Self-separating core-shell spheres with a carboxymethyl chitosan/acrylic acid/Fe3O4 composite core for soil Cd removal

• Published in: Carbohydrate polymers 2024-11, Vol.343, p.122428, Article 122428
• Main Authors: Hu, Tian, Liu, Bu-Ning, Bu, Huaitian, Hu, Han-Jian, Zhu, Qi-Shun, Tang, Shipeng, Li, Yongtao, Wang, Jinjin, Jiang, Gang-Biao
• Format: Article
• Language: English
• Subjects: Cd activation and adsorption; Cd removal in soil; Core-shell sphere; Self-separated
• ISSN: 0144-8617; 1879-1344; 1879-1344
• DOI: 10.1016/j.carbpol.2024.122428

Cadmium (Cd) removal from soil is crucial as Cd enters the food chain and affect food safety, thus impose severe threaten to human health. We developed PPC@PC-Fe, a dual-functional core-shell sphere for efficient soil Cd reduction. The shell (PPC) was composed of encapsulated citric acid (CA) in a polylactic acid (PLA) and polyethylene glycol (PEG) network, which endows a function of activating Cd; and the core (PC-Fe) consisted of a polyacrylic acid/carboxymethyl chitosan (PAA/CMC) hydrogel with Fe3O4 nanoparticles to adsorb adjacent activated Cd. Upon water contact, the shell dissolved, releasing CA to activate soil Cd. Simultaneously, the swellable PC-Fe core absorbed water and expanded in size, promoting the disintegration of PLA in the shell, which triggered the automatic separation of core from shell, enabling the exposed PC-Fe core to rapidly adsorb Cd. Furthermore, the PC-Fe core can be magnetically removed after adsorption of Cd. Soil culture tests showed that 2 % PPC@PC-Fe reduced soil Cd from 6.009 mg/kg to 4.834 mg/kg in 10 days, with the acid-soluble Cd being the predominantly target to be activated and remove. This study demonstrates an effective stepwise activation and adsorption mechanism by a single carrier, with simple magnetic collection minimizing secondary pollution. It offers an innovative approach to the remediation of cadmium-contaminated sites in the field. •A core-shell self-separated sphere (PPC@PC-Fe) has been synthesized for soil Cd removal.•The PPC@PC-Fe has can activate and adsorb Cd successively in the flooded soil.•The prior activation treatment can significantly increase the Cd removal rates in the soil.•Soil Cd decreased from 6.009 to 4.834 mg/kg with 2 % PPC@PC-Fe treatment.