Experimental determination of liquid-liquid phase balance involving salts for the recovery of phenol from wastewater

Abstract

The search for alternative processes for minimizing pollutants, e.g., organic contaminants removal from wastewater, can be considered an interdisciplinary research topic. Among the group of contaminants released by chemical industries is the phenol, this compound is one of the most toxic contaminants and it is capable to cause environmental and health damages. It is under a severe environmental regulation for discharges or even accidental leaks, where maximum tolerable limit in the source stream is 0,5 ppm. This compound can be found in nature, but in cases of large volumes needs the industrial manufacturing is required. Thus, a preventive pollution strategy must consider environmental problems related to contamination of aqueous (or not) streams of wastewater. The data available for liquid-liquid phase equilibrium considering phenol removal from water is scarce. In this research an experimental study to determine liquid-liquid equilibrium for the system of project (phenol+water+salts+solvent) is proposed. The system (phenol+water) is being theoretically and computationally studied. This study requires binary interaction parameters and because the scarceness of data available in open literature a comparative approach with data obtained through commercial simulators using thermodynamics models (NRTL, UNIQUAC, etc) is not feasible. Another important issue is the possibility to evaluate the salts usage (MgCl2 e BaCl2) for increasing the ternary system heterogenic region (phenol+água+solvent) without decreasing in the distribution coefficient and selectivity. These salts were considered because their capability for increasing system solubility. Since systems are diluted, the liquid-liquid extraction can be applied for expected separation, thus experimental data are again required. A solvent (A) will be evaluated/studied, a “green” solvent environmentally safety will be preferentially considered. This solvent will be selected on basis of system miscibility behavior. The liquid-liquid extraction will be carried out at 25°C. The aim of this study is to propose a complete process of liquid-liquid extraction for separating phenol from wastewater streams, the main focus is to use experimental data for a regression of the parameters of equilibrium thermodynamic model and use this data for simulating extraction process applying Aspen Plus simulator. Thus, it will be expected to obtain an overall evaluation of phenol recovery process.