Use of surfactant-modified adsorbents in the removal of microplastics from wastewater

Microplastics (<0.5 mm plastic particles) accumulate in water bodies due to their persistency to degradation. This work proposes the use of surfactant in microemulsion system to modify the surface of adsorbents. The experiments tested five adsorbents: coconut bagasse, sugarcane bagasse, banana peel bagasse, bentonite, and diatomite. The microplastic sample was obtained by crushing five different types of plastic, simulating the process of fragmentation that occurs in nature. Tween 80 was used as surfactant in the microemulsion system. First, a pseudoternary phase diagram was obtained to delimitate the microemulsion area. A surfactant-rich microemulsion was used as adsorbent surface modifier. The microemulsion system was characterized by surface tension, droplet size, polydispersion index, and pH. Batch adsorption tests were performed by contacting the microplastic-bearing effluent with each microemulsion-modified and non-modified adsorbent. The procedure performed in this work had the ability to remove almost 80% of the microplastics, indicating the ability of the adsorbents used to reduce the concentration of microplastics that typically accumulate in water bodies.