Adsorption and Competitive Adsorption on Zeolites of Nitrophenol Compounds Present in Wastewater

This work investigates the removal of various nitrophenolic compounds (ortho-nitrophenol (ONP), paranitrophenol (PNP), meta-nitrophenol (MNP), and 2,4-dinitrophenol (2,4-DNP)) from aqueous solution using hydrophobic FAU zeolites. The adsorption equilibrium of nitrophenols from aqueous solutions by FAU can be well-described using the Fowler-Guggenheim equation. The relative affinity of nitrophenols toward the FAU is dependent on the pH solution and on the pollutant solubility in water. Their sorption capacity is in the following order: ONP > 2.4-DNP > PNP > MNP. In binary mixtures, the most important parameter that governs the adsorption in zeolites seems to be the solubility of pollutants in water. Thus, the less-soluble compound (in this case, ONP) was adsorbed more easily than the other components present in the binary mixture. Finally, hydrophobic FAU zeolite seems to be an efficient adsorbent; it is able to be easily regenerated under air or by solvent leaching, through retention of these initial adsorption properties.