Low fouling sulphonated carbon soot-polysulphone membranes for rapid dehydration of stabilized oil-water emulsions

Severe fouling is observed during water recovery from oil in water emulsions. Mixed-matrix membranes include hydrophilic additives, such as metal oxide nanoparticles, decrease fouling tendencies. However, most metal oxide nanoparticles are either expensive or synthesized from hazardous precursors. Candle soot is an inexpensive source of almost monodisperse carbon nanoparticles, but it is superhydrophobic. We report hydrophilization of candle soot by facile one-pot sulphonation. Addition of sulphonated candle soot (SCS) to polysulphone decreased water contact angle of polysulphone membranes to 31 degrees. SCS addition increased surface energy and gave antifouling surface. DI water flux of SCS-1.0 membranes was 314 LMH/bar, while fouled flux increased by over 2.5 fold for separation of 5% diesel-water emulsions with greater than 99.99% rejection. An optimum exists between the amount of SCS filler and antifouling potential. Membranes with 0.75% SCS additive achieved highest flux recovery of 92% of DI water flux on water flushing. Long term studies showed excellent stability and membrane flux recovery on flushing. Thus, membranes with SCS exhibit high degree of resistance for heavily fouling stabilized oil-water emulsions with high oil content. These membranes exhibit excellent potential for further large scale development and for wide range of applications.