Efficient removal of naphthalene-2-ol from aqueous solutions by solvent extraction: Fid-Bau Portal

Efficient removal of naphthalene-2-ol from aqueous solutions by solvent extraction

Jingjing Shao Yan Cheng Chunping Yang Guangming Zeng Wencan Liu Panpan Jiao Huijun He

Naphthalene-2-ol is a typical biologically recalcitrant pollutant in dye wastewater.Solvent extraction of naphthalene-2-ol from aqueous solutions using mixed solvents was investigated.Various extractants and diluents were evaluated,and the effects of volume ratio of extractant to diluent,initial p H,initial concentration of naphthalene-2-ol in aqueous solution,extraction time,temperature,volume ratio of organic phase to aqueous phase（O/A）,stirring rate and extraction stages,on extraction efficiency were examined separately.Regeneration and reuse of the spent extractant were also investigated.Results showed that tributyl phosphate（TBP） achieved 98% extraction efficiency for naphthalene-2-ol in a single stage extraction,the highest among the 12 extractants evaluated.Extraction efficiency was optimized when cyclohexane and n-octane were used as diluents.The solvent combination of 20% TBP,20% n-octanol and 60% cyclohexane（V/V） obtained the maximum extraction efficiency for naphthalene-2-ol,99.3%,within 20 min using three cross-current extraction stages under the following extraction conditions：O/A ratio of 1：1,initial p H of 3,25°C and stirring rate of 150 r/min.Recovery of mixed solvents was achieved by using 15%（W/W） Na OH solution at an O：A ratio of 1：1 and a contact time of 15 min.The mixed solvents achieved an extraction capacity for naphthalene-2-ol stably higher than90% during five cycles after regeneration.