Open Access

ARTICLE

Study on the Adsorption Properties of Sodium Alginate-Modified Polyacrylic Acid Composite Hydrogel for Heavy Metal Cu²⁺ in Aqueous Solution

Hui Fan, Xinqiang Li^*
College of Architectural Engineering, Anhui University of Applied Technology, Hefei, 230011, China
* Corresponding Author: Xinqiang Li. Email:
(This article belongs to the Special Issue: Innovative Smart Polymeric Materials for Sustainable Energy Solutions: Bridging Advances in Energy and Biomedical Applications)

Journal of Polymer Materials https://doi.org/10.32604/jpm.2026.075290

Received 29 October 2025; Accepted 30 December 2025; Published online 19 January 2026

Abstract

To meet the needs of the treatment of Cu²⁺ pollution in aqueous solution, the sodium alginate-modified polyacrylic acid (PAA/SA) composite hydrogel was prepared by solution polymerization with acrylic acid (AA) as monomer, sodium alginate (SA) as filler, N, N’-methylenebisacrylamide (MBA) as crosslinking agent, and potassium persulfate (K₂S₂O₈) as initiator. The characterization results showed that the introduction of SA significantly improved the physical and chemical properties of PAA hydrogel materials. Scanning electron microscopy (SEM) showed that as the SA content increased, the materials gradually evolved from a dense blocky structure to a porous network. When the SA content was 10 wt%, it exhibited a fragmented layered morphology. The Brunauer Emmett Teller (BET) showed that the specific surface area reached 37.65 m²/g and the porosity increased to 12.47%. Fourier transform infrared (FT-IR) spectroscopy confirmed that SA was successfully embedded into the PAA network through hydrogen bonding and ion crosslinking, and the carboxyl vibration peak shifted from 2378 to 2352 cm⁻¹. Mechanical tests showed that at 10 wt% SA, the maximum stress was 13.1 kPa. The adsorption experiment showed that the equilibrium adsorption capacity of the PAA/SA hydrogel for Cu²⁺ was 11.03 mg/g, with an adsorption efficiency of 42.65%. Dynamics studies showed that the adsorption process follows a first-order kinetic model (R² = 0.986–0.997), indicating a physical adsorption mechanism dominated by liquid film diffusion. The optimal process conditions were found to be a dosage of 1.5 g/L, and the effect of temperature on adsorption was limited. The material maintained 67.4% of its initial adsorption capacity after six adsorption-desorption cycles. These parameters are generally superior to those of similar materials reported in the literature, indicating broad application prospects. Such a kinetic and isotherm model resulted from the combined effects of functional groups, electrostatic attraction, and chelation. In practical applications, pH, ionic strength, and competing ions will affect the adsorption performance of PAA/SA composite hydrogels.

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Keywords

Polyacrylic acid (PAA) hydrogel; sodium alginate (SA); solution polymerization; copper ions; adsorption kinetics; adsorption isotherm

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