Preparation and characterization of dialdehyde starch urea (DASU) and, it`s sorption potential for Co(ii), Pb(ii) and Zn(ii) ions from aqueous solution
Dialdehyde starch urea (DASU) was prepared by the reaction of dialdehyde starch (DAS) from periodate oxidized cassava starch with urea, which was then used to adsorb Co(II), Pb(II) and Zn(II) ions from aqueous solution. Starch modified starches and starch complexes were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) to determine the structure and morphology respectively. The percentages of aldehyde contents of the three kinds of DAS, designated as DAS1, DAS2 and DAS3 were 45.2%, 61.2% and 86.94% respectively. The results indicated that the higher the concentration of periodates, the higher the percentage of aldehyde content in DAS. DAS1 with the content of the aldehyde groups of 45.2% had an average molecular weight of 85,853, while the average molecular weight of DAS2 with the content of the aldehyde groups of 61.2% was 15,466. When the content of aldehyde groups increased to 86.94%, the average molecular weight of DAS3 was fund to decrease to 13,182. The Degree of substitution (DS) of urea was 0.67and DS significantly increase with the increase in percentages of nitrogen content in the polymer adsorbent. Adsorption capacity for Co(II), Pb(II) and Zn(II) ions were found to be 16.01mg/g, 21.73mg/g and 7.18mg/g respectively.
Keywords: Starch Polymer, Dialdehyde starch, Dialdehyde Starch Urea, Chelating resin