Object  To explore the promoting action of photothermal conversion effect of submicron Prussian blue (smPB) on its photo-Fenton catalytic degradation of methylene blue (MB) pollutants.

Method  Using sodium ferrocyanide and polyethylenimine (PEI) as main materials, smPB with photothermal and photo-Fenton-catalytic degradation was prepared by hydrothermal slow crystallization method using amino groups on PEI chain to control the process of PB crystallization. The structure and morphology of smPB were characterized by SEM, TEM, FTIR, UV-vis and XRD. The photothermal conversion effect of smPB in aqueous solution was tested by sunlight from the solar simulator. The catalytic degradation efficiencies of smPB Fenton, photo-Fenton and photothermal-Fenton were tested under different catalytic conditions.

Result  The results showed that the photothermal conversion rate of smPB was about 90%. The temperature of 100 mL aqueous solution containing 20 mg smPB increased by about 8.8 ℃ at the condition of sunlight power irradiation for 1 h. Under the photothermal condition, the degradation rate was more than 99% within 40 min when 100 mL MB(ρ=20 mg/L) was degraded by 20 mg smPB in photothermal-Fenton catalysis.

Conclusion  The preparation method of smPB is simple and has many functions such as photothermal conversion, photo-Fenton and Fenton. The catalytic degradation efficiency of smPB photothermal-Fenton is greatly improved compared with Fenton or photo-Fenton, and the photothermal effect has a promoting effect on photo-Fenton.