THE IMPACTS OF UV DIRECT PHOTOLYSIS AND (UV/H2O2, UV/NaOCl) ADVANCED OXIDATION PROCESSES ON THE DEGRADATION OF MONOCHLORAMINE USING LOW PRESSURE (LP) LAMP

The aim of this study was to investigate the use of photochimicals processes (photolysis, H2O2/UVLP and NaOCl/UVLP) to eliminate monochloramine compound using a Low Pressure Hg lamp as an irradiation source (254 nm). First, it was found that the direct photolysis treatment might be rate of depletion under UV dose at 8000 mj/m2). Besides, this degradation was greatly improved by H2O2/UVLP thank’s to the high production of •OH from photolysis of H2O2. However, no big advantages were observed when we have employed NaOCl/UVLP comparatively to H2O2/UVLP. This fact would be attributed to the weak production of radicals •OH which was showed by a test conducted with a probe molecule: the terephthalic acid (TA). In addition the system NaOCl/UVLP could generate also Cl• creating thus, a competition between these two species towards the target compound. In another site, kinetics data for the three systems were best represented by a pseudo-first-order and the photodecomposition of monochloramine has conducted to the formation of by-products like: nitrate and nitrite. No formation of ammonia was observed during this process.