In situ loading metal oxide particles on bio-chars: Reusable materials for efficient removal of methylene blue from wastewater

Dyeing wastewater produced from textile industry has attracted considerable attention due to its pollution on environment. In this study, bio-char (BC), TiO2/bio-char (BC-T), TiO2/MgO/ZnO/bio-char composites (BC-TMZ) were prepared and utilized to remove methylene blue (MB). The surface morphology and composition of BC, BC-T and BC-TMZ were described by XRD, EDS, SEM, BET and TEM. Furthermore, the synergistic removal effects of as-prepared materials in MB solutions were explored under different bio-char dosage, initial MB concentration, reaction time and different light irradiation conditions. Finally, the residual MB solutions after treatment are characterized by LC-MS. The results indicated that the metal oxide particles (Fe2O3, ZnO, MgO and TiO2) have been loaded into pores of the BC-TMZ. Moreover, the BC-TMZ which act as both adsorbent and catalytic, possesses excellent reusability (reused for 4 times) to remove MB from solution. The adsorption behaviors of BC-TMZ were described by Pseudo-second order model and Langmuir model well. The maximum adsorption-catalytic capability of BC-TMZ (0.8 g/L) for MB (50 mg/L) was 62.5 mg/g with UV light irradiation (253.7 nm, 40W) in 4 h. The MB molecules can be decomposed completely by BC-TMZ. The BC-TMZ is potential to be used as a reusable material for the removal of pollutants. (C) 2019 Elsevier Ltd. All rights reserved.