Adsorption of polynuclear aromatic hydrocarbons from aqueous solution: Agrowaste-modified kaolinite vs surfactant modified bentonite

Abstract

. The adsorption efficiency of a new hybrid clay adsorbent for polynuclear aromatic hydrocarbons (PAHs) is compared with known modified clay adsorbents. The new hybrid clay adsorbent (HYCA) showed far higher adsorption capacities for the adsorption of various PAH molecules compared with sodium dodecyl sulfate modified and humic acid modified Bentonite clay adsorbents. With the new hybrid clay adsorbent (HYCA), the adsorption of some of the larger PAH molecules was complete in the first 1 h as compared with ≈ 62% and ≈ 76% observed for both humic acid modified and sodium dodecyl sulfate modified Bentonite clay adsorbents respectively. In 24 h adsorption of the PAHs was complete for all adsorbents with HYCA adsorbent showing better efficiency in the removal of the PAH molecules from aqueous solutions. No significant change was observed with increase in time up to 48 h. The adsorption was observed to be more spontaneous with HYCA adsorbent than with either modified Bentonite adsorbents. The enthalpy of adsorption did not follow any specific order and were not consistent for all PAH molecules considered.

KEY WORDS: Adsorption, Polynuclear aromatic hydrocarbons, Enthalpy, Hybrid clay, Bentonite

Bull. Chem. Soc. Ethiop. 2016, 30(3), 369-376

DOI: http://dx.doi.org/10.4314/bcse.v30i3.5