Treatment of 1,10-phenanthroline laboratory wastewater using the solar photo-Fenton process.

The red Fe(2+)-phenanthroline complex is the basis of a classical spectrophotometric method for determination of iron. Due to the toxicity of this complexing agent, direct disposal of the wastewaters generated in analytical laboratories is not environmentally safe. This work evaluates the use of the solar photo-Fenton process for the treatment of laboratory wastewaters containing phenanthroline. Firstly, the degradation of phenanthroline in water was evaluated at two concentration levels (0.1 and 0.01%, w/v) and the efficiencies of degradation using ferrioxalate (FeOx) and ferric nitrate were compared. The 0.01% w/v solution presented much higher mineralization, achieving 82% after 30min of solar irradiation with both iron sources. The solar photo-Fenton treatment of laboratory wastewater containing, in addition to phenanthroline, other organic compounds such as herbicides and 4-chlorophenol, equivalent to 4,500mgL(-1) total organic carbon (TOC) resulted in total degradation of phenanthroline and 25% TOC removal after 150min, in the presence of either FeOx or ferric nitrate. A ratio of 1:10 dilution of the residue increased mineralization in the presence of ferrioxalate, achieving 38% TOC removal after 120min, while use of ferric nitrate resulted in only 6% mineralization over the same period.