Removal of arsenic from wastewaters using electrocoagulation

Area of Science:

• Environmental Science
• Chemical Engineering

Background:

• Pharmaceutical industrial effluents often contain toxic arsenic species, including arsenite [As(III)] and arsenate [As(V)].
• Conventional treatment methods like chemical coagulation can be inefficient and generate sludge.

Purpose of the Study:

• To investigate the efficacy of electrocoagulation using aluminum, iron, and hybrid Al/Fe anodes for arsenic removal.
• To optimize parameters like pH, current density, and contact time for maximum arsenic removal efficiency.

Main Methods:

• Electrocoagulation experiments were conducted using sacrificial anodes made of aluminum, iron, and a hybrid Al/Fe combination.
• Various working parameters including pH, current density, contact time, and metal ion concentration were systematically studied.
• Performance was evaluated using synthetic samples and actual pharmaceutical industrial wastewater spiked with arsenic.

Main Results:

• Optimal arsenic removal was achieved at increased pH and higher current densities (0.0082 to 0.0816 mA cm⁻¹).
• Iron sacrificial electrodes demonstrated significantly higher removal efficiency compared to aluminum and hybrid Al/Fe electrodes.
• A pharmaceutical wastewater sample with 28 ppm arsenic was treated to 0.005 ppm within 15 minutes.

Conclusions:

• Electrocoagulation, particularly with iron electrodes, is a highly efficient and rapid method for removing arsenite and arsenate from pharmaceutical wastewater.
• This electrocoagulation technique offers a cleaner and faster alternative to conventional methods like chemical coagulation.