Photodegradation of 2-naphthol Using Nanocrystalline TiO2

The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ″Degussa P-25″ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved.The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ″Degussa P-25″ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved

The effect of treatment parameters on the coagulation-flocculation of leachate from the Great Agadir controlled discharge

One of the main obstacles to the management of public landfills is leachate from urban garbage. They do pose a harm to the environment and to human health given the amount of pollutants they contain. Depending on the type and age of the waste, the climate, and the terrain of the location, each landfill's composition is different. One of the locations with a leachate management issue is the controlled landfill in Greater Agadir. Leachates have been reduced using a recirculation and sprinkler system, although efficiency is still very poor. The leachate water was diagnosed as having significant organic contamination. This study aims to describe the leachates from several Greater Agadir areas and assess the efficacy of the coagulation-flocculation method of treatment. FeCl3 considerably changed the hue of the leachate, which had a neutral pH, 90% turbidity, and 78.2% COD elimination. This leachate appears to be best suited for modest doses of 3g/L.The research conducted here has also demonstrated that the polyacrylamide flocculant, with a mass of 3 g in the presence of a mass of 3 g ferric chloride, has a turbidity level of 92% and 97% for COD. For 3 g/L of ferric chloride, however, the bioflocculant from "Opuntia cactus" juice also provides good flocculation, with a turbidity removal rate of 98.14% and a COD removal rate of 87%

Adsorption studies of cationic and anionic dyes on synthetic ball clay

This study evaluated the use of synthetic ball clay to remove Methylene Blue (cationic dye) and Congo Red (anionic dye) from aqueous solution. The ball clay was prepared by sol‐gel process and characterized using X‐ray diffraction (XRD), specific surface area (BET), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The effect of different operational parameters for enhanced dyes adsorption by ball clay was studied, such as: adsorbent mass, contact time, initial concentration of pollutant and solution pH. The Experimental results showed that all these parameters have an impact on the removal efficiency of these dyes by the ball clay. The equilibrium adsorption data obtained at 20°C were analyzed by Langmuir and Freundlich isotherm models. The results showed that the synthesized ball clay sample is an efficient adsorbent for the adsorptive removal of dyes from aqueous solution

New Sustainable Biosorbent Based on Recycled Deoiled Carob Seeds: Optimization of Heavy Metals Remediation

In this study, an efficient biosorbent was developed from deoiled carob seeds, a agroindustrial waste. The biosorption efficiency was evaluated for cadmium and cobalt ions removal from aqueous solution under various parameters such as treating agent, solution pH, biosorbent dosage, contact time, initial metal ions concentration, and temperature. The effect of some major inorganic ions including Na+, K+, Ca2+, Mg2+, and Al3+ on the biosorption was also established. Based on this preliminary study, four independent variables including solution pH, biosorbents dosage, initial metal concentration, and treating agent were chosen for the optimization of the process using full-factorial experimental design. It was found that chemical pretreatment of the raw deoiled carob seeds with NaOH strongly enhances its biosorption potential. Thus, the optimal conditions for high biosorption of cadmium(II) and cobalt(II) were achieved at pH of 6, biosorbent dosage of 1 g/L, and initial metal concentration of 50 mg/L. The biosorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Boehm titration, and the point of zero charge (pHPZC)

Effect of Ag doping on photocatalytic activity of ZnO-Al2O3 derived from LDH structure: Synthesis, characterization and experimental study

In this research, Ag-ZnO-Al2O3 heterostructure catalyst was derived from the calcination of Ag-doped layered double hydroxide (LDH) through a solid-state process. With the aim of entirely understanding the structural and functional features, catalysts were analyzed by XRD, TGA/DTA, and FTIR techniques. The photocatalytic performance was evaluated by measuring the methyl orange (MO) photodegradation under UV irradiation. The impact of the key parameters, namely, irradiation time, catalyst dose, initial pH of solution, and the starting concentration of MO, were investigated and discussed. The characterization results exhibit a well crystallized hexagonal LDH structure. The experimental findings revealed approximately 95.8 % degradation yield after 210 min of irradiation for Ag-ZnO-Al2O3. The optimal conditions were found to be 20 mg/L of catalyst dose, 20 mg/L of MO initial concentration and initial pH of 4. In the whole, the results confirm that the Ag-ZnO-Al2O3 catalyst shows the highest adsorption and photocatalytic performances. After three recycling tests, the Ag-ZnO-Al2O3 photocatalyst maintained good recycling stability and a high photodegradation performance (90.7%). Finally, the use of Ag-ZnO-Al2O3 as heterostructure photocatalyst offer a promising approach for the degradation of more organic compounds in environmental remediation

Activated carbon from Thapsia transtagana stems: central composite design (CCD) optimization of the preparation conditions and efficient dyes removal,166, 259–278

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Factorial experimental design for the optimization of catalytic degradation of malachite green dye in aqueous solution by Fenton process

This work focuses on the optimization of the catalytic degradation of malachite green dye (MG) by Fenton process “Fe2+/H2O2”. A 24 full factorial experimental design was used to evaluate the effects of four factors considered in the optimization of the oxidative process: concentration of MG (X1), concentration of Fe2+ (X2), concentration of H2O2 (X3) and temperature (X4). Individual and interaction effects of the factors that influenced the percentage of dye degradation were tested. The effect of interactions between the four parameters shows that there is a dependency between concentration of MG and concentration of Fe2+; concentration of Fe2+ and concentration of H2O2, expressed by the great values of the coefficient of interaction. The analysis of variance proved that, the concentration of MG, the concentration of Fe2+ and the concentration of H2O2 have an influence on the catalytic degradation while it is not the case for the temperature. In the optimization, the great dependence between observed and predicted degradation efficiency, the correlation coefficient for the model (R2=0.986) and the important value of F-ratio proved the validity of the model. The optimum degradation efficiency of malachite green was 93.83%, when the operational parameters were malachite green concentration of 10 mg/L, Fe2+ concentration of 10 mM, H2O2 concentration of 25.6 mM and temperature of 40 °C

Effectiveness of beetroot seeds and H3PO4 activated beetroot seeds for the removal of dyes from aqueous solutions

Raw beetroot seeds (BS) and H3PO4 activated beetroot seeds (H3PO4-BS) were evaluate for their effectiveness in removing methylene blue (MB) and malachite green (MG) from aqueous solution. BS were carbonized at 500°C for 2 h, and then impregnated with phosphoric acid (phosphoric acid to BS ratio of 1.5 g/g). The impregnated BS were activated in a tubular vertical furnace at 450°C for 2 h. Batch sorption experiments were carried out under various parameters, such as solution pH, adsorbent dosage, contact time, initial dyes concentration and temperature. The experimental results show that the dye sorption was influenced by solution pH and it was greater in the basic range. The sorption yield increases with an increase in the adsorbent dosage. The equilibrium uptake was increased with an increase in the initial dye concentration in solution. Adsorption kinetic data conformed more to the pseudo-second-order kinetic model. The experimental isotherm data were evaluated by Langmuir, Freundlich, Toth and Dubinin–Radushkevich isotherm models. The Langmuir maximum monolayer adsorption capacities were 61.11 and 74.37 mg/g for MB, 51.31 and 213.01 mg/g for MG, respectively in the case of BS and H3PO4-BS. The thermodynamic parameters are also evaluated and discussed