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Proceeding Paper

The Photodecomposition of Selected Organic Micropollutants in the Presence of Chlorides †

Faculty of Energy and Environmental Engineering, Silesian University of Technology, Konarskiego 18, 44-100 Gliwice, Poland
Presented at Innovations-Sustainability-Modernity-Openness Conference (ISMO’22), Bialystok, Poland, 26–27 May 2022.
Environ. Sci. Proc. 2022, 18(1), 19;
Published: 27 September 2022
(This article belongs to the Proceedings of Innovations-Sustainability-Modernity-Openness Conference (ISMO’22))


This paper determined the influence of selected inorganic substances on the UV-based decomposition of organic micropollutants from a group of pharmaceuticals, pesticides, industrial additives, hormones, and food additives, depending on the number of days in water. It was determined that the presence of NaCl and CaCl2 did not significantly affect the photodecomposition of micropollutants. A marked decrease in compound decomposition compared to the solution without inorganic compounds was noted in suspensions with Al3+ and Fe3+ cations. The addition of NH4+ affected the increase in compound decomposition, which was especially noted for compounds belonging to the group of pesticides, industrial additives, and hormones.

1. Introduction

The presence of several types of organic pollutants in different water streams is a well-known problem in many branches of industry [1]. However, this problem is most acute in the development of drinking water treatment technologies. The presence of even small amounts of micropollutants in drinking water can have a negative impact on human health. One of the most popular techniques for the decomposition of micropollutants are UV-based advanced oxidation processes [2]. Their effectiveness strongly depends not only on the selected oxidation processes, the reagent doses, and the operation time, but also on the physicochemical composition of the treated water matrix. Therefore, it is necessary to determine the influence of individual organic and inorganic compounds on the course of the micropollutants decomposition process.
This paper presents a comparison of removal degrees of selected organic micropollutants in water solutions during the UV radiation process in the presence of NaCl, AlCl3, FeCl3, CaCl2, or NH4Cl.

2. Materials and Methods

Gas chromatography with mass detection (GC-MS) proceeded by solid-phase extraction (SPE) was used for the estimation of the tested micro-polutants in the initial and post-processed water samples. Details of both procedures were given in previous studies [3]. The research was conducted on deionized water solution spiked with a mixture of selected organic micropollutants: benzocaine, BE; diclofenac, DCL; ibuprofen, IBU; caffeine, CAF; carbamazepine, CBZ; triallat, TRI; triclosan, TCS; oxadiazon, ODZ; bisphenol, A BPA; 4-tert-octylphenol, OP; β-estradiol, E2; 17α-ethinylestradiol, EE2; mestranol, EEME; progesterone, P4; butylated hydroxytoluene, BHT; and acridine, ACR. The prepared solution was subjected to UV radiation, emitted by a medium-pressure mercury vapor UV lamp with a power of 150 W by Heraeus (Hanau, Germany), with and without the addition of 0.5 g/L of NaCl, AlCl3, FeCl3, CaCl2, or NH4Cl.

3. Results and Discussion

Liao et al. [4] indicated that the presence of both organic and inorganic substances affect the course of the micropollutant’s decomposition process. The removal degrees of tested micropollutants exposed to 10 min of UV radiation in the presence of selected salts are summarized in Table 1.
It was observed that the removal of individual micropollutants in the presence of NaCl and CaCl2 was very similar to those observed in the process carried out in deionized water solutions. In the cases of CAF and CBZ only, it was observed that the presence of Cl and Na+ ions decreased the degree of their removal. Sun et al. [5] showed that the presence of Cl ions in water solutions exposed to artificial UV light in combination with the chlorine action negatively affects the decomposition of CAF.
The introduction of Al3+ and Fe3+ ions into the solutions resulted in a decrease in the removal degrees of the tested organic micropollutants, and the removal degrees of individual pollutants in solutions containing Fe3+ ions were lower than those noted in solutions containing Al3+ ions. For example, the DCF removal degree was equal to 45% in the solution containing Fe3+, and it did not exceed 40% in water solutions with the addition of Al3+. The decrease in compound decomposition may be related to the appearance of light color and turbidity in solutions containing Al3+ and Fe3+, which may cause the absorption of energy carried by UV radiation waves, leading to a disturbance in their proper penetration of the reaction mixture [6].
The presence of NH4+ ions in UV-irradiated water solutions increases the number of HO radicals [7]. This results in an increase in the removal degree of BE, DCF, and IBU, as well as compounds belonging to the group of pesticides, industrial admixtures, and hormones. On the other hand, the decomposition of CAF, CBZ, and ACR was at a lower level than in the solution without NH4+.
High concentrations of Cl ions may also negatively affect the decomposition of micropollutants during integrated oxidation processes [8]. Cl ions, competing with micropollutants, react with HO radicals according to Equations (1) and (2) [9], leading to a reduction in their number in the reaction mixture and the production of more selective and much weaker oxidants [10]. This is particularly important during the treatment of solutions with high salinity.
Cl + HO HClO
HClO + H + Cl + H 2 O

4. Conclusions

The conducted research has shown that the presence of chloride salts influences the decomposition process of the tested micropollutants. The presence of AlCl3 and FeCl3 decreases the efficiency of the micropollutant decomposition process during UV irradiation, which may be related to the change in color and the turbidity of solutions containing these types of salts. Only the presence of NH4+ ions had a beneficial impact on the course of the organic pollutant decomposition.


This work was supported by Ministry of Science and Higher Education Republic of Poland within statutory funds (no. 08/040/BKM22/0175).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The author declares no conflict of interest.


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Table 1. Micropollutant’s removal degree after 10 min of UV process in the presence of selected inorganic compounds.
Table 1. Micropollutant’s removal degree after 10 min of UV process in the presence of selected inorganic compounds.
CompoundRemoval Degree, %
Inorganic Compound
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MDPI and ACS Style

Kudlek, E. The Photodecomposition of Selected Organic Micropollutants in the Presence of Chlorides. Environ. Sci. Proc. 2022, 18, 19.

AMA Style

Kudlek E. The Photodecomposition of Selected Organic Micropollutants in the Presence of Chlorides. Environmental Sciences Proceedings. 2022; 18(1):19.

Chicago/Turabian Style

Kudlek, Edyta. 2022. "The Photodecomposition of Selected Organic Micropollutants in the Presence of Chlorides" Environmental Sciences Proceedings 18, no. 1: 19.

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