Multipurpose Use of a Corncob Biomass for the Production of Polysaccharides and the Fabrication of a Biosorbent

Through fully exploiting waste biomasses as versatile matrices, value-added products and functional materials can be readily generated, which is of great significance to address many serious issues, especially environmental deterioration and waste of resources. Herein, a corncob biomass is selected as general platforms for achieving multipurpose applications, namely, the extraction of polysaccharides that can be used as health care products and the fabrication of a functional biosorbent for environmental remediation. The polysaccharide extraction from the corncob particles is systematically investigated to optimize the extraction conditions and hence to obtain a good yield. After extraction, the corncob particles are further chemically modified with phosphoric acid to produce a biosorbent which is subsequently used to deal with malachite green (MG) as a typical aquatic pollutant. The adsorption mechanism underlying the efficient removal of the MG contaminant is also unraveled through a study of the various factors influencing the adsorption efficiency, in addition to investigations of the adsorption kinetics, thermodynamics, and isothermal adsorption models. The modified corncob based adsorption is found to be a spontaneous and endothermic process and follows pseudo-second-order kinetics as well as a Freundlich adsorption isotherm. The modified corncob particles exhibit a favorable morphology, microstructure, and surface properties that facilitate their uptake of MG in comparison to their unmodified counterparts. Phosphate functionalities and additional carboxyl groups are effectively incorporated onto the modified corncob-bearing coarsened surface, pores, and cracks, improving the adsorption performance by means of ionic bonding and electrostatic interactions between these newly introduced ionizable groups and the cationic MG molecules.