الفهرس 
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Abstract
The present study aims to investigate thoroughly the factors affecting the removal rate of Cr(VI) by electro-coagulation technique, in a batch reactor, using a new cell design with vertical oriented iron fins anode and tubular iron cathode. Variables studied on the removal efficiency of Cr(VI) were:(1) Current density, (5, 10, 20, 30, 40 mA/cm2).(2) Initial Cr(VI) concentration, (500, 1000, and 1500 ppm).(3) Rotation speed of the anode, (0, 100, 200, 300 and 400 rpm). (4) Anode fins height, (0, 1, 2, 3 and 4 mm). (5) Anode orientation, (vertical and horizontal).The study revealed the following results: The present work has shown that the performance of the cell with vertically oriented anode is superior to the horizontal anode in removal and reduction of Cr+6 and that related to the problem of current distribution at the surface of horizontal anode. The upper half of the horizontal cylinder anode laying above the cathode does not receive the sufficient current. Accordingly the amount of Fe+2 & Fe+3 dissolved is less than that of the vertical orients, where the current distribution is more uniform. The study revealed that the removal rate of Cr+6 increases with increasing (the current density, anode fins length), and decreasing with increasing initial Cr+6 concentration. The present study recommended that no mechanical stirring is preferred in the design of electro-coagulation reactors because no significant effect on the rate of Cr(VI) removal by changing in the rotation speed of anode. Nevertheless at vigorous stirring of solution caused decreasing of Cr(VI) removal because it dispersed the coagulated Cr(VI) on iron hydro-oxide Fe(OH)3.