Bio-Based Polyurethane Foams with Enriched Surfaces of Petroleum Catalyst Residues as Adsorbents of Organic Pollutants in Aqueous Solutions

Abstract

In this study the surface of bio-based polyurethane foam was enriched with different contents of catalyst residue from the petroleum industry. The foams were prepared with different residue contents, 20, 50, and 80 wt% relative to the total mass of the polyols and were characterized by several techniques, with X-ray diffraction, X-ray fluorescence spectrometry, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, microtomography, Fourier transform infrared spectroscopy and thermogravimetric. To determine the removing process the effects of various operating parameters, pH of the solution (2–12), initial concentration of pesticides (5–50 mg L−1), contact time (15–1440 min), and amount of adsorbent (30–400 mg) were investigated in a batch adsorption technique. The specific surface area of the residue was determined by the BET method as up to 150 m2/g and mean pore diameter of 4.20 ± 0.42 nm (mesopore), which explains the excellent results of the materials in the adsorption process. The high adsorption capacity is probably due to the presence of highly concentrated catalyst residue on the foam surface. Trifluralin pesticide was removed in water using these polyurethane foams with 20.0 mg L−1 initial concentration of herbicide, 30.0 mg adsorbent mass of, 5.0 pH, and 25.0 °C temperature. The chemically prepared foams with 50 wt% residue (PURC50) have higher adsorption capacities (70%) and can be used to remove trifluralin from natural waters effectively. The efficiency of removing the herbicide increased to 83% with the use of 400.0 mg adsorbent mass. The adsorption efficiency of the pure catalyst residue reaches a maximum (95.3%). The established adsorption method was appropriate for adsorption of trifluralin in contaminated waters.