THE INFLUENCE OF HUMIC ACID COLLOID ON ADSORPTION BEHAVIORS OF ACETAMINOPHEN ONTO SEDIMENT

Oscillating balance method was employed to study the adsorption behavior of Acetaminophen (APAP) onto sediment and its kinetic and thermodynamic properties with the presence of Humic Acid Colloid (HA). The results showed that the equilibrium time of the APAP adsorption onto sediment with the existence of HA was 12 h, while it was 24 h without HA, which indicated that adding HA can accelerate the APAP adsorption onto sediment. The adsorption kinetics were found to follow the pseudo-first-order kinetics model. Langmuir and Freundlich model can preferably describe the isothermal adsorption process of APAP onto sediment under different concentrations of HA. But Langmuir model fitted better, and four kinds of error function values were smaller. Thermodynamics results showed that the APAP adsorption onto sediment was spontaneous, endothermic and entropy-increasing. The value of Delta G degrees of adsorption process remained negative with HA, but the absolute value increased, indicating that it tended to chemisorptions. With the presence of HA, the change of pH impacted on APAP adsorption onto sediment sharply. The adsorption quantity of APAP onto sediment was larger when pH was 6.0-9.0, while decreased at PH < 6.0 or PH > 9.0. This could be caused by Van Der Waals Force and electrostatic adsorption.