Sorption Behavior of 4-Chlorophenol from Aqueous Solutions By a Surfactant-modified Mexican Zeolitic Rock in Batch and Fixed Bed Systems

The removal of 4-chlorophenol from aqueous solutions by both a Mexican clinoptilolite-heulandite zeolitic rock and the modified zeolitic material with the surfactant hexadecyltrimethylammonium bromide (HDTMABr), using batch and packed-bed (column) configurations, was investigated. The unmodified zeolitic rock did not show any adsorption of 4-chlorophenol. The effects of pH, contact time and concentration of 4-chlorophenol on the adsorption process by the surfactant modified material were examined. The sorption of 4-chlorophenol was not affected by the pH range from 4 to 9.5. 4-chlorophenol retention reached equilibrium in about 18 h and the rate of 4-chorophenol adsorption by the modified material was faster in the first 10 h than later. The experimental data were treated with the models: pseudo-first order, pseudo-second order, fractional power and Elovich models. Although, the last three gave correlation coefficients higher than 0.96, the pseudo-second order model was the best to describe the reaction rate. The experimental data follow a linear isotherm which is characteristic for sorption of organic solutes by the partition mechanism. The Bed Depth-Service Time Model was applied to the sorption results in order to model the column operation. The results showed that the surfactant modified zeolitic rock could be considered as a potential adsorbent for 4-chlorophenol removal from aqueous solutions.