Eco-friendly, stimuli-responsive sponge with magneto-photothermal effect for efficient and continuous cleanup of viscous crude oils

Oil spills pose significant global environmental and resource wastage issues due to the slow flow of high-viscosity crude oil. Current cleanup methods, such as chemical dispersion, in situ burning, microbial degradation, and mechanical oil skimmers, have limitations such as low recovery rates, secondary pollution, and time consumption. To address these challenges, we developed an eco-friendly magneto-photothermal sponge combining magnetic and photothermal heating. This innovation enables safe, efficient, and continuous cleanup without direct contact. The magneto-photothermal sponge, fabricated through a simple dip-coating and template method, consists of nontoxic polydimethylsiloxane (PDMS) sponge with a biocompatible SiO2/Fe3O4/polydopamine layer. It exhibited rapid adsorption, high capacity (131% to 344% for various oils), sustained superhydrophobicity, and reusability. Owing to its magnetothermal and photothermal properties, it was rapidly heated to 178 ℃ in 3 min under an alternating magnetic field and to 63.5 ℃ in 5 min under solar irradiation. The sponge efficiently absorbed viscous crude oils, with a recovery rate of 93.33 g·h−1·cm−2, which surpasses that reported in previous studies. Combining solar and magnetic heating enhanced recovery, being 13 and 1.2 times more effective than individual solar and magnetic heating, respectively. This low-cost, high flame retardant, durable, dual-heating approach offers an efficient, safe, and eco-friendly solution for cleaning viscous heavy oil spills.