Caracterização e aplicação na remoção de cromo hexavalente de um bioadsorvente obtido de endocarpo de spondias purpurea l

• Autor(a) principal: Barbosa, Antonio Rank Sermilher de Sales
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Digital da Universidade Federal Rural do Semi-Árido (RDU)
• dARK ID: ark:/74562/001300000bgpp
• Texto Completo: https://repositorio.ufersa.edu.br/handle/prefix/3723
• topic: adsorção; seriguela; bioadsorvente; cromo hexavalente; adsorption; jocote; waste reuse; ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

The quick expansion of industrial activities has contributed to increase the concentration of toxic metals in wastewater. So, several technologies have been used in the removal of these metals, among them the adsorption has become a widely used method due its advantages: convenience, easy operation, low wastes, easy recovery of metals, low cost and adsorbents reuse. Adsorption using agricultural wastes appears as a promising alternative due its biodegradability, availability and low cost. This work aims to test different activation treatments to obtain an adsorbent from jocote endocarps (Spondias purpurea L.) for adsorption of hexavalent chromium. The untreated endocarps (SPST) and chemically treated with sodium hydroxide (SPOH), ferric chloride (SPFE), cetylpyridinium chloride (SPCCP) and sulfuric acid (SPSO4) were used in the adsorption tests. They were characterized by granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TG) analysis, adsorption of nitrogen at 77 K method, zero charge point, infrared spectroscopy with Fourier transform (FTIR) and analysis of surface groups. The kinetic and equilibrium studies were performed, applying kinetic is and adsorption isotherms models. The adsorption experiments showed that the endocarp treated with 98 % sulfuric acid reached a 96.8 % removal efficiency in 120 min, while the untreated endocarp, SPST, obtained a removal of only 39.3 %. The adsorbents SPOH, SPCCP and SPFE provided an adsorption ranging from 35 % to 56 %. The maximum adsorption capacity for hexavalent chromium obtained was 12.1 mg/g in 120 min using SPSO4. The experimental data for adsorption kinetics of hexavalent chromium in the adsorbent SPST, was best fitted by Elovich model, while for adsorbent SPSO4 the best model was the pseudo-second order model. The equilibrium experimental results were best explained by the Freundlich isotherm at 28 °C and by the Temkin isotherm at 38, 48 and 58 °C when S. purpurea endocarp treated with sulfuric acid was used. The isotherms that best described adsorption in the untreated endocarp were Langmuir at 28 °C and Dubinin-Radushkevich at 38 and 48 °C. The results showed that the bioadsorbents obtained from the crushed endocarps of S. purpurea L. have potential for the removal of hexavalent chromium