Enzymatic degradation of polyacrylamide in aqueous solution with peroxidase and H₂O₂

Abstract

Polyacrylamides are often used in water-based hydraulic fracturing for natural gas and oil production. However, residual polymer remaining in the fractured rock can limit production. A novel approach for degrading partially hydrolyzed polyacrylamide (HPAM) was investigated using hydrogen peroxide and horseradish peroxidase (HRP). This sustainable HRP/H 2 O 2 system degraded the polymer in solution, reducing its viscosity in both pure water and brine solutions. Molecular weight measurements confirmed that the viscosity reduction was due to a significant degradation of the polymer backbone and not primarily by other mechanisms such as amide hydrolysis or rearrangement, and so forth. The reduction in viscosity and molecular weight was first order with respect to H 2 O 2 concentration. The kinetics of viscosity reduction and molecular weight are closely correlated which would allow the quicker and simpler viscosity method to help engineer future processes.

Treatment of partially hydrolyzed polyacrylamide by mixed bacteria isolated from wastewater

“…As well known, during the degradation of HPAM, the chemical bonds of HPAM are broken by cellular enzymes, then low‐molecular fragments are released, which can be utilized by bacteria for growth and metabolism. So, at a low initial concentration of HPAM, these cultivated cells could effectively degrade the HPAM by hydrolysis of cellular enzymes and synthesize cellular components 1 . As a result, the biomass could slightly increase with rise in initial HPAM concentration to 400 mg/L.…”

“…So, at a low initial concentration of HPAM, these cultivated cells could effectively degrade the HPAM by hydrolysis of cellular enzymes and synthesize cellular components. 1 As a result, the biomass could slightly increase with rise in initial HPAM concentration to 400 mg/L. However, with further increase in the initial concentration of HPAM to 1,000 mg/L, the decreased biomass can be ascribed to the fact that an increase in initial HPAM concentration above 300 mg/L would be followed by a strengthening viscosity of the culture medium, which caused obvious inhibition to cell growth and metabolism.…”

“…Currently, hydrolyzed polyacrylamide (HPAM) has been widely applied to sewage treatment, 1 soil additional agent, 2 paper manufacturing and textile industries, 3,4 plug thief zone, 5 in high‐salinity environments, 6 managing mine tailings 7 due to the special properties of well water solubility, flocculating, thickening, shearing resistance. HPAM has been extensively used as additives of drilling fluid being injected into the stratum to drive the crude oil.…”

Adsorption behavior and shear degradation of ultrahigh‐molecular‐weight hydrolyzed polyacrylamide in a capillary flow

“…Ultrahigh‐molecular‐weight partially hydrolyzed polyacrylamides (HPAMs) are widely used to enhance the viscosity of displacing fluid for reducing the water‐to‐oil mobility ratio in enhanced oil recovery (EOR) . However, in oilfield polymer flooding, the displacing fluid viscosity decreases due to mechanical, chemical, thermal, and biological effects . Viscosity decrease can result in the decrease of sweep efficiency and displacement efficiency .…”

Degradation of Acrylic Acid/acrylamide Superabsorbent Copolymer

“…) that could react to each other to generate the polymer fragments [26,27]. Hydrogen peroxide is recognized as the reactive oxygen species that can derive free radicals in water, especially under acidic condition, and considered as a sustainable or green liquid oxidant [27].…”