Regularities of adsorbtion of low-molecular analogues of humic acids onto natural kaolinite

About the author:

Arkadiy A. Kayugin, Cand. Sci. (Chemistry), Associate Professor, Department of Organic and Ecological Chemistry, Tyumen State University

Abstract:

The study concerns adsorption of ortho- and para-cresols, catechol, resorcinol, hydroquinone, benzoic, salicylic, p-hydroxybenzoic acids onto natural kaolinite depending on concentration and pH. The sorption experiment was conducted under static conditions at simultaneous presence of phenols or carboxylic acids in the solution at a constant ionic strength, with subsequent determination of the equilibrium concentration of substances by HPLC with a UV detector. We studied the dependence of the level of extraction of substances from the solution on the number and position of functional groups. The position of the hydroxyl groups on the benzol ring has a more pronounced effect on the sorption of organic molecules than their number. Hydroxyl groups showed greater affinity to the kaolinite surface than carboxyl groups. The pH-dependence of acids and phenols sorption is more pronounced at higher initial concentrations of the compounds. The obtained regularities may be extended to the sorption of natural organicsubstances, in particular humic substances onto clays.

References:

1. Wattel-Koekkoek, E. J. W., Buurman, P. Mean residence time of kaolinite and smectitebound organic matter in Mozambiquan soils. Soil Science Society of America Journal. 2004. Vol. 68. Pp. 154–161.

2. Xing, B. Sorption of naphthalene and phenanthrene by soil humic acids. Environmental Pollution. 2001. Vol. 111. Pp. 303-309.

3. Collins, M. J., Bishop, A. N., Farrimond, P. Sorption by mineral surfaces: rebirth of the classical condensation pathway for kerogen formation. Geochimica et Cosmochimica Acta. 1995. Vol. 59. Pp. 2387-2391.

4. Evanko, C. R., Dzombak, D. A. Influence of structural features on sorption of NOM-analogue organic acids to goethite. Environmental Science and Technology. 1998. Vol. 32. Pp. 2846-2855.

5. Horányi, G. specific adsorption of simple organic acids on metal(hydr)oxides: a radiotracer approach. Journal of Colloid and Interface Science. 2002. Vol. 254. Pp. 214-221.

6. Kang, S., Xing, B. Adsorption of dicarboxylic acids by clay min-erals as examined by in situ ATR-FTIR and ex Situ DRIFT. Langmuir. 2007. Vol. 23. Pp. 7024-7031.

7. Giannakopoulos, E. et al. Adsorption and radical stabilization of humic-acid analogues and Pb2+ on restricted phyllomorphous clay. Langmuir. 2006. Vol. 22. Pp. 6863-6873.

8. Serjeant, E. P., Dempsey, B. Ionization constants of organic acids in aqueous solution. Pergamon, Oxford. 1979. 989 p.

9. Juang, R.-Sh, Lin, S.-H., Tsao, K.-H. Mechanism of sorption of phenols from aqueous solutions onto surfactant-modified montmorillonite. Journal of Colloid and Interface Science. 2002. Vol. 254. Pp. 234-241.

10. Mousavi, S. M., Alemzadeh, I., Vossoughi, M. Use of modified bentonite for phenolic adsorption in treatment of olive oil mill wastewater. Iranian Journal of Science & Technology, Transaction B, Engineering. 2006. Vol. 30. № B5. Pp. 613-619.

11. Kayugin, A. A. Raspredelenie kadmiia v model’nykh sistemakh, soderzhashchikh kaolinit i guminovye kisloty [Distribution of Cadmium in Model Systems Containing Kaolinite and Humic Acid]: Diss. Cand. Sci. (chem.). Tyumen. 2009. 151 p. (in Russian).