Cr(VI) reduction by activated carbon and non-living macrophytes roots as assessed by Kβ spectroscopy

In this work, the behavior of cationic-exchange resin, activated carbon, and non-living aquatic macrophytes biomasses on the Cr(VI) and Cr(III) uptake and Cr(VI) reduction was investigated. The high-resolution X-ray fluorescence (HR-XRF) technique was used to study the adsorption process, as well as to study Cr(VI) reduction and removal from metal solutions. Batch Cr ions sorption experiments at pH 3.5 were carried out in order to speciate 3d-transition metal onto the surface of these types of adsorbents by a Kβ spectra analysis. Cr-Kβ satellite lines have been characterized for all Kβ spectra of Cr ions onto treated samples and reference material. Based on their energy position and intensity of Cr-Kβ satellite lines as well as their related to reference material shift energy, activated carbon and non-living aquatic macrophytes roots were found to act mainly as good adsorbents, first reducing Cr(VI) to Cr(III) and then followed by a Cr(III) adsorption. Although cationic-exchange resin was treated with Cr(VI) solution, no evidence of any Cr-Kβ spectral satellite lines was shown in it, suggesting that Cr(VI) was not removed in a cationic-exchange process. Evidence of reduction of hexavalent chromium by adsorbent materials was assessed by Kβ spectral lines analysis.Fil: Módenes, Aparecido N.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Espinoza Quiñones, Fernando R.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Palácio, Soraya M.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Kroumov, Alexander D.. University of Kentucky; Estados UnidosFil: Stutz, Guillermo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Tirao, German Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Camera, Adriana S.. Universidade Estadual Do Oeste Do Pará; Brasi

Evolutive follow-up of the photocatalytic degradation of real textile effluents in TiO2 and TiO2/H2O2 systems and their toxic effects on Lactuca sativa seedlings

Textile industry wastes raise a great concern due to their strong coloration and toxicity. The objective of the present work was to characterize the degradation and mineralization of textile effluents by advanced oxidative processes using either TiO2 or TiO2/H2O2 association and to monitor the toxicity of the products formed during 6 h irradiation in relation to that of the in natura effluent. The results obtained demonstrated that the TiO2/H2O2 association was more efficient in the mineralization of textile effluents than TiO2 alone, with high mineralized ion concentrations (NH4+, NO3-, and SO4(2-)) and significant organic matter reduction rates (represented by the COD and TOC). The toxicity of the degradation products to lettuce seeds (Lactuca sativa) was not significant, since percent germination was not significantly affected and neither was root and sprout percent growth. However, while the TiO2/H2O2 association was more toxic in the first hours of irradiation and less so in the end of the 6 h irradiation, the toxicity of TiO2 increased only slightly in the end of the experiments. Comparatively, the photogenerated products of both the TiO2 and the TiO2/H2O2 association were less toxic than the in natura effluent

Combined Application of Coagulation/Flocculation/Sedimentation and Membrane Separation for the Treatment of Laundry Wastewater

The wastewater from industrial laundries has a high quantity of contaminants from the washing process, as well as chemical additives. Aiming at the treatment of this type of wastewater, the present study evaluated the performance of a combined coagulation/flocculation/sedimentation process (C/F/S) and membrane separation to treat laundry wastewater in relation to physicochemical parameters of water quality. For this purpose, a Doehlert experimental design was applied to the C/F/S step using the natural coagulant Tanfloc POP® with maximum color and turbidity removal efficiency obtained of 80.27% and 86.50%, respectively, under conditions of pH of 6.4 and a coagulant concentration of 110 mg·L−1. The supernatant from the C/F/S step was used in the sequential microfiltration (MF) and ultrafiltration (UF) experiments. The maximum values of color, total nitrogen, dissolved solids, and turbidity removal were similar to MF and UF membranes at transmembrane pressure of 1.4 bar, with the greatest flow of permeates (92.2 L·h−1·m−2) presented by the MF membrane at 1.4 bar. The total efficiency of the combined C/F/S-MF process indicated the quality of the treated wastewater since it reduced 98.4% of the color, 99.1% of turbidity, 71.7% of the surfactants, and more than 55% of the total dissolved solids (TDS), chemical oxygen demand (COD), and total organic carbon (TOC) from the industrial laundry wastewater. This study showed that the C/F/S-MF combined process could be an efficient treatment of laundry wastewater