A bowl-shaped biosorbent derived from sugarcane bagasse lignin for cadmium ion adsorption

Lignocellulosic materials have received wide interest in adsorption of contaminants in water due to their abundance, eco-friendliness, and low cost. However, the development of new adsorbents from lignocellulose with excellent performance is still a big challenge. In this work, a new bowl-shaped biosorbent (BSB) with surface functionality is prepared from lignin that is extracted from the abundant sugarcane bagasse. The product is characterized by scanning electron microscopy, infrared spectrum, thermo gravimetric analysis and N-2 adsorption techniques. The results show that the obtained BSB is obviously bowl-shaped in microscale with an enlarged surface area, and contains numerous oxygen and nitrogen functional groups. It exhibits an enhanced adsorption capacity toward Cd2+ that is 3.2 times of the original lignin. The adsorption process of Cd2+ by the BSB is well fitted by the Freundlich isothermal model and the pseudo-second-order kinetic model, respectively. The adsorption mechanism involves surface complexation, ion-exchange, electrostatic attraction, chemical precipitation and physical adsorption, etc., among them, the surface complexation is the rate-controlling step. Moreover, it shows a good reusability during five repeated cycling for Cd2+ adsorption. [GRAPHICS] .