Chemometric Evaluation of a Biodegradable Tannic Acid-Polyurethane System for the Removal of Pb(II) and Hg(II) Ions from Water

The industrialization has brought advances that have enabled a better quality of life for people and improved production stages and business models. However, some impacts still need to be resolved, such as water pollution. Industrial pollutants containing potentially toxic metal ions are expensive for the industry, so studying new materials and new processes has helped solve this problem. Adsorption processes using biodegradable adsorbent materials have been presented as relevant alternatives for reusing metallic ions from water bodies and sewage networks. In this perspective, tannic acid (TA) immobilization in biodegradable polyurethane (PU) foams based on vegetable oil (castor oil) was used to remove metal ions Hg (II) and Pb (II) from water. The preliminary study was carried out in TA's immobilization in PUs, with a 2k order factorial experimental design. The responses were obtained and evaluated by gravimetry and UV-Vis spectroscopy using Central Composite Design (CCD). The molar concentration of 0.1000 mol L-1 by TA solution at pH equal to 7 and 19 hours of contact time was defined as optimal conditions for TA adsorption in the PU. The optimized PU-TA system was evaluated for removing Pb (II) and Hg (II) ions in aqueous solutions, and the tests showed that 59.93% and 51.48% were removed from water, respectively. The use of the PU-TA adsorbent system for removing metals in water can be widely valuable in industrial plants that need water treatment.