Effects of Linear Alkylbenzene Sulfonate and Polyoxyethylene Sorbitan Monolaurate Surfactants on Pristine and Aged Microplastic Removal by Electrocoagulation

Abstract

Various types of pollutants are present in wastewaters, which can combine and form even more toxic components or interfere with the treatments used for purification. Among emerging contaminants are microplastics and surfactants, which coexist in different types of wastewaters. This study aimed to assess the effects of the anionic surfactant linear alkylbenzene sulfonate (LAS) and the nonionic surfactant polyoxyethylene sorbitan monolaurate (Tween 20) on the removal of microplastics from pristine and aged glitter PVC surfaces using electrocoagulation with aluminum electrodes. To avoid interference from other substances, a benchtop reactor operating in batch mode with particles suspended in ultrapure water was developed for the experiments. The analysis methods employed included counting with the aid of a magnifying glass, gravimetry, zeta potential measurements, and scanning electron microscopy. The results revealed that the addition of surfactants led to a reduction in the removal efficiency of plastic microparticles. The lowest removal percentages were observed at a concentration of 100 ppm, and the inclusion of Tween 20 resulted in a decrease of 23% for pristine microplastics and 45% for aged microplastics. In contrast, the addition of LAS led to a decrease of 6% for pristine microplastics and 24% for aged microplastics. Therefore, the decrease in removal efficiency was more pronounced for degraded microplastics in both the Tween 20 and LAS experiments. Comparing the reduction in removal efficiency between the two types of surfactants, it can be observed that the nonionic surfactant (Tween 20) had a greater impact on the removal of microplastics by electrocoagulation.