Activation of peroxymonosulfate by FeOOH modified biochar for the degradation of tetracycline hydrochloride

For preventing environmental pollution and realizing resource utilization of agricultural and forestry wastes, biochar was formed after high temperature pyrolysis of citrus peels under anoxic conditions, and employed as catalyst to activate peroxymonosulfate (PMS) for degrading tetracycline hydrochloride (TC) in wastewater. Furthermore, alpha-FeOOH modified biochar was fabricated through an alcohol-assisted hydrothemal method for proving the catalytic activity of biochar. The prepared catalysts were characterized by several characterization techniques. Results showed that the catalytic activity of alpha-FeOOH modified biochar was much better than that of biochar or alpha-FeOOH, which is attributed to the synergistic effects of biochar and alpha-FeOOH on the PMS activation. Meanwhile, the effects of PMS concentration, co-existing ions (Cl-, NO3-), and humic acids (HA) on the degradation of TC were investigated through static experiments. More importantly, radical trapping experiment tests suggested that hydroxyl radical (center dot OH), sulfate radical (SO4 center dot-), and singlet oxygen (O-1(2)) were generated during the process of catalyst activation of PMS, and O-1(2) played the main role for TC degradation.