The occurrence of new emerging contaminants in surface waters has recently grabbed increased attention of the scientific community. The adoption of Advanced Oxidation Processes (AOPs) represents an efficient strategy to remove recalcitrant compounds from aqueous streams and achieve high mineralization levels. Amongst AOPs, the photo-Fenton process has been widely investigated due to the possibility of using a renewable energy source (i.e., solar energy) and low concentration of catalyst. On the other hand, the use of photo-Fenton process is restricted to acidic pH values, with associate high operating costs for industrial scale applications. To overcome these drawbacks, photo-Fenton processes modified by adding selected chelating agents can be successfully performed at neutral pH. The present review aims at examining and comparing the most relevant papers dealing with photo-Fenton processes at neutral pH that appeared in the literature so far. Such papers were classified by chelating species adopted. In particular, for each iron(III)-ligand complex, the mechanism of photolysis, the speciation diagram, the light absorption properties, the quantum yields, biodegradation and toxicity, and some example of applications are reported. As a conclusion, suitable criteria for choosing chelating agent and operating conditions in photo-Fenton processes at neutral pH are proposed.

Homogeneous photo-Fenton processes at near neutral pH: A review

Remediation of wastewater using various nano-materials

Degradation of fifteen emerging contaminants at microg L(-1) initial concentrations by mild solar photo-Fenton in MWTP effluents.

Optimizing the treatment of landfill leachate by conventional Fenton and photo-Fenton processes

Metal-free photocatalytic degradation of 4-chlorophenol in water by mesoporous carbon nitride semiconductors

Performance of a fed-batch reactor treating a wastewater containing 4-chlorophenol

In this study, photochemical advanced oxidation processes (AOPs) utilizing the combinations of UV, UV/H2O2, and UV/H2O2/Fe2+ (Photo-Fenton process) were investigated in lab-scale experiments for the degradation and mineralization of phenol. The major parameters investigated were the initial phenol concentration, pH, hydrogen peroxide, and iron doses, and the effect of the presence of radical scavengers ( , and Cl− ions). It was observed that the phenol degradation efficiency decreased with increasing phenol concentration and pH in UV process. Maximum phenol oxidation efficiency for an initial concentration of 100 mg L−1 and at pH 3 was around 30% in direct photolysis. The efficiency increased to 97% with UV/H2O2 process, however, there was still negligible mineralization (9%) and the required irradiation time was still long (300 min). The results showed that the Photo-Fenton process was the most effective treatment process under acidic conditions. Complete disappearance of 100 mg L−1 phenol was a...

Photochemical Degradation and Mineralization of Phenol: A Comparative Study

Intention, Goal, Scope, Background
Since the intermediate products of some compounds can be more toxic and/or refractory than the original compund itself, the development of innovative oxidation technologies which are capable of transforming such compounds into harmless end products, is gaining more importance every day Advanced oxidation processes are one of these technologies However, it is necessary to optimize the reaction conditions for these technologies in order to be cost-effective

Photochemical degradation and mineralization of 4-chlorophenol.

The fate and effect of 4-chlorophenol in an upflow anaerobic fixed-bed reactor

Intention, Goal, Scope, Background
Advanced oxidation processes are powerful methods which are capable of transforming refractory, nonbiodegradable and/or toxic organic compounds into harmless end products such as carbon dioxide and water. However, one commen problem of all advanced oxidation processes is the high demand of electrical energy for ultraviolet lamps, which causes high operational costs. Minimization of the required irradiation time, and therefore the energy consumption, by optimization of other reaction conditions such as catalyst-oxidant type and concentration, pH, temperature, pollutant/oxidant ratio etc., therefore continues to gain importance.

Ulusoy Bali

Papers

Performance of a fed-batch reactor treating a wastewater containing 4-chlorophenol

Photochemical Degradation and Mineralization of Phenol: A Comparative Study

Photochemical degradation and mineralization of 4-chlorophenol.

The fate and effect of 4-chlorophenol in an upflow anaerobic fixed-bed reactor

Ferrioxalate-mediated photodegradation and mineralization of 4-chlorophenol.