Highly effective iron-carbon-bentonite-alginate beads (Fe°/C-BABs) as catalyst to treat benzalkonium chloride in fixed-bed column systems

Novel iron-carbon-bentonite-alginate beads (Fe°/C-BABs) were successfully prepared with the ion-gelation method and demonstrated high activities in persulfate activation for benzalkonium chloride (BAC) oxidation. The beads were measured in terms of size, mass, and Fe content and then characterized via scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The performance of Fe°/C-BABs as filler was evaluated in a continuous fixed-bed with paralleled PS and BAC feeding. The effects of initial PS (100 mM) concentration, pH (3-11), fixed bead weight (10-30 g), and flow rate (225-540 mL h−1) were investigated. Results indicated that the Fe°/C-BABs effectively activated PS to treat BAC in the solution. The optimal conditions for the degradation of BAC were pH 7.0, [BAC] = 50 mg L−1, [PS] = 100 mM, bead weight = 30 g, PS flow rate = 25 mL h−1, and BAC flow rate = 225 mL h−1; the removal rate of BAC reached 93.3%.The economic cost analysis was carried out under the optimal experimental conditions. To deeply understand the degradation mechanism of pollutants, the intermediates of BAC degradation were analyzed via gas chromatography/mass spectrometry analysis, and a degradation path pathway was proposed.