Chem. J. Chinese Universities ›› 2024, Vol. 45 ›› Issue (7): 20240086.doi: 10.7503/cjcu20240086

• Physical Chemistry • Previous Articles     Next Articles

Mechanism of Hydrolysis of Microcystins Enhanced by Lewis Acid Sites on the Surface of Pyrite-Fe(Ⅲ)

LAN Xing1, HE Yuting1, ZHANG Qing1, FANG Yanfen1(), DENG Anping2, ZHAO Haixia3, ZHANG Zhaonian4   

  1. 1.School of Materials and Chemical Engineering,China Three Gorges University,Yichang 443002,China
    2.Yichang East Sunshine Biochemical Pharmaceutical Co. ,Ltd. ,Yichang 443300,China
    3.College of Basic Medical Sciences,China Three Gorges University,Yichang 443002,China
    4.Yichang Ecological Environment Monitoring Center of Hubei Provincial Department of Ecological Environment,Yichang 443002,China
  • Received:2024-02-21 Online:2024-07-10 Published:2024-04-25
  • Contact: FANG Yanfen E-mail:fangyf@ctgu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22076098);the Outstanding Youth Project of the Natural Science Foundation of Hubei Province, China(2023AFA054);the 111 Project of China(D20015)

Abstract:

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(S n2 ‒, 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.

Key words: Microcystins, Lewis acid site, Hydrolysis, Pyrite, Catalytic mechanism

CLC Number: 

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