Patent ID: 8097165

Claim:
A method for eliminating natural organic substances/contaminants from a liquid medium, the method comprising treating the liquid medium with an insoluble, cationic or cationizable starch, thus sorbing such organic substances/contaminants onto such starch, and then ridding the same from the liquid medium thus purified, wherein the cationic or cationizable functional groups are introduced into the starch via free-radical polymerization comprising the grafting of monomers containing at least one cationic or cationizable group onto the starch, and, wherein the monomers comprising at least one cationic or cationizable functional group employed to perform such free-radical polymerization are selected from the group of compounds consisting of formulae (I), (II), (III) and (IV) below: a compound of general formula (I): in which: A n⊖ represents a Cl ⊖ , Br ⊖ , I ⊖ , SO 4 2⊖ , CO 3 2⊖ , CH 3 —OSO 3 ⊖ , OH ⊖ or CH 3 —CH 2 —OSO 3 ⊖ ion, R 1 to R 5 , which may be identical or different, are each an alkyl radical having from 1 to 20 carbon atoms, a benzyl radical or an H atom, and n is 1 or 2, or a compound of general formula (II): in which: X represents an —NH group or an oxygen atom O, R 4 represents a hydrogen atom or an alkyl radical having from 1 to 20 carbon atoms, R 5 represents an alkylene radical having from 1 to 20 carbon atoms, R 1 , R 2 and R 3 , which may be identical or different, are each an alkyl radical having from 1 to 20 carbon atoms, B N⊖ represents a Cl ⊖ , Br ⊖ , I ⊖ , SO 4 2⊖ , CO 3 2⊖ , CH 3 —OSO 3 ⊖ , OH ⊖ or CH 3 —CH 2 —OSO 3 ⊖ ion, and n is 1 or 2, or a compound of general formula (III): in which: R 1 to R 6 , which may be identical or different, are each a hydrogen atom or an alkyl radical having from 1 to 20 carbon atoms, with the proviso that one of the groups R 1 to R 6 is a —CH═CH 2 radical, C N⊖ represents a Cl ⊖ , Br ⊖ , I ⊖ , SO 4 2⊖ , CO 3 2⊖ , CH 3 —OSO 3 ⊖ , OH ⊖ or CH 3 —CH 2 —OSO 3 ⊖ ion, and n is 1 or 2, and a compound of general formula (IV): in which: D n⊖ represents a Cl ⊖ , Br ⊖ , I ⊖ , SO 4 2⊖ , CO 3 2⊖ , CH 3 —OSO 3 ⊖ , OH ⊖ or CH 3 —CH 2 —OSO 3 ⊖ ion, and n is 1 or 2.