Investigation of the Distribution and Placement of Metal-Organic Frameworks in Polyvinyl Alcohol/Sodium alginate Composites and Their Effects on Adsorption Properties for Dye Removal: A Comparison of Different Synthesis Methods

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Document Type : Original Article

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Department of Polymer Engineering, Faculty of Engineering, Golestan University, Gorgan, Iran

Abstract

In this work, we investigated the incorporation of metal-organic frameworks (MOFs) into polyvinyl alcohol (PVA) and sodium alginate (SA) composites, analyzing the integration of ZIF-8 into this matrix blend and the effect of its distribution and location on adsorption properties. The PVA/SA@ZIF-8 hydrogels were prepared using three synthesis methods: one-step in situ, two-step in situ, and direct mixing. Morphology, elemental distribution, and structural integrity of the composites were characterized by FESEM, EDS, FTIR, XRD, and DLS analyses. In terms of ZIF-8 integration, the two-step in-situ method yielded the most effective distribution and integration, resulting in superior adsorption capacity. We comprehensively evaluated the removal efficiency of basic violet dye under varied conditions, including hydrogel dosage, pH, temperature, initial dye concentration, and contact time. Results demonstrated that the two-step in-situ-synthesized hydrogels exhibited the best performance, achieving approximately 99% dye removal at an optimal dosage of 20 mg, pH 12, and T = 60 °C. The maximum dye removal efficiency for this method was observed at the initial dye concentration of 5 mg/L, reaching about 69%. Kinetic studies indicated a predominant chemisorption process (Pseudo-Second-Order R²≈ 0.99), and thermodynamic evaluation confirmed a spontaneous (ΔG∘= −3.96 kJ/mol at T=298 K) and endothermic (ΔH∘ = +21.85 kJ/mol) adsorption. These results collectively demonstrate the great promise of engineered PVA/SA composites incorporating MOFs for use in environmental remediation and industrial processes, driving the next generation of material design for sustainability.

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Progress in Color, Colorants and Coatings

Articles in Press, Accepted Manuscript
Available Online from 26 October 2025

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