No abstract

The current work investigated the optimization of synthetic textile wastewater (STW) containing methyl orange, crystal violet, and neutral red reactive dye degradation on manganese dioxide coated on graphite electrode using the Box-Behnken design (BBD). Carbon coated by manganese oxide (C/ MnO2 ) electrode was prepared by the sol-gel method. Graphite substrates were obtained from spent lithium-ion batteries for recycling and reducing the price of the electrode material in electrochemical processes. C/MnO2 was used as anode and cathode in an electrochemical cell during experiments. In addition, BBD was applied to design the experiments and find the optimal conditions for the degradation of STW. From the proposed model, the rate of the removal efficiency of chemical oxygen demand (COD) reached 83.63% with the optimum conditions (6.989 hours, concentration of 1.5 g/L NaCl, and current density of 50 mA/cm2 ). Based on the obtained optimum values, the specific energy consumption was around 30.359 kWh (kg COD)-1. Furthermore, the C/MnO2 electrode was characterized by Raman spectroscopy, and MnO2 films were prepared from the sol-gel process and deposited on graphite. Thus, using graphite coated with manganese dioxide, indirect anodic oxidation (IAO) can be efficient for the removal of the organic matter from the real textile dye bath.

Orange peel powder was activated using different methods and was used to remove Tartrazine (E102) from an aqueous solution. The following three adsorbents were synthetized: orange peel powder activated thermally (POAT), orange peel powder activated with sulfuric acid (POAA), orange peel powder activated with soda (POAS). These adsorbents were then characterized by Fourier Transform Infra-Red Spectrometry (FTIR), Raman spectroscopy, powder X-Ray Diffraction (XRD), and point-of-zero charge. The experimental parameters such as contact time, dose of adsorbent, initial concentration of Tartrazine, pH, and temperature were studied. The adsorption capacities of Tartrazine for the optimal POAT, POAA, and POAS were found to be 121.74, 122.25, and 116.35 mg/g, respectively. The experimental data were analyzed by Freundlich and Temkin isotherm models, as well as the pseudo-second-order kinetic model.

In this study, rice husk and jatropha shell were employed as precursors for the production of activated carbon by thermal and chemical activation process using phosphoric acid (H3PO4). The thermally activated carbon derived rice husk (RH) and jatropha shell (JS) and phosphoric acid activated derived rice husk (RH-Ac) and jatropha shell (JS-Ac) were characterized using BET, XRD, FTIR, Raman spectroscopy, SEM and XPS analysis. It showed that the cavities developed on the surfaces of RH-Ac and JS-Ac were be more high than those RH and JS. The BET surface area of RH, JS, RH-Ac and JS-Ac were 694.3 m2/g, 723.1 m2/g, 1261.3 m2/g and 1327.7 m2/g, respectively. The XPS analysis revealed that RH and JS exhibited the relative lower contents of carbonyl and phenol carbon than RH-Ac and JC-Ac. The as-prepared RH-Ac and JC-Ac were employed for the adsorption of Cu2+ and Fe2+ due to it better physicochemical properties. The most important influencing factors the adsorption of these metal ions such as pH, contact time, initial concentration were systematically studied. Experimental results were well analyzed by Langmuir model with the maximum adsorption ability of Cu2+ (22.773 mg/g), Fe2+ (25.431 mg/g) onto RH-Ac and Cu2+ (32.458 mg/g) and Fe2+ (56.179 mg/g) onto JS-Ac, which showed to be high in comparison to the similar activated carbon available obtained by other researchers. The pseudo 2nd order model showed that adsorption kinetic of Fe2+ and Cu2+ ions onto the JS-AC and RH-Ac has domination towards chemisorption. Moreover, thermodynamic parameters suggested that RS-Ac and JS-Ac for Cu (II) and Fe (II) adsorption phenomenon was endothermic and spontaneous. The high availability, facile production along with high performance of RH-Ac and JS-Ac make it an economically adsorbent for Fe (II) and Cu (II) adsorption.