RESUMO
The aim of this work was to efficiently remove cobalt (Co) from aqueous solutions by using a novel Electromembrane Extraction (EME) technique. This novel electrochemical cell design featured two distinct glass chambers, incorporating a Supported Liquid Membrane (SLM) composed of a polypropylene flat membrane saturated with 1-octanol and a carrier substance, as well as electrodes constructed from graphite and stainless steel. The investigation covered an exploration of various effective parameters like, carrier type, voltage across the cell, donor solution pH, and the initial Co concentration, with the overarching goal of comprehending their individual effect on Co removal efficiency. Notably, two different carriers, tris(2-ethylhexyl) phosphate (TEHP) and bis(2-ethylhexyl) phosphate (DEHP), were systematically evaluated in combination with 1-octanol. The findings underscored the pivotal role of the cell voltage in significantly enhancing the mass transfer rate of cobalt across the membrane, thereby advancing the effectiveness of the removal process. After a comprehensive optimization process, the optimal operating conditions were established as follows: employing 1-octanol with 1.0 % v/v bis(2-ethylhexyl) phosphate as a carrier, applying a voltage of 60 V, maintaining an initial pH of 5, utilizing an initial cobalt concentration of 15 mg/L, conducting an extraction for 6 h, and employing a stirring rate of 1000 rpm. Remarkably, these conditions led to the attainment of an impressive removal efficiency of 87 %. In stark contrast, when no voltage was applied, the removal efficiency did not surpass 40 %. This underscores the pivotal role of the applied voltage in enhancing the cobalt removal process under the specified conditions.
RESUMO
In the present study a sequential process composed of electrocoagulation (EC) followed by electrooxidation (EO) was utilized at the laboratory scale to remove the chemical oxygen demand (COD) from wastewater generated in Iraqi vegetable oil refinery plant.in the EC, impacts of operating variables such as current density (10-30 mA cm-2) and pH (4-10),and EC time (30-90 min) on the COD removal (RE%) were investigated using response surface methodology (RSM) based on Box- Behnken design(BBD). a mathematical correlation that relates the operating factors with RE% was developed and its regression coefficient was 99.02% confirming the significant of the model. Response surface plots showed that RE% increased with increasing current density and time while it decreased with increasing pH. The optimum removal with a lower cost for EC process were achieved at current density of 30mA/cm2, pH of 4, and electrolysis time of 90 min in which RE% of 69.19% was obtained with requirement of 0.513kWh/kg COD as specific energy consumption (SEC). The effluent exit from EC was treated by EO for a period of 240min at a current density of 30mA/cm2 and an initial pH value of 4 to obtain RE% of 96% at SEC of 1.554 kWh/kg COD. Combining EC with EO resulted in a total RE% of 98.72% and a total SEC of 2.067 kWh/kg COD. Based on the results of present study, the applicability of a sequential electrocoagulation-electrooxidation process for treatment vegetable oil wastewaters is feasible.