Investigation of the parametar influences of UV/H2O2 process on humic acid degradation

Abstract

Degradation of the humic acids (HA) in aqueous solution by UV radiation in the presence of H2O2 (UV/H2O2 process) was investigated. Low-pressure mercury vapor lamps with the emission maximum at 253.7 nm were used as a UV light source. Process efficiency was monitored by the UV/VIS spectrophotometric analysis of the HA residual concentration. Without H2O2 presence, UV radiation had negligible effect on the HA in aqueous solutions. The addition of H2O2 greatly improved the efficiency of the HA degradation by UV light and the optimum H2O2 concentration was 0.01 mol dm-3. The UV light intensity, pH value, presence and concentration of the carbonate and nitrate anions were investigated. With the increase of UV light intensity the process efficiency improved. The increase of pH had negative effect on the process efficiency. The presence of carbonate and bicarbonate ions inhibited the HA degradation. The presence of nitrate ions up to the concentration of 5 mmol dm-3 had no significant effect on the process efficiency.

Keywords

• humic acids
• photodegradation
• UV light
• H2O2