Tetracycline adsorption via dye-attached polymeric microbeads

In this study, the adsorption of tetracycline (TC) onto polymeric microbeads was investigated. For this purpose, suspension polymerization was used to synthesize poly(2-hydroxyethyl methacrylate) [poly(HEMA)] microbeads. Cibacron Blue F3GA (CB) was covalently attached to poly(HEMA) microbeads and the microbeads were tested as an adsorbent for subsequent TC adsorption. The effects of various parameters, such as pH value, initial TC concentration, temperature, and contact time, were investigated. The maximum adsorption capacity (Q) of microbeads was found to be 9.63 mg g-1 at pH 7.0. The results showed that the adsorption process was fast and occurred spontaneously within the first 5 minute. The adsorption process was fitted to the Freundlich isotherm model. The thermodynamic parameters of the adsorption, the enthalpy (∆H°) and entropy (∆S°), were calculated as 69.26 kJ mol-1 and 0.290 kJ mol-1 K-1, respectively. The Gibbs free energy (∆G°) was also calculated in the range of -11.069 kJ mol-1 to -17.159 kJ mol-1 with increase in temperature from 277 K to 298 K indicating that the TC adsorption process was spontaneous and endothermic. The results revealed that the poly(HEMA) microbeads could be effectively used to adsorption of TC from aqueous solution.