Competitive adsorption of sulfamethoxazole and bisphenol A on magnetic biochar: Mechanism and site energy distribution

Ruotong Jin; Cailian Zhao; Yanxing Song; Xiaojie Qiu; Chenxi Li; Yingxin Zhao

doi:10.1016/j.envpol.2023.121662

Competitive adsorption of sulfamethoxazole and bisphenol A on magnetic biochar: Mechanism and site energy distribution

Environ Pollut. 2023 Jul 15:329:121662. doi: 10.1016/j.envpol.2023.121662. Epub 2023 Apr 18.

Authors

Ruotong Jin¹, Cailian Zhao², Yanxing Song¹, Xiaojie Qiu¹, Chenxi Li¹, Yingxin Zhao³

Affiliations

¹ School of Environmental Science and Engineering, Tianjin University, Tianjin, 300350, PR China.
² Lijiang Eco-environment Burea, Lijiang, 674110, PR China.
³ School of Environmental Science and Engineering, Tianjin University, Tianjin, 300350, PR China. Electronic address: yingxinzhao@tju.edu.cn.

PMID: 37080522
DOI: 10.1016/j.envpol.2023.121662

Abstract

Competitive adsorption and complementary adsorption between emerging pollutants has been observed in multiple studies. Investigation of the preference of pollutants for different types of adsorption sites can provide a supplementary perspective for understanding complementary adsorption. In this study, the simultaneous adsorption of two typical emerging pollutants, sulfamethoxazole (SMX) and bisphenol A (BPA), on magnetic biochar (MBC-1) was investigated. The results showed that the modification with ferric chloride optimized the surface properties of biochar (aromaticity, hydrophobicity, and oxygen-containing functional groups, etc.), and helped to remove SMX and BPA through various interactions. The equilibrium adsorption capacity of the two adsorbents was inhibited by competitive adsorption in the mixed solute systems, which was due to the same adsorption mechanism. When pH = 7, the SMX and BPA adsorption mainly involved pore filling, hydrophobic effect, π-π EDA, and hydrogen bonding. In addition, electrostatic force, surface coordination, and ion exchange have also been proven to be related to the adsorption of SMX and BPA. In the co-adsorption system, BPA's competitive advantage might be due to its superior hydrophobicity, charge property, and molecular diameter. In the competitive adsorption experiment, the total adsorption capacity (Q_i) of the competitive solute exceeded the adsorption inhibition (△Q_i) of the main solute, indicating that the two solutes occupied their preferred adsorption sites, which confirmed the complementary adsorption phenomenon. Complementary adsorption can be explained by the preference of SMX and BPA for different types of adsorption sites. BPA preferentially occupied high-energy sites in the co-adsorption system, such as π-π EDA interaction, ion exchange, and surface coordination. At the same time, SMX tended to be removed by hydrophobic interaction and hydrogen bonding.

Keywords: Complementary adsorption; Emerging pollutants; Magnetic biochar; Site energy distribution.

MeSH terms

Adsorption
Charcoal / chemistry
Environmental Pollutants*
Magnetic Phenomena
Sulfamethoxazole / chemistry
Water Pollutants, Chemical* / analysis

Substances

biochar
Sulfamethoxazole
bisphenol A
Charcoal
Environmental Pollutants
Water Pollutants, Chemical