Abstract
Biochar is a beneficial adsorbent for the treatment of organic pollutants in the environment. The association of oxygen functional groups and adsorption behaviors has not been well investigated. In this paper, the oxidation-modified biochar (O-BC) and the reduction-modified biochar (R-BCX) were prepared by Co2+/peroxymonosulfate chemical oxidation and high-temperature reduction, respectively. The modified biochars were used to remove sulfamethoxazole (SMX) from water, and the adsorption amounts of biochar followed the order of R-BC700 (14.66 mg·L−1) > O-BC (4.91 mg·L−1) > BC (0.16 mg·L−1). Additionally, the effects of water chemical conditions (i.e., ionic strength, solution pH and humic acid (HA) concentration) on the adsorption of SMX on biochar, were further investigated. Combining physical adsorption, X-ray electron spectroscopy, and zeta potentiometer characterization techniques, the effect of functional groups on the adsorption mechanism was further explored, revealing the importance of various oxygen functional groups for SMX adsorption. The results showed that C=O and C=C, resulting in π–π interaction, were in favor of the adsorption of SMX, while C-O was not conducive to the adsorption of SMX, due to the steric hindrance and the negative surface charge. Additionally, the hydrophobic effect of the biochar was also one of the adsorption mechanisms.
Highlights
In recent decades, the use of emerging micro-pollutants, such as drugs and personal care products, has increased, which has become a concern for sewage and wastewater treatment plants
The bioaccumulation of antibiotics in aquatic organisms will accumulate along the biological chain, which could induce resistance genes in animals or microorganisms
The adsorption isotherm results showed that both oxidations modified biochar (O-biomass charcoal (BC)) and the reductionmodified biochar (R-BCX) presented a significant improvement in the adsorption capacity for SMX; the adsorption capacity of biochar presented the adsorption order of R-BC700 (14.66 mg·g−1 ) > oxidation-modified biochar (O-BC) (4.91 mg·g−1 ) > BC (0.16 mg·g−1 )
Summary
The use of emerging micro-pollutants, such as drugs and personal care products, has increased, which has become a concern for sewage and wastewater treatment plants. Antibiotics and their metabolites are frequently detected at a trace level (μg·L−1 ) in surface water bodies [1]. Due to their widespread use, antibiotics have been constantly released into the environment, and are classified as emerging pseudo-persistent pollutants. Due to the high stability and long half-life (85–100 days) of SMX, it poses a serious threat to human health
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