Study On The Release Mechanism Of Fiber Microplastics During The Washing Process Of Drum Washing Machines

The fiber microplastics(diameter < 5 mm)produced in the washing machine of synthetic fiber textiles are one of the main pollution factors in the water environment and the land environment,which can directly affect the organism through the food chain through the biological feeding.At present,the research on fiber microplastics pollution focuses on the types,contents,distribution and ecological risks of fiber microplastics.There are few systematic studies on the washing parameters and the interaction between the parameters in the drum washing process,and there is a lack of explanation of the generation mechanism of fiber microplastics.Based on this,this paper selects a wall-mounted drum washing machine as the research object,and uses 100% polyester filament fabric to systematically study the influence of washing conditions on the release of fiber microplastics.Firstly,scanning electron microscope,biological microscope,microbalance(precision 0.1mg)and Image J image processing method were used to quantitatively detect the fiber microplastics in the fabric,and the physical properties of the fiber microplastics were characterized.The results showed that the abundance of fiber microplastics decreased with the increase of size,and the content of fiber microplastics with particle size between 300 and 400 μm was the highest.Microbalance error is large;Because of the limited observation area and complex operation,scanning electron microscope is more accurate and applicable when the number of fiber microplastics is small.The calculation accuracy of the common biological microscope is higher,and the counting results of the Image J software are not much different from the counting results of the common biological microscope.Secondly,the effects of water,temperature,load,detergent addition amount,time and their interaction on the release of fiber microplastics were studied by JMP customized experiments.The results showed that the average length of the release of fiber microplastics during washing was 300～400μm,and the diameter distribution was 13±1μm,of which 20% was less than 100μm.Time,water amount and detergent content are the main factors affecting the length of fiber microplastics.The length of fiber microplastics decreases with the increase of time,and increases with the increase of water amount and detergent content.The diameter decreases with the increase of time,increases with the increase of temperature,decreases first and then increases with the increase of water volume,and the diameter is less affected by load.The mass of fiber microplastics decreases with the increase of time and increases with the increase of load.With the increase of water amount,the mass of fiber microplastics decreases first and then increases.There is an interaction between water amount and load.The fabric motion trajectory tracking system was used to record the fabric motion image in one washing cycle,and the image processing software was used to analyze and process the fabric motion image and calculate the fabric motion data.The relationship between mechanical action and the amount of fiber microplastics released was explored by regression analysis.The results showed that the fabric covering area,movement height,height of centroid and distance between centroid and cylinder center were significant factors affecting the amount of fiber microplastics released.The amount of fiber microplastics released increased with the increase of fabric covering area,movement height and centroid height.It decreases with the increase of the distance between fabric center of mass and cylinder center.The research of this subject can provide guidance for the optimization of washing parameters of washing machine and reduce the release of fiber microplastics during washing process.