الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Chromium compounds are identified as highly toxic and potentially carcinogenic pollutants, they are mainly produced by activities such as cement, textiles, and leather tanning industries. With stricter environmental regulations imposed, advanced and cost effective teclmiques for the removal of chromium from wastewater become more and more important. Many processes have been developed for chromium removal such as adsorption, membrane separation, chemical precipitation, photocatalysis, etc. Electrocoagulation is an important water treatment teclmology that has been widely usee: for removing heavy metals and organic pollutants, it is also an efficient technique compared to other processes because it is cost effective, easy to operate and reduces the possibility of generation of secondary pollutants. The performance of electrocoagulation by iron electrodes for the treatment of aqueous solutions containing hexavalent chromium ions using a fixed bed electrochemical batch reactor was studied. A novel cell design consisted mainly of a circular batch cylindrical reactor that made of glass with 2 L capacity of aqueous solution. The cathode consisted of a circular horizontal iron plate that has a 11 Cm diameter and placed on the cell bottom; the back of it insulated with epoxy resin. A new anode design consisting of hex nuts was added and connected together with a thin rod of iron and placed above a perforated plastic sheet that located above the horizontal cathode. The anode-cathode distance was kept (I mm). The helical shape in the nuts increases the anode surface area (392 cnr’) and allows high chromium removal rate within very short coagulation time by using a very small value of electrical current and voltage so the power consumption and the operating cost will be saved. Parameters affecting the electrocoagulation process, such as initial hexavalent chromium concentration, applied current, Electrolyte [sodium chloride and sodium sulfate] concentration and initial pH of the solution were investigated. The results showed that: 1.Residual hexavalent chromium concentration increased with increasing initial hexavalent chromium concentration and decreased with increasing the applied current and initial pH of the solution, by Studying the effect of sodium chloride, it was found that residual hexavalent chromium concentration decreased with increasing sodium chloride concentration at first and then the residual hexavalent chromium concentration gradually increase. 2.Fe consumption decreases with increasing initial concentration of hexavalent
chromium, and increases with increasing initial pH of the solution and the current, by Studying the effect of sodium chloride, it was found that iron consumption decreases with increasing sodium chloride concentration from 0.5 to 1.5 giL. Beyond 1.5 g/L, the iron consumption increases.3. Energy consumption and the operating cost decreases with increasing initial
concentration of hexavalent chromium and sodium chloride concentration, and increases with increasing initial pH of the solution and the applied current. 4.The optimum conditions for the electrocoagulation process by using the present cell based on minimum residual hexavalent chromium concentration, energy consumption and operating cost was 100 mg of hexavalent chromium IL , 0.55 A, 1.5 g of sodium chloride/L and pH of 1.