Use of functinalized adsorbents for tetracycline removal in wastewater: adsorption mechanism and comparison with activated carbon

The present study investigated the application of functinalized adsorbents in the removal of tetracycline in water by adsorption. Activated carbon was impregnated with iron chloride, copper sulfate and hydrogen peroxide, in order to improve its adsorption properties. The solids were characterized by adsorption/desorption isotherms N2, XRD, FTIR and SEM. The influence of pH, adsorbent concentration and contact time parameters was evaluated. The results using activated carbon as adsorbent and initial TC concentration of 20 mg.L−1 showed that 93% TC removal was achieved at pH 4.0, contact time of 120 minutes and 30 g.L−1 adsorbent concentration. Experiments applying the functionalized solids showed a faster initial adsorption kinetics. Also, no pH adjustment was required (pH 6.0). In addiction, a minimum of 50% reduction in adsorbent mass (15, 10 and 5 g.L−1 for CA–H2O2, CA–Fe and CA–Cu, respectively) was observed, compared to the untreated solid. The pseudo-second-order kinetic model was chosen as the optimal model for the study. The application of FeCl3, CuSO4 and H2O2 composites as adsorbent solids are technically feasible for the removal of tetracycline in wastewater treatment.