Characterization of amphoteric bentonite-loaded magnetic biochar and its adsorption properties for Cu2+ and tetracycline

Hongyan Deng; Haixia He; Wenbin Li; Touqeer Abbas; Zhifeng Liu

doi:10.7717/peerj.13030

Characterization of amphoteric bentonite-loaded magnetic biochar and its adsorption properties for Cu²⁺ and tetracycline

PeerJ. 2022 Mar 1:10:e13030. doi: 10.7717/peerj.13030. eCollection 2022.

Authors

Hongyan Deng^#¹, Haixia He^#¹, Wenbin Li¹, Touqeer Abbas², Zhifeng Liu³

Affiliations

¹ College of Environmental Science and Engineering, China West Normal University, Nanchong, China.
² Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Zhejiang University, Zhejiang, China.
³ Qinba Mountains of Bio-Resource Collaborative Innovation Center of Southern Shaanxi Province, Hanzhong, China.

^# Contributed equally.

Abstract

To realize simultaneous adsorption of heavy metal and antibiotic pollutants by a BC-based recyclable material, Fe₃O₄ magnetic biochar (MBC) was prepared by co-precipitation method. Then different ratios of dodecyl dimethyl betaine (BS-12)-modified bentonite (BS-B) were loaded on the surfaces of biochar (BC) and MBC to prepare BS-B-loaded BC and MBC composites, called BS-B/BC and BS-B/MBC, respectively. The physicochemical and structural properties of the composites were characterized by scanning electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, specific surface area (S_BET) analysis, and vibrating sample magnetometry, and the adsorption efficiencies of BS-B/BC and BS-B/MBC to Cu²⁺ and tetracycline (TC) were studied. The following results were obtained. (1) Compared with BS-B/BC, BS-B/MBC had decreased pH and cation exchange capacity (CEC) and increased S_BET. The pH, CEC, and S_BET of BS-B/BC and BS-B/MBC decreased with the increase in the BS-12 proportion of BS-B. The surface of BS-B/MBC became rough after Fe₃O₄ loading. (2) The residual rate of BS-B/MBC was higher than that of BS-B/BC after high-temperature combustion, and the residual rate decreased with the increase in the BS-12 proportion of BS-B. The 2D infrared spectra showed that Fe₃O₄ and BS-12 were modified on the surface of BS-B/MBC. MBC and BS-B/MBC had splendid magnetism and could be separated by external magnetic field. (3) Compared with unmagnetized ones, the adsorption effects of Cu²⁺ and TC on different BS-B/MBCs improved, and the average adsorption rate reached the largest value of 91.92% and 97.76%, respectively. Cu²⁺ and TC adsorptions were spontaneous, endothermic, and entropy-increasing processes. The pH and S_BET of the material had a great influence on Cu²⁺ and TC adsorptions, respectively, than CEC.

Keywords: Adsorption capacity; Bentonite; Dodecyl dimethyl betaine; Magnetized biochar; Surface characteristics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Anti-Bacterial Agents*
Bentonite* / chemistry
Magnetic Phenomena
Tetracycline

Substances

biochar
zwittergent 3-12
Bentonite
Anti-Bacterial Agents
Tetracycline

Grants and funding

This work was supported by the Fundamental Research Funds of China West Normal University (18B023), the Tianfu Scholar Program of Sichuan Province (2020-17), the Sichuan Province Science and Technology Support Program (2018JY0224) and the National Natural Science Foundation of P.R. China (41271244). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.