Aplicação de biocarvão de aguapé (eichhornia crassipes) e derivados de grafeno para adsorção de Cr(VI) em solução aquosa

• Autor(a) principal: Lima, Lucas dos Santos
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/jspui/handle/riufs/15096
• topic: Química; Biocarvão; Carbono ativado; Adsoção; Materiais carbonáceos; Derivados de grafeno; Adsorção de cromo; Carbonaceous materials; Graphene derivatives; Chromium adsorption; CIENCIAS EXATAS E DA TERRA::QUIMICA

Studies that apply biochar as adsorbent material of contaminants present in the environment are growing and promising, mainly due to the environmental appeal in the use of this carbonaceous material. In this work, samples of biochar and graphene derivatives were used as adsorbents of Cr(VI) ions in aqueous media. The samples of biochar were obtained from the pyrolysis of the biomass of waterapple (Eichhornia crassipes) at 500 °C, forming the biochar B5. Subsequently, it was submitted to the activation process with nitric acid (HNO3), resulting in the formation of the activated biochar B5AT. The samples of graphene derivatives, known as graphene oxide (GO) and reduced graphene oxide (rGO), were synthesized from graphite. A hybrid material was also formed using biochar and rGO (B5ATM:rGOM) by maceration. Characterizations to determine the chemical composition of the biochar samples showed oxygenated and nitrogenated functional groups, especially for the sample activated with HNO3 acid. The synthesized graphene derivatives showed morphology and structural organization in agreement with the literature. The materials were applied for the adsorption of Cr(VI) ions and the macerated biochar B5M stood out in relation to the others, presenting a higher adsorption capacity of the metal ions in acid medium. The kinetic study showed a decrease in the adsorption rate at times greater than 5 hours of contact of the B5M adsorbent with the Cr(VI) solution. The nonlinear Elovich kinetic model applied to the B5M adsorbent showed the best fits for the adsorption rate, suggesting that the adsorption process occurs by chemisorption, while the Sips isotherm model provided the best adsorption equilibrium parameters, the maximum adsorption capacity was 97.25 mg g-1 . These results suggest that the adsorption process occurs in monolayer and that the adsorbent material B5M exhibits a high degree of heterogeneity.