Surfactants can compete with microplastics for surfaces using adhesives as substrates for microplastic sequestration

Experimental efforts supplemented by modeling gauged whether common additives found in soaps and laundry detergents interfered with polyacrylate adhesive-based capture of microplastics. On the experimental front, poly(2-ethylhexyl acrylate) (PEHA) samples were evaluated using gravimetric analysis, probe tack, and functional assessments of adhesive-coated glass slides immersed into DI water solutions containing both microparticles and additives (solvents, softeners, and non-ionic surfactants). Nylon-6 spheres and polyethylene terephthalate microplastics were chosen for adsorption using a count-based method by ImageJ imaging analysis. Molecular dynamics computations simulated 2-ethyl-hexylacrylate (2-EHA) adhesive and microplastic interactions in the presence of water, citrate, glycerol and tergitol detergent additives. The experimental work showed that fewer microplastics were collected when tergitol was added and was in line with lower experimental Work of Adhesion (WoAaq) results for nylon and PETE (94.5% and 54.5% reductions respectively). Computational results also confirmed lower adhesion in the presence of tergitol. The experiments also showed that the adhesive swelled while equilibrating in additive solutions. Models suggested that tergitol most negatively impacted particle binding through a competitive “blocking” of the adhesive substrate while the other additives were less conclusive about potential interferences based on competitive binding.