Facile synthesis and adsorption characteristics of a hybrid composite based on ethyl acetoacetate modified chitosan/calcium alginate/TiO2 for efficient recovery of Ni(II) from aqueous solution

Abstract

Abstract In this study, chemical modification of chitosan has been carried out using epichlorohydrin as crosslinking agent and ethyl acetoacetate as a modifier to graft acetoacetyl moiety. The said organo-functionalization on chitosan and sodium alginate not only offered a novel support for TiO2 immobilization but also enhanced sorption performance for Ni(II) recovery from aqueous medium. So, a composite consisting of acetoacetyl moiety grafted chitosan, sodium alginate and titanium oxide (EAA-MCS/TiO2) was prepared and characterized by fourier transform-infra red (FT-IR) spectroscopy and scanning electron microscopy (SEM). The hybrid composite (3EAA-MCS/TiO2) which had TiO2 to EAA-MCS mass ratio of 20.0% by weight showed maximum sorption efficiency. The formulated sorbent was conditioned in the form of hydrogel beads for operation. Isothermal sorption and kinetics studies were performed at pH = 6.0 to configure the nature of sorption. Pseudo-2nd order rate expression better explained the sorption kinetics and chemisorption is the predominant mode of uptake. Langmuir adsorption model better explained the sorption process (R 2 ∼ 0.99) and maximum monolayer sorption capacity (q m ) at sorption/desorption dynamic equilibrium was computed as 403 mg/g at optimized pH.