Photo-Fenton degradation of Persistent Organic Pollutants present in Real Contaminated Waters using Solar pilot plant Reactors

Project Information

SPFPs

Grant agreement ID: 844209

DOI

10.3030/844209

Project closed

EC signature date 23 April 2019

Start date 1 December 2020

End date 22 March 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 172 932,48

EU contribution

€ 172 932,48

Coordinated by

UNIVERSIDAD COMPLUTENSE DE MADRID
Spain

Periodic Reporting for period 1 - SPFPs (Photo-Fenton degradation of Persistent Organic Pollutants present in Real Contaminated Waters using Solar pilot plant Reactors)

Reporting period: 2020-12-01 to 2022-11-30

Summary of the context and overall objectives of the project

Hexachlorocyclohexane isomers (HCHs) and mainly its γ isomer (Lindane) were among the most worldwide extensively used organochlorine pesticides. Considering the carcinogenic, persistent, bio accumulate, and endocrine-disrupting properties of Lindane has become a heavily scrutinized substance and has been recently flagged for regulatory intervention. In 2009, Lindane was included in the Stockholm Convention on Persistent Organic Pollutants (POPs) to achieve the global elimination of these substances. Consequently, the development of cost-effective, safe, and environmental technologies for the destruction of POPs is necessary.
Due to their chemical properties, POPs resist the natural degradation processes present in the environment. Different Advanced Oxidation Processes (AOPs) have received considerable attention as a nonconventional method to remove POPs. However, many have the disadvantage of their high cost. A very useful alternative from the economic and environmental point of view is the use of solar energy integrated into these processes. These are the Solar-Enhanced Advanced Oxidation Process (SEAOPs).
In the present research project, a detailed study associated with the Per Sulphate (PSPs) and Photo-Fenton (PFPs) degradation process of POPs present in real contaminated waters using pilot-plant Solar Reactors (RS) was done. At this point, experimental work, and rigorous modelling of photochemical reactors, considering the fundamentals of chemical reactions and transport phenomena were performed. Moreover, the dissemination, communication, and exploitation of the results were done. Throughout the research work carried out, the effectiveness of SEAOPs applied to the degradation of POPs present not only in synthetic matrices but also in real systems was validated. The project was developed mainly in the facilities of the Intensification of Chemical and Environmental Processes (INPROQUIMA) research group (Universidad Complutense of Madrid (UCM)), under the supervision of Prof. Dra. A. Santos.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

First, the effectiveness of the PFPs process in the degradation of the 124-Trichlorobenzene (124-TCB) was studied. The 124-TCB is a semi-volatile Chlorinated Organic Compounds (COCs) with relatively high toxicity and persistence, representing a risk to human health and environmental safety. Here, the heterogeneous (goethite as a catalyst) and homogeneous (ferrioxalate as a catalyst) PFPs processes were analysed using hydrogen peroxide as an oxidant. A commercial visible light-emitting diode lamp (VIS LED) was used as an efficient light source. In both degradation processes, high conversions of the pollutant were observed, as well as reductions in the levels of toxicity present in the system. The following scientific articles were published:
• Lorenzo, D; Santos, A; Sánchez-Yepes, A; Conte, L; Domínguez, C. Abatement of 1,2,4-TCB by wet peroxide oxidation catalysed by goethite and enhanced by a visible LED light at neutral pH. Catalysts, 11 (2021), 139. Collaborative work carried out prior to the start of the scholarship
• Conte, L; Dominquez, C; Checa-Fernandez, A; Santos, A. Vis LED Photo-Fenton Degradation of 124-Trichlorobenzene at a Neutral pH Using Ferrioxalate as Catalyst. Int. J. Environ. Res. Pub. Health. 19 (2022), 9733.

Validated the usefulness of the homogeneous PFPs (LED and ferrioxalate), the removal of HCHs found in real groundwater was studied. Specifically, groundwater contaminated by chlorinated compounds (DNAPLs from Lindane production) from two industrial landfills in Sabiñánigo (Spain) was studied. Results show that it is possible to attain high conversion of HCHs using sodium persulfate as an oxidant. A good dechlorination grade was obtained during the photo-oxidation with persulfate, confirming the ability of sulphate radicals to break the C-Cl bond in COCs, including HCHs. The following scientific article was published:
• Conte, L; Cotillas, S; Sánchez-Yepes, A; Lorenzo, D; Santos, A. LED visible light assisted photochemical oxidation of HCHs in aqueous phases polluted with DNAPL. Proc. Saf. Environ. Prot. 168 (2022), 434-442.

The homogeneous system was studied in the degradation of Lindane but using a solar simulator. Here, the oxidation and dechlorination of Lindane in the aqueous phase were successfully achieved with the “innovative” system proposed. Moreover, a kinetic model to describe the removal of this pesticide and chlorine mineralization has been developed. The model proposed fits well with the experimental results and can help to predict the degradation of Lindane. The following scientific article was published:
• Conte L; Legnettino G; Lorenzo D; Cotillas S; Prisciandaro M; Santos A. Degradation of Lindane by persulfate/ferrioxalate/solar light process: Influential operating parameters, kinetic model, and by-products. Appl. Catal. B., 324 (2023), 122288.

Based on these results, the behaviour of the system was evaluated by considering a mixture of HCHs isomers sing a pilot plant-scale solar reactor and real waters. The results showed the capacity of the solar process to completely degrade the HCHs isomers in relatively short reaction times. In addition to fully reducing the toxicity of the system. Therefore, the innovative process developed in this research project opens the possibility of treating real water contaminated with HCHs using larger-scale solar reactors. Currently, a scientific article is being drafted.

On the other hand, from collaborative work with INPROQUIMA researchers’ co-workers, studied the on-site application of the alkaline activation of the persulfate intensified by ultrasound for the treatment of HCHs-polluted soils. Here, by increasing the ultrasound power and the initial concentration of the oxidant, the degradation of HCHs and the hydrolysis products increases. The following scientific article was published:
• Checa-Fernández, A; Santos, A; Conte, L; Romero, A; Domínguez, C. Enhanced remediation of a real HCH-polluted soil by the synergetic alkaline and ultrasonic activation of persulfate. Chem. Eng. J., 440 (2022), 13591. Collaborative work.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The possibility of using the sun as a photochemical and thermal energy source for the activation of the PSPs and PFPs processes transforms them into high-impact scientific alternatives. However, very few scientific references have studied the real implementation of these technologies. In this research project, state-of-the-art knowledge and state-of-the-art technology were used to study the application of the PSPs and PFPs process to the degradation of POPs present in real contaminated matrices. The influence of main operational conditions on the process effectiveness was evaluated. To understand the interrelationships between these variables a kinetic model that includes reactions intermediaries in the HCHs degradation processes was developed. The validation of these technologies using a pilot plant solar reactor was performed.
The application of a renewable, abundant, and clean energy source, namely solar radiation, has transformed the PFPs and PSPs process into a non-expensive, competitive method to remove POPs. Furthermore, the technological innovation proposed can be used to remove different recalcitrant contaminants from the industry's effluents, drinking water, and municipal wastewater treatment plants. Thus, the research project carried out could provide an economic solution to real environmental issues with high social demand.

Image Summary Conte, L