Analytical and isothermal studies of equilibrium sorption of Cr (VI)‎ and p-nitrophenol onto organokaolin

الملخص EN

Removal of toxic heavy metals and organic pollutants from contaminated water is of great interest in the field of water handling.

Organoclays have unique adsorption behavior towards hydrophobic organic contaminants.

Thus, the present study focus on separation of Cr(VI) from Cr(III) and p-nitrophenol (PNP) from the aqueous solutions using new organokaolin synthesized for the first time from local clay.

The method is based on using Iraqi’s kaolin in the presence of hexadecyltrimethyl ammonium bromide as surfactant.

Infrared spectroscopy and x-ray diffraction are employed to characterized innovated clay.

The optimum adsorption conditions for the removal of Cr(VI) and PNP were: mass of organokaolin, 0.5 g; pH, 1 & 11, Temp.

15 & 35 °C; contact time, 80 min for the removal of Cr(VI) and p-nitrophenol, respectively.

Under the optimum conditions, removal rate of 96%for the adsorption of Cr (VI) and PNP was achieved.

Higher value of r² refers to the goodness of fitting of Langmuir equation rather than Temkin and Freundliche equations for the sorption of Cr(VI) on the organokaolin.

From the calculated thermodynamic parameters, ∆G, ∆H and ∆S values, the adsorption process has been found endothermic in nature.

The developed method was applied successfully for the analysis of 15 water samples collected from areas of Baghdad.

Good recoveries were obtained ranging from 97.4-101.1% (RSD < 2.15%) and 97.8-100.1% (RSD= 1.8%) for Cr(VI) and PNP, respectively.