Enhancement of oil droplet removal from o/w emulsion by adding methylated milk casein in flotation technique

Abstract

To clarify oil-in-water (o/w) emulsion, flotation experiments were conducted by adding methylated milk casein (MeCS), which is a biodegradable flocculant. Emulsion used in this study was prepared by ultrasonic emulsification of heavy oil (bunker-A) and sodium dodecyl sulfate (SDS) solution. It was found that addition of MeCS enhanced clarification of oil droplets from o/w emulsion solution due to floc formation by adding MeCS. An optimum dosage of MeCS to form effective floc was determined by the relative turbidity in a clarification experiment. In flotation experiments, clarification ability was evaluated by removal rate constant, k , obtained by fitting of turbidity data to a pseudo-first-order kinetic equation. In case of varying dosage of MeCS and keeping superficial gas velocity, U g , at constant value (5.48 × 10 −2 cm/s), removal rate was greatly influenced by amount of MeCS dosage. The maximum value of k was also obtained at the most optimum dosage of MeCS, and k decreased with adding lesser or larger amount of MeCS than the optimum dosage. On the other hand, in case of keeping the dosage of MeCS at the optimum dosage, and varying superficial gas velocity, up to U g < ca. 0.2 cm/s, k was increased with increasing superficial gas velocity, and increase in removal rate of oil droplets was mostly proportional with increase in bubble surface area production rate. 

Removal kinetic model of oil droplet from o/w emulsion by adding methylated milk casein in flotation

“…The procedure of flocculation experiment is similar to that in the previous study (Maruyama et al, 2009). This experiment was conducted to determine the optimum amount of MeCS added to the emulsion.…”

“…Preparation method of o/w emulsion was almost the same manner in the previous study (Maruyama et al, 2009). In the most experiments, 1 mL of heavy oil was added to with laser scattering size distribution analyzer (LA-300 HORIBA, Ltd., Japan).…”

“…Because wastewater including o/w emulsion has influences on aqueous environments, for removal of oil droplets from aqueous environments, several techniques have been proposed, such as filtration (Belkacem et al, 1999;Hilal et al, 2004;Lobo et al, 2006;Hu et al, 2007), chemical destabilization (Rios et al, 1998), dissolved air flotation (Abo-El Ela et al, 1980;Fukushi et al, 1998;Zouboulis et al, 2000;Al-Shamrani et al, 2002a;Al-Shamrani et al, 2002b), electrocoagulation (Carmona et al, 2006;Cañizares et al, 2008), flotation (Maruyama et al, 2009) and so on.…”

“…As one of these techniques, the authors proposed flotation involving adding flocculant to o/w emulsion for enhancement of removal (Maruyama et al, 2009). In the previous study, the authors used biodegradable methylated milk casein (MeCS) as flocculant, which is a poly-cationic polymer, and reported that addition of MeCS to oil droplets charged negatively enhanced removal of the oil droplets as flocs from o/w emulsion.…”

“…In the previous study, the authors used biodegradable methylated milk casein (MeCS) as flocculant, which is a poly-cationic polymer, and reported that addition of MeCS to oil droplets charged negatively enhanced removal of the oil droplets as flocs from o/w emulsion. The removal kinetics could be evaluated by adopting the pseudo first-order kinetic equation (Maruyama et al, 2009). However, the rate constant, k, in the previous study is practical coefficient and lacks physical or physicochemical meaning.…”