Mechanism of Hydrolysis of Microcystins Enhanced by Lewis Acid Sites on the Surface of Pyrite-Fe(Ⅲ)
Natural mineral(Pyrite)can effectively degrade microcystins(Microcystins,MCs)in water at warm temperature(60℃)(k=0.072 min‒1),but how to break through the heat bottleneck and attain efficient degradation of MCs at room temperature[(25±5)℃]are still a technical issue in water treatment nowadays.In this study,the addition of iron ions(Fe3+,FeCl3)can accelerate the hydrolysis efficiency of microcystins-RR(Microcystin-RR,MC-RR)in pyrite system at room temperature(hydrolysis contribution rate 77.94%),and the degradation rate constant(0.36 h‒l)was three times higher than that of pyrite alone(0.12 h‒l).X-ray photoelectron spectroscopy(XPS),cyclic voltammetry(CV),in situ attenuated total reflection-Fourier transform infrared spectroscopy(in situ ATR-FTIR)and density functional theory(DFT)suggested that the addition of Fe3+enhanced the amount of iron sites of Lewis acid on pyrite surface by forming Fe(Ⅲ)—O bond,and then hydrolyzed MC-RR amide bond through its coordination with C=O.Additionally,the addition of Fe3+can oxidize the multivalent sulfur species on the surface of pyrite(Sn2 ‒,S22 ‒)to elemental sulfur(S0),further promoting the hydrolysis of MC-RR by forming hydrogen bond(—NH…S).This study not only provides a normal temperature mineral treatment technology for cyanobacteria bloom treatment,but also provides a theoretical basis for the self-purification mechanism of amide organic pollutants in natural water.
国家科技期刊平台
NSTL
万方数据
