The Use of Sodium Persulfate in Hydraulic Fracturing Fluids: A Degradation Study Based on Furfural

Hydraulic fracturing has allowed natural gas to become a viable energy source via extraction of unconventional shale reserves, but this process requires an enormous amount of water. To ensure a productive fracture, a proprietary blend of chemical additives is added to the water. In this research, a hydraulic fracturing chemical additive – an enzyme breaking agent – is analyzed for organic components using gas chromatography mass spectrometry. The chemical changes that occur over the course of a fracture are also investigated using one model chemical found in the additive, furfural, in order to help assess the environmental risk that hydraulic fracturing poses. This is done by studying furfural’s interactions with sodium persulfate, which is added to hydraulic fracturing fluids as an oxidizing breaking agent. Sodium persulfate is also used as a powerful disinfectant for the treatment of groundwater contamination. Once activated, sodium persulfate reacts to form sulfate radicals. Various conditions may be used to activate persulfate in order to increase the rate of sulfate radical production, including temperature and the presence of iron. This study focuses on the use of Fe (III) and the influence of temperature, initial pH, initial persulfate dose, iron concentration, hydraulic fracturing brine, and elevated pressure on the kinetics of furfural degradation. The goal of this research is to determine the efficiency and optimal conditions necessary for employing sodium persulfate as a treatment option for furfural contamination and the identification of reaction byproducts. Kinetic parameters, including pseudo first-order reaction rate constants and activation energies, are presented.