Preparation and performance of FeCo bimetallic organic frameworks with super adsorption and excellent peroxymonosulfate activation for tetracycline removal

As bifunctional materials for adsorption and peroxymonosulfate (PMS) activation, iron−cobalt bimetallic organic frameworks (FeCo−MOF) were successfully fabricated via a facile method at room temperature, and characterized by XRD, SEM, TEM, XPS, TGA, BET and FTIR. Due to the high specific surface area and electrostatic interaction, FeCo−MOF showed excellent adsorption capacity. 30 mg of FeCo−MOF can adsorb 87.5% of tetracycline (TC) in a 100 mL aqueous solution (70 mg/L). The adsorption data are well fitted by the Langmuir model and pseudo−second−order adsorption kinetics, indicating the TC capture probably was monolayer molecular adsorption and chemisorption. Meanwhile, FeCo−MOF/PMS had the outstanding catalytic activity for TC degradation via PMS activation. 10 mg of FeCo−MOF can remove 91% of TC within 5 min in a 100 mL aqueous solution (20 mg/L) with PMS (0.1mmol·L−1). Quenching experiments showed that •OH, SO4•−, O2•− and 1O2 all participate in the TC degradation. The effects of PMS concentration, pH value, reaction temperature on TC degradation were investigated. Although the coexisting inorganic anions and small molecule acids inhibited the catalytic performance of FeCo−MOF/PMS, the TC removal rates were still greater than 80%, indicating the FeCo−MOF/PMS system has a strong anti−interference ability to complex water environments. In addition, the complete degradation of various pollutants, including TC, methylene orange (MO) and methyl blue (MB), and TC degradation in different water bodies confirmed the wide applicability of the FeCo−MOF/PMS system.