Enhanced adsorption of lead (II) ions onto cellulose nanoparticles/chitosan composite based on loofah sponge: kinetic and thermodynamic studies

The purpose of this work is to study the efficiency of lead ions removal via adsorption onto created solid nanomaterials. Three solid adsorbents were synthesized as cellulose nanoparticles (CN) extracted from plant loofah sponge using alkali treatment and acid hydrolysis techniques, chitosan beads (CZ), and cellulose nanoparticles/chitosan beads composite (CZC). The generated solid adsorbents were investigated using TGA, N₂ adsorption/desorption, ATR-FTIR spectroscopy, SEM, TEM, XRD, and pH_PZC. Based on our findings, CZC had a pH_PZC of 7.2, a larger specific surface area (645.3 m²/g), and a total pore volume (0.372 cm³/g). The batch adsorption of lead ions was well-fitted by pseudo-second order, Elovich, Langmuir, Temkin, and Dubinin-Radushkevich on all the samples. Cellulose nanoparticles/chitosan composite had the highest Langmuir adsorption capacity (221.104 mg/g) at 47°C, 120 min as shaking time, 2 g/L as adsorbent dose, and pH 6.5. Nitric acid had the highest desorption percentage (92%). The thermodynamic investigation revealed that lead ion adsorption is endothermic, favorable, spontaneous, and physisorption. Our findings showed that CZC has a high adsorption capacity and rapid kinetics, indicating its potential for employment in water treatment.