Copper removal from aqueous solutions using a polyelectrolyte derived from sunflower oil: Physico-chemical aspects

Interactions between polymers and different metal ions represent an interesting field of study due their potential use for wastewater remediation. In turn, polymers with technological applications can be obtained from renewable raw materials. In this work, polyesters weighing 2822 Da were obtained from the reaction of an epoxidized biodiesel from sunflower oil. The polyesters were reacted with aqueous sodium hydroxide solutions to obtain polyelectrolytes. The polyelectrolytes were characterized with respect to their structure by Nuclear Magnetic Resonance Spectroscopy, Infrared Fourier Transform Spectroscopy and Gel Permeation Chromatography; their physicochemical behavior in aqueous media as well as their capacity to remove copper ions were characterized by electrical conductivity (EC) and Static and Dynamic Light Scattering measurements (SLS and DLS). The critical aggregation concentration (CAC) was 1.3 × 10−1 g L−1 polyelectrolyte derived from sunflower oil (PESFO). The polyelectrolyte's EC abruptly increased when the PESFO concentration increased above the CAC. PESFO in ionic aqueous media developed a rigid rod morphology and had a strong interaction with water and ions (up to 5.1 g L−1). Its capacity to remove copper(II) ions from aqueous media was determined, and the interactions between Cu/PESFO were characterized by FTIR. The polyelectrolyte removed up to 35 mg Cu(II)/g PESFO.