Waste bamboo-derived magnetically separable bamboo-activated carbon: from characterization to effective remediation of fluoride (F−) ions from water

Abstract

An effective and affordable nanoadsorbent, magnetically separable magnetite-activated bamboo carbon (MABC), was obtained from waste bamboo biomass via pyrolysis of bamboo chunks and the co-precipitation method using ferrous and ferric chloride as iron precursors. The synthesized nanosorbents were characterised using XRD, SEM, and DLS techniques to study the surface characteristics and morphology. Chemical composition, optical absorption, and magnetic properties were studied using FTIR spectroscopy, UV-vis spectroscopy, and VSM, respectively. The BET surface area, porosity and surface charge were determined using N₂ adsorption–desorption isotherm and zeta potential technique. The cytotoxicity and antimicrobial properties of BC, ABC and MABC were investigated against prokaryotes and eukaryotes. The result demonstrates the nontoxic nature of BC, ABC and MABC, indicating their significant potential for addressing water treatment using sustainable and eco-friendly nanosorbents. Comparative fluoride ion removal studies were performed using ABC and MABC NPs. About 99.6% of F⁻ ions were adsorbed using MABC and 75.9% were adsorbed using ABC. Thus, MABC NPs were used as sorbents for the rest of the fluoride ion adsorption parameters. The batch fluoride ion sorption was performed at various sorption parameters, such as diverse solution pH (1.0–8.0), temperature (25–45 °C), agitation times (10–60 min), and adsorbent dose (0.01–0.04 g L⁻¹). The pseudo-second-order kinetic model exhibited the best fit with F⁻ ion adsorption (95.96 mg g⁻¹) compared with the pseudo-first-order model (12.30 mg g⁻¹), thereby indicating chemisorption adsorption. The exhausted MABC was recovered from the aqueous solution using a bar magnet. Regeneration studies of exhausted MABC were successfully performed using NaOH (0.1 M) as a desorbing agent.