Both chemical industry and academia search for alternative solvents to meet the cleaner technology requirements since the most widely used solvents are volatile and harmful. In this book, the technical feasibilities of room temperature ionic liquids (RTILs) as bulk liquid membranes (BLM) for phenol removal from Industrial Wastewater was investigated. Room temperature ionic liquids (RTILs) used as a membrane mainly due to their properties of low vapor pressure, low volatility and they are often stable. Four ionic liquids with high hydrophobicity were used: 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim] [PF6], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [Bmim][NTf2], 1-Ethyl-3-methyimidazolium bis(trifluoromethanesulfonyl) imide [Emim][NTf2] and 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], in which, phenol Extraction efficiency and stripping efficiency were studied. The effect of different types of anion and hydrophobicity of the ionic liquids on the phenol extraction and stripping efficiencies were investigated. Different operating parameters of feed phase pH, feed concentration, NaOH concentration were studied.