Filtration apparatus comprising polymer modified graphene oxide membranes

A method for fabricating a graphene oxide membrane, including:

• dispersing a plurality of graphene oxide sheets in an aqueous solution;
• adjusting a pH of the aqueous solution to between about 7.0 to 10;
• adding a polymeric component and at least one carbodiimide additive to the aqueous solution;
• after adding the polymeric component and the at least one carbodiimide additive, stirring the aqueous solution for a period of time at a predetermined temperature;
• after the adding and the stirring, casting the aqueous solution on a support substrate;
• and
• drying the aqueous solution on the support substrate to produce the graphene oxide membrane.

A filtration apparatus, comprising:

• a support;
• a graphene oxide membrane disposed on the support, the graphene oxide membrane comprising a plurality of graphene oxide layers, each graphene oxide layer including at least one graphene oxide sheet covalently coupled to a chemical spacer;
• and
• a polymeric additive disposed on the graphene oxide membrane,
• wherein:
• the filtration apparatus is characterized by a lactose rejection rate with a 1 wt % lactose solution and a MgSO4 rejection rate with a 0.1 wt % MgSO4 solution, the lactose rejection rate being at least about 20% greater than the MgSO4 rejection rate.