Optimizing date palm leaf and pistachio shell biochar properties for antibiotic adsorption by varying pyrolysis temperature

Authors: Schmidt, Michael - Mike; Ashworth, Daniel; Marquez Celis, Nydia; Ibekwe, Abasiofiok - Mark

Submitted to: Bioresource Technology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2022
Publication Date: 1/6/2023
Citation: Schmidt, M.P., Ashworth, D.J., Marquez Celis, N., Ibekwe, A.M. 2023. Optimizing date palm leaf and pistachio shell biochar properties for antibiotic adsorption by varying pyrolysis temperature. Bioresource Technology Reports. 21. Article 101325. https://doi.org/10.1016/j.biteb.2022.101325.
DOI: https://doi.org/10.1016/j.biteb.2022.101325

Interpretive Summary: Agricultural irrigation accounts for roughly 70% of freshwater consumption worldwide. As water resources globally become more stressed due to increased demand and future climate uncertainty, alternative water sources are receiving greater attention as irrigation water sources. One widely available source of water is treated wastewater, which provides a steady source of nutrient-rich water for irrigating crops. Treated wastewater, however, contains trace levels of antibiotics that may foster antibiotic resistance in plants, livestock and humans. Biochar, a material formed from pyrolyzing biomass feedstock, represents a possible adsorbent for antibiotic removal from wastewater streams and, thus, a potential mitigation strategy for antibiotic resistance risk. Here we study biochars from different feedstock sources (date palm leaf and pistachio nut shell) and pyrolysis temperatures (400-800°C) to determine the most effective material for removing three prominent antibiotics (trimethoprim, sulfamethoxazole and sulfapyridine) from water. We found that all biochars removed trimethoprim from solution similarly, while sulfamethoxazole and sulfapyridine were removed more effectively by biochars produced at 800°C. Biochars showed excellent antibiotic removal under environmentally-relevant concentrations, with up to 97.6, 98.1 and 99.5% of TMP, SMX and SPY removal efficiencies, respectively. These results demonstrate the capacity of biochar materials for removing antibiotics from water and show potential for developing a biochar-based water treatment system in the future.

Technical Abstract: This study implemented biochars produced from two arid agricultural byproducts, date palm leaves and pistachio shells, at pyrolysis temperatures from 400-800°C to remove trimethoprim, sulfamethoxazole and sulfapyridine antibiotics from mixed solutions. By altering pyrolysis temperature and feedstock, produced biochars yielded a range of physicochemical properties resulting in distinct antibiotic adsorption. Antibiotic adsorption capacity generally decreased with increasing pyrolysis temperature, while adsorption affinities were temperature independent for trimethoprim and increased with pyrolysis temperature for sulfamethoxazole and sulfapyridine. Correlation against biochar properties suggested cation exchange capacity and functional group composition related well to adsorption capacity and polarity/hydrophobicity was linked to adsorption affinities. Antibiotic removal efficiencies by biochars from both feedstocks compared favorably against previous reports, with up to 97.6, 98.1 and 99.5% of trimethoprim, sulfamethoxazole and sulfapyridine removed, respectively. This work relates biochar production conditions to properties and subsequent antibiotic adsorption, demonstrating application of these materials for removing antibiotics from wastewater.