Floculação iônica através de tensoativos aniônicos na remoção de cobre e corantes

Abstract

The presence of heavy metals and dyes in industrial wastewater 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 may be a viable alternative in the removal of these pollutants. In this work, ionic flocculation was used to remove copper ions by sodium hexadecanoate, through an innovative process approach, identifying the Krafft point as a limiting factor to carry out the ionic flocculation. Thermodynamic parameters were evaluated and a statistical design of the copper ion removal process was made. About 95% of the copper ions could be removed using a surfactant/metal molar ratio of 2, pH 4.6 and temperature 60 ° C. The use of the anionic surfactant soap base in 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 shape. In addition, a study of mixed micelles systems, formed by the binary mixture of sodium dodecanoate and sodium hexadecanoate, was performed from the determination of micellar composition and interfacial properties. The variation of the molar composition of the mixture directly influenced the molar composition of the micelle, surface parameters and micelle shape. By increasing the amount of the longer chain surfactant the micelle changed from lamellar form to cylindrical form.