Production of Carboxymethyl Starches from Oxidized Starches and Determination of Their Tanning Characteristics

Hydrogen peroxide and sodium metaperiodate oxidation of starch and their possible utilization in tanning/retanning were examined in our previous studies. In the present part, accordingly with our previous findings, hydrogen peroxide and sodium metaperiodate oxidation products having appropriate molecular weight/size were selected and additionally carboxymethylated. The yields of the processes (carboxymethyl starches) were characterized comprehensively and the effect of carboxymethylation process on structures and tanning abilities were tried to be identified. The characterization results revealed that the carboxymethyl groups were successfully included into the structure and the water solubility of oxidized starches (especially periodate oxidized ones) increased by carboxymethylation process. From the evaluation of the tanning results and considering its properties i.e. gentle tanning effect with less astringency and correspondingly a relatively soft leather handle and smooth grain, it is concluded that dialdehyde carboxymethyl starch (CMS 1:0.7) can be utilized as yet another good alternative sustainable green tanning/retanning agent from starch.