Single-step pyrolysis of biomass waste-derived activated carbon encapsulated zero-valent nickel NPs for the purification of antibiotic-contaminated water

Abstract

In this study, zero-valent nickel NPs immobilized on biowaste-based activated carbon (ZVNi@AC) were prepared using a single-step pyrolytic reduction/activation method. ZVNi@AC was characterized using various techniques, including BET, SEM, TEM, EDS, FTIR, XRD and point of zero charge (pH_pzc) analysis. The nanocomposite is composed of highly porous activated carbon and decorated with ZVNi NPs, with a surface area of 975 m² g⁻¹. The modified activated carbon (ZVNi@AC) demonstrated a superior adsorption performance (367.59 mg g⁻¹) for cephalexin antibiotic removal compared to the unmodified activated carbon (287.91 mg g⁻¹). Cephalexin adsorption onto ZVNi@AC was most effective at pH 4.5 and 40 °C, where more than 95% of cephalexin was removed within 36 min. Thermodynamic analysis revealed the adsorption process to be spontaneous (negative ΔG°) and endothermic (positive ΔH°). The excellent removal efficiency, reaching up to 92%, of ZVNi@AC for five cycles demonstrated the potential application of this adsorbent for antibiotic removal from wastewater.