Electrocatalytic Degradation of Octadecylamine and 4-Dodecylmorpholine by the Ti/SnO2-Sb/β-PbO2 Anode at High Salinity Conditions: Activity and Mechanism Insights

Increased levels of octadecylamine (ODA) and 4-dodecylmorpholine (DMP) in the aqueous, primarily utilized as flotation agents in the worldwide production of potash fertilizer, imperil the stability of ecosystems and the downstream production of high-end chemicals. Nevertheless, there is a dearth of exhaustive studies pertaining to the elimination of ODA and DMP. Herein, the Ti/SnO2-Sb/beta-PbO2 anode was fabricated by a thermal decomposition-electrodeposition technique for the electrocatalytic degradation of ODA and DMP. The degradation efficiency of ODA and DMP can achieve complete degradation, reaching 100%, after treatment periods of 10 min and 120 min, respectively. Meanwhile, the TOC removal efficiency of ODA and DMP is up to 85% and 61% at 30 min and 120 min, respectively. In particular, sulphate exhibits inhibitory degradation activity of ODA and DMP in comparison to chloride salt. The recycling and accelerated lifetime tests indicate excellent stability and recyclability of the Ti/SnO2-Sb/beta-PbO2 electrode. The mechanism of electrocatalytic degradation involves indirect electrochemical oxidation mediated by free radicals. The primary reactive species responsible for the degradation of DMP and ODA, as determined through scavenger quenching experiments and ESR, are center dot OH and Cl center dot. The degradation of the ODA and DMP commences with the elimination of N element, leading to the formation of the NO3-. The carbon chain subsequently undergoes the breakdown. The degradation pathways of ODA and DMP were also proposed based on the GC-MS and H-NMR analyses, respectively. Moreover, the Ti/SnO2-Sb/beta-PbO2 anode performed excellently in the removal of ODA and DMP in real samples, TOC removal from ODA and DMP in natural samples was 56% and 52%, respectively, within 180 min. This study provides the first exploration of electrocatalytic degradation mechanisms and pathways of ODA and DMP based on the Ti/SnO2-Sb/beta-PbO2 anode.