Biowaste-derived magnetite biochar for adsorption of norfloxacin from water samples

Abstract

Pharmaceutical residues in water resources pose serious risks to human health and aquatic ecosystems. Herein, an environmentally friendly magnetite-loaded biochar was synthesized from K2CO3 activated tea waste and evaluated for the adsorptive removal of norfloxacin, a widely used fluoroquinolone antibiotic, from water samples. This study combines novel K2CO3 activated tea waste with the facile separation of magnetite adsorbent. The synthesized nanoparticles were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller and dynamic light scattering. A validated spectrofluorimetric method has been developed for monitoring norfloxacin concentration throughout the treatment protocol. The effects of solution pH, adsorbent dosage, initial norfloxacin concentration, and contact time on adsorption efficiency were systematically investigated using a 24 full factorial experimental design. Initial drug concentration was identified as the most significant factor, followed by contact time. Under optimized conditions, a removal efficiency of 92 ± 0.41% was achieved for 25 µg mL− 1 norfloxacin within 2 h at pH 5. Adsorption kinetics and isotherm models were subsequently evaluated to elucidate the adsorption behavior. The adsorbent exhibited a maximum adsorption capacity of 136.99 mg g− 1. The reusability of these nanoparticles has been investigated for six treatment cycles, demonstrating the efficacy of the adsorbent after several uses. Furthermore, the applicability of the developed method was validated by screening and analyzing real water samples, including Nile River and tap water. The greenness and whiteness levels of the proposed method were assessed using Complex GAPI, AGREE, BAGI, and WAC tools. These findings demonstrate the potential of converting agricultural waste into a reusable adsorbent for facile and cost-effective treatment of antibiotic-contaminated water.