A Technology Of Recovering A Surfactant At A High Concentration By Intensifying Foam Drainage Of The Synergic Effects Of Temperature And Component On Foam Separation

Foam separation is one of the most economic and effective technologies to treat the wastewaters. However when a surfactant concentration is equal to or more than its critical micelle concentration(CMC), its enrichment ratio will decrease rapidly. So the synergic effects of temperature and component of intensifying foam drainage in foam separation were studied to recover the surfactant at a high concentration from its wasterwater.In this paper, the synergic effects of temperature and a column with spiral interal component were studied to intensify foam drainage to treat the cetyltrimethyl ammonium bromide(CTAB) at a high concentration. A CTAB enrichment ratio of 4.05 was obtained by using the column with spiral interal component under the optimal conditions of temperature 70 oC, volumetric air flow rate 50 mL/min, liquid loading volume 300 mL when the CTAB concentration in its aqueous solution was 1.55 g/L. In order to further improve the enrichment ratio of CTAB, the synergic effects of temperature and a column with vertical ellipsoid-shaped foam channel(VEC) of intensifying foam drainage were studied by a two-stage foam separation technology to recover CTAB and SDBS at high concentrations from their aqueous solution. A high CTAB enrichment ratio of 7.03 was obtained under the optimal conditions of concentration 3.1 g/L, temperature 60 oC, volumetric air flow rate 100 m L/min and liquid loading volume 300 m L. By this technology, the recovery percentage of CTAB reached 99.8% and the CTAB concentrations in the residual solution and foamate were 0.031 g/L and 21.8 g/L, respectively. Under the same conditions, the SDBS concentrations in the residual solution and foamate were 0.154 g/L and 34.2 g/L, respectively.Though a high concentration in the foamate could be obtained by using the two-stage foam separation technology, the concentration in the residual solution was still high. Therefore, a three-stage foam separation technology was developed to further decrease the concentration in the residual solution. The first stage used a column with VEC under the optimal conditions of temperature 60 oC, volumetric air flow rate 100 mL/min, liquid loading volume 300 mL and pH 7.2. The second and third stages used conventional columns under the conditions of temperatures of 60 oC and 25 oC, the volumetric gas velocities of 170 mL/min and 650 m L/min, respectively. Under these conditions, A high sodium dodecylbenzene sulfonate(SDBS) enrichment ratio of 26.3 was obtained when the SDBS concentration in its wastewater was 1.3 g/L. The recovery percentage could reach as high as 99.0% and the concentrations in the foamate and residual solution were 34.2 g/L and 0.015 g/L, respectively.