Resíduos sólidos de curtumes como adsorventes para a remoção de corantes em meio aquoso

The tanning process in the leather industry generates very high quantities of chromium-containing solid waste ("wet blue" leather). Environmental concerns and escalating landfill-costs are becoming increasingly serious problems for the leather industry and an alternative disposal is needed. In this work, we are presenting a novel application for this solid waste, which is the removal of organic contaminants from aqueous-solution. The adsorption isotherm of "wet blue" leather waste from the AUREA tanning company in Erechim-RS (Brazil) showed that this material presents high adsorption capacities of the reactive textile dyes.

Biodegradação de efluente têxtil por Pleurotus sajor-caju

Effluents generated by the textile industry are of environmental concern because of the presence of dyes with complex molecular structure, which confer them recalcitrant characteristics. Indigo is one of the most widely used dyes within the textile sector and studies have suggested that edible fungi may be capable of its biodegradation. A textile effluent was mixed with sugarcane bagasse and inoculated with Pleurotus sajor-caju, the decolorization being evaluated after 14 days, when the process was observed. Enzymatic activities of laccase, peroxidase and manganese peroxidase were determined, the production of these ligninolytic enzymes being evident and a synergism among them being likely in the decolorizing process.

Aplicação da tecnologia de eletrofloculação na recuperação do corante índigo blue a partir de efluentes industriais

The indigo blue dye is widely used in the textile industry. When discarded, besides polluting the environment, it affects the appearance and transparency of aquatic bodies, causing damage to flora and fauna. The removal of this dye from industrial effluents is difficult due to its resistance towards degradation. This work proposes the recovery of indigo blue by electroflocculation, as a subsidy for the treatment of effluents from the jeans industry.

Preparação de amostra de fígado bovino e estudo de micro homogeneidade para a determinação de Cd E Pb por espectrometria de absorção atômica com atomização eletrotérmica e amostragem direta de sólido

This work describes a systematic study for bovine liver sample preparation for Cd and Pb determination by solid sampling electrothermal atomic absorption spectrometry. Samples were prepared using different procedures: (1) drying in a household microwave oven followed by drying in a stove at 60 ºC until constant mass, and (2) freeze-drying. Ball and cryogenic mills were used for grinding. Particle size, sample size and micro sample homogeneity were investigated. All prepared samples showed good homogeneity (He < 10) even for low sample mass, but samples dried in a microwave oven/stove and ground in a ball mill presented the best homogeneity.

Decolorization and toxicity of municipal waste by horseradish (Cochlearia armoracia)

The Municipal Station of Americana, SP, Brazil, treats a volume of 400 l s-1 of effluent, of domestic and textile origin, and produces about 20 t of sludge per day. The plant horseradish, which contains high amount of peroxidases, was able to decolorize this effluent in 2 h and the solid waste in 2 days, at concentrations of 10 and 50%, respectively. However, there was an increase in the toxicity for the bioassays with Hydra attenuatta, Selenastrum capricornutum and lettuce seeds, indicating formation of more toxic substances. Since horseradish showed the ability to decolorize these residues, it can be used as pre-treatment resulting in a sludge of less complex composition.

O emprego de quitosana quimicamente modificada com anidrido succínico na adsorção de azul de metileno

The adsorption capacity of alpha-chitosan and its modified form with succinic anhydride was compared with the traditional adsorbent active carbon by using the dye methylene blue, employed in the textile industry. The isotherms for both biopolymers were classified as SSA systems in the Giles model, more specifically in L class and subgroup 3. The dye concentration in the supernatant in the adsorption assay was determined through electronic spectroscopy. By calorimetric titration thermodynamic data of the interaction between methyene blue and the chemically modified chitosan at the solid/liquid interface were obtained. The enthalpy of the dye/chitosan interaction gave 2.47 ± 0.02 kJ mol-1 with an equilibrium constant of 7350 ± 10 and for the carbon/dye interaction this constant gave 5951 ± 8. The spontaneity of these adsorptions are reflected by the free Gibbs energies of -22.1 ± 0.4 and -21.5 ± 0.2 kJ mol-1, respectively, found for these systems. This new adsorbent derived from a natural polysaccharide is as efficient as activated carbon. However 97% of the bonded dye can be eluted by sodium chloride solution, while this same operation elutes only 42% from carbon. Chitosan is efficient in dye removal with the additional advantage of being cheap, non-toxic, biocompatible and biodegradable.

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

This paper presents the study of the oxidation of three textile dyes (Remazol black B, Remazol Brilliant Orange 3R and Remazol Golden Yellow RNL) using electrochemical and photoelectrochemical methods. In both methods, electrolysis experiments were performed at a current density of 50 mA cm-2 in an aqueous solution of each dye (30 mg L-1), using a photoelectrochemical flow-cell. For all the dyes studied, the photoelectrochemical method was demonstrated to be more efficient than the electrochemical one. Photoelectrochemical oxidation resulted in complete decoloration after 90 min of electrolysis and total organic carbon (TOC) removal reached up to 36%. It was observed that the dyes presenting chromophores at higher wavelengths are removed the quickest, which indicates that photosensitised (photoassisted) oxidation occurs. The level of color was reduced to levels below the standards presented in the literature, which indicates the viability of the photoelectrochemical process as part of the treatment of textile effluents.

2-fenilbenzotriazóis (PBTA): uma nova classe de contaminantes ambientais

This work is a literature review of PBTAs, the phenylbenzotriazoles generated from the reduction and chlorination of azo dyes. The PBTAs and the non- chlorinated PBTAs were isolated for the first time from river blue rayon organic extracts that showed high mutagenic activity in the Salmonella/microsome genotoxicity assay. To date, 8 PBTAs have been identified and beside their mutagenic activity in bacteria they cause genotoxic effects in fish and mammalian cell cultures. Due to the large number of textile dyeing facilities in Brazil, studies to determine them in the aquatic environment seem to be relevant.

Estudo sobre a utilização da lama vermelha para a remoção de corantes em efluentes têxteis

Red mud is the principal residue of the alumina (Al2O3) industry. Generated during the Bayer process, it is characterized by strong alkalinity and ion exchange. Iron oxides are the principal component (30 to 60%). Annually millions of tons of red mud are generated in the world. Red mud disposal is responsible for a large part of the cost of alumina production. On the other hand, textile industry wastewaters containing dyes have a great impact on the environment and on human health. In this paper the possibility of applying red mud for the removal of dyes was investigated by two processes: adsorption and degradation by the Fenton reagent.

Imobilização de ferro (II) em matriz de alginato e sua utilização na degradação de corantes têxteis por processos Fenton

In this work Fenton and photo-Fenton processes for textile dye degradation were investigated using iron (II) immobilized in alginate spheres. Photomicrographs obtained by scanning electron microscopy showed an irregular and porous surface with a homogeneous distribution of iron. The Fenton process was used to evaluate the degradation efficiency of reactive dyes and this procedure showed a low degradation effect. The association of artificial visible light or solar radiation in the Fenton process (foto-Fenton process) showed degradation ratios of 70 and 80% respectively in 45 min. It was also observed that the iron-alginate matrix can be reused.

Preparação de carvão ativado em baixas temperaturas de carbonização a partir de rejeitos de café: utilização de FeCl3 como agente ativante

Ferric chloride as a new activating agent was used to obtain activated carbons from agroindustrial waste. This material was prepared at three temperatures of pyrolysis, 200, 280 and 400 ºC. The carbonaceous materials obtained after the activation processes showed high specific surface areas (BET), with values higher than 900 m² g-1. The materials showed different behaviors in the adsorption of methylene blue dye and reactive red textile dye in water solutions. An important fact in the use of FeCl3 as an activating agent is that the activation temperature is at 280 ºC, well below of those commonly employed in chemical or physical activations described in the literature.

Reutilização de efluente de tingimentos de fibras acrílicas pós-tratamento fotoeletroquímico

On a laboratory scale effluents were produced from bichromic dyeing of acrylic fabrics with the basic dyes Blue Astrazon FGGL 300% and Yellow Gold Astrazon GL 200%. The residual dyeing baths were subjected to a photoelectrochemical treatment and reused in a second dyeing process. In the reutilization study, dyeings with treated effluent were compared with standard dyeings with distilled water. The results of dyeings using 100% of treated effluent were unsatisfactory, but the substitution of 10 to 30% of the treated effluent by distilled water resulted in reduced and more acceptable values for difference in colour intensity (ΔE) between 1.86 and 0.3.

Degradação fotoeletroquímica de corantes dispersos em efluente têxtil utilizando fotoanodos de Ti/TiO2

The degradation of disperses dyes in aqueous solution and in effluents from textile industry has been investigated by photoelectrocatalytic oxidation using nanoporous thin films electrodes of Ti/TiO2. Samples of dispersil black dye and dispersil blue dye after 300 min of photoelectrolyzed at applied potential of +1.0 V and UV irradiation exhibited 100% of discoloration and 90% and 64% reduction total organic carbon, respectively. The proposed method was applied with success in a textile industry effluent containing residues of these dyes, which after 300 min of treatment leads to reduction of 60% of COD and 64% removal of TOC.

Avaliação da biodegradabilidade de efluentes têxteis do beneficiamento secundário de malhas de poliéster tratados com Reagente de Fenton

From the environmental point of view, the textile sector is outstanding for the generation of large amounts of biorecalcitrant effluents. In this paper the textile effluent biodegradability, both before and after its treatment with Fenton's Reagent, were compared by means of biologic tests. These tests showed that the Fenton treatment lowered the biodegradabilty of practically all tested effluents, except one specific effluent from a scouring bath of polyester fibers, which achieved a 93% COD removal. This removal was due to a significant phase separation (oil/water).

Utilization of Sn/Nb2O5 composite for the removal of methylene blue

In this work, the oxidation of methylene blue textile dye in the presence of hydrogen peroxide, using niobium oxide impregnated with different proportions of tin (1, 5 and 10% in mass) as catalyst was studied. The materials were characterized by TPR, XPS, XRD and FTIR. The oxidation tests monitored by ESI-MS showed that the composite containing the higher amount of tin was the most efficient in the removal of the dye. The XRD, XPS, and TPR data presented evidence of the formation of the tin-niobium oxide composite containing Sn0 and supported SnO2.