Solid Complex of Hydrogen Peroxide as a Safe and Green Oxidant for Polysaccharide Modification

Nowadays the bioresources including plant polysaccharides stay in focus of many researches according to ecological politics as well as oil reserves depleting. The well-known polysaccharide modification methods very often suffer from toxic by-products or difficult processing. In order to solve the problem a new method for corn starch oxidation is presented. The process allows oxidizing the hydroxyl groups of anhydroglucose units of amylose and amylopectin (starch) by means of urea- hydrogen peroxide (UHP) action. Oxidation reaction was carried out without pasting the starch, so the granular structure was not destroyed. In a product –CHO as well as –COOH group content was established. The degradation of polysaccharide chains was investigated using gel permeation chromatography. Finally the topology of granule surface before and after modification was observed using SEM microscopy. The rate of oxidant consumption and efficiency of oxidation was monitored by permanganate titration. All the reaction was compared to process that employed hydrogen peroxide water solution. As a result a series of new starch modification products were obtained. The degree of modification (oxidation) was similar to those obtained using hydrogen peroxide. On the other hand the consumption of oxidant is slower what allows the full controlling of the process. Additionally the lower degradation of starch components (amylose and amylopectin) was detected and the surface of the starch granules is less destroyed. In fact the important advantage of the UHP process is also the safe and easy set-up when solid but green oxidant is replacing relatively unstable liquid solutions of H₂O₂. The application of UHP for starch oxidation opens a new path for safe and green renewable material processing for industrial application.