Taguchi-Based Process Optimization for Improving Iron Removal …
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3.2.3 Effect of Inter-electrode Distance
The effective electrode area along with the inter-electrode distance between the
cathode and the anode has a significant role in the electrocoagulation process.
Increase in inter-electrode distance decreases the S/N ratio and it is shown in Fig. 4.
This is due to the fact that as the applied voltage is constant as the inter-electrode
distance increases the resistance for the applied current also increases leading to poor
coagulation formation. The maximum S/N ratio was observed at 8 mm (S/N ratio:
37.02) and the least of 35.99 at 14 mm. The electrode setup plays a significant role
in the effective surface area and also the inter-electrode distance. The equation that
governs the variation in the voltage drop (ηIR) is:
ηI R = I ·
d
s ∗ k
(4)
where, I = current (A), d = distance between two electrode (m), S = active
anode surface (m
2 ), k = specific conductivity (103 mS/m) (Ghosh et al. 2008).
From the above equation, it can be inferred that at constant anodic surface area
and conductivity of the solution, voltage drop increases with the increase in interelectrode distance. The resistance between the electrodes and the distance between
them are directly related. Thus, with the increase in the inter-electrode distance the
electric current decreases and to achieve the required current intensity, the voltage
had to be increased.
3.2.4 Effect of pH
The solution pH plays a significant role in the autocatalytic disappearance of aqueous
Fe(II) with the incentive of iron removal in slightly basic (pH > 7) range. Electrocoagulation is believed to be a satisfactory technology due to the formation of more
OH
− ions in the electrolysis of water. In electrocoagulation where Al electrode is
used, it has been witnessed that at somewhat basic ambiance Al(OH) 3 precipitation
occurs and the sweep-flock mechanism dominates (Fig. 5).
From Fig. 5, we can evaluate that initial pH has not much effect on the removal of
iron from the solution. The S/N ratio lies from 36.56 to 36.73. However, maximum
removal was obtained at pH 6 with S/N ratio of 36.73.
3.2.5 Effect of Conductivity
In this study, conductivity was maintained using sodium chloride (NaCl) salt.
Conductivity increases the mobility of the ions present in the electrocoagulation
process. Addition of salt increases the conductivity of the solution, which was directly
influenced the cell voltage, energy consumption, and current efficiency in the electrolytic cell. The use of NaCl was also accompanied by the production of chloride
335
3.2.3 Effect of Inter-electrode Distance
The effective electrode area along with the inter-electrode distance between the
cathode and the anode has a significant role in the electrocoagulation process.
Increase in inter-electrode distance decreases the S/N ratio and it is shown in Fig. 4.
This is due to the fact that as the applied voltage is constant as the inter-electrode
distance increases the resistance for the applied current also increases leading to poor
coagulation formation. The maximum S/N ratio was observed at 8 mm (S/N ratio:
37.02) and the least of 35.99 at 14 mm. The electrode setup plays a significant role
in the effective surface area and also the inter-electrode distance. The equation that
governs the variation in the voltage drop (ηIR) is:
ηI R = I ·
d
s ∗ k
(4)
where, I = current (A), d = distance between two electrode (m), S = active
anode surface (m
2 ), k = specific conductivity (103 mS/m) (Ghosh et al. 2008).
From the above equation, it can be inferred that at constant anodic surface area
and conductivity of the solution, voltage drop increases with the increase in interelectrode distance. The resistance between the electrodes and the distance between
them are directly related. Thus, with the increase in the inter-electrode distance the
electric current decreases and to achieve the required current intensity, the voltage
had to be increased.
3.2.4 Effect of pH
The solution pH plays a significant role in the autocatalytic disappearance of aqueous
Fe(II) with the incentive of iron removal in slightly basic (pH > 7) range. Electrocoagulation is believed to be a satisfactory technology due to the formation of more
OH
− ions in the electrolysis of water. In electrocoagulation where Al electrode is
used, it has been witnessed that at somewhat basic ambiance Al(OH) 3 precipitation
occurs and the sweep-flock mechanism dominates (Fig. 5).
From Fig. 5, we can evaluate that initial pH has not much effect on the removal of
iron from the solution. The S/N ratio lies from 36.56 to 36.73. However, maximum
removal was obtained at pH 6 with S/N ratio of 36.73.
3.2.5 Effect of Conductivity
In this study, conductivity was maintained using sodium chloride (NaCl) salt.
Conductivity increases the mobility of the ions present in the electrocoagulation
process. Addition of salt increases the conductivity of the solution, which was directly
influenced the cell voltage, energy consumption, and current efficiency in the electrolytic cell. The use of NaCl was also accompanied by the production of chloride