A super-hydrophilic NH2-MIL-125 composite film with dopamine-modified graphene oxide is used for water treatment

Abstract

It is always concerning about how to remove oil–water emulsions and dyes simultaneously and how to find a suitable separation film. Therefore, a modified super-hydrophilic anti-fouling separation film was prepared by combining NH₂-MIL-125(Ti) with reduced graphene oxide (RGO), obtained through modifying graphene oxide (GO), with polydopamine (PDA). The complex film contains hydrophilic functional groups such as carboxyl, amino and benzene rings. It has super-hydrophilicity and super-hydrophobicity underwater, because of the presence of RGO and nanomaterials. The complex film has a high throughput and retention rate for separating oil–water emulsions and dyes. The oil–water retention rate is above 99% (flux > 600 L m⁻² h⁻¹) and the dye retention rate is above 99% (flux > 700 L m⁻² h⁻¹) except for Congo red. Furthermore, the oil–water retention rate is still close to 99.4%, and the retention rate is above 96% after ten cycles. In addition, the composite film has some stability even after immersion under strong acid and alkali conditions for 30 days. The prepared composite film shows good prospects for the simultaneous removal of oil–water emulsions and dye contaminants.