Study on the Adsorption Mechanism of Cu²⁺ by Sodium Alginate Loaded with Biochar

¹ School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, Jiangxi, China
² School of Software Engineering, Jiangxi University of Science and Technology, Nanchang 330013, Jiangxi China

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

In this study, corn straw biochar (BC) was employed as a base material, and sodium alginate (SA) was utilized as an immobilization carrier to successfully prepare sodium alginate-loaded biochar composite gel beads (SA-BC) for adsorbing Cu²⁺ in the solution. The bead-shaped structure of this composite offers excellent stability and reusability, making it suitable for continuous-flow column operations and practical wastewater treatment applications. The results revealed that the incorporation of sodium alginate formed a dense coating layer and a porous network that enhanced the stability and adsorption performance of the material. Kinetic analyses revealed that Cu²⁺ uptake by SA-BC was best described by a pseudo-second- order model, suggesting that the adsorption proceeded mainly through chemisorptive interactions. The material achieved a maximum adsorption capacity of approximately 140.66 mg·g^-1. FTIR analysis further confirmed that the adsorption of Cu²⁺ primarily relied on the coordination interactions of carboxyl and hydroxyl functional groups. Overall, the composite material exhibits excellent adsorption capacity, operational convenience, and environmental friendliness, providing a promising and sustainable approach for the removal of heavy metal pollutants.