Polysulphone microcapsules containing silicone oil for the removal of toxic volatile organics from water

Abstract

Removal of volatile organic contaminants (VOCs) from water is an important task for environmental protection. Silicone oil has many merits but can not be directly applied in extraction of VOCs due to its high viscosity, which can negatively affect the mass transfer. Therefore a new purification method with extractant microcapsules has been developed in this work. Polysulphone microcapsules containing silicone oil were prepared successfully using a solvent evaporation method. The mass transfer performance was determined with toluene as the recovered component and with the prepared microcapsules as the separation agent. Extraction equilibrium could be reached in ∼ 60 min. The maximum uptake of toluene was 24.5 mg g⁻¹ microcapsules. Microcapsules were reused four times and showed very good stability. Using microcapsules containing silicone oil as the separation agent, high and stable extraction capacity has been successfully achieved, especially without any phase dispersion and phase separation processes. It may be concluded that low energy will be required in the new separation process.

Key Words: :

• Microcapsule
• extraction
• solvent evaporation
• silicone oil
• VOC

Abbreviations
C	=	toluene concentration in microcapsules (kg m−3);
Cin	=	average concentration of toluene in microcapsules (kg m−3);
Cw	=	toluene concentration in aqueous phase (kg m−3);
D	=	distribution coefficient between microcapsule phase and aqueous phase;
DA	=	apparent diffusion coefficient of toluene in microcapsules (m2 s−1);
n	=	the amount of microcapsules;
N	=	mass transfer flux (kg s−1);
t	=	time (s);
r	=	radial coordinate, r = 0 − R (m);
V	=	volume of aqueous phase (m3)

Abbreviations
C	=	toluene concentration in microcapsules (kg m−3);
Cin	=	average concentration of toluene in microcapsules (kg m−3);
Cw	=	toluene concentration in aqueous phase (kg m−3);
D	=	distribution coefficient between microcapsule phase and aqueous phase;
DA	=	apparent diffusion coefficient of toluene in microcapsules (m2 s−1);
n	=	the amount of microcapsules;
N	=	mass transfer flux (kg s−1);
t	=	time (s);
r	=	radial coordinate, r = 0 − R (m);
V	=	volume of aqueous phase (m3)