Sorption of benzene derivatives onto insolubilized humic acids

New environmental friendly sorption materials were synthesized and studied to remove organic contaminants in wastewater purification. Humic acids extracted from green-waste compost (HA(comp)) and from leonardite (HA(leo)) were chemically characterized by infrared spectroscopy, carbon nitrogen and hydrogen analysis, ash content, hydrophobicity tests, and molecular weight distribution. Humic acids were thermally immobilized at 330 A degrees C for 1.5 h and their sorbent properties towards of some benzene derivatives (toluene, o-xylene, phenol, and benzyl alcohol) with the batch equilibrium method were studied. HA(comp) was found to be less rich in aromatic rings and more hydrophobic than HA(leo). The maximum amount of sorbate bound at the equilibrium was consistently higher for the immobilized HA from compost than from leonardite and increased with the n-octanol/water partition coefficient of the adsorbate. The data point to hydrophobic interactions as the main force involved in the sorption of the compounds tested. The results showed that these materials can have potential applications in wastewater purification.