Preparation and properties of photothermal superhydrophobic melamine sponge for heavy oil absorption

Abstract

Frequent oil spills lead to significant environmental issues and economic losses. In this work, a photothermal superhydrophobic melamine sponge (OPCM) was prepared with carbon black, polydopamine and octadecylamine for absorbing heavy oil. The surface properties, morphology and structure of OPCM were characterized by various characteristic techniques, including interfacial tensiometer, infrared thermography, SEM, FT-IR and XPS. Experimental results showed that the water contact angle of OPCM increased from 0° to 152.6°, signifying a change in wettability from superhydrophilicity to superhydrophobicity. And the surface temperature of OPCM rose rapidly from 25°C to 76.2°C within 1 min under the simulated sunlight irradiation of 1.0 kW/m². Furthermore, three kinds of heavy oils with viscosities of 44204 mPa·s, 9373 mPa·s, and 3671 mPa·s were selected for the absorption test. The test indicated that the maximum absorption capacities of OPCM for these oils were 126 g oil/g OPCM, 117 g oil/g OPCM, and 114 g oil/g OPCM, respectively. At the same time, from the perspective of circular economy, after 11 cycles of oil absorption, the absorption capacities of OPCM remained at 107 g oil/g OPCM, 102 g oil/g OPCM, and 100 g oil/g OPCM. Because of the photothermal conversion property and thermal conductivity of OPCM, the viscosity of heavy oil decreased and the fluidity increased. Additionally, the capillary force and hydrophobic interaction improved the absorption efficiency of OPCM for heavy oil. The sponges OPCM are potentially useful for in addressing oil spills and environmental issues during crude oil production and transportation.