In this project, we used hydrothermal method instead of traditional pyrolysis to transform rigid PU waste into high-end activated carbon for capacitor and adsorption. We have investigated several factors to increase the adsorption capacity and to decrease the cost of chemicals and electrical power. Our experimental results indicated that the obtained activated carbon has 6% of nitrogen element and > 1,000 m2/g of specific surface area with 21%-43% production yield. In the Hg sorption experiment, the adsorption capacity was >10,000 g/g significant larger than that of commercial activated carbon FGD. In a 1M NaCl electrolyte solution, at a scanning speed of 5 mV/s, the activated carbon material ions can have enough time to diffuse into the activated carbon pores within a specific applied potential, and the best capacitance value is 53.9 F/g. The capacitor patterns all have obvious oxidation/reduction peaks, which means that the nitrogen-containing functional groups provide a certain amount of pseudo capacitance, which helps to improve the overall capacitance characteristics. Field capacitance test indicators are salt adsorption capacity 2.84 mg/g, total removal rate 41%, best removal rate per unit time 43%, average salt absorption rate per unit weight of carbon electrode 0.568 mg/g-min, current efficiency 111%, The energy consumption per ton of water is 0.261 kWh/m3, the energy consumption per mole of salt absorption is 0.100 kWh/mole, and the energy consumption per gram of salt absorption is 1.708 Wh/g-salt. This work not only reduces solid waste but also generates new resource. Further work will focus on the accreditation and certification of obtained products for wide applications in environmental-related field.

Hydrothermal carbonization, Polyurethane wastes, Activated carbon