Abstract:

In order to obtain starch-based adsorbent with good adsorption capacity for methylene blue (MB) dye, cross-linked amino starch (ACSt) was prepared from corn starch as raw material by three steps of esterification, crosslinking and ammonolysis.  The products were characterized by Fourier transform infrared spectroscopy, X ray diffraction and scanning electron microscopy. It was found that amino groups are introduced into the starch molecules, indicating ACSt is successfully synthesized. The crystallinity is reduced and the compact structure of particles is destroyed. The adsorption properties of ACSt on MB were investigated. The results show that in alkaline environment, ACSt shows good adsorption properties to MB. The adsorption behavior of ACSt on MB conforms to the pseudo second order kinetic plot and Langmuir isothermal adsorption model, indicating that chemisorption is the decisive step in the whole adsorption process and the adsorption process is mainly monolayer adsorption, respectively. Thermodynamics studies show that the adsorption is an exothermic, spontaneous and entropy reduction.

Key words: cross-linked amino starch, methylene blue, printing and dyeing wastewater, adsorption property