Method for separating microplastics from animal excrement

A method, comprising:

• 1) freeze-drying an animal fecal sample, and collecting N g of the animal fecal sample dried;
• 2) transferring the animal fecal sample dried in 1) into a beaker, adding a Fenton's reagent comprising 20 g/L of FeSO4·7H2O and 30% hydrogen peroxide solution (H2O2), with a volume ratio of the FeSO4·7H2O to the 30% H2O2 being 1:2.5;
• stirring a mixture of the animal fecal sample and the Fenton's reagent until no bubbles are produced;
• constantly adding the Fenton's reagent to the mixture, in each addition, 30% H2O2 is no more than 50 ml, and controlling a temperature of the mixture below 40° C.;
• filtering the mixture through a plurality of cellulose nitrate-cellulose acetate (CN-CA) membranes, and transferring the plurality of CN-CA membranes into a plurality of 500 mL beakers with each beaker having no more than 3 CN-CA membranes;
• adding 100 mL of 65% HNO3 to each beaker, placing the each beaker in a water bath firstly at 50° C. for 30 min and then at 70° C. for 15 min;
• cooling the each beaker in an ice bath, and filtering a solution in the each beaker through a first polytetrafluoroethylene (PTFE) membrane;
• and
• 3) transferring the first PTFE membrane obtained in 2) into a 500 mL beaker, adding 200 mL of absolute ethanol to the beaker;
• ultrasonically treating a mixture of the first PTFE membrane and absolute ethanol;
• washing the first PTFE membrane with absolute ethanol three times, removing the first PTFE membrane out of the beaker, and filtering a solution in the beaker through a second PTFE membrane;
• drying a retentate on the second PTFE membrane and microscopically examining the retentate by using micro-Raman spectrometer to obtain a Raman spectrum, and identifying microplastic particles from the retentate.