| High salinity organic wastewater is difficult to deal espceially those with high organic compounds concentration and strong toxicity. Existing treatment methods difficult to reach the national requirements, the effective separation of salt and organic matter is the key to wastewater treatment. Multieffect evaporation, electrodialysis and reverse osmosis have been covered in separating of inorganic salt and organics that are rarely used in real project due to the cost and membrane pore blocking with organic matter. According to the theory of similar dissolve mutually, membrane extraction extract organic matter from water and currently used for separation and purification of some single organics, however its application is less related in isolating salt to organic components.In this paper, methyl silicone rubber membrane extraction system was applied to remove o-toluidine(o-T) and p-toluidine(p-T), which are common contaminants at high salinity water. Tube membrane can be used in extracting o-T and p-T with their single and binary systems based on flow rate, pH, tempreture, ionic strength of NaCl and feed concentration. The results obtained are listed as following:With membrane extraction, o-T and p-T can be processed expediently, the removal efficiency reached 95% and 96%, respectively. The recocery rate of o-T and p-T existed maximum when the feed flow rate was 9mL/min and 12mL/min which increased first and then decreased under velocity increased from 2mL/min to 20mL/min.The boundary layer resistance was minimum when Re of o-T andp-T were 12539.0 and 12532.8 no less than 12000. The flow changed from transition to turbulence and membrane resistance and desorption rates became the main factors of mass transfer. The effect of pH on the extraction process of o-toluidine and p-toluidine is large. The maximum extraction efficiency obtained at the pH is approximately 1, and mass flux descended linearly with pH. The removal rate of o-T increased and the removal rate of p-T decreased with increasing temperature. Polar difference was the main reason.Increase of NaCl could reduce the partition coefficient Kp of o-T and p-T between methyl silicone rubber and water, and the mass transfer flux increased with the mass driving force increasing. The feed concentration had little effect on membrane extraction efficiency when the value changed Og/L to 8 g/L. But production of plastic declined the selectivity of silicone rubber owing to high concentration.The aromatic amine mixed organic compounds(o-T and p-T) in high salt water was extracted by the methyl silicone rubber membrane. The total removal and recovery rate of aromatic amine were 87.95% and 68.14%. The single removal rate of o-T andp-T were 83.99% and 92.00%, recovery rate were 70.97%?65.24%. The Kp of p-T was bigger than o-T, resulting in a larger interaction force between methyl silicone rubber membrane and p-T. Therefore its removal rate was higher than that of o-T. But the diffusion coefficient Dm of p-T reduced as the large adsorption capacity, and the desorption rate declined, so the recovery rate was lower than that of o-T. The mass transfer rate of aromatic amine debased as the different coupling force between mixture and single component of o-T and p-T. Eventually, the treatment efficiency of mix organics was lower than that of single matter in the high salnity water.Research on aging process of methyl silicone rubber membrane suggestsed that the influence of acidity was greater than tempreture and salinity. The mechanical behavior and retention rate of Na+ satisfied the requirements of membrane after aging of 40d. The methyl silicone rubber membrane had advantages of long life and low replacement frequency.The studies provided new idea for high salinity organic wastewater, supplied new way to separating inorganic salts and organic matter, offered theoretical basis and analytical methods for the application and popularization of membrane extraction. |
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