Theoretical and experimental investigation on rapid and efficient adsorption characteristics of microplastics by magnetic sponge carbon

Hongxian Li; Minghui Tang; Jun Wang; Lulu Dong; Ling Wang; Qi Liu; Qunxing Huang; Shengyong Lu

doi:10.1016/j.scitotenv.2023.165404

Theoretical and experimental investigation on rapid and efficient adsorption characteristics of microplastics by magnetic sponge carbon

Sci Total Environ. 2023 Nov 1:897:165404. doi: 10.1016/j.scitotenv.2023.165404. Epub 2023 Jul 7.

Authors

Hongxian Li¹, Minghui Tang², Jun Wang¹, Lulu Dong¹, Ling Wang¹, Qi Liu¹, Qunxing Huang¹, Shengyong Lu¹

Affiliations

¹ State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
² State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China. Electronic address: lytmh1214@zju.edu.cn.

PMID: 37423291
DOI: 10.1016/j.scitotenv.2023.165404

Abstract

Microplastic pollution control has always been a thorny problem all over the world. Magnetic porous carbon materials have shown a good development prospect in microplastic adsorption due to their excellent adsorption performance and easy magnetic separation from water. However, the adsorption capacity and rate of magnetic porous carbon on microplastics are still not high, and the adsorption mechanism is not fully revealed, which hinders its further development. In this study, magnetic sponge carbon was prepared using glucosamine hydrochloride as the carbon source, melamine as the foaming agent, iron nitrate and cobalt nitrate as the magnetizing agents. Among them, Fe-doped magnetic sponge carbon (FeMSC) exhibited excellent adsorption performance for microplastics due to its sponge-like morphology (fluffy), strong magnetic properties (42 emu/g) and high Fe-loading (8.37 Atomic%). FeMSC could adsorb to saturation within 10 min, and the adsorption capacity of polystyrene (PS) reached as high as 369.07 mg/g in 200 mg/L microplastic solution, which was almost the fastest adsorption rate and highest adsorption capacity reported so far in the same condition. The performance of the material against external interference was also tested. FeMSC performed well in a wide pH range and different water quality, except in the strong alkaline condition. This is because the surface of microplastics and adsorbents will have many negative charges under strong alkalinity, significantly weakening the adsorption. Furthermore, theoretical calculations were innovatively used to reveal the adsorption mechanism at the molecular level. It was found that Fe-doping could form chemisorption between PS and the adsorbent, thereby significantly increasing the adsorption energy between the adsorbent and PS. The magnetic sponge carbon prepared in this study has excellent adsorption performance for microplastics and can be easily separated from water, which is a promising microplastic adsorbent.

Keywords: Anti-interference; Magnetic sponge carbon; Mechanism; Microplastics adsorption; Theoretical calculation.