RESUMO
In this work, different carbonaceous materials based on floated sludge from a poultry industry wastewater treatment plant (PI-WTP) were synthesized. These materials were characterized and investigated in methylene blue dye (MB) adsorption. The influences of the initial pH solution, adsorbent dosage, kinetics, equilibrium, and thermodynamics were evaluated in the adsorption experiments. A simulation of a real textile effluent was also carried out to evaluate the adsorbent. The results of the adsorbents' characterization demonstrated that adding ZnCl2 + lime, followed by pyrolysis and acid leaching, significantly improved the material's properties, leading to abundant porosity and high surface area. The adsorption experiments indicated that the natural pH of the solution (8.0) and the AC-II dosage of 0.75 g L-1 are optimal for MB removal. Elovich and Sips' models (with a maximum adsorption capacity of 221.02 mg g-1 at 328 K) best fitted the experimental kinetic and equilibrium data, respectively. The adsorption process is spontaneous and endothermic according to thermodynamic parameters. The discoloration efficiency of the simulated effluent was 67.8%. In conclusion, the floated sludge, a residue produced on a large scale that needs to be disposed of correctly, can be converted into a value-added material (carbonaceous adsorbent) and applied to treat colored effluents.
Assuntos
Esgotos , Poluentes Químicos da Água , Animais , Esgotos/química , Azul de Metileno/química , Aves Domésticas , Adsorção , Poluentes Químicos da Água/química , Termodinâmica , Cinética , Concentração de Íons de HidrogênioRESUMO
A new alternative aerogel was prepared from low-cost chitin and psyllium biopolymers to adsorb crystal violet (CV) dye from liquid media and possibly treat effluents containing other dyes. The aerogel was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), which demonstrated that aerogel has a typical structure of amorphous materials and presented a randomly interconnected porous structure that resembles an open pore network. 2.5 g L-1 of aerogel was able to remove 86.00% of CV from solutions, and the natural pH of the CV solution was considered the more adequate for adsorption. The pseudo-second-order (PSO) model satisfactorily described the adsorption kinetics, and the Freundlich model was suitable to represent the adsorption equilibrium. The maximum experimental capacity achieved was 227.11 mg g-1, which indicates that aerogel is very efficient and competitive with several adsorbents. Tests using a simulated effluent showed that aerogel has excellent potential to treat real colored effluents.
Assuntos
Quitina/química , Corantes/química , Violeta Genciana/isolamento & purificação , Psyllium/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cinética , Porosidade , Termodinâmica , Água/químicaRESUMO
A high quality activated carbon was developed from biological sludge of a beverage wastewater treatment plant (BWTP). The material was characterized and its adsorption potential to remove Allura Red AC and Crystal Violet dyes from aqueous media was verified. The ACBS (activated carbon from beverage sludge) revealed mesoporous features, presenting average pore diameter of 6.32â¯nm, pore volume of 0.5098â¯cm3â¯g-1 and surface area of 631.8â¯m2â¯g-1. Adsorption was adequate using 0.25â¯gâ¯L -1 of ACBS, and, the process was favored at pHâ¯2.0 for Allura Red AC and pHâ¯8.0 for Crystal Violet. From the kinetic viewpoint, the data were satisfactorily represented by the pseudo-second order model. Freundlich and Sips models were suitable to represent the adsorption equilibrium of the Allura Red and Crystal Violet, respectively. The maximum values for adsorption capacities were 287.1â¯mgâ¯g-1 for Allura Red and 640.7â¯mgâ¯g-1 for Crystal Violet. The adsorption of both dyes was thermodynamically spontaneous, favorable and endothermic. In brief, the residual sludge of a wastewater treatment plant may be used as an eco-friendly precursor for ACBS production. ACBS was an efficient adsorbent material able to uptake dyes from aqueous solutions.