Enhanced degradation of quinoline in near-neutral pH aqueous solution by magnetically recoverable biochar: Performance, mechanism and variables effects

Abstract

BackgroundQuinoline is a highly toxic nitrogen-containing heterocyclic organic compound. Iron-carbon microelectrolysis is a potential method for treating quinoline in aqueous solution, but commercially available iron-carbon fillers (ICF) are difficult to recover from aqueous solution and have extremely poor degradation effects on near-neutral pH quinoline solution. MethodsIn this study, the magnetically recoverable biochar (MR-BC) was prepared by impregnation-pyrolysis method and used to enhance the degradation of quinoline in near-neutral pH aqueous solution. Significant findingsThe highest removal rate of 1.00 g MR-BC to 50 mg·L−1 quinoline wastewater can reach 99.98% within one hour, while ICF only removes 7.03% of quinoline. Nontoxic hydro-cinnamic acid and cinnamic acid are the main degradation products of quinoline by the MR-BC in near-neutral pH aqueous solution. It is supposed that the degradation process is a result of synergistic effects between MR-BC and quinoline molecules, such as chemical adsorption (π-π and hydrogen bond), electrostatic attraction, reactive oxygen species (ROS) oxidation and atomic hydrogen ([H]) reduction. In addition, the kinetic fitting results indicated that the degradation of quinoline by MR-BC is more consistent with pseudo-second-order kinetics.