Wastewater Treatment by Using Polyurethane Foams Modified with Bis-[2-ethylhexyl] Phosphoric Acid: Kinetics, Equilibrium and Desorption Studies

Background: Water pollution is an important environmental problem, undoubtedly, the presence of toxic heavy metals forms the main source of water contamination. Sorption characteristics of polyurethane foams modified with bis (2-ethylhexyl)phosphoric acid (DEHPA) for the removal of zinc, lead and cadmium ions from contaminated solutions were investigated. Methods: Operating variables, such as initial pH of the aqueous solution (1-6), ion concentrations (5-100 mg/l), sorbent dosage (1-8 g) and contact time (0-60 min), were studied. Results: A value of 98 ± 3% of initial amount of studied ions (20 mg/l) was eliminated using 5 g of polyurethane sorbent modified with DEHPA (0.01 M in methanol) at pH 5. The selectivity order for metal ions toward the sorbent is Zn> Pb> Cd. Analysis of the equilibrium sorption data using Langmuir, Freundlich and Temkin models revealed that the Langmuir model was well suited to describe the zinc, lead and cadmium ions sorption. Power function, simple Elovich, pseudo first-order and pseudo second-order kinetics were applied for kinetic study in batch sorption and it was found that experimental data can be suitably described by pseudo second-order model. Conclusion: Removal of studied metal ions from real samples shows that the modified polyurethane foam is useful for the treatment of polluted waters.