Electrocoagulation using aluminium anodes activated with Mg, In and Zn alloying elements.

Area of Science:

• Environmental Engineering
• Materials Science
• Electrochemistry

Background:

• Industrial wastewater often contains a complex mixture of pollutants, including phosphates, heavy metals like zinc, and organic dyes.
• Effective removal of these contaminants is crucial for environmental protection and public health.
• Electrochemical methods offer a promising approach for simultaneous pollutant removal.

Purpose of the Study:

• To investigate the simultaneous removal of phosphates, Zn²⁺, and Orange II from synthetic wastewater using Al-Mg and Al-Zn-In alloy anodes.
• To compare the efficiency and energy consumption of the two alloy types for pollutant removal.
• To elucidate the mechanisms behind the removal of each pollutant by the alloys.

Main Methods:

• Electrochemical treatment was performed using Al-Mg and Al-Zn-In alloys as anodes in synthetic wastewater.
• Experiments were conducted at a constant current density of 11.7 mA cm^-2 and a surface area to volume ratio of 19.0 m^-1.
• Pollutant concentrations were monitored, and removal efficiencies were calculated. Polarization plots were used to assess anode behavior.

Main Results:

• The Al-Zn-In alloy achieved higher removal efficiencies: 95-96% for phosphate, 99% for Zn²⁺, and 88-96% for Orange II.
• The Al-Mg alloy showed lower efficiencies: 89-93% for phosphate, 96% for Zn²⁺, and 50-60% for Orange II.
• The Al-Zn-In anode exhibited less passive behavior and lower energy demand (1.30 kWh m^-3) compared to Al-Mg (2.55 kWh m^-3).

Conclusions:

• Al-Zn-In alloy is more effective than Al-Mg for the simultaneous removal of phosphates, Zn²⁺, and Orange II from wastewater.
• Phosphate and Orange II removal is facilitated by the generation of cationic polynuclear aluminum species.
• Zn²⁺ removal occurs through the precipitation of insoluble Zn(OH)₂.