Recovery of Waste Polyurethane from E-Waste—Part I: Investigation of the Oil Sorption Potential

Abstract

The shredding of end-of-life refrigerators produces every year in Italy 15,000 tons of waste polyurethane foam (PUF), usually destined for energy recovery. This work presents the results of the investigation of the oil sorption potential of waste PUF according to ASTM F726–17 standard. Three oils (diesel fuel and two commercial motor oils) having different densities (respectively, 0.83, 0.87, and 0.88 kg/dm3) and viscosities (respectively, 3, 95, and 140 mm2/s at 40 °C) were considered. The waste PUF was sampled in an Italian e-waste treatment plant, and its characterization showed 16.5 wt% particles below 0.71 mm and 13 wt% impurities (paper, plastic, aluminum foil), mostly having dimensions (d) above 5 mm. Sieving at 0.071 mm was applied to the waste PUF to obtain a “coarse” (d > 0.71 mm) and a “fine” fraction (d < 0.71 mm). Second sieving at 5 mm allowed an “intermediate” fraction to be obtained, with dimensions between 0.71 and 5 mm. The oil sorption tests involved the three fractions of waste PUF, and their performances were compared with two commercial oil sorbents (sepiolite and OKO-PUR). The results of the tests showed that the “fine” PUF was able to retain 7.1–10.3 g oil/g, the “intermediate” PUF, 4.2–7.4 g oil/g, and the “coarse” PUF, 4.5–7.0 g oil/g, while sepiolite and OKO-PUR performed worse (respectively, 1.3–1.6 and 3.3–5.3 g oil/g). In conclusion, compared with the actual management of waste PUF (100 wt% sent to energy recovery), the amount destined directly to energy recovery could be limited to 13 wt% (i.e., the impurities). The remaining 87 wt% could be diverted to reuse for oil sorption, and afterward directed to energy recovery, considered as a secondary option.

Recovery of Waste Polyurethane from E-Waste. Part II. Investigation of the Adsorption Potential for Wastewater Treatment

“…The samples (1 kg each) were collected according to standard methods UNI 10802:2013 and UNI 14899:2006 at the end of the working day. The samples were assumed to be representative, considering that 3300 t/y EoL refrigerators entering the plant roughly correspond to over 300 items shredded per day [4]. The collected samples were quartered to obtain representative secondary samples for the characterization and adsorption tests.…”

“…The collected samples were quartered to obtain representative secondary samples for the characterization and adsorption tests. A complete characterization of the waste PUF is reported in a previous study [4], describing the investigation of the oil absorption potential of the same material (whole material and selected particle-size fractions). Compared to our previous study [4], this research explored the adsorption potential for wastewater treatment of the fraction of waste PUF with dimensions between 0.71 and 5 mm.…”

“…A complete characterization of the waste PUF is reported in a previous study [4], describing the investigation of the oil absorption potential of the same material (whole material and selected particle-size fractions). Compared to our previous study [4], this research explored the adsorption potential for wastewater treatment of the fraction of waste PUF with dimensions between 0.71 and 5 mm. The main features of the considered waste PUF are reported in Table 2.…”

“…The scientific and technical literature offers several potential perspectives for material recovery from waste PUF, mostly as an oil absorbent [4][5][6][7], additive for construction materials [8][9][10][11], and adsorbent of pollutants from wastewater [12,13]. Nowadays, the market competition in the field of wastewater treatment technologies is increasing due to the need of achieving effective removal performances with limited costs.…”

Recovery of Waste Materials: Technological Research and Industrial Scale-Up

“…Two different hydrometallurgical routes for the recovery of copper and then gold were tested, moreover a flow sheet of the process was proposed. In another study, Santucci V. and Fiore S. proposed two papers [6,7], the first one considered the valorization of polyurethane foam (PUF) deriving from end-of-life refrigerators through a simple sieving process to obtain three fractions to be used as oil adsorbent. Particularly, the obtained fine fraction (d < 0.71 mm) revealed oil sorption performance at least 3-4 times higher than that of commercial products.…”