Application of organo-beidellites for the adsorption of atrazine: Fid-Bau Portal

Application of organo-beidellites for the adsorption of atrazine

Grundgeiger, Emily / Lim, Yet Hong / Frost, Ray L. / Ayoko, Godwin A. / Xi, Yunfei

Abstract The surfaces of natural beidellite were modified with cationic surfactant octadecyl trimethylammonium bromide at different concentrations. The organo-beidellite adsorbent materials were then used for the removal of atrazine with the goal of investigating the mechanism for the adsorption of organic triazine herbicide from contaminated water. Changes on the surfaces and structure of beidellite were characterised by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and BET surface analysis. Kinetics of the adsorption studies were also carried out which show that the adsorption capacity of the organoclays increases with increasing surfactant concentration up until 1.0 CEC surfactant loading, after which the adsorption capacity greatly decreases. TG analysis reveals that although the 2.0 CEC sample has the greatest percentage of surfactant by mass, most of it is present on external sites. The 0.5 CEC sample has the highest proportion of surfactant exchanged into the internal active sites and the 1.0 CEC sample accounts for the highest adsorption capacity. The goodness of fit of the pseudo-second order kinetic confirms that chemical adsorption, rather than physical adsorption, controls the adsorption rate of atrazine.

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Highlights • Natural beidellite based adsorbents were synthesized. • The prepared adsorbents were characterized by XRD, FTIR, SEM, BET and TG. • The optimized removal parameters for atrazine in waterwere obtained. • Due to the pore-blocking effect, 2.0CEC-OBd removed less atrazine than 0.5CEC and 1.0CEC-OBd. • The prepared adsorbents showed potential prospects in environmental remediation.