Electrochemical Transformation of 4-Chlorophenol for the Determination of Chloride in Advanced Oxidation Processes
Authors: Molina Mayela , Roa-Morales G. , Balderas Patricia , Amado Deysi , Rangel Reyna NATIVIDAD , Barrera Carlos Eduardo 
Published: February 2020

Water is necessary natural resources for life on the planet, however in the last decades it has become evident the contamination of this by the diverse anthropogenic activities that generated a wide range of chemical species that are hardly removed by conventional treatments, therefore, other feasible alternatives have been sought to obtain a better efficiency for the removal of said pollutants.

When the degradation of the organic matter of the effluents is carried out by applying different physicochemical processes, it is possible to form less toxic chemical species. One of the techniques for the removal of contaminants are the advanced oxidation processes (POA), these processes have been used for the degradation or mineralization of organic compounds of refractory and toxic effluents, where the hydroxyl radical is generated in situ (•OH) that due to its chemical properties has the ability to degrade or mineralize the refractory matter, resulting in less toxic byproducts and halogen oxyanions, which improve the efficiency of the treatment.

There are different types of POA, however advanced electro-oxidation processes (PEOA) have shown great efficiency in the oxidation of organic matter by changing the electrolyte and the electrode system with some variation to improve the process. It is worth mentioning that the degradation of organic matter in these processes is of the utmost importance, since it is mostly used for the elimination of certain organic molecules that are found in the aqueous medium and that are toxic.

In recent years, different studies have been carried out in which it is shown that chlorophenolic molecules, such as 4-chlorophenol (4- (CPh)) is degraded by advanced electro-oxidation processes. The 4-CPh is degraded by applying an electrochemical process through the •OH and releases the Cl that is in the molecule and is transformed as Cl- which reacts with the different radial in the medium with the possibility of generating oxidizing agents as oxyanions. However, the Cl- species can not only be obtained from the molecule, but it can also be present in the supporting electrolyte or by the nature of the sample.

The degradation of the chlorophenolic molecules will allow the formation of chemical species that will depend on the pH in which the reaction is found, considering that in recent studies that at higher pH values it is very probable that there is the formation of chlorates. However, in the majority of the investigations, only reference is made to the fact that the formation of chlorates does not predominate at acid pH

For the identification of organic matter degradation, different analytical techniques are used to monitor degraded species. The most used techniques for the identification of these species are high efficiency chromatography (HPLC), UV-VIS spectrophotometry for organic species, however for the anionic species the use of ion chromatography (IC) is made.

Figure 1