Zerovalent Iron Nanoparticles for HPAM Polymer Degradation in Produced Fluids

Abstract The partially hydrolyzed polyacrylamide (HPAM) polymer is commonly used in polymer flooding during the chemical enhanced oil recovery (EOR) process. The produced water obtained as a result contains residual HPAM, which should be treated before disposing of or reinjecting the produced fluids. Furthermore, HPAM can also cause biofouling and scaling problems near the well bore, clog filtering units, interfere with conventional water treatment procedures, and decrease the effectiveness of reinjection systems. Therefore, it is essential to treat the produced water before it is stored, reused, or discarded. In this study, we propose a novel method for degrading the HPAM using zero-valent iron (nZVI) nanoparticles. The nZVI were synthesized via the reduction of ferric ions with a strong reducing agent and subsequently characterized using DLS, FTIR, XRD, XPS, and FESEM. The nZVI acts as a potent reducing agent, which generates highly reactive hydroxyl free radicals. These free radicals can attack the polymer chain, leading to its degradation. We used DLS and viscosity measurements to study the effect of zero-valent iron nanoparticles on HPAM. The DLS showed that the size distribution of the polymer decreased with the addition of nZVI, and reduction was also observed in the viscosity. Furthermore, increasing the concentration of nZVI from 0.1 wt% to 0.2 wt% further reduced the size distribution and viscosity of the HPAM solution. This suggests that the higher concentration of nZVI particles provides a greater surface area for polymer adsorption and promotes oxidation through highly reactive hydroxyl free radicals.