Extraction and enrichment of zinc from chloride media using emulsion liquid membrane: Emulsion stability and demulsification via heating-ultrasonic method.

Abstract

Emulsion liquid membrane (ELM) is highly efficient in heavy metal ion separation from wastewater. However, substantial effort is required to overcome the instability in the process. Hence, this research demonstrates the stability of water-in-oil-in-water (W/O/W) emulsion and demulsification for zinc recovery from chloride media. Iron (III) oxide (Fe2O3) nanoparticles were used as a solid stabilizer in the formation of water-in-oil (W/O) emulsion. Several operating parameters affecting the stability of W/O/W emulsion by means of breakage/swelling and globule size diameter were studied, such as organic-to-internal phase (O/I) ratio, agitation speed, time, and treatment ratio. The most stable formulated W/O/W emulsion was used in the demulsification process using heating-ultrasonic method. The study was conducted by manipulating the temperature, frequency, and time. Meanwhile, experiments on the effect of modifier type, carrier, and stripping agent concentration were carried out for zinc recovery. The most stable W/O/W emulsion was obtained at 1.35:1O/I ratio, 300 rpm agitation speed, 3 min agitation time, and 1:5 treatment ratio. Complete demulsification was achieved at a temperature of 50 °C, 40 kHz frequency, and 210 min contact time. At the best condition of 3% (w/v) 1-octanol, 0.03 M carrier concentration (D2EHPA/Cyanex 302), and 1.375 M acidic thiourea, approximately 93.14% zinc was extracted, and 4.65 times enrichment was obtained in the recovery phase. Hence, it can be concluded that enhancing the stability of emulsion could potentially make ELM applicable in the industry.