Uncovering potentials of integrated TiO2(B) nanosheets and H2O2 for removal of tetracycline from aqueous solution

This study investigates the impacts of hydrogen peroxide (H2O2) addition on the removal of tetracycline (TC) from aqueous solution by TiO2(B) nanosheets (NSs) and compares the changes of its characteristics due to adsorption treatment. The morphology and textural properties of the TiO2(B) NSs structure before and after the treatment were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Effects of pertinent parameters such as dose of TiO2(B) and/or H2O2 concentration, initial adsorbate concentration, pH, and temperature on the TC adsorption by TiO2(B) NSs were examined. The adsorption mechanisms of TC by the integrated treatment of TiO2(B) NSs and H2O2 are also presented. The results demonstrated that the integrated treatment of TiO2(B)-H2O2 system had significantly improved the TC removal by 250% (with its adsorption capacity (q(max)) of 212.77 mg g(-1)), as compared to that of the TiO2-H2O2 system (paired t-test; p <= 0.05) under the same optimum conditions (2 g L-1 of TiO2(B) NSs; 20 mM of H2O2; 0.1 g L-1 of initial TC concentration). The enhanced TC adsorption by the integrated TiO2(B)-H(2)O(2)system not only is due to the H-bonding between the TC molecules and the-OOH groups formed on TiO2(B) surface, but it is also because of electrostatic interactions. Their adsorption isotherms followed the Elovich model and were also applicable to both the Langmuir and the Freundlich models. In spite of the adsorbent's promising performance, its treated effluents still could not meet the required TC effluent limit of <62.5 mu g L-1. This suggests that further subsequent treatment like biological processes is still necessary to completely remove the target pollutant from the wastewater samples. (C) 2017 Elsevier B.V. All rights reserved.