Hamzah, B. et al. 2018. Mercury(II) extraction from solution with W/O type of liquid membrane emulsion using surfactant combination (span-80 + span-20) and 1-phenyl-3-methyl-4- benzoyl-5 -pyrazolone as carrier of cation. International Journal of Engineering & Technology. 7, 4 (Dec. 2018), 4278–4281. DOI:https://doi.org/10.14419/ijet.v7i4.17440.