▎ 摘　　要

NOVELTY - A filtration apparatus comprises a support substrate, and a graphene oxide membrane including graphene oxide sheets arranged on the support substrate, where each of the graphene oxide sheets covalently coupled to a chemical spacer. The graphene oxide membrane has a lactose rejection rate (r1) of at least 50% with 1 wt.% lactose solution (S1) at room temperature, and after the graphene oxide membrane is contacted with a solution that is at least 80 degrees C for preset time, the graphene oxide membrane has a lactose rejection rate (r2) of at least 50% with 1 wt.% lactose solution (S2) at room temperature. USE - Filtration apparatus used for processing of black liquor (claimed). Uses include but are not limited to concentration of molecules e.g. whey and lactose, kraft pulping e.g. wood pulp, sulfite pulping, desalting such as lactose, dye, chemicals and pharmaceuticals, fractionation e.g. sugars, extraction e.g. nutraceuticals, and plant oils, recovery e.g. catalyst and solvent, and purification. ADVANTAGE - The filtration apparatus can endure high-pressure operations. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for processing of black liquor, which involves flowing black liquor through the filtration apparatus, where the black liquor comprises lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, and sodium hydroxide.