Fabrication and characterization of biodegradable oxygen-releasing micromaterials for treatment of hypoxic environmental waters

Abstract

Micromaterials were fabricated and structurally characterized from naturally occurring biodegradable substrates and encapsulated to provide a sustainable oxygen release mechanism for the treatment of environmental anoxic water systems. In this study, micromaterials composed of collagen and whey protein concentrate (WPC) polypeptides were fabricated by electrospraying, and the micromaterials encapsulated oxygen-producing calcium peroxide (CaO2). Electrospraying, or electrospinning, allows for direct encapsulation of materials within a polymer matrix when a high voltage is applied. As collagen and WPC are water soluble, when placed in water the fabricated micromaterials gradually dissolved; and thereby, released the encapsulated peroxide that combined with water and produced oxygen. The oxygen released by the micromaterials was monitored and dissolved oxygen production rates were determined. As collagen and WPC have different dissolution rates, the oxygen release rate was controlled by the composition of the micromaterial. Oxygen release rate constants ranged from 9.8 × 10−3 h-1 to 5.8 × 10-2 h-1 and corresponded to the materials as follows from slowest to fastest: WPC micromaterial < composite of collagen and WPC < collagen micromaterial << crude CaO2. As direct application of crude CaO2 in environmental waters would immediately produce oxygen at toxic hyperoxic levels, it is necessary to introduce oxygen at controlled rates in order to ensure the health of aquatic organisms. By quantitatively combining calcium peroxide encapsulated in micromaterials constructed of biodegradable polypeptides with varying dissolution rates, the production of oxygen can be controlled and customized for treatment of specific water systems.