Novel chitosan coated oil palm trunk fibers synthesized using ionic liquid for malachite green removal

More than eight thousand chemicals, including hazardous dyes affecting human health and aquatic ecosystems, are discharged into the environment by various industries. A novel chitosan-coated oil palm trunk fiber (CSOPT) composite was synthesized using a mixture of imidazolium-based ionic liquid and acetic acid (as solvents) and applied to remove hazardous malachite green (MG) dye from the water-based solutions under batch mode. The CSOPT properties have been examined using spectroscopy and quantitative approaches. The biosorption of MG onto CSOPT was evaluated under several experimental settings. The data indicate that the synthesized CSOPT adsorbent exhibited a stream-like surface and a semicrystalline structure, characterized by a reduced specific area and pore diameter attributed to the presence of chitosan (CS) molecules on the raw oil palm trunk fibers (OPT). Biosorption studies showed that the maximal biosorption capacity of CSOPT towards MG was 1025 mg/g at a contact duration of 20 min, solution pH of 8, and CSOPT weight of 0.01 g. The higher biosorption capacity of CSOPT was attributed to the presence of OPT particles in its structure. The kinetics results of MG biosorption showed that it followed the PSO kinetic model through high values of correlation constants (R²) and small chi-square (χ²) values. The MG biosorption isotherm onto the CSOPT surface exhibited a multilayer stepwise pattern, denoting type L4 isotherm. Desorption of MG using 0.10 M HCl was only 0.78 %, indicating the presence of strong electrostatic attractions, as well as other molecular interactions such as H-bonding, Yoshida H-bonding, n-π, and π-π stacking. These results suggest that CSOPT offers a practical and alternative solution for removing MG from wastewater.