Ronaldo Pelegrini

Degradation of reactive dyes I. A comparative study of ozonation, enzymatic and photochemical processes

The environmental problems associated with textile activities are represented mainly by the extensive use of organic dyes. A great number of these compounds are recalcitrant and shown carcinogenic or mutagenic character. In this work three processes were studied for degradation of an anthraquinone dye (C.I. reactive blue-19). The ozonation process leads to complete decolorization with a very short reaction time; however, effective mineralization of the dye was not observed. The enzymatic process promotes quick decolorization of the dye; nevertheless, maximum decolorization degrees of about 30% are insignificant in relation to the decolorization degree achieved by the other processes. The best results were found for the photocatalytical process. The use of ZnO or TiO2 as photocatalysts, permits total decolorization and mineralization of the dye with reaction times of about 60 min.

Novas tendências para o tratamento de resíduos industriais contendo espécies organocloradas

The toxic character of organochloride compounds, their habitual presence in many industrial effluents, and mainly the low efficiency of the current remediation processes, are important aspects that have been promoted to study new degrading technologies. Among the great number of new physical and chemical alternatives, the photochemical and electrochemical processes have been played an important role, mainly due to their high degradation capacity through relatively low-cost procedures. In these contexts biological processes, the use of white-rot fungi, or even ligninolytic enzymes produced from them, are also very promising alternatives. However, the necessity of long reaction time and the high cost of the enzyme production process are some of the drawbacks that difficult the definitive consolidation of these processes.

Evaluation of ZnO, TiO2 and supported ZnO on the photoassisted remediation of black liquor, cellulose and textile mill effluents

Treatment of effluent from the cellulose and textile industries by applying a heterogeneous photocatalytic procedure using UV-light and free and supported catalysts is reported. When Krafi and textile effluents are submitted to UV-irradiation in the presence of free Ti02 and ZnO or silica gel supported ZnO, the colour fades progressively to reach substantial decolorization ratios. This decolorization process is accompanied by a considerable reduction of total phenol concentrations in the black liquor and final effluent. For bleaching mixture, the reduction of phenol concentration is not significant, and on the contrary, for textile effluents an increase of phenolic compound concentrations is observed during the initial phase of the photocatalytic process The progressive degradation of the different chemical species contained in the effluents was demonstrated by HPLC analysis and total organic carbon contents determination. This degradation permitted an important reduction of the acute toxicity of the effluents. 019% Elsevier Science Ltd

Photoelectrochemical degradation of lignin

We have evaluated the efficient of degradation of lignin by an photoelectrochemical process. Using a Ti/Ru0.1Sn0.6Ti0.3O2 electrode, a quartz reaction device and an artificial ultraviolet light, decoloration ratios higher than 70%, and reductions of 51% and 83% in TOC and total phenol products, respectively, were observed for a reaction time of 6 h. Comparing these values with the sum of the decoloration ratios (or TOC and total phenol reductions) obtained by separate measuring of electrochemical and photochemical procedures, a significant synergetic effect between these two processes was observed. Furthermore, the degradation capacity of the photoelectrochemical process increases as the SnO2 content is increased.

Photoelectrochemical discoloration and degradation of organic pollutants in aqueous solutions

Organic compounds responsible for the color of wastewaters are usually refractory to biological digestion. In this paper the photo-assisted electrolysis process is used for color removal from three of the most colored wastewaters, which are daily generated in large amounts: the E1 bleach Kraft mill effluent, a textile reactive dye effluent and a landfill leachate. Electrolysis was carried out at 26,5 mA cm-2 in a flow reactor in which the anode surface was illuminated by a 400 W high pressure Hg bulb. In all experiments 70-75% of color reduction was observed which was also followed by a net organic load oxidation.

Descoloração e degradação de poluentes orgânicos em soluções aquosas através do processo fotoeletroquímico

Organic compounds responsible for the color of wastewaters are usually refractory to biological digestion. In this paper the photo-assisted electrolysis process is used for color removal from three of the most colored wastewaters, which are daily generated in large amounts: the E1 bleach Kraft mill effluent, a textile reactive dye effluent and a landfill leachate. Electrolysis was carried out at 26,5 mA cm-2 in a flow reactor in which the anode surface was illuminated by a 400 W high pressure Hg bulb. In all experiments 70-75% of color reduction was observed which was also followed by a net organic load oxidation.