Surface interactions of oxytetracycline on municipal solid waste-derived biochar–montmorillonite composite

ABSTRACT

A composite material prepared from municipal solid waste-derived biochar and montmorillonite (MSW-BC-MMT) was studied as a remediation medium for the removal of oxytetracycline (OTC) from aqueous systems. The morphological characterization using SEM images revealed that the composite had a heterogeneous flaky, plate-like surface appearance. Based on N₂ adsorption experiments and compared to the pristine biochar, the composite showed an increased specific surface area by 1.5 folds. The three-parameter Redlich Peterson isotherm model and two-parameter Temkin isotherm model were best fitted with R² = 0.998 and 0.997, respectively, both for the pristine biochar and the MSW-BC-MMT composite. Additionally, the kinetics was best described using the pseudo-second-order model, suggesting that OTC adsorption onto the composite takes place via chemisorption. A capacity of 233 mg g⁻¹ was observed for the MSW-BC-MMT, which is suggested to be predominantly governed by π-π electron donor–acceptor interactions, electrostatic attraction and surface complexation. As evidenced by FTIR results, OTC was presumed to be adsorbed via hydrogen bonding as well. The value addition of MSW by producing MSW-derived biochar is considered a favorable solution for solid waste management. Therefore, the production of the MSW-BC-MMT composite becomes useful due to its significance in acting as a simultaneous MSW management technique and a low-cost material for antibiotic OTC remediation.

GRAPHICAL ABSTRACT

KEYWORDS:

• Oxytetracycline
• municipal solid waste
• biochar
• montmorillonite
• clay-biochar composite
• wastewater treatment

Acknowledgements

This work was carried out with the support of the Research Council (ASP/01/RE/SCI/2017/83), Faculty of Applied Sciences, University of Sri Jayewardenepura, Sri Lanka. Analytical support from the Instrument Centre, Faculty of Applied Sciences, University of Sri Jayewardenepura, Sri Lanka, is also acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the Research Council [ASP/01/RE/SCI/2017/83].

Notes on contributors

Meththika Vithanage

Vithanage group of the Ecosphere Resilience Research Centre (ERRC), University of Sri Jayewardenepura, led by Prof. Meththika Vithanage focuses on research on atmosphere, water, soil and waste. The presence of contaminants in emerging concern (CECs) in aqueous environments and other contaminants such as trace metals, herbicides, etc. that comes from the anthropogenic origin are increasing their prevalent use in the fast-moving urban economy and “consumerism” society. These contaminants get leached into the environment and water where treatment gets costly or involve in re-formulation into other dangerous compounds. At ERRC, we monitor water and wastewaters for their quality, especially drinking water and wastewaters like landfill leachate and hospital wastewater. We further focus at the material level for remediating contaminants from water, i.e. trace metals, dyes, antibiotics, pesticides etc. Surface modification of bio-geo-based sorbents selective for both organic and inorganic contaminant uptake is where our expertise lies.