Decomplexation of electroplating wastewater by ozone-based advanced oxidation process

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes

Background:

• Electroplating wastewater poses significant environmental and health risks due to heavy metal contamination.
• Traditional precipitation methods are ineffective for removing complexed metals without prior decomplexation.
• Ethylenediaminetetraacetic acid (EDTA) and citric acid are common complexing agents in electroplating wastewater.

Purpose of the Study:

• To investigate and compare the performance of four ozone-based advanced oxidation processes (AOPs) for decomplexing electroplating wastewater.
• To evaluate the degradation and mineralization efficiencies of EDTA and citric acid using different AOPs.
• To determine the optimal AOP selection based on the specific target contaminant.

Main Methods:

• Four ozone-based AOPs were investigated: O3, O3/H2O2, O3/UV, and O3/H2O2/UV.
• EDTA and citric acid were used as model contaminants to represent complexed metals.
• Degradation and mineralization efficiencies were measured over a 60-minute treatment period.

Main Results:

• The O3/UV process achieved the highest degradation (65%) and mineralization (53%) of EDTA within 60 minutes.
• The O3/H2O2/UV process demonstrated the highest degradation (77%) and mineralization (56%) of citric acid in 60 minutes.
• Process efficiency varied depending on the specific contaminant and the AOP employed.

Conclusions:

• Ozone-based AOPs are effective for decomplexing and mineralizing contaminants in electroplating wastewater.
• The choice of AOP is crucial and depends on the nature of the target contaminant.
• O3/UV and O3/H2O2/UV offer efficient treatment solutions for specific complexed metals found in industrial effluents.