Trimethylamine functionalized clay for highly efficient removal of diclofenac from contaminated water: Experiments and theoretical calculations

Abstract The importance of the adsorption process and growth demand for using of cost-effective methods has increased the use of low-cost inorganic sorbents. In this study, a batch system was used to remove diclofenac sodium (DF) using pumice modified with trimethylamine (TMAP). Analysis of FTIR, XRF, SEM and BET were used for determining the adsorbent properties. Adsorbent dosage (0.1-1.5 g/L), contact time (0-90 min), solution pH (3-11) and initial DF concentration (0-1000 mg/L), parameters affecting the adsorption process, were investigated. Results of the laboratory data fitted using six isotherm models and the obtained results of Temkin model (R2=0.9762) is better described how the equilibrium results changes. Also, Langmuir isotherm showed that the amount of maximum adsorption capacity at pH = 3, T= 25°C, DF concentration of 1000 mg/L and contact time of 90 min using adsorbent dosage 1.5 g/L was 387.25 mg/g. The pseudo-second-order kinetic model (R2=0.9997) showed better description of the experimental data. Finally, the results showed that modified pumice was able to remove diclofenac in aqueous solution as a low-cost adsorbent.