A method of removing microplastic particles from a water-based liquid, comprising the exposure of the liquid to a solid surface on which is retained a sorbitan monooleate surfactant, in a concentration suitable for entrapping substantially all microplastic particles. The method is useful for removing microplastic particles and microfibres from fresh and saline natural waters, effluent water, such as grey water, storm water and waste waters from industrial processes, in addition to any kind of product based on water, such as mineral waters, milk, fruit juices, beverages, pharmaceutical and veterinary products.