Abstract
Background and PurposeMicrocystin-LR (MC-LR), a common toxic species in contaminated aquatic systems, persists for long periods because of its cyclic structure. Ag3PO4 is an environment-friendly photocatalyst with relatively good degradation capacity for hazardous organic pollutants. This study aimed to investigate the degradation capacity of Ag3PO4 for MC-LR under visible light.MethodsAn Ag3PO4 photocatalyst was synthesized by the ion-exchange method and characterized by X-ray diffraction, field-emission scanning electron microscope, and UV-Vis spectrophotometer. MC-LR was quantified in each sample through high-performance liquid chromatograph. The degradation efficiency of MC-LR was affected by initial pH, initial Ag3PO4 concentration, initial MC-LR concentration, and recycle experiments. The degradation intermediates of MC-LR were examined by liquid chromatography-mass spectrometry (LC/MS).ResultsThe degradation process can be well fitted with the pseudo-first-order kinetic model. The maximum MC-LR degradation rate of 99.98% can be obtained within 5 h under the following optimum conditions: pH of 5.01, Ag3PO4 concentration of 26.67 g/L, and MC-LR concentration of 9.06 mg/L. Nine intermediates were detected and analyzed by LC/MS. Three main degradation pathways were proposed based on the molecular weight of the intermediates and the reaction mechanism: (1) hydroxylation on the aromatic ring of Adda, (2) hydroxylation on the diene bonds of Adda, and (3) internal interactions on the cyclic structure of MC-LR.ConclusionAg3PO4 is a highly efficient catalyst for MC-LR degradation in aqueous solutions.
Highlights
Eutrophication promoted by human activities causes the proliferation of cyanobacteria or blue–green algae [1]
This study aims to investigate the degradation capacity of Ag3PO4 for MC-LR under visible light
The results suggested that Ag3PO4 catalysts exhibited the best photocatalytic performance for MCLR degradation at pH 5.01
Summary
Eutrophication promoted by human activities causes the proliferation of cyanobacteria or blue–green algae [1]. Microcystis species are the most prevalent Cyanobacteria worldwide; these species produce hepatotoxin microcystins (MCs), a possible carcinogen. Microcystin-LR (MC-LR) is a common toxic species in contaminated aquatic systems and persists for long periods. MCs are stable in natural aquatic systems because of their cyclic structure. The degradation of MC-LR is always slow by physical or biological methods. Developing a method for the fast removal of MCLR is a significant research work. Microcystin-LR (MC-LR), a common toxic species in contaminated aquatic systems, persists for long periods because of its cyclic structure. Ag3PO4 is an environment-friendly photocatalyst with relatively good degradation capacity for hazardous organic pollutants. This study aimed to investigate the degradation capacity of Ag3PO4 for MC-LR under visible light
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