Desenvolvimento de partículas magnéticas de quitosana modificadas com etilenodiamina e ferro (III) e seu emprego na remoção de arsênio (V) de águas

• Autor(a) principal: Silva, Danilo de Castro
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2158
• topic: Adsorção; Quitosana; Arsênio (V); Adsorption, Chitosan, Arsenic (V); CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

In the present study, particles cross-linked magnetic chitosan modified with ethylenediamine and Fe(III) adsorption of (PMQ-EDA-Fe(III)) was prepared for As(V) ions. Prepared cross-linked magnetic PMQ-EDA-Fe(III) was characterized by means of SEM, FTIR, CHN and wide angle X-ray diffraction (XRD). The adsorption properties of cross-linked magnetic PMQ-EDA-Fe(III) toward As(V) were evaluated. Various factors affecting the uptake behavior such as pH, temperature, contact time, initial concentration of metal ion, effect of other ions and desorption were studied. The equilibrium was achieved after about 80 min for As(V) (50 mg L-1) at pH = 7. The adsorption kinetics followed the mechanism of the pseudo- second order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm models. According to the Langmuir model the maximum adsorption capacities were 43.48 mg g-1 for As(V) at 313.15 K. Cross-linked magnetic PMQ-EDA-Fe(III) displayed higher adsorption capacity for As(V). The inhibition by competition of anions was dependent on the type of ionic species. The metal ion-loaded cross-linked magnetic PMQ- EDA-Fe(III) were regenerated with an efficiency around 89.29 % using as -1 extracting solution sodium hydroxide 0.5 mol L (NaOH) on the first cycle and after 3th cycle of reuse, efficiency was reduced 55.74 %. Adsorption studies were performed using columns with different heights, varying from 2 to 5 cm and with flow rates of 1 and 2 mL min-1. It could be observed that the times of efficiency drops and saturation of the fixed bed column increase in accordance with size of the bed. The maximum adsorption capacity with a flow of 2 mL min -1 was 37.56 mg g-1 and for 1 mL min-1 was 25.39 mg g-1. Determination of parameters for the Bohart and Adam model presented good As(V) retention xviii capacity, where adsorptive capacity per volume of the bed, No equal to 27.8 g L-1 and the kinetic constant, K equal to 0.063 L mg -1 h-1. The actuation potential of the PMQ-EDA-Fe(III), was also tested using natural water samples contaminated with arsenic collected in the Iron Quadrangle region, MG. Results of the analyses in water showed total As concentrations varying between 0.64 and 220.6 μg L-1, demonstrating that in some samples this quantity is greater than the maximum limited recommended by Brazilian administration for monitoring of water destined for human consumption, which is 10.0 μg L -1. The As removal rate was 98.39% with the PMQ-EDA-Fe(III).