Degradation of Cationic Polyacrylamide Flocculants upon Contact with Metal Surfaces during Rheological Measurements

Abstract Cationic polyacrylamide (CPAM) flocculants, commonly employed in wastewater treatment plants, experience degradation when in contact with various surfaces. This study investigates the degradation process of several CPAMs upon contact with metal surfaces during rheological measurements. The study focuses on observing changes in the rheological properties of CPAM, transitioning from elastic to viscous behavior under the influence of shear and oscillatory solicitations within metallic Couette systems. A detailed examination of how the degradation process is affected by various factors like Couette material, polymer composition, concentration, and temperature is presented. Key findings suggest that degradation predominantly results from chemical interactions rather than mechanical stress, leading to changes in molecular weight, hydrolysis of cationic groups, and alterations in ionic strength. Techniques including Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) analysis, and polyelectrolyte titration were utilized to analyze these molecular changes. This study provides essential insights into the behavior of CPAM in contact with metal surfaces, offering implications for its application in various environmental and industrial processes.