Methylene blue sorption phenomena onto pectin, brea gum, montmorillonite based hydrogels: kinetic and thermodynamic assessment

GAMBONI, JIMENA ELIZABETH; BERTUZZI, MARÍA A.; SLAVUTSKY, ANIBAL M.

JOURNAL OF POLYMERS AND THE ENVIRONMENT

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2022

1566-2543

The wastewater treatment, particularly the removal of organic contaminants, is oftencarried out by adsorption with solids. Hydrogels present a great swelling capacity thatcan be enhanced by the incorporation of nano-clays such as montmorillonita (Mt).Methylene blue is a common component of industrial effluents and its ecotoxicity inwell-known. The aim of this work was to evaluate the adsorption capacity of hydrogelsbased on pectin and brea gum with Mt nanoparticles. The hydrogels were physicallycharacterized, it was observed that Mt is exfoliated into the matrix, and affects theswelling and erosion of them. Incorporation of Mt caused an increment of swelling ofapproximately 150% at pH = 6.5. The effects of various experimental parameters havebeen investigated. The temperature effect on the adsorption rate indicated anendothermic process with activation energy of 33.231 kJ mol -1 . The removal % ofMB at 45°C, pH = 2.5 and 75 mg L -1 of MB solution presented a value of 97%. Theadsorption kinetic was analysed through different mathematical models (pseudo-firstorder, pseudo-second order, intra-particle, and Boyd models). Statistics and furtheranalysis of the kinetics constants indicated that the pseudo-second order model betterrepresents the behaviour of the samples. The application of intra particle model andBoyd model indicates that the adsorption phenomenon occurs in two stages. The firststage, of short duration, is related to the boundary layer. The second stage, whichcontrols the process, is related to the chemical adsorption of the dye on the polymericstructure of the hydrogel.