OBTAINING NEW FLOCCULANTS BASED ON HIGH-SUBSTITUTED CATIONIC STARCHES

Abstract

In this work synthesis of the high-substituted cationic starches by reaction of starches of different botanical origin with 3-chloro-2-hydroxypropyltrimetylammonium chloride in the presence of the alkaline catalyst was carried out by semi-dry way. The assessment of their flocculating properties on the model systems of kaolinic dispersions was carried out. It was established that the efficiency of a starch cationization substantially depends on its nature. This is due to various initial supermlecular structure and morphology of starch granules. The largest rate and degree of a cationization was characteristic for potato starch, and the least – for corn. The offered heterogeneous method of synthesis allows to receive the high-substituted cationic starches with preservation their granular and minimum changes in supramolecular structure. At achievement of particular extent of high-substituted (DScat> 0.1) cationic starches form the transparent colloid dispersions in cold water. Cationization of starches to higher DScat. demands increase in a consumption of cationic reagent and the catalyst. Formation of cationic bonds in starch was confirmed with results of element and IR-spectroscopical analyses. When carrying out a cationization of starch in an alkaline condition there can be changes of the supramolecular structure of a polysaccharide depending on a temperature and type of starch. Unessential decrease in a degree of crystallinity of all types of starches after their cationization at ambient temperature was demonstrated by the diffractograms received in work. Despite slight amorphicity of starch after their cationization it should be noted that all cationic starches having DScat> 0.1, easily disperse in cold water with formation of the homogeneous transparent pastes. The kinetics and efficiency of a flocculation of model kaolinic suspensions with synthesized cationic starches was investigated. Kaolinic suspensions for lack of flocculant are rather stable for a long time. Introduction to the system of cationic starch leads to fast destabilization of kaolinic dispersions. At the same time for all cationic starches with increase in a dose in the range of 0.5 – 7.5 mg/g(kaolin) the flocculation rate of particles of kaolin dispersions increases. The most efficiently a flocculation of dispersions of kaolin happens to the largest rate in the presence of cationic potato starch. It was established that the efficiency of a flocculation of mineral kaolinic systems is defined not only by a molecular mass of polymer, but also the sizes of non-draining chains which in the strong degree depend on a charge of microions and a rigidity of a polymeric chain. It was shown that the synthesized flocculants are not inferior in efficiency to the polyacrylamide derivants which are applied now.Forcitation:Butrim S.M., Bildyukevich T.D., Butrim N.S., Yurkshtovich T.L., Kaputskiy F.N. Obtaining new flocculants based on high-substituted cationic starches. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 89-95