In　membrane　distillation　(MD),　the　membrane　as　a　separating　agent　can　be　used　for　separating　a　mixture　with　close　boiling　point　or　forming　azeotrope,　but　this　separating　agent　doesn’t　need　to　be　recycled.　The　separation　principle　of　MD　is　based　on　the　selectivity　of　a　membrane　material　to　components　with　different　structures　and　properties.　For　example,　for　a　hydrophobic　membrane,　volatile　organic　compounds　are　more　preferential　than　water　to　pass　through　the　membrane.　As　a　special　distillation　process,　an　outstanding　advantage　of　MD　is　energy　saving,　but　more　work　is　needed　before　it　is　extensively　applied　in　the　industry.　©　2022　Elsevier　B.V.