Dopamine-assisted interface engineering: Fabrication of polyacrylamide hydrogel-modified stainless steel mesh for efficient oil/water separation

Abstract

The rapid surge in industrial advancements has resulted in the production of significant volumes of oily wastewater, thereby posing a severe environmental challenge. Consequently, the exploration of innovative, eco-friendly hydrophilic materials for oil/water separation has gained significant prominence in contemporary academia. This research investigated the efficacy of utilizing hydrogel modified stainless steel mesh (SSM) in oil/water separation applications. The polyacrylamide hydrogel modified SSM (PAAm/PDA@SSM) were successfully prepared using a straightforward immersion technique with polydopamine (PDA) serving as the adhesive layer. The microstructure and hydrophilicity of the modified SSM were examined. It was observed that the modified SSM exhibited hydrophilic characteristics in ambient air, as evidenced by a water contact angle measurement of 34.5 °. The oil/water separation performance was studied. The study used different amounts of AAm to modify SSM with different pore sizes and found that the PAAm₂.₅/PDA@SSM, featuring a pore size of 300 mesh and an AAm quantity of 2.5 g, demonstrated the most effective separation. This modified SSM achieved a separation efficiency of 99.6 % for a 2/8 n-hexane/water mixture, demonstrating a water flux rate of 480 L·m⁻²·h⁻¹. Then, different proportions of n-hexane/water mixtures were separated using PAAm₂.₅/PDA@SSM, with separation efficiencies all above 98 % and water fluxes above 315 L·m⁻²·h⁻¹. Furthermore, the PAAm₂.₅/PDA@SSM demonstrated high efficacy in separating various oil/water mixtures, achieving separation efficiencies surpassing 98 % and water fluxes surpassing 149 L·m⁻²·h⁻¹. Simultaneously, the water flux of the water/oil emulsions was measured to exceed 92 L·m⁻²·h⁻¹, achieving a separation efficiency of 98.8 %. After undergoing 10 consecutive separations, followed by soaking in assorted solutions for 24 h, exposure to air for 15 days, low/high temperatures treating for 12 h, and 15 cycles of abrasion with sandpaper, the oil/water mixture separation efficiency consistently surpassed 97.4 %. Thus, the prepared PAAm₂.₅/PDA@SSM showcased remarkable stability and reusability. The present study provides a scientific basis for further optimization and industrial application of hydrogel-modified SSM.