Adsorption of Tetracycline on Simulated Suspended Particles in Water

Abstract

The mechanism of adsorption of a typical antibiotic (tetracycline, TC) on particles in the aquatic environment and the parameters affecting adsorption were investigated. Experiments were conducted to elucidate the effects of pH and various cation species with different concentrations. The results show that the adsorption of TC on particles is rapid during the first four hours in the mixing stage. The adsorption process becomes slow after the first four hours. The adsorption of TC on particles can be described well by a Langmuir equation. The maximum adsorption of TC on particles occurs at pH 4.5, however it is reduced by strongly acidic (pH<4) or alkaline (pH>9) conditions. Moreover, the adsorption process is also inhibited by various cations (e.g. Na+ and Ca2+) in the range of 0.0001-0.1 mol·L-1 ionic concentrations. A special finding concerns Al3+ ions; at a low concentration of these ions (0-0.0001 mol·L-1) the adsorption of TC on particles improves, whereas at increased concentrations the adsorption is weakened. In summary, an effective removal of the particles is critical to control TC pollution in natural waters because of the rapid adsorption of TC on particles.