Size and structure evolution of kaolin-Al(OH)3 flocs in the electroflocculation process: a study using static light...

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Electrochemistry

Background:

• Electroflocculation (EF) is an emerging alternative to conventional coagulation/flocculation for water treatment.
• The process involves electrical current application, leading to in-situ coagulant generation and unique electrochemical conditions.
• Competing redox reactions, primarily water electrolysis, influence pH and shift coagulation mechanisms.

Purpose of the Study:

• To investigate the size and structural evolution of kaolin-aluminum hydroxide flocs formed during electroflocculation.
• To elucidate the kinetic aspects of floc formation in the EF process.
• To understand the impact of operational parameters on floc characteristics.

Main Methods:

• Utilized static light scattering techniques to analyze floc size and structure.
• Operated a batch electroflocculation cell with concentric stainless steel cathode and aluminum anode.
• Applied constant electrical currents ranging from 0.042A to 0.22A, with analyses at set time intervals.

Main Results:

• Electroflocculation produced flocs with diverse growth rates and structural properties, dependent on operating conditions.
• Observed sigmoidal growth patterns with a linear correlation between floc growth rate and applied current.
• Floc growth rate showed dependency on initial pH and aluminum dosing, particularly within the optimal sweep floc regime.
• All formed flocs were fragile, exhibiting compaction and structural changes during growth.

Conclusions:

• Electroflocculation is capable of generating flocs with controllable size and structural characteristics.
• The study provides the first report on the size and structural evolution of flocs in the electroflocculation process.
• Findings highlight the potential of EF for tailored water treatment applications based on floc properties.