Development of lignin based multifunctional hybrid materials for Cu(II) and Cd(II) removal from the aqueous system

In the paper the synthesis and comprehensive physicochemical characterization of a new group of adsorbents containing inorganic oxides and functional biopolymers from the lignocellulose group o such as TiO2/lignin, TiO2-SiO2/lignin and MgO-SiO2/lignin are presented. The obtained materials were evaluated taking into account their physicochemical properties and utility as sorbents towards Cu(II) and Cd(II) ions. Among others, surface activity, porous structure, particle size distribution, SEM images, adsorptive properties (BET isotherms) and electrokinetic properties (zeta potential and electrophoretic mobility) as well as effectiveness of the surface functionalization by the FT-IR method were determined. In addition, the optimum conditions for the adsorption process, its theoretical description and determination of interactions at the adsorbent-adsorbate interface were also included. The kinetic, adsorption and thermodynamic parameters were calculated using the common models. The adsorption and the kinetic data were well described using the Langmuir and pseudo-second order models. The results showed the affinity is greater in the case of Cd(II) and next Cu(II). The metal ion adsorption is a heterogeneous, endothermic and spontaneous reaction on the hybrid material surface.