on granular activated carbon (CAG). The influence of pH, contact time and CAG dosage were analyzed by batch experiments. Adsorption Kinetic was studied using the models of pseudo-first-order and pseudo-second-order. The adsorption equilibrium data was studied with Langmuir, Freundlich, and Redlich-Peterson isotherm models. The process thermodynamic also was studied. It was obtained 88 % of removal under the experimental conditions of natural pH, 60 min of adsorption and 8 g.L-1 of CAG. The kinetic model that showed the best results was the pseudo-secondorder and Langmuir was the isotherm model that best described the adsorption behavior. The thermodynamic parameters obtained showed a spontaneous, endothermic and reversible process. The desorption efficiency also was studied by regenerant solvents. The best results were obtained using a solvent combination of ethyl acetate, ethanol, and water (50:25:25), and it was obtained a caffeine removal of 57 %, achieving 70 % when a new solution is used in each regeneration step.

This work studied the removal of paracetamol through the adsorption process using the granular activated carbon. The results indicated that it was possible to obtain 95% of removal under the experimental conditions of pH 6, 120 min of process and 5 g L−1 of solid adsorbent. The kinetic model that best fit the experimental data was the pseudo-first order. The isotherm model that best fit the experimental data was the Sips. The thermodynamic tests indicated that the adsorption process was favorable and spontaneous and confirmed the endothermic nature of the process. In fixed bed column adsorption, the best operating condition found was obtained using the flow rate of 3 mL min−1 and bed mass equal to 0.5 g. In this case, the system presented the highest volume of treated PAR effluent, of 810 mL per gram of carbon in the bed, besides a longer rupture time and bed saturation.

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This work evaluates the application efficiency of coal tailings beneficiation as a solid sorbent in the treatment of real wastewater contaminated with nitrate. The solid was characterized by XDR, SEM, FTIR and TGA. Adsorption experiments were performed in batch evaluating the effects of pH, solids concentration and contact time parameters. The kinetics of nitrate adsorption was evaluated using pseudo-first-order and pseudo-second-order models. Equilibrium isotherms for this system were analyzed at three different temperatures (298, 308 and 318 K) by Langmuir, Freundlich and Sips models. The best results from the adsorption experiments were pH 6, contact time of 60 min and 1 g 100 mL −1 of solid. The thermodynamics model that best described the behavior of the process was Sips. By applying these conditions to real wastewater, a nitrate removal of 93% was achieved. This result shows that adsorption using coal beneficiation tailings is technically possible.

O Violeta Cristal é um corante sintético muito usado na indústria têxtil. Os efluentes industriais contendo este tipo de composto, podem causar importantes problemas ambientais e de saúde.Neste contexto, o presente trabalho buscou as melhores condições operacionais para remoção do corante Violeta Cristal (VC) utilizando carvão ativado granular (CAG) como adsorvente. Foram realizados ensaios de adsorção avaliando a influência do pH, tempo de contato, concentração do sólido adsorvente e concentração inicial de corante. O pH foi variado entre 4 e 9, a quantidade de adsorvente foi variada entre 0,5 e 3 g, o tempo de contato foi estudado em diferentes intervalos, entre 5 e 480 min. Para a construção das isotermas, a concentração inicial da solução de VC foi variada entre 100 e 1000 mg.L-1e os modelos matemáticos utilizados para descrever os dados de equilíbrio foram os de Langmuir e Freundlich. Os resultados indicaram que os melhores resultados de adsorção foram obtidos com pH 6, tempo de contato de 270 minutos e massa de 2 g de CAG. Para determinar o tempo de contato mais apropriado, utilizou-se solução de mesma concentração anterior em pH 6 e 2 g de CAG. Com esses dados, ajustou-os as isotermas de Langmuir e Freundlich. A que melhor descreveu os dados experimentais foi a isoterma de Freundlich com um coeficiente de determinação de 0,9933. Com base na pesquisa realizada pode-se concluir que o processo proposto apresenta viabilidade técnica para aplicação do processo de adsorção na remoção do corante VC de efluentes têxteis, contribuindo para o avanço nos estudos da área já que foi alcançado uma taxa de remoção de aproximadamente o 89% do corante VC nas condições operacionais estabelecidas.

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