calcined Cu/Al layered double hydroxides: synthesis, caracterization and dye removal properties in tubular reactor

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Synthesis, characterization, and photocatalytic degradation of anionic dyes using a novel ZnO/activated carbon composite

Zinc oxide/activated carbon from Thapsia transtagana stems (ZnO/ACTTS) composite demonstrated good photocatalytic properties for removing methyl orange (MO) dye from aqueous solution. This study utilized the chemical activation method using phosphoric acid to prepare activated carbon, which was then used to synthesize the ZnO/ACTTS composites by the hydrothermal technique at different percentages of the amount of ZnO (15, 30, 50 and 75 %). XRD, FTIR, and SEM-EDX were used to characterize the produced composite materials. The photocatalytic degradation of the catalysts was investigated for the degradation of MO dye from aqueous solution. The effects of zinc oxide content, pH of solution, and catalyst dosage were studied. Experimental results indicate that the ZnO/ACTTS (75 %) composite with exhibited good activity under acid pH conditions with an optimal catalyst dosage of 0.5 g/L. Photodegradation kinetics followed a pseudo-second order kinetics. ZnO/ACTTS composite will be a catalyst to degrade a wide range of dyes from the textile industry in the aquatic medium

Synthesis, characterization and efficient photocatalytic properties of spinel materials for dye degradation

In this research, Co0.5Zn0.5Al2O4 spinel oxides photocatalysts were elaborated from layered double hydroxides Co-Zn-Al/CO3 precursor by calcination at 300, 400, 500, 600, 800, and 1000 °C. XRD, FTIR, TGA/DTA, and SEM/EDX analysis were used for characterized of prepared photocatalysts. The photocatalytic efficiency of the prepared materials was tested by photodegradation of methyl orange (MO) azo dye as a model of textile contaminants under UV illumination. The effect of various operational factors such as irradiation time, initial pH, catalyst dose, methyl orange concentration and reuse were investigated. The enhancement of the photodegradation was strongly dependent on the calcination temperature. A synergic effect between the adsorption and photodegradation was observed. After 50 min of irradiation, the catalyst calcined at 400 °C showed the highest efficiency (98.2%). After regeneration (up to five cycles), the photocatalyst showed high stability

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)

Performance of Zn‐, Mg‐ and Ni‐Al layered double hydroxides in treating an industrial textile wastewater

In this study, Zn‐Al, Mg‐Al and Ni‐Al layered double hydroxides were successfully synthesized via co‐precipitation method. Samples were characterized by XRD, FTIR, TGA‐DTA, TEM and pHPZC analysis. XRD patterns showed a basal spacing increase in the order of Zn‐AlNO3 (8.85Å)> Mg‐AlNO3 (7.95Å)> Ni‐AlNO3 (7.82Å). TEM images indicated that the Zn‐AlNO3 presents circular to shaped particles with an average particle size of approximately 30 to 40 nm. Small plates assigned to sheets with hexagonal form were observed in the case of Mg‐AlNO3. Ni‐AlNO3 display nanostructured sphere in diameter between 5 and 10 nm. The materials were used for the removal of methyl orange (MO), as a model dye and for the treatment of a real effluent generated by a textile factory. Maximum adsorption was occurred in acidic pH solution. Kinetic data were tested using pseudo‐first‐order, pseudo‐second‐order kinetic and intra‐particle diffusion models. The best fit was obtained with the pseudo‐second‐order kinetic model. Equilibrium data were correlated to Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models. The best conditions for color and COD removal from the textile effluent sample were obtained at lower values of pH. Reduction of COD to limits authorized by Moroccan standards was obtained with 0.5g/L of LDH dosage

Adsorption behavior of methylene blue onto powdered Ziziphus lotus fruit peels and Avocado kernels seeds

In this research, two agroforestry by‐products were used as adsorbents for the removal of methylene blue (MB), as a model dye, from aqueous solution. The Ziziphus lotus fruit peels (ZLP) and Avocado kernel seed (AKS) were dried and powdered to particles of sizes <125 μm. Adsorption study was carried out in batch mode under different condition by varying initial dye concentration, contact time, initial solution pH, adsorbent dosage and reaction temperature. Rate constants of the adsorption were calculated by kinetic measurements. Equilibrium data were correlated to Langmuir and Freundlich isotherm models. The best fit was obtained by Langmuir model with maximum monolayer adsorption capacities of 66.04 mg/g in the case of ZLP and 59.07 mg/g in the case of AKS. The surface properties of the adsorbents were characterized by FTIR spectroscopy, SEM‐EDX analysis and the point of zero charge

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

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