Title: Removal of Chromium from Wastewater by Electrochemical Techniques
Author : Doaa El-Sayed Abd El-Halim Hassan Youssef
Collection : M.Sc. Chemistry
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 use: 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.
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