Nanocellulose/bentonite composite: a novel material for heavy metal removal from aqueous solutions

Creating novel materials that improve the effectiveness of the water treatment system is crucial to addressing the increasing contamination of water sources by pollutants. The husks of a rice variety known as Bao Dhan were used to prepare a nanocellulose/bentonite (RNC-BENT) composite material that was used as an adsorbent for the removal of Ni (II) and Cr (VI) from aqueous solutions. The novelty of this study lies in the valorization of agricultural waste into a hybrid nanocellulose-bentonite composite with superior adsorption performance compared to many conventional materials. The adsorbent was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The effect of pH, contact time and initial adsorbate concentration were also studied. Pseudo-second-order kinetics for the adsorption validate chemisorption. The Freundlich adsorption model explained the metal ion adsorption behavior, with Ni (II) and Cr (VI) having maximal adsorption capacities of 22.46 mmol/g and 19.71 mmol/g, respectively. The desorption efficiency of the adsorbent was determined using 0.01 M HNO3. For both heavy metals, minimal reduction in adsorption capacity was observed after four regeneration cycles.