Solvent-Based Elimination of Organic Matter from Marine-Collected Plastics

The physical-chemical characterization of plastic litter from the marine environment requires the prior removal of the biofouling attached to their surface without causing any degradation in the polymer. The absence of a standardized protocol for digesting biofouling and organic matter of both macro and microplastic samples extracted from seawater has been the main motivation for this research work, which aims to evaluate the effectiveness of different solvents (hydrogen peroxide, ethanol, a commercial enzymatic detergent, and potassium hydroxide) for the digestion of organic matter and biofouling in different samples recovered from the Spanish Atlantic and Mediterranean coast. Moreover, the potential effect of those solvents on the physical-chemical structure of polymers, four virgin plastic reference materials (low-density polyethylene, polyamide, poly(ethylene terephthalate) and polystyrene) without any type of prior degradation has been characterized in terms of Fourier transform infrared spectroscopy (FTIR) and optical microscopy. Results indicate that the hydrogen peroxide at 15% concentration applied for one week at 40 °C is the most effective solvent for organic matter and biofouling removal, without causing any apparent damage on the structure of plastic samples analyzed.