Enhanced separation of nitrophenols from wastewater by using ammonium ionic liquid with thiocyanate anion in supported liquid membrane

Abstract

ABSTRACT The present investigation deals with separation of various types of nitrophenols using SILM technique. Several ionic liquids were developed and the SILM parameters such as role of ILs, feed and strip phase concentration, wastewater pH, salt effect and mixture of pollutants were thoroughly investigated. The percentage extraction and stripping, flux, apparent rate constants and selectivity were evaluated. The selected ammonium IL being more polar than the imidazolium IL showed better separation of 2-nitrophenol. The SILM constituting an ammonium IL with SCN anion exhibited extraction efficiency of >96% and Ka: 0.264 h−1. The change in feed concentration showed maximum transport of nitrophenol at 300 ppm concentration (Ka: 0.673 h−1). The membranes were repeated for 4 cycles which demonstrated good stability for runs of more than 48 hours. The selectivity of 2-nitrophenol, 2,4-dinitrophenol, 2,4,6- trinitrophenol over nitrobenzene was 26, 36 and 58, respectively. The morphology of membranes was studied by using FTIR and FE-SEM and the transport mechanism was elucidated. With the optimized parameters, a concentration factor of 7 can be achieved in the present SILM system. The application of SILM including ammonium IL with SCN anion shows a promising potential for the treatment of various types of nitrophenol bearing wastewater.