Arsenic removal from drinking water by electrocoagulation using iron electrodes

Arsenic removal from drinking water was investigated using electrocoagulation (EC) followed by filtration. A sand filter was used to remove flocs generated in the EC process. Experiments were performed in a batch electrochemical reactor using iron electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as current density (1.5–9.0 mA cm−2), initial arsenic concentration (50–500 μg L−1), operating time (0–15 min), electrode surface area (266–665 cm2), and sodium chloride concentrations (0.01 and 0.02M) were examined. The EC process was able to decrease the residual arsenic concentration to less than 10 μg L−1. Optimum operating conditions were determined as an operating time of 5 min and current density of 4.5 mA cm−2 at pH of 7. The optimum electrode surface area for arsenic removal was found to be 266 cm2 taking into consideration cost effectiveness. The residual iron concentration increased with increasing residence time, and maximum residual iron value was measured as 287 μg L−1 for electrode surface area of 266 cm2. The addition of sodium chloride had no significant effect on residual arsenic concentration, but an increase in current density was observed.