Leachability of microplastic from different plastic materials

The use of plastic has become common. Large amounts of plastic waste are disposed in landfill without the ability to biodegrade. These plastic materials often disintegrate into microplastic that end up in the leachate, a wastewater stream containing harmful contaminants extracted from the plastic. These particles can eventually contaminate the groundwater. The main objective of this research is to evaluate the leaching of microplastics originated from different types of plastic materials and to evaluate the role of pH in the disintegration process. In this study, seven different types of plastic wastes were investigated. These include Polyethylene Terephthalate (PET), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS), and Polycarbonate (PC). Batch leaching tests were carried out to generate leachate from these plastic materials. The leachate generated from the test was eventually tested for different water quality parameters. Characterization of microplastic particles was conducted using SEM-EDX, FT-IR and particle size analyser. Results revealed that leachates from PET, LDPE, PS and PP contained fibres in addition to other particles. Results showed that PC (19868 items/L) has the largest, while PET (4099 items/L) has the smallest number of microplastic particles per litre. The results indicated PC (184.1 mg/L) has the highest concentration in mass/L and PS (43.1 mg/L) has the smallest concentrations. The study also revealed pH has a significant impact on the leachability of plastic materials and the turbidity of the leachate. Acidic and basic pH levels are more aggressive to plastic materials than neutral pH levels. SEM analysis found that PET and LDPE leachates contained fibres. EDX analysis conducted on the microplastics indicated the presence of elements indicative of the plastic types. FT-IR analysis was not conclusive for all the materials. Microplastic sizes were mostly small and less than 500 nm for most of the samples. The study concludes that the microplastic particles can disintegrate from the original plastic materials under suitable conditions. The outcome of this study can be used for efficient use of different plastic materials and management of its eventual waste materials.