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

Enhanced photocatalytic degradation of acetaminophen from wastewater using WO3/TiO2/SiO2 composite under UV–VIS irradiation

peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 26/8/2019This study investigates the photocatalytic degradation of acetaminophen (Ace) from synthetic wastewater by individual TiO2, TiO2/SiO2 and/or WO3/TiO2/SiO2 composite under UV-VIS illumination. To characterize changes in their morphology and crystal structures before and after treatment, Χ-ray diffraction (ΧRD), Fourier transform infrared spectroscopy (FTIR) , DRS UV-VIS absorption spectra, Brunaer-Emmer-Teller (BET) and scanning electron microscopy (SEM) techniques were used. The effects of varying loading ratios of the WO3 on the TiO2/SiO2 composite for Ace degradation were studied. Operating parameters such as initial concentration, reaction time, dose of photocatalyst and pH were tested. Degradation by-products were also presented. It is found that the photodegradation performance of the WO3/TiO2/SiO2 composite as a photocatalyst in this study could be enhanced by optimizing the loading ratio of the WO3. About 3% (w/w) of WO3/TiO2/SiO2 was found to improve the degradation of Ace from 33% to 95% at the same initial concentration of 5 mg/L. The resulting oxidation by-products included hydroquinone and 1,4-benzoquinone. Under the same conditions, the result of photocatalytic degradation by the 3% (w/w) of WO3/TiO2/SiO2 composite was significantly higher (95%) than that by the individual TiO2/SiO2 (42%) and/or by the TiO2 alone (33%). Under optimized conditions (1.5 g/L; 3% (w/w) of WO3/TiO2/SiO2 composite; pH 9; 4 h of reaction time), 95% of Ace removal with an initial concentration of 5 mg/L could be attained. However, the treated effluents still could not meet the discharge standard of less than 0.2 mg/L set by China’s and US legislation. This indicates that further subsequent treatment like biological processes is still necessary for completing the removal of target pollutant from the wastewater samples

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