Adsorption kinetics of methylene blue from wastewater using pH-sensitive starch-based hydrogels

In this work, starch/poly(acylic acid) hydrogels were synthesized through a free radical polymerization technique. The molar ratios of acrylic acid to N , N ′-methylenebisacrylamide were 95:5, 94:6, and 93:7. The samples exhibited an amorphous porous structure, indicating that the size of the pores...

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Bibliographic Details
Published in:Scientific reports 2023-07, Vol.13 (1), p.11900-11900, Article 11900
Main Authors: Mohammadzadeh, Fatemeh, Golshan, Marzieh, Haddadi-Asl, Vahid, Salami-Kalajahi, Mehdi
Format: Article
Language:English
Subjects:
639/301
639/638
704/172/169
Absorption
Acrylic acid
Adsorption
Dyes
Humanities and Social Sciences
Hydrogels
Kinetics
Methylene blue
multidisciplinary
pH effects
Science
Science (multidisciplinary)
Starch
Wastewater
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Summary:In this work, starch/poly(acylic acid) hydrogels were synthesized through a free radical polymerization technique. The molar ratios of acrylic acid to N , N ′-methylenebisacrylamide were 95:5, 94:6, and 93:7. The samples exhibited an amorphous porous structure, indicating that the size of the pores was contingent upon the amount of cross-linking agent. The quantity of acrylic acid in structure rose with a little increase in the amount of the cross-linking agent, which improved the hydrogels’ heat stability. The swelling characteristics of the hydrogels were influenced by both the pH level and the amount of cross-linking agent. The hydrogel with a ratio of 94:6 exhibited the highest degree of swelling (201.90%) at a pH of 7.4. The dominance of the Fickian effect in regulating water absorption in the synthesized hydrogels was demonstrated, and the kinetics of swelling exhibited agreement with Schott's pseudo-second order model. The absorption of methylene blue by the hydrogels that were developed was found to be influenced by various factors, including the concentration of the dye, the quantity of the cross-linking agent, the pH level, and the duration of exposure. The hydrogel 95:5 exhibited the highest adsorption effectiveness (66.7%) for the dye solution with a concentration of 20 mg/L at pH 10.0. The examination of the kinetics and isotherms of adsorption has provided evidence that the process of physisorption takes place on heterogeneous adsorbent surfaces and can be explained by an exothermic nature.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-023-39241-z