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Wastewater treatment is of great concern in the textile industries because dyes, which are released into wastewater, are stable due to their structures and that some of the existing conventional techniques are not effective for aqueous removal of dyes. Among the advanced techniques for treatment of industrial effluents, adsorption is one of the most effective processes for removal of dyes from industrial wastewater. Similarly, activated carbons from different sources have been successfully applied as adsorbents for dye removal from aqueous solutions. In this context, this research evaluated the performance of activated carbon produced from peach pit (APC-1.0) for removal of a textile dye, Procion Red MX-5B (PR-5B), through batch adsorption process. The characteristic features of the peach activated carbon were obtained through Fourier transforms infrared spectroscopy, and scanning electron microscopy. The effectiveness of the activated to remove PR-5B from aqua system was compared with that of commercial activated carbon (CAC). In the kinetic study, the contact time was evaluated between 0 and 480 min using two different initial concentrations. Adsorption isotherms of PR-5B onto the two adsorbents were investigated in six different temperatures (298–326 K). The thermodynamic parameters of the process indicated spontaneous and exothermic adsorption. Equilibrium data were best described by Liu isotherm model with maximum removal capacities of 297.2 and 174.0 mg g−1 for APC-1.0 and CAC, respectively. [ABSTRACT FROM AUTHOR]

This work evaluates the application efficiency of coal tailings beneficiation as a solid sorbent in the treatment of real wastewater contaminated with nitrate. The solid was characterized by XDR, SEM, FTIR and TGA. Adsorption experiments were performed in batch evaluating the effects of pH, solids concentration and contact time parameters. The kinetics of nitrate adsorption was evaluated using pseudo-first-order and pseudo-second-order models. Equilibrium isotherms for this system were analyzed at three different temperatures (298, 308 and 318 K) by Langmuir, Freundlich and Sips models. The best results from the adsorption experiments were pH 6, contact time of 60 min and 1 g 100 mL−1 of solid. The thermodynamics model that best described the behavior of the process was Sips. By applying these conditions to real wastewater, a nitrate removal of 93% was achieved. This result shows that adsorption using coal beneficiation tailings is technically possible. [ABSTRACT FROM AUTHOR]

Metal-zeolite composite catalysts have found numerous applications in adsorption, gas separation, petroleum refining and chemical industry. The key issue in the design of these catalysts is localization of the metal within the zeolite structure. This paper focuses on a new approach to the synthesis of nickel-zeolite composite catalysts selectively containing metal nanoparticles inside the zeolite pores. In the catalysts prepared by conventional impregnation, metal particles from the external surface of the zeolites were selectively removed by extraction with bulky polymer molecules of poly-4-styrenesulfonic acid. The method is particularly suitable for the ZSM-5 zeolite with relatively narrow micropores. The nickel zeolite catalysts were tested in hydrogenation of toluene and 1,3,5-tri-isopropyl benzene (TIPB). The removal of nickel particles from the zeolite external surface leads to a considerable decrease in the hydrogenation rate of the bulky TIPB molecules, while toluene hydrogenation rate was affected to a much lesser extent and was almost proportional to the nickel content. The proposed methodology can be extended to other types of microporous catalysts. [ABSTRACT FROM AUTHOR]