Textile waste-derived functional carbon materials for selective pharmaceutical pollutant removal

Abstract

The physical and chemical attributes of functional carbon materials depend on the conditions of synthetic pyrolysis, which consequently influence pollutant removal efficacy. In this study, textile waste (e.g., denim waste)-derived functional carbon materials (DFCMs) were synthesized using CO2 and N2 as pyrolysis carrier gases, after which their surface characteristics were systematically examined. Comparative analysis revealed the formation of numerous C–H bonds in CO2-DFCM, whereas bonds of oxygen-containing functional groups and amine groups emerged in N2-DFCM. Furthermore, an assessment of the contact angle between DFCM and water molecules revealed a high contact angle of 94.6° for CO2-DFCM, whereas N2-DFCM exhibited a 69.8° contact angle. These findings demonstrate that CO2-DFCM is hydrophobic, whereas N2-DFCM is hydrophilic. Similarly, capillary strength analyses revealed that CO2-DFCM and N2-DFCM possess capillary forces of −8.41 × 106 N m−2 and 2.35 × 107 N m−2, respectively. These surface disparities also manifested in varying antibiotic adsorption capacities, with CO2-DFCM exhibiting heightened removal rates for hydrophobic antibiotics such as sulfamethoxazole and acetaminophen, whereas N2-DFCM exhibited superior removal rates for tetracycline acid and oxytetracycline hydrochloride, antibiotics with hydrophilic properties. Collectively, the outcomes of our kinetic, isotherm, and hydrothermal dynamic modeling provide insights into the adsorption mechanisms of antibiotics onto DFCMs, revealing distinct mechanisms dependent on the antibiotic type.