NaOH–ball-milled co-modified magnetic biochar and its oil adsorption properties--颗粒学报PARTICUOLOGY

Wei, Z., Li, H., Jia, M., & Lin, T. (2023). NaOH–ball-milled co-modified magnetic biochar and its oil adsorption properties. Particuology, 83, 40-49. https://doi.org/10.1016/j.partic.2023.02.005

NaOH–ball-milled co-modified magnetic biochar and its oil adsorption properties

Zehua Wei, Haihong Li^*, Miaomiao Jia, Ting Lin

School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an, 710048, China

10.1016/j.partic.2023.02.005

Volume 83, December 2023, Pages 40-49

Received 2 December 2022, Revised 1 February 2023, Accepted 4 February 2023, Available online 23 February 2023, Version of Record 13 March 2023.

E-mail: 1624116019@qq.com

Highlights

• Preparation of carbon based oil absorbing materials from agricultural solid waste walnut shells.

• Modification of biochar surface groups, pore structure and magnetic properties using simple co-modification methods.

• Co-modified adsorbents exhibit good oil absorption and reuse properties.

• Solid-phase partitioning, hydrogen bonding, electrostatic interaction, and π-π bonding synergize the adsorption of oil.

Abstract

A magnetic biochar adsorbent (BM–OH–BC) was prepared through NaOH–ball milling co-modification with walnut shells as the raw material, and its oil adsorption characteristics were investigated. The adsorption properties of oil pollutants were compared before and after the NaOH-ball-milling co-modification, and the mechanism of NaOH-ball-milling on oil pollutants was investigated by scanning electron microscope-energy dispersive X-ray spectroscopy, BET, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The experimental results showed that the oil adsorption capacity of BM–OH–BC can reach 2.75 g/g, which is 129% higher than that of unmodified biochar. Moreover, after five adsorption and desorption cycles, the adsorption rate of BM–OH–BC only decreased by 5.9%, which was because the oil adsorption of BM–OH–BC is mainly chemical adsorption. The adsorption processes involving single layer, heterogeneous phase and multilayer made BM–OH–BC have excellent adsorption properties. After biochar co-modification, the specific surface area of BM–OH–BC increased to 466 m²/g, the total pore volume increased to 0.245 cm³/g, the average pore size decreased to1.90 nm, and the number of hydrophobic non-polar functional groups increased, leading to the enhancement of its oil absorption capacity. This study provides a reference for the treatment of oil-contaminated water bodies.

Graphical abstract

Keywords

Biochar; Oil pollution; Adsorption properties; Modification mechanism

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