RESUMEN

The majority of textile wastes are made up of toxic dyes. Additionally, because these compounds are soluble, wastewater may include significant concentrations. In this work, the green alga Lychaete pellucida is used for the bioremoval of four common azo dyes, Reactive Blue 4 (RB4), Reactive Red 120 (RR120), Reactive Brilliant Yellow 3G (RBY3G), and Reactive Green12 (RG12), with the application of two models of sorption isotherms, Langmuir and Freundlich. The spectrophotometer method was used to identify optimum conditions (temperature, pH, dye concentrations, algal biomass, and contact time) to remove these dyes onto dry freshwater macroalgae. The optimum pH for L. pellucida was 8. The optimum biosorbent amount is 2 g/L. Then, the best-removed dye concentration was 5 mg/L, the optimum contact duration was 120 min, and the optimum temperature was 25 °C. Under optimum conditions, the percent of dye removal was about 95% for all used azo dyes. This is the first report on the use of Lychaete pellucida for the efficient biodegradation of hazardous azo dyes.

Asunto(s)

RESUMEN

Consequences of loading level of ceria (5, 10 and 20-wt%) on the structural, textural and surface acid-base properties as well as the impacts on catalytic activity towards isopropanol decomposition on pure and phosphated alumina is described. The obtained results indicated that composites mainly kept γ-alumina structure and the addition of ceria and/or phosphate has no effect on the bulk structure of alumina. Textural characteristics show that the phosphated composites have higher surface area than phosphate free samples. Pyridine adsorption as followed by FTIR indicated the presence of Lewis acid sites with different strengths. Moreover, results of gas phase decomposition of isopropanol show a systematic inhibition in propene selectivity based on ceria ratio.

RESUMEN

In this work, a new extraction method termed aerosol phase extraction has been developed for the first time. The new method was based on the nebulisation of the sample onto the extracting solution to maximize the contact surface. The influential parameters are: agitation time, chelating agent concentration and inorganic acid concentration. The method has been applied to the extraction of molybdenum with organophosphorus chelating agents such as tributyl phosphate (TBP) and bis(2-Ethylhexyl) phosphoric acid (D2EHPA) dissolved in n-hexane from aqueous hydrochloric and phosphoric acid solutions. In order to test the efficiency of the method, the aqueous phase has been analyzed by means of Inductively Coupled Plasma Atomic Emission Spectrometry. The extraction of molybdenum under aerosol phase was found to be faster than the conventional extraction method. Equilibrium time was shortened under aerosol phase extraction and molybdenum extraction yields were comparable, or better as compared to the conventional method.

RESUMEN

An experimental parametric study was carried out to investigate the effects of [H(2)O(2)], [Fe(3 +)] and [H(2)O(2)]/[Fe(3 +)] ratio on the photo-Fenton degradation of a azo dye Basic Blue 41 (BB41) in aqueous solution. This method consists of coupling between Fenton's reagent and UV irradiation in order to catalyze the in situ generation of hydroxyl radicals, a powerful oxidizing agent which leads to degradation of organic pollutants until total mineralization. The kinetics study of the reaction between BB41 and hydroxyl radicals showed that the degradation of BB41 follows the first-order kinetics. It was found that the concentration of H(2)O(2) and ferric iron as well as their ratio [H(2)O(2)]/[Fe(3 +)] are key factors governing the removal of BB41 in aqueous medium and that the optimal ratio [H(2)O(2)]/[Fe(3 +)] is equal to 10 for 0.2 mM Fe(3 +) concentration. The initial BB41 concentration and the [H(2)O(2)]/[BB41] ratio are also found as significant operating parameters on the mineralization efficiency. The optimization of the operating conditions permitted to obtain a quasi-total mineralization of synthetic BB41 aqueous solutions. When these optimal conditions were applied to the real wastewater, 90% of TOC removal was obtained after 8 h of irradiation time.

Asunto(s)

RESUMEN

Fe-pillared montmorillonite has been used as a Fenton-type heterogeneous catalyst for the removal of cinnamic acid in water. The influences of the cinnamic acid, catalyst and H2O2 concentrations and pH on the removal rate of cinnamic acid have been studied. The results show that the efficiency of Fe-pillared montmorillonite is higher than that of the Fe ions in the homogeneous phase, and less sensitive to pH.

Asunto(s)