No abstract

Galvanic sludge results from the treatment of effluents generated by the industrial metal surface treatment of industrial material, which consists in the deposition of a metal on a surface or a metal surface attack, for example, electrodeposition of conductors (metals) and non conductive, phosphate, anodizing, oxidation and/or printed circuit. The treatment proposed here is exposure of the galvanic sludge to the high temperatures provided by thermal plasma, a process which aims to vitrify the galvanic sludge and render metals (iron, zinc, and chromium) inert. Two different plasma reactors were assembled: with a DC transferred arc plasma torch and with a DC nontransferred arc plasma torch. In this way it was possible to verify which reactor was more efficient in the inertization of the metals and also to investigate whether the addition of quartzite sand to the sludge influences the vitrification of the material. Quantification of water content and density of the galvanic raw sludge were performed, as well as analyzes of total organic carbon (TOC) and identify the elements that make up the raw sludge through spectroscopy X-ray fluorescence (XRF). The chemical composition and the form of the pyrolyzed and vitrified sludge were analyzed by scanning electron microscopy with energy-dispersive X-ray spectrometer (SEM-EDS) analysis, which it is a analysis that shows the chemical of the sample surface. The inertization of the sludge was verified in leaching tests, where the leachate was analyzed by flame atomic absorption spectroscopy (FAAS). The results of water content and density were 64.35% and 2.994 g.cm(-3), respectively. The TOC analysis determined 1.73% of C in the sample of galvanic raw sludge, and XRF analysis determined the most stable elements in the sample, and showed the highest peaks (higher stability) were Fe, Zn, and Cr. The efficiency of the sludge inertization was 100% for chromium, 99% for zinc, and 100% for iron. The results also showed that the most efficient reactor was that with the DC transferred arc plasma torch and quartzite sand positively influenced by the vitrification during the pyrolysis of the galvanic sludge.

No abstract

Este estudo investigou o efeito da temperatura da solução sobre a descoloração do azul de metileno em um reator de plasma de descarga elétrica do tipo ponta-plano. Os resultados mostraram um aumento da porcentagem inicial de descoloração do corante com o aumento da temperatura da solução de 4 para 28 o C, mas de 28 para 37 o C não houve alteração. Entretanto, quando a temperatura foi elevada para 47 o C a porcentagem de descoloração inicial do corante diminuiu. A formação de peróxido de hidrogênio em água durante o tratamento por plasma diminuiu com o aumento da temperatura de 4 para 47 o C. A reação de descoloração ocorreu por um complexo mecanismo onde processos de zero e primeira ordem ocorreram numa mesma temperatura, seguindo ordem zero no início do processo e primeira ordem com o progresso da reação. A energia de ativação envolvida no processo de primeira ordem foi de 13,09 kJ mol o C. The dye decolorization reaction occurred via a complex mechanism where zero-and first-order processes took place at the same temperature, following zero-order in the initial step and first-order with the progress of the reaction. The activation energy involved in the first-order process was 13.09 kJ mol -1 .

No abstract