▎ 摘　　要

NOVELTY - Filtration apparatus comprises: a support substrate; and an alkylated graphene oxide membrane disposed on the support substrate, where the alkylated graphene oxide membrane comprising graphene oxide layers, each graphene oxide layer including at least one graphene oxide sheet covalently coupled to a chemical spacer, the chemical spacer (I), and indicates a point of connection to a carbon atom on the alkylated graphene oxide sheet. USE - The apparatus is useful for preparing a graphene oxide membrane and processing black liquor (all claimed), separating a mixture by passing some components e.g. filtrate or permeate and retaining others preferentially with a balance of the mixture (rejects) according to any of a variety of properties of the membrane and/or of components of the material being filtered. ADVANTAGE - The apparatus: enables to prepare alkylated graphene oxide membrane, which has high conductivity rejection rate for synthetic weak black liquor, and high flux of greater than 5.0E-04 gallons per square foot per day per psi (GFD/psi) for synthetic strong black liquor; and ensures graphene oxide membranes which are chemically engineered to achieve the desired filtration characteristics e.g. high conductive rejection. DETAILED DESCRIPTION - Filtration apparatus comprises: a support substrate; and an alkylated graphene oxide membrane disposed on the support substrate, where the alkylated graphene oxide membrane comprising graphene oxide layers, each graphene oxide layer including at least one graphene oxide sheet covalently coupled to a chemical spacer, the chemical spacer of formula (-A-R1) (I), and indicates a point of connection to a carbon atom on the alkylated graphene oxide sheet. A=O, NH or S; and R1=optionally substituted 1-5C alkyl. INDEPENDENT CLAIMs are also included for: preparing a graphene oxide membrane, comprising (i) stirring a first mixture of a graphene oxide material and a base in water to exfoliate graphene oxide layers from the graphene oxide material, (ii) adding 1-5C alkyl halide to the first mixture to form a second mixture, (iii) heating the second mixture at greater than 60° C to form alkylated graphene oxide, (iv) removing water from the second mixture to obtain the alkylated graphene oxide, (v) dispersing the alkylated graphene oxide in a solvent to form an alkylated graphene oxide dispersion, and (vi) casting the alkylated graphene oxide dispersion onto a support substrate to form the graphene oxide membrane; graphene oxide membrane is produced by the method; and processing black liquor, comprising flowing black liquor through the filtration apparatus, where the black liquor comprises lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, and sodium hydroxide.