Insight into the adsorption kinetics, mechanism, and thermodynamics of methylene blue from aqueous solution onto pectin-alginate-titania composite microparticles

Abstract

In the present study, pectin-alginate-titania (PAT) composites were synthesized and the adsorptive removal behavior of methylene blue (MB) from aqueous solution, as a model of synthetic organic effluents, onto the prepared PAT composites were investigated by monitoring the effect of contact time, initial MB concentration, and temperature. The adsorption isotherm data were fitted well with the Freundlich isotherm model, suggesting the surface heterogeneity of the PAT composites and that the MB adsorption occurred on the active sites on multilayer surface of the composites. The adsorption kinetics of MB was demonstrated to be pseudo-second order, governed by two intraparticle diffusion rates, and the adsorption process was exothermic, spontaneous, and more disorder. The Langmuir isotherm model suggested that the maximum adsorption capacity of MB on the PAT composites was in the range of 435–637 mg g–1. In general, it increased with the TiO2 NPs content in the PAT composites, due most likely to the increase in surface area exposing more functional groups of the pectin and alginate to interact with the synthetic dye. The adsorptive removal of MB by the PAT composites was found to be more efficient compared with many other reported adsorbents, such as graphene oxide hybrids, pectin microspheres, magnetite-silica-pectin composites, clay-based materials, chemically treated minerals, and agricultural waste. The present study therefore demonstrated for the first time that PAT composites are not only promising to be utilized as an adsorbent in wastewater treatment, but also provide an insight into the adsorption mechanism of the synthetic dyes onto the biopolymers-titania composites. Graphic abstract Insight into the adsorption kinetics, mechanism, and thermodynamics of methylene blue from aqueous solution onto pectin-alginate-titania composite microparticles.

Structural analysis and dye removal behavior of amorphous titania embedded poly(vinyl butyral) hybrid fiber

“…The peak intensity around the Ti-O-C band at 1132 cm À1 and around the Ti-O band at 600 cm À1 is decreased due to the interactions of MB. Furthermore, the presence of nitrogen atoms in the MB dye structure could form hydrogen bonds with -OH groups of PVB-amTiO 2 F. 4,38 But we could not nd such evidence from the FTIR spectra in our study. Since the fragment of MB bears a positive charge, it should be favorably adsorbed to the negative sites of the PVB-amTiO 2 F surface and subsequently could be attacked by the very active cOH fraction under visible light, according to the same process described by Kanna et al 11 Overall, the mode of MB removal by PVB-amTiO 2 F was mostly by adsorption ($68%), but with combined prolonged adsorption and photocatalytic activity, it could be enhanced up to $85% or more.…”

“…Furthermore, the regression coefficients ( R 2 ) for the pseudo-second-order kinetics model were 0.997 and 0.994 for MB absorption on 10 wt% and 50 wt% PVB–amTiO 2 F, respectively, better than the Lagergren pseudo-first-order kinetic model. This result indicated that the pseudo-second-order model of MB's adsorption kinetics on PVB–amTiO 2 F provides more in-depth information, so the kinetics could be categorized as chemisorption, 38 because of electrostatic interactions between the fiber and dye functional groups. 12 Similar MB adsorption kinetics on the other adsorbents have also been commonly studied.…”

“…The peak intensity around the Ti-O-C band at 1132 cm À1 and around the Ti-O band at 600 cm À1 is decreased due to the interactions of MB. Furthermore, the presence of nitrogen atoms in the MB dye structure could form hydrogen bonds with -OH groups of PVB-amTiO 2 F 4,38. But we could not nd such…”

Adsorption Behavior and Dynamic Interactions of Anionic Acid Blue 25 on Agricultural Waste

“…In particular, the detrimental effects of the pollutants, such as heavy metals and synthetic dyes, on the entire ecosystem and human health have prompted the drive to develop effective approaches to remove the pollutants from wastewaters [ 1 , 2 ]. A variety of physical, chemical, and biological approaches, such as membrane filtration [ 3 ], flocculation [ 4 ], advanced oxidation [ 5 , 6 ], ozonation [ 7 ], adsorption [ 8 , 9 , 10 , 11 ], ion exchange [ 12 ], Fenton processes [ 13 ], and biodegradation [ 14 ] have been explored to remove heavy metal and dye effluents from wastewater. Among these promising methods to remove the pollutants, adsorption has attracted much attention because it is simple, cheap and practical to implement and can be handled even by a small-scale industry using non-toxic materials.…”

Adsorption of Acid Blue 25 on Agricultural Wastes: Efficiency, Kinetics, Mechanism, and Regeneration

“…Among most promising practical methods to achieve this, adsorption has received a great attention due to its simplicity and applicability (Piaskowski et al, 2018;Rafatullah et al, 2010). To date a wide range of materials, such as activated carbons (Alwi et al, 2020;Srivatsav et al, 2020), natural clays (Alshameri et al, 2019), zeolite-based composites (Zamri et al, 2021), and agricultural wastes (Zaidi et al, 2019) have been utilized as adsorbents. In particular, agricultural wastes have several obvious advantages, including their availability in large quantity at low cost, and because their surfaces contain a variety of functional groups (De Gisi et al, 2016).…”