Decomplexation of Pb-EDTA by electron beam irradiation technology: efficiency and mechanism

As a common heavy metal complex in industrial wastewater, Pb-EDTA has garnered much attention due to its detrimental impact on both human health and the ecological environment. The degradation of heavy metal complexes by traditional methods requires subsequent treatment to recover heavy metals. This article attempts to find an effective method to simultaneously degrade both organic matter and heavy metal pollutants. Experimental results indicate that 1 mM Pb-EDTA can be effectively removed at 10 kGy with a degradation efficiency of 91.62%. Most lead ions were still in a stable complex state, with a removal rate of 24.42% (10 kGy). When the absorbed dose increased to 80 kGy, the degradation efficiency of Pb-EDTA was 95.24%. At this time, the removal rate of Pb²⁺ reached 68.82%. Through radical scavenging experiments and further mechanism analysis, it was demonstrated that electron beam irradiation primarily generates ·OH radicals, disrupting the structure of Pb-EDTA, gradually decarboxylating, and ultimately generating formic acid, acetic acid, and NO₃ ^-. The released metal ions were reduced by e_aq ^- and ·H to obtain lead monomers. Residual toxicity analysis indicates that the toxicity of degradation products generated by electron beam irradiation is significantly reduced. Experimental results showed that electron beam irradiation can effectively degrade Pb-EDTA and recover lead ions simultaneously.