Advanced oxidation of hypophosphite and phosphite using a UV/H2O2 process

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes

Background:

• Hypophosphite and phosphite are common contaminants in industrial wastewater, particularly from electroless nickel plating.
• Conventional treatment methods may be insufficient for complete removal of these compounds.
• Advanced Oxidation Processes (AOPs) offer potential for effective pollutant degradation.

Purpose of the Study:

• To investigate the efficacy of the ultraviolet (UV)/hydrogen peroxide (H2O2) process for oxidizing hypophosphite and phosphite.
• To evaluate the influence of operational parameters on the oxidation efficiency.
• To assess the applicability of the UV/H2O2 process for real industrial wastewater treatment.

Main Methods:

• Laboratory-scale batch photoreactor experiments were conducted.
• The effects of H2O2 dosage, H2O2 feeding mode (batch vs. continuous), and initial solution pH were systematically studied.
• Synthesized and real wastewater samples from the electroless nickel plating industry were used.

Main Results:

• The UV/H2O2 process demonstrated high efficiency in oxidizing both hypophosphite and phosphite, while UV or H2O2 alone showed minimal effect.
• Continuous feeding of H2O2 maximized the reaction rate.
• The process was effective across a broad pH range (5-11).
• Complete oxidation of hypophosphite and phosphite was achieved within 60 minutes in real wastewater, with over 90% chemical oxygen demand removal obtained after 90 minutes.

Conclusions:

• The UV/H2O2 process is a powerful and environmentally friendly method for treating wastewater containing hypophosphite and phosphite.
• The process effectively oxidizes these contaminants to phosphate without requiring additional catalysts.
• This AOP presents a viable solution for industrial wastewater remediation.