Efficient adsorption performance and mechanism of fluoroquinolone antibiotic onto the acid wash-assisted Co NPs/N-C adsorbent

Abstract

In this study, ZIF-67 was employed as a template, and applied a novel combined treatment method of thermal and acid treatment to provide rapid mass transfer channels and additional adsorption sites for pollutant molecules, thus achieving high adsorption capacity and shorter adsorption time. The adsorption of Co NPs/N-C on ciprofloxacin reached equilibrium within 70 min with a maximum adsorption capacity of 486.20 mg·g−1. Furthermore, the adsorption capacity was enhanced by 1.9 times after acid-wash. The fitted data indicated that the pseudo-second-order kinetics model could more accurately describe the adsorption process, with intraparticle diffusion and liquid film diffusion jointly determining the adsorption rate, primarily involving chemical adsorption. The Langmuir model best described the antibiotic adsorption isotherm, indicating monolayer adsorption on Co NPs/N-C. Based on various characterizations before and after adsorption, it was confirmed that antibiotics were adsorbed onto Co NPs/N-C through hydrogen bonding and π-π interactions. Additionally, this adsorbent exhibited strong continuous treatment capability, a simple and efficient desorption method, as well as efficient treatment efficiency for actual water bodies. This study suggests that Co NPs/N-C can be considered an efficient and promising adsorbent, and the proposed strategy can potentially serve as an antibiotic adsorbent for continuous wastewater treatment.