A DFT Study Toward the Reaction Mechanisms of TNT With Hydroxyl Radicals for Advanced Oxidation Processes

2016 ◽  
Vol 120 (20) ◽  
pp. 3747-3753 ◽  
Author(s):  
Xi He ◽  
Qun Zeng ◽  
Yang Zhou ◽  
Qingxuan Zeng ◽  
Xianfeng Wei ◽  
...  
Environments ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 116
Author(s):  
Yi-Ping Lin ◽  
Ramdhane Dhib ◽  
Mehrab Mehrvar

Polyvinyl alcohol (PVA) is an emerging pollutant commonly found in industrial wastewater, owing to its extensive usage as an additive in the manufacturing industry. PVA’s popularity has made wastewater treatment technologies for PVA degradation a popular research topic in industrial wastewater treatment. Although many PVA degradation technologies are studied in bench-scale processes, recent advancements in process optimization and control of wastewater treatment technologies such as advanced oxidation processes (AOPs) show the feasibility of these processes by monitoring and controlling processes to meet desired regulatory standards. These wastewater treatment technologies exhibit complex reaction mechanisms leading to nonlinear and nonstationary behavior related to variability in operational conditions. Thus, black-box dynamic modeling is a promising tool for designing control schemes since dynamic modeling is more complicated in terms of first principles and reaction mechanisms. This study seeks to provide a survey of process control methods via a comprehensive review focusing on PVA degradation methods, including biological and advanced oxidation processes, along with their reaction mechanisms, control-oriented dynamic modeling (i.e., state-space, transfer function, and artificial neural network modeling), and control strategies (i.e., proportional-integral-derivative control and predictive control) associated with wastewater treatment technologies utilized for PVA degradation.


Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3398 ◽  
Author(s):  
John F. Guateque-Londoño ◽  
Efraím A. Serna-Galvis ◽  
Yenny Ávila-Torres ◽  
Ricardo A. Torres-Palma

In this work, the degradation of the pharmaceutical losartan, in simulated fresh urine (which was considered because urine is the main excretion route for this compound) by sonochemistry and UVC/H2O2 individually, was studied. Initially, special attention was paid to the degrading action of the processes. Then, theoretical analyses on Fukui function indices, to determine electron-rich regions on the pharmaceutical susceptible to attacks by the hydroxyl radical, were performed. Afterward, the ability of the processes to mineralize losartan and remove the phyto-toxicity was tested. It was found that in the sonochemical treatment, hydroxyl radicals played the main degrading role. In turn, in UVC/H2O2, both the light and hydroxyl radical eliminated the target contaminant. The sonochemical system showed the lowest interference for the elimination of losartan in the fresh urine. It was established that atoms in the imidazole of the contaminant were the moieties most prone to primary transformations by radicals. This was coincident with the initial degradation products coming from the processes action. Although both processes exhibited low mineralizing ability toward losartan, the sonochemical treatment converted losartan into nonphytotoxic products. This research presents relevant results on the elimination of a representative pharmaceutical in fresh urine by two advanced oxidation processes.


Author(s):  
Victor Odhiambo Shikuku ◽  
Wilfrida N. Nyairo

Advanced oxidation processes (AOPs), namely the Fenton oxidation, ozonation, electrochemical oxidation, and photocatalysis, are potential alternative techniques for dye removal from textile effluents. Their inherent ability to completely mineralize pollutants including those recalcitrant to biodegradation and to be compatibly integrated in conventional technologies present grounds for consideration of AOPs as alternative wastewater treatment options. Advanced oxidation involves generation and subsequent reaction of various radicals and reacting species with the target compounds. This chapter discusses the fundamentals and chemistry and efficiencies of the Fenton process, ozonation, electrochemical oxidation, and photocatalysis processes for complete dye removal from wastewater. The reaction mechanisms, performance, and factors affecting efficiency are discussed.


2015 ◽  
Vol 17 (17) ◽  
pp. 11796-11812 ◽  
Author(s):  
Daisuke Minakata ◽  
Weihua Song ◽  
Stephen P. Mezyk ◽  
William J. Cooper

In this study, we shed light on the initial addition of hydroxyl radicals (HO˙) to multiple carboxylated and hydroxylated benzene compounds in aqueous-phase advanced oxidation processes (AOPs).


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