Effect of Chemical Agents on the Morphology and Chemical Structures of Microplastics

Increased demand for plastics leads to a large amount of plastic manufacturing, which is accompanied by inappropriate disposal of plastics. The by-products of these waste plastics are microplastics (MPs; less than 5 nm in size), which are produced because of various environmental and physicochemical factors, posing hazardous effects to the ecosystem, such as the death of marine organisms due to the swallowing of plastic specks of no nutritional value. Therefore, the collection, preparation, identification, and recycling of these microsized plastics have become imperative. The pretreatment of MPs requires numerous chemical agents comprising strong acids, bases, and oxidizing agents. However, there is limited research on the chemical resistance of various MPs to these substances to date. In this study, the chemical resistance of five species of MPs (high-density polyethylene, low-density polyethylene, polystyrene, polyethylene terephthalate, and polypropylene) to sulfuric acid, hydrochloric acid, hydrogen peroxide, potassium hydroxide, and sodium hydroxide was studied. The MPs were reacted with these chemical reagents at preset temperatures and durations, and variations in morphology and chemical structures were detected when the MPs were reacted with mineral acids, such as sulfuric acid. The data pertaining to these changes in MP properties could be a significant reference for future studies on MP pretreatment with strong acids, bases, and oxidizing agents.