Efficacy of magnetic APTES-modified hydrochar for remediation of Cr(VI) from water-base solutions

Overview & Synopsis

This study investigates an innovative approach for chromium removal using a novel adsorbent synthesized from macadamia nutshell biomass. Hydrochar derived from macadamia nuts was functionalized with magnetite (Fe₃O₄) nanoparticles and further grafted with 3-aminopropyltriethoxysilane (APTES) to enhance its adsorption capacity. Characterization was conducted using techniques such as FTIR, XRD, and XPS to confirm the functional groups on the adsorbent. The batch adsorption experiments showed that the material was highly efficient in removing Cr(VI) under different pH, contact time, adsorbent dosage, and initial chromium concentration conditions. The results showed that APTES-modified hydrochar had a higher chromium adsorption capacity than unmodified hydrochar, reaching 420.8 mg/g as the highest adsorption capacity at pH 2. The kinetic adsorption data fitted best in a rate model of pseudo-second order. This study shows that APTES-modified hydrochar has the potential to be used as a sustainable and cost-effective adsorbent for chromium remediation in aqueous solutions. Graphical abstract