Comparative performance of anodic oxidation and electrocoagulation as clean processes for electrocatalytic degradation of diazo dye Acid Brown 14 in aqueous medium.

In this study, a laboratory scale for the treatment of a recalcitrant and toxic synthetic wastewater containing diazo dye, acid brown 14 (AB-14) has been comparatively performed by two electro-catalytic treatment processes, namely anodic oxidation (AO) and electrocoagulation (EC) using a new batch electrochemical cell. Additionally, the influence of several operating parameters such as; current density (j), initial dye concentration (Co), NaCl concentration (CN), and pH on the color removal efficiency and chemical oxygen demand (COD) are evaluated. The powerful capability of the AO and EC of AB-14 which related to the mechanistic reaction pathway is shown. The poor degradation is ascribed to higher Co and pH, while the enhancement of j and CN is responsible for better degradation of AB-14 dye. The results indicate that the EC is more effective than AO under the same operational condition. A kinetic model is developed for evaluation of the pseudo-first-order-rate constant (kapp) as a function of various operational parameters. The results emphasize the high efficiency of AO and EC and the clean processes which are hopeful alternative for the treatment of the large volume wastewater of the textile industry.

Management of agricultural waste for removal of heavy metals from aqueous solution: adsorption behaviors, adsorption mechanisms, environmental protection, and techno-economic analysis.

In the last decades, Egypt has been suffering from the phenomenon of black cloud resulting from burning rice husk and increasing the demand for water leading to the water crisis. An alternative, low-value and surplus agricultural byproduct (rice husk, RH) has an enormous potential for the removal of Cu(II) ions from water. The present study focuses on the chance of the use of rice husk as a bio-adsorbent without any chemical treatment instead of burning it and soiling the environment. The elemental, structural, morphological, surface functional, thermal, and textural characteristics of RH are determined by XRF, XRD, SEM, FT-IR, TGA, and BET surface area, respectively, and contributed to the understanding of the adsorption mechanism of Cu(II) ions in aqueous solution. Also, the performance analysis, adsorption mechanism, influencing factors, favorable conditions, etc. are discussed in this article. The results obtained from optimization by batch mode are achieved under the following conditions: initial concentration, 150 ppm; amount of rice husk, 1 g; average particle size, 0.25 mm; temperature, 25 °C; pH, 4; agitation rate, 180 rpm; and contact time, 60 min. RH exhibits a high degree of selectivity for Cu(II) adsorption. The adsorption isotherm is fitted well with Langmuir and Freundlich models with R 2 0.998 and 0.997, respectively. The adsorption is well governed by the pseudo-second-order kinetics. It is observed that the rate of adsorption improves with decreasing temperature, and the process is exothermic and non-spontaneous. Particular attention has being paid to factors as production processes, fixed/operational cost, production cost, and profit. The techno-economical analysis is presented in this study that provides precise demands on capital for a fixed investment, provisions for operational capital, and finally provisions for revenue. The social, economical, and environmental benefits by industrial point of view using low-cost adsorbent are also discussed.

Photocatalytic parameters and kinetic study for degradation of dichlorophenol-indophenol (DCPIP) dye using highly active mesoporous TiO2 nanoparticles.

Highly active mesoporous TiO2 of about 6nm crystal size and 280.7m(2)/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared spectroscopy), TGA (thermogravimetric analysis), DSC (differential scanning calorimetry) and BET (Brunauer-Emmett-Teller) surface area. The degradation of dichlorophenol-indophenol (DCPIP) under ultraviolet (UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1g/L of catalyst, 10mg/L of DCPIP, pH of 3 and the temperature at 25±3°C after 3min under UV irradiation. Meanwhile, the Langmuir-Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model. The results proved that the prepared TiO2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.