RESUMO
The multicomponent adsorption of synthetic dyes has great relevance in the treatment of effluents due to the complexity of the adsorbate-adsorbent interactions. Therefore, this study provides useful information about the adsorption capacity of methylene blue (MB) and crystal violet (CV) in a bioadsorbent (mandarin peels) in a single-component and competitive system using detailed multivariate calibration analysis. The PLS1 multivariate calibration model was used to quantify the adsorbates. In mono and two-component systems, the adsorption capacity of CV (1.26-1.36 mg g-1) was superior when compared to MB (0.925-0.913 mg g-1), characterizing synergistic adsorption for CV and antagonistic adsorption for MB. The Sips model was effective for describing single-component systems, suggesting that adsorption did not occur in the monolayer. For competitive adsorption, modified, unmodified, and extended models were used to understand the interactions between the dyes and the bioadsorbent. The modified Redlich-Peterson (MRP) model was effective in describing the behavior of the binary system, indicating that the interaction forces with the adsorbate were significant. Thus, the bioadsorbent showed promising results for competitive adsorption, thus being of relevance to the industrial sector. Density functional calculations were also performed to characterize the atomic interactions for the removal of both dyes on mandarin peels.
Assuntos
Azul de Metileno , Poluentes Químicos da Água , Azul de Metileno/química , Violeta Genciana , Adsorção , Calibragem , Teoria da Densidade Funcional , Cinética , Corantes/química , Poluentes Químicos da Água/análiseRESUMO
Removal of phenol from wastewater is essential to achieve permitted concentrations according to the recommendations of USEPA. The adsorption capacity of phenol in activated adsorbent with KOH of Enterolobium contortisiliquum (TAC) was evaluated at different temperatures. The Langmuir isotherm represented the equilibrium data of this study. Thermodynamic process was endothermic, spontaneous, and reversible. The mass transfer parameters ranged from KE 0.68 to 0.96 × 10-3 (cm s-1), Ds 8.95 to 14.35 × 10-9 (cm2 s-1), and Dp 5.023 × 10-8 (cm2 s-1). The PVSDM model represented the adsorption kinetics. Intraparticle diffusion limits the mass transfer process Biot > 100. The two-stage process minimized the total amount of TAC required to achieve the permitted specification of phenol concentration in wastewater from different industrial sectors. TAC showed significant performance in the removal of phenol from wastewater.
Assuntos
Fenol , Poluentes Químicos da Água , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Fenóis , Termodinâmica , Águas ResiduáriasRESUMO
Liquid effluents from various dyeing industries often have a high concentration of dyes that diffuse into river systems and can be toxic and non-degradable in the environment. In this study, the potential of the use of timbaúva seed husks in the preparation of four adsorbents tested in the removal of methylene blue was analyzed: in natura, chemically activated material (qmax = 1.24 ± 0.04 mg g-1), carbonized (qmax = 1.96 ± 0.03 mg g-1), and activated carbon (qmax = 1.983 ± 0.04 mg g-1). The adsorbents were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and CHN elemental analysis to assist in the proposed dye adsorption mechanism in the adsorbents tested. In the adjustment of the kinetic parameters, the pseudo-second order model was predominant by the statistical analysis of the ARE and R2. The carbonized samples were better adjusted to Langmuir isotherms. The removal efficiency of the methylene blue dye in aqueous solutions at the concentrations and conditions studied was 86.78%. The coal from the seed husks of timbaúva has shown excellent performance in adsorption of the methylene blue dye and, therefore, can have technological application.
Assuntos
Azul de Metileno/análise , Poluentes Químicos da Água/análise , Adsorção , Corantes , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Anthocyanin pigments are suitable as natural dyes for food, cosmetics and dietary supplements, due to the demand for healthier products and their antioxidant properties. This work aimed to extract the anthocyanin pigments from red cabbage and its separation of the solution by adsorption operation onto chitosan films. The anthocyanin was extracted from red cabbage in water hot at 90⯰C by 15â¯min. Chitosan was obtained from shrimp waste, and its films were produced by casting technique (tensile strength of 25.1⯱â¯1.9â¯MPa, elongation of 10.5⯱â¯3.5% and thicknesses of 103.1⯱â¯1.3⯵m). The anthocyanin adsorption assays were performed in batch, and the highest adsorption capacity was around 140â¯mgâ¯g-1. The equilibrium experimental data were adjusted by Henry, Langmuir and Freundlich models, and all models showed a good fitting (R2â¯≥â¯0.96 and AREâ¯≤â¯6.5%). The thermodynamic parameters represented endothermic and physical adsorption. The kinetic behavior was evaluated by empirical models, being the pseudo-first order model that showed the best fitting (R2â¯≥â¯0.97 and AREâ¯≤â¯8.5%). This work presented suitable information about the anthocyanin molecules immobilization onto chitosan films and, these results could be important to the use these pigments with chitosan in different areas.