Enhanced adsorption performance of tetracycline in aqueous solutions by methanol-modified biochar

• The MeOH-biochar showed significant increase in adsorption capacity to tetracycline.
• The inherent organic pollutants in biochar decreased after methanol modification.
• The filtration volume has a 2-fold of enhancement after methanol modification.
• The improvement of adsorption to TC attributes to the change in O-containing groups.

Tetracycline (TC), a commonly used personal care and veterinary drug, is produced in large-scale, during which high concentrations of wastewater is discharged into environment and difficult to biodegrade. Adsorption is a cost-effective and environment-friendly approach to TC wastewater. In this study, ubiquitous rice husk biochar was modified by methanol to improve TC adsorption capacities and reduce the inherent organic compound content in the biochar. The modified biochar showed approximately 45.6% enhancement of adsorption capacity in 12 h and 17.2% in equilibrium time compared with Ori-char. X-ray photoelectron spectroscopy suggested that the main factor responsible for the enhancement of TC adsorption is the change in O-containing groups in the modified biochar, which affects π–π electron–donor–acceptor interactions between the biochar and TC. The fixed bed experiment show that the effective filtration volume of MeOH-char is 1059 bed volumes, which is approximately 2-fold of that of Ori-char.

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