Concentration of anionic surfactants from aqueous solutions on sorbents of various nature
- PDF / 133,027 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 63 Downloads / 216 Views
1311
Concentration of anionic surfactants from aqueous solutions on sorbents of various nature* L. P. Bondareva and A. G. Prushinskaya Voronezh State University of Engineering Technologies, 19 prosp. Revolutsii, 394036 Voronezh, Russian Federation. E-mail: [email protected] The sorption isotherms of anionic surfactants (AS) from the aqueous solution on eight polar and nonpolar sorbents were obtained. The equilibrium characteristics of sorption were determined. The SV-50 activated carbon is recommended for the effective recovery of AS based on the values of maximum adsorption and concentration equilibrium constants. It has been established that, when the content of AS is much higher than the maximum permissible concentrations, adsorption proceeds via a monomolecular mechanism, and the onset of multilayer formation corresponds to half of the critical micelle concentration. A sorbent layer consisting of activated carbon SV-50 and ion exchange fiber FIBAN AK-22-1 is proposed for the concentration of AS from aqueous solutions. 0.1 M Solution of sodium sulfate is selected as a solution for elution. The concentration was carried out using sodium dodecyl sulfate as an example. An elution curve was obtained, and the characteristics of the concentration were calculated for AS. The proposed sorption extraction allows to reduce the detection limit of AS for the determination by ion-selective electrodes. Key words: anionic surfactant, adsoption, activated carbon, concentration.
Continuous monitoring of the content of pollutants in natural waters requires the improvement of methods for their determination. Organic compounds and, first of all, the most common pollutants, namely, anionic surfactants (AS) have a negative effect on the biosphere. Even a slight excess of the maximum permissible concentration (MPC) level of these substances negatively affects the human body and aquatic ecosystems in general, preventing oxygen saturation of the water and aggressively affecting living organisms.1 Extraction-photometric method2 is widely used for determination of AS in aqueous solutions, but the method shows high accuracy of determination, is laborious and has a range of detectable concentrations below the MPC level. Potentiometric, fluorometric, and chromatographic analysis methods3—5 are less commonly used. The potentiometric method is the simplest and most expressive, but the existing ion-selective electrodes are able to determine the concentration of anionic surfactants only above the MPC. This problem can be eliminated by preliminary sorption concentration of the substance. Due to amphiphilic properties, AS are able to be retained by sorbents of various nature. According to the polarization equalization rule of P. A. Rebinder,6 during * Based on the materials of the XXI Mendeleev Congress on General and Applied Chemistry (September 9—13, 2019, St. Petersburg, Russia).
adsorption from a polar liquid, a surfactant is displaced onto the surface of a less polar solid phase to form a monomolecular adsorption layer with hydrocarbon radicals or
Data Loading...
