Photocatalytic bleaching of p-nitrosodimethylaniline and a comparison to the performance of other AOP technologies

Abstract

a b s t r a c tIn this paper, the performance of a developed photo reactor has been studied using the process of bleaching of p-nitrosodimethylaniline (RNO). The effect of available surface area in the reactor has been tested with the TiO 2 suspension system as reference, as well as the influence of operating parameters as pH and aerobic/anaerobic conditions. The bleaching of RNO by UV light alone was found to be significantly slower compared to the bleaching observed when applying photocatalysis, but the initial bleaching rate when applying TiO 2 in suspension was still 7 times faster compared to the most efficient immobilized TiO 2 treatment set up. An approximate linear correlation between the surface area of the TiO 2 available for reaction and the initial rate of bleaching was found. In addition, the kinetics of the photocatalytic bleaching was found to obey L-H kinetics. The pH of the solution was found to influence the rate of bleaching presumably due to the change in the surface charge of TiO 2 . Also aerobic/anaerobic conditions and the presence of hydroxyl radical scavenger had a profound influence on the bleaching rate, where the reductive bleaching process was found to be much faster than the oxidative bleaching paths. When comparing the obtained rates of bleaching of RNO in the photocatalytic reactors to two competitive AOPs, UV/S 2 O 8 2− and conductive-diamond electrochemical oxidation (CDEO), the CDEO process was the most energy efficient for bleaching of RNO.

A pathway of nanocrystallite fabrication by photo-assisted growth in pure water

“…In the present study, OH radical generation was also investigated (Fig. 4(a–d)) by monitoring the bleaching of p -nitrosodimethylaniline (PNDA) as the intensity of the characteristic absorption peak at λ = 440 nm decreased3233. These results confirm the photochemical reactions proposed for the SPSC process, in which H 2 gas and OH radicals were generated during the photo-assisted growth of ZnO nanorods.…”

Study of electrochemical bleaching of p-nitrosodimethylaniline and its role as hydroxyl radical probe compound

“…13 is mainly carried out in sulfuric acid solutions under carefully monitored conditions, and the RNO bleaching efficiency of persulphate is insignificant. Finally, reduction of RNO has in a study of photocatalytic bleaching of RNO been showed to be a fast pathway for color removal in aqueous solution [31]. In the one-compartment cell, reductive bleaching of RNO may be achieved at the Si-BDD cathode and can be the most likely candidate for the baseline bleaching.…”

Insight on the fundamentals of advanced oxidation processes. Role and review of the determination methods of reactive oxygen species

“…Another example is the use of quinoline, which led to the formation of numerous products until their complete mineralization in photo‐Fenton and photocatalysis systems . Moreover, compounds such as p‐Nitrosodimethylaniline (RNO) (reaction ) and 1,5‐diphenyl carbazide (DPCI, reaction ) react with other ROS pointing out the need to add scavengers to quantitatively measure the concentration of each ROS specie. …”