Kinetic and thermodynamic analysis of adsorption of naproxen by activated sludge

Abstract

Naproxen, a new environmental drug pollutant, shows “false persistence” in the environment and causes certain risks to human health and ecological environment, which has attracted extensive attention. The activated sludge in the sewage treatment technology plays a significant role in the control of the naproxen content. This paper carried out the kinetics and thermodynamic analysis of the adsorption process of naproxen by activated sludge. The experimental results show that the adsorption process of naproxen by activated sludge conforms to the pseudo-second-order kinetic equation and the linear fitting R2 value is more than 0.99 at different initial concentrations. The Freundlich equation and Langmuir equation were adopted to carry out the adsorption models fitting. The Freundlich equation could represent the adsorption results satisfyingly. There is a negative correlation between the initial concentration of naproxen and the adsorption rate. The adsorption effect is determined by the hydrophobicity of naproxen and the electrostatic reaction between naproxen and activated sludge. After adsorption, there is no obvious naproxen desorption in activated sludge.