Effects of alternating and direct current in electrocoagulation process on the removal of fluoride from water

Abstract

BACKGROUND: When direct current (DC) is used in electrocoagulation processes, an impermeable oxide layer may form on the cathode and corrosion of the anode may occur due to oxidation. This prevents effective current transfer between the anode and cathode, so the efficiency of the electrocoagulation process declines. These disadvantages of DC have been reduced by adopting alternating current (AC). The main objective of this study is to investigate the effects of AC and DC on the removal of fluoride from water using an aluminum alloy as anode and cathode.

Arsenic and fluoride contaminated groundwaters: A review of current technologies for contaminants removal

“…A primary mechanism of coagulation and electrocoagulation was explained in sections 3.1.1 and 3.2.1. Vasudevan et al (2011) studied the effect of various coexisting ions on the removal F using electrocoagulation. The solutions with F concentration of 5e20 mg/L were treated with As(V) (0e5.0 mg/L) as a competing ion.…”

Evaluation of electrocoagulation for the pre-treatment of coal seam water

“…As the iron concentration was further elevated the costs rapidly increased to values which were probably commercially unacceptable. Vasudevan et al [59] also confirmed the applicability of electrocoagulation for reduction of iron levels in water. Notably, they investigated the effect of co-existing ions in solution in relation to inhibition of iron removal.…”

“…Likewise, Vasudevan et al [59] also found up to 99.6% reduction of iron from pure water with EC at a current density of 0.06 A/dm 2 and a pH of 7.0 using zinc electrodes. This behaviour was probably due to the very low solubility of Iron (III) hydroxide Fe(OH) 3 .…”

Evaluation of Non-Conventional Coagulants to Remove Turbidity from Water

“…As it was expected, the plots of the inverse concentration of suspended solids versus time are linear; it means that the coagulation-flocculation process can be explained as a second-order reaction. Other authors have found second-order kinetics when removing pollutants from water, such as fluoride (Vasudevan et al 2011), arsenic (V) (Urik et al 2009) or phosphates (Vasudevan et al 2009). Coagulants employed must present high efficiency rates, as there can be present in waters particles of different sizes and different settling characteristics, such as flocs and aggregates with significant differences in their transport behaviours (Droppo et al 2005).…”