RESUMO
Galvanic effluents are composed of a wide range of heavy metals, requiring adequate treatment to remove these contaminants and to meet the limits established by environmental agencies. Considering this aspect, the present study had as main objectives: (i) to evaluate the efficiency of the electrocoagulation (EC) in the treatment of a galvanic effluent, with the purpose of removing total Cr, Cu, Mn, Ni and (ii) reuse the sludge generated for inorganic pigment production. EC tests were carried out through factorial design 23 with triplicate central point. pH (3, 7, 11), reaction time (15, 22.5 and 30 min) and current density (10, 17.5 and 25 mA/cm2) were the control variables. Under ideal experimental conditions (pH 7.00; t = 22.5 min and DC = 17.5 mA/cm2) were removed 96.94% of Mn, 97.63% of Cu and 99.99% of total Cr and Ni, allowing to meet the limits provided in CONAMA Resolution 430/2011. The production of inorganic pigments from a mixture of 10% sludge (generated in the ideal experimental condition) and Al2O3 and TiO2 proved to be technically viable. It was obtained 8.27 g of a brown inorganic pigment, composed mainly of Al1.82Cr0.18O3, Ca0.999(Ti0.805Fe0.201)O2.899 and Fe2.18O4Ti0.42. Therefore, the results obtained demonstrate that EC is an effective technique in galvanic effluents treatment. The sludge generated in this process showed to be appropriated to be reused in inorganic pigment production and could be considered as an alternative to reduce the environmental impact related to electroplating process.
Assuntos
Metais Pesados , Purificação da Água , Corantes , Eletrocoagulação/métodos , Resíduos Industriais/análise , Esgotos , Purificação da Água/métodosRESUMO
The development of hydrogel films for biomedical applications is interesting due to their characteristics. Hydrogel films based on gelatin and poly(vinyl alcohol) (PVA) are developed and characterized using a rotatable central composite design. The optimized hydrogel film is obtained by the function desirability of the Statistica® software and is also characterized by swelling kinetics, oxygen permeability, adhesiveness, TGA, DSC, and XRD. The results of the experimental design show that gelatin and PVA concentrations have a significant influence on the response variables, and the exposure doses to UV light show no significant effect. The optimized hydrogel film is elastic, presents good mechanical resistance and swelling capacity in water and exudate solution, is permeable to oxygen, and is capable of adjusting itself and maintains contact close to the skin. In this way, considering all the properties evaluated, the optimized film has characteristics suitable for biomedical applications as wound dressings.