الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 206 |  |  |
| | | from | 206 | | |
Abstract
Effluent discharge from insecticide industries may contain methomyl. Removal of methomyl from the effluent by anodic oxidation, as well as electrocoagulation was carried out using three different electrochemical cells. Namely: unstirred parallel plate electrodes, rotating cylinder anode and fixed bed electrochemical reactor.
The first cell (unstirred parallel plate cell) consists of stainless steel or aluminum anode and stainless steel plate as a cathode. The process was followed up by measuring the chemical oxygen demand (COD) during the electrolysis at different parameters e.g. current density, action time, sodium chloride concentrations, intensity and coil position of magnetic field and pollutant initial concentrations.
The optimum condition for COD removal was found using current density of 20 mA/cm2 and 30 mA/cm2 for stainless steel and aluminum anode respectively at 25 o C. It was found that after 120 min. of reaction time, the maximum removal of COD about 91.4% and 86.3% using stainless steel and aluminum electrode respectively. In this study using parallel plates configuration cell, the optimum conditions were suggested as, Stainless steel anode, NaCl concentration =3.5 g/l, , CD = 20 mA/cm2, Magnetic flied= 0.029 Tesla vertical position, high concentration was proper in order to minimize the power consumption.
The second cell (rotating cylindrical anode) consists of rotating variable speed cylindrical anodes stainless steel or aluminum. Variables studied were time, current density, anode rotating speed, sodium chloride concentrations, intensity and coil position of magnetic field and methomyl initial concentrations. It was found that methomyl removal increase with increasing rpm for a certain limits of anode speed range from 200 to 400 rpm and decrease again with increase of anode speed for maximum 600 rpm available speed. For achieving 100% removal percentage on rpm of 400 in case of stainless steel anode after 80 min. of start experimental steps. While achievement of removal maximum in case of Aluminum anode was observed after 120 min. at removal efficiency 85% under the same conditions. So that the optimum conditions were suggested as, Stainless steel anode, NaCl concentration =3.5 g/l, CD = 40 mA/cm2, Magnetic field= 0.029 Tesla vertical position, high initial concentration was proper in order to minimize the power consumption.
In the third cell (fixed bed electrochemical cell) two types of anodic fixed bed pellets (stainless steel and aluminum pellets) were used as anodic electrode and the cathode was stainless steel screen. Variables studied were initial methomyl concentration, anode pellet diameter applied current density and solution flow rate (operation was once through without circulation). The optimum conditions for the removal of methomyl were achieved in case of using Al anode at current density = 15 mA/cm2, NaCl concentration = 3.5 g/L, flow rate ranged of 20-40 ml/min., magnetic intensity of 0.029 Tesla and initial concentrations of methomyl were 500 ppm and 50 ppm. While in case of using stainless steel (SS) anode achievement at current density = 10 mA/cm2, NaCl concentration = 3.5 g/l, flow rate ranged of 20-30 ml/min. magnetic intensity of 0.029 Tesla and initial concentrations of methomyl were 500 ppm and 50 ppm. Using SS. anode consumes lower values of power than Al anode at the flow rate changes from 5 to 70 ml/min., the study led to consider the optimum conditions in that type of electrochemical reactor if SS. used as anode and the initial methomyl concentration 500 ppm (high strength) the flow rates apply have to range from 20 to 50 ml/min. and if the initial concentration of methomyl 50 ppm (low strength) the flow rate have to range from 20 to 60 ml/min.