Use of sodium carboxylates in the removal of metal and dye by ionic flocculation
Sodium carboxylates, dye removal, metal removal, ionic flocculation.
The presence of heavy metals and dyes in waste water is dangerous and very toxic to the ecosystem and human life, especially at levels above the allowed limit. Both pollutants have resistance to biodegradation, causing serious damage to living organisms and photosynthetic activities. Therefore, it is necessary to use treatment methods that can remove these pollutants to acceptable levels. The use of surfactants can be an alternative in the removal of these pollutants, the present work used ionic flocculation in the removal of copper ions using sodium hexadecanoate, through an innovative approach of the process, identifying the Krafft point as a limiting factor for ionic flocculation occurs. The thermodynamic parameters and a statistical design of the copper ion removal process were evaluated. It was possible to remove about 95% of the copper ions using a surfactant/metal molar ratio of 2, the pH of 4.6 and the temperature of 60 ° C. The effect of the addition of anionic surfactant soap base on the removal of ionic dyes was also studied. The use of this surfactant in the process of precipitation removal, ionic flocculation and in a process combining the ionic flocculation with the liquid-liquid extraction was evaluated. The addition of surfactant to the liquid-liquid extraction process increased the removal efficiency from 26% to 91%. Carboxylates of different chain lengths were used to remove Acid Red 57 by ionic flocculation, and it was observed that the percentage of dye removed and the interfacial properties were influenced by both the chain length of the surfactant and the micellar form. In addition, a study of systems containing mixed carboxylate sodium micelles was carried out, from the determination of the micellar composition and the interfacial properties. The variation of the molar composition of the mixture directly influenced the molar composition of the micelle, the surface parameters and the micelle shape. Increasing the amount of the higher chain surfactant the micelle passed from the lamellar form to cylindrical form.