In order to synthesis more efficient adsorbant of heavy metal ions, the condensation reaction of chitosan (CS) with salicylaldehyde (SD) to form Schiff base(SB) in ethanol using a ultrasonic liquid processor was studied and was contrasted with conventional method. The IR spectra of condensed chitosan from the two methods showed that their molecular structures were identical. The reaction conditions such as the kind of solvents, power density and irradiation time of ultrasonic, the pH condition and the reactant ratio were optimized using an orthogonal design. It was found that a shorter reaction time and a higher product yield could be got for the ultrasonic-assisted synthesis than that of traditional method. A condensation degree of 89.63% could be achieved under the optimization conditions: using 180 kW ultrasonic, taking 95% ethanol as solvent, at pH 4.0, with the SD/CS ratio of 6:1, ultrasonic irradiating for 60 min. The adsorption of Cr (VI) ions onto chitosan and its condensation with salicylaldehyde was investigated in magnetic field. Batch adsorption experiments were carried out as a function of magnetic power and reacted time. The results showed that, magnetic field strengthen the adsorption capacity, especial for Schiff bases.
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