RESUMO
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.