ADSORPTION OF Cr (VI) AND Co (II) BY PALYGORSKITE MODIFIED WITH CATIONIC SURFACTANTS

• Main Author: N. V. Zhdanyuk
• Format: Article
• Language: English
• Published: Odessa I. I. Mechnikov National University 2017-09-01
• Series: Vìsnik Odesʹkogo Nacìonalʹnogo Unìversitetu: Hìmìâ
• Subjects: палигорськіт, адсорбція, хром, кобальт, поверхнево-активні речовини
• Online Access: http://heraldchem.onu.edu.ua/article/view/109391
• ISSN: 2304-0947; 2414-5963

The effect of cationic surfactants with different lengths of alkyl radical on the flocculation of suspensions of palygorskite as well as the adsorption properties of synthesized composites has been tested. Palygorskite of the Cherkassy (Ukraine), having cationic exchange capacity (CEC) of 0.25 mmol / g was chosen as an object of the study. For modification of palygorskite surface the following surfactants (S) have been used: hexadecyltrimethylammonium bromide, alkylbenzyldimethylammonium chloridе, dodecyltrimethylammonium bromide, tetramethylammonium chloride. The pattern of changing the structure of palygorskite dispersions modified by cationic surfactants with alkyl chains of different length has been experimentally proven. The maximum flocculation of the systems has been observed at the modification of palygorskite with surfactant/ cation exchange capacity ratio (S / CEC) = 1. With increasing of S / CEC the surface gradually becomes hydrophilic. However, only one from tested surfactants: hexadecyltrimethylammonium bromide can provide the highest ability to change the surface of the mineral. For alkylbenzyldimethylammonium chloride and dodecyltrimethylamonium bromide only partial change of surface hydrophobicity has been observed. Regarding the use of tetramethylammonium chloride for synthesis of organo-palygorskite, it could be argued that the introduction of surfactants with short length radical in the modification of sorbents has little effect on flocculation of the suspension. More probably the addition of such surfactant stabilizes the dispersions. It has been experimentally proven that the maximum values of sorption of Cr (VI) are observed at palygorskite modified with long chain cationic surfactants, whereas Co (II) has been better extracted with natural palygorskite. The use of hexadecyltrimethylammonium bromide as the modifier of phyllosilicates at surfactant/cation exchange capacity ratio (S/CEC) = 0,75 and more is justified. The obtained results confirmed the possibility of using organo-palygorskite to extract anionic form of heavy metals.