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Environmental problems on a global scale have become more prominent with the population growth. For the removal of organic contaminants, the solar energy and environmentally friendly photocatalysis are needed to substitute the fossil fuels. In this contribution, we report the synthesis, characterization and photocatalytic capability of CuAl2O4 nanoparticles. The spinel was elaborated by nitrate route and characterized physically and electrochemically for their correlations and application in photocatalysis through the degradation of Basic Red 46 (BR 46), a hazardous dye under visible illumination. The effects of several operational factors like the pH, catalyst dose and initial dye BR 46 concentration were optimized. The results revealed that the photocatalytic performance reached 93% at pH 10, 1 g/L of catalyst dose at a concentration of 10 mg/L of BR 46 within 120 min of irradiation. The quasi-total mineralization was confirmed by the total organic carbon (TOC) and dissolved organic carbon (DOC). Additionally, the prepared photocatalyst possesses a good cyclability with no significant change after five successive photocatalytic cycles. Furthermore, the radical scavenger tests revealed that the specie O2·− and the holes h+ have the significant effects on the removal of BR 46. Based on the latest results, a photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Hexavalent chromium Cr(VI) is well known to be a toxic and non-biodegradable contaminant and can cause significant environmental damage if it is not eliminate from wastewater. However, it can be reduced to Cr(III), which is less toxic by photocatalysis process using the heterosystem NiAl2O4/ZnO. NiAl2O4 prepared by nitrate method crystalize in a spinel structure and was characterized, by XRD, FTIR, and SEM techniques. NiAl2O4 acts as electrons pump and the electron transfer to chromate is mediated via ZnO. Under the optimized conditions, the percentage of Cr(VI) reduction was 62 % for 20 mg/L, NiAl2O4/ZnO ratio (1/1) at pH~3.7 and under visible light. An improvement up to 72% was obtained when the reaction occurs in a Rishton reactor with six bleds after 6 h illumination. It is therefore concluded that the Cr(VI) photocatalytic reduction followed a pseudo first order kinetic model, in agreement with the Langmuir-Hinshelwood mechanism. This work revealed that the NiAl2O4/ZnO heterosystem exhibits a better photocatalytic efficiency for the photoreduction of Cr(VI) mainly due to the good separation of electron-hole pairs (e-/h+) in this combination. [ABSTRACT FROM AUTHOR]

The purpose of this study is to test the biological treatment of leachates from Corso landfill (East of Algiers). These leachates are characterized by high concentrations of organic matter, (CODmax=6000 mgO2/L; BOD5 max= 3400 mg / L), which gives a ratio BOD5 / COD of 0.56 showing that the leachate is young and has a good biodegradability, and confirming the fact that a biological treatment is possible. Similarly, high level of mineral matter was observed (Conductivity max= 43mS/cm), pH is neutral to basic tendency; values vary between 7 and 8.5. The results obtained after the kinetics of biodegradation allowed reducing the COD of 60% on average. In addition, a significant decrease in color after treatment was observed. [ABSTRACT FROM AUTHOR]

The $$\hbox {Co}^{2+}$$ reduction on the hetero-system $$\hbox {CuFe}_{2} \hbox {O}_{4}/\hbox {SnO}_{2}$$ under solar light is reported for the first time. The spinel $$\hbox {CuFe}_{2} \hbox {O}_{4}$$ , prepared by co-precipitation, is characterized photoelectrochemically, and the conduction band ( $$-1.63 \hbox { V}_{SCE}$$ ) is more cathodic than the $$\hbox {Co}^{2+}$$ level. $$\hbox {SnO}_{2}$$ , synthesized by chemical route, is used as electrons bridge to mediate the electron transfer. The photocatalysis is investigated in batch mode by varying the catalyst dose, the $$\hbox {Co}^{2+}$$ concentration and pH. Reduction efficiency of 62% is obtained under sunlight ( $$102\,\hbox {mW cm}^{-2}$$ ) and optimal conditions ( $$\hbox {Co}^{2+}: 50\,\hbox {mg L}^{-1}, \hbox { pH } \sim 5.5, \hbox {CuFe}_{2} \hbox {O}_{4}/\hbox {SnO}_{2}: 1/1$$ ). The reduction follows a zero-order kinetic with a rate constant of $$0.29\,\hbox {mol L}^{-1} \,\hbox {mn}^{-1}$$ . The decrease in the conversion rate over illumination time is due to the competitive hydrogen formation on ultrafine co-clusters. $$\hbox {H}_{2}$$ evolution rate of $$0.19 \, \upmu \hbox {mol}\,(\hbox {mg catalyst})^{-1}\,\hbox { mn}^{-1}$$ under artificial light ( $$29\,\hbox {mW cm}^{2}$$ ) is obtained. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis, characterization and photocatalytic degradation of alizarin red S (ARS) on the novel new hetero-system ZnO-SnO2, The hetero-system, prepared by chemical route, was characterized by spectroscopy, energy dispersive spectroscopy (EDS) analysis, microscopy, diffuse reflectance and powder X-ray diffraction. Photo-degradation of ARSwas investigated on ZnO, SnO2 and ZnO- SnO2 hetero-system. The effect of catalysis dose, initial pH, initial concentration were investigated, the photocatalytic degradation was performed under sunlight irradiation, 84% of (20 mg/L) was degraded within 120 min for concentration. Batch kinetic experiments showed that the degradation follows a pseudo- first-order kinetic with a high correlation coefficient (0.994) according to the Langmuir- Hinshelwood model. [ABSTRACT FROM AUTHOR]

The aim of this study was the tartrazine dye removal from aqueous solutions using a solid waste from the essential oil extraction ofInula viscosa. Experiments carried out in batch mode showed that the adsorption depended on physical parameters such as pH, adsorbent dose, initial pollutant concentration, and temperature. The results of scanning electron microscopy and energy dispersion X-ray indicated that the potential to adsorb tartrazine dye ontoI. viscosawas related to the adsorbent structure. The nature of the surface groups on the adsorbent was determined from the Fourier transform infrared spectroscopy and specific surface area. The dye retention was found to be pH-dependent and the tartrazine adsorption decreased with increasing pH over the pH range (1–6). The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models were used to analyze the adsorption behavior. The maximum adsorption capacity was found to be ~43.1 mg g−1at pH 2 and 298 K. Dye adsorption kinetic was well described by a pseudo-second-order model. The thermodynamic parameters indicated that the adsorption of tartrazine was spontaneous and endothermic, and the process was governed by physisorption owing to the low enthalpy. Therefore,I. viscosais promising as a low-cost adsorbent for the dye removal from aqueous solutions. [ABSTRACT FROM PUBLISHER]