Separation performances of a multi-stage continuous bubble cap foam fractionation column

ABSTRACT

A multi-stage continuous bubble cap foam fractionation column was developed to achieve high separation performance using cetyltrimethyl ammonium bromide (CTAB) as a model surfactant. The effect of design and operating parameters on the overall performances was investigated at a steady state. The results illustrated that with increasing the airflow rate, the enrichment ratio of CTAB was decreased and its recovery percentage increased. When the feeding concentration of CTAB was greater than 0.2 g/L, the adsorption of CTAB at the gas-liquid interface was closed to equilibrium. Based on mass balances and equilibrium relationships, a new method of the number of theoretical stages by stage-to-stage calculation and graphics were presented on the foam fractionation column.

KEYWORDS:

• Foam fractionation
• bubble cap
• enrichment ratio
• recovery percentage

Nomenclature

Aconductivity value, μs/cm

Csurface-active substance concentration, g/L

C_Ffeeding concentration, g/L

C_n nth stage CTAB concentration, g/L

C_Qfoamate concentration, g/L

CTABcetyl trimethyl ammonium bromide

C_Weffluent concentration, g/L

${\mathrm{C}}_{\mathrm{n}}^{\ast }$effective concentration, g/L

d₃₂average bubble diameter, m

Eenrichment ratio

Ffeeding flow rate, L/min

H₀tray spacing, mm

Kadsorption constant

mnumber of bubbles

nstage number

N_fnumber of feeding stage

N_cnumber of bubble caps per tray

N_unumber of stages

Qfoamate flow rate, L/min

Q_gairflow rate, mL/min

Rrecovery percentage

Sspecific surface area, m²/min

Weffluent flow rate, L/min

Greek letter

$\mathrm{\Gamma }$Surface excess, g/m²

Additional information

Funding

This work was financially supported by Key Basic Research Program of Hebei, China (No. 16964002D).