Harsh environment-tolerant, superhydrophilic and underwater superoleophobic cellulose hydrogel-coated copper foam for efficient and repeatable oil/water separation

Abstract

The increasingly serious situation of oil leakage makes it crucial to design a separation material that is convenient, green and durable to address the problem of separating oil–water mixtures. In this work, immersion coating and heating techniques are used to modify a layer of cellulose hydrogel on the hydrophobic copper foam surface for oil/water separation. Excellent superhydrophilic and underwater superoleophobic qualities were displayed by the modified copper foam. Different oil–water mixtures can be separated using the modified copper foam. The separation efficiency can reach 99.999% after 100 cycles, and the maximum flux reached 145 587 L m⁻² h⁻¹. Moreover, after soaking in 1 M HCl, NaCl, and NaOH solutions for 1 day or undergoing 30 abrasion tests, the separation efficiency remained above 99.993%. In general, the cellulose-modified copper foam offers excellent durability, sustainability, and environmental protection. It also has significant potential for oily wastewater treatment.