Adsorption–desorption of tetracycline onto molecularly imprinted polymer: isotherm, kinetics, and thermodynamics studies

Molecularly imprinted polymer (MIP) was obtained by the bulk polymerization method. The MIP was characterized by different spectroscopic techniques like a TGA, SEM, and N2 adsorption– desorption and pHPZC. The adsorption of tetracycline (TC) onto MIP from solution was studied, in which the influence of pH, initial TC concentration, MIP mass, temperature, and contact time were investigated. The surface area of MIP was 172.9 m2/g the highest removal efficiency was obtained at a pH of 5, MIP dose of 0.6 g/L, TC concentration of 25 mg/L, the temperature of 50°C, and reaction time of 60 min°C. The adsorption kinetic was explored and best represented by the pseudo-second-order kinetic model and the adsorption isotherm experimental data had the best fitness with the Langmuir model, suggesting that homogeneous uptake was the principal mechanism adopted in the process of TC adsorption. The maximum adsorption capacity based on the Langmuir model was 416.5, 476.2, 588.3, and 666.5 mg/g at temperatures of 20°C, 30°C, 40°C, and 50°C, respectively. The thermodynamics of the adsorption indicated the endothermic and spontaneous nature of the process. The usability after six cycles was approved so that the adsorption capacities were associated with insignificant reduction (from 153.4 (92.04%) to 140.6 mg/g (84.38)) after the employed cycles.