Phenolic pollutants raise health and environmental concerns due to their widespread occurrence in industrial wastewaters. Electrooxidation was studied for phenol degradation in different supporting electrolytes: NaCl, Na₂SO₄, H₂SO₄. Experiments were performed at constant current density 20 mA cm⁻². Two anode materials were tested ‒ boron-doped diamond (BDD) and mixed-metal oxide (MMO). Degradation process and its impact was investigated from technological, analytical, and ecotoxicological viewpoints. Removal efficiency was monitored by phenol index spectrophotometric method and phenol removal quantified with HPLC-DAD. Additionally, transformation by-products were tracked with GC-MS and LC-MS, as well as ion chromatography. Finally, ecotoxicity was investigated using Daphnia magna. Electrooxidation was efficient and had low energy consumption. The use of BDD anode led to higher removal efficiencies and induced more progressive degradation to simple organic acids, compared to MMO. Selection of electrolyte affected degradation pathways and detoxification pattern. Treatment by BDD in NaCl led to complete phenol removal in 30 min, but undesired chlorinated aromatic by-products were formed. Treatment in sulphate medium led to slower processes irrespective of pH, but less problematic by-products with minimal ecotoxicological impact emerged. By using multi-aspect methodology, this study reevaluates phenol electrooxidative degradation and contributes to better understanding of electrooxidation performance in water treatment.

This study focused on testing the efficacy of iron (Fe) electrode in an electrochemical treatment (electrocoagulation) of wastewater containing a mixture of organic dyes. The mixture consists of the following azo dyes: Acid Black 194, Acid Black 107 and Acid Yellow 116. The present organic dyes are toxic, cause skin and eye irritation and are extremely dangerous to aquatic organisms. The study was conducted on a synthetic wastewater prepared in a laboratory electrochemical reactor. During the research, the impact of the current density, various concentrations of dye and supporting electrolyte, electrolysis duration and pulsed current regime were tracked. The results are shown through color removal efficiency, chemical oxygen demand (COD) removal efficiency, current efficiency, and specific energy consumption. At the initial concentration of dye (γ=200 mg/L) and concentration of supporting electrolyte (γNaCl=1 g/L) the color removal efficiency of 80.64% was achieved for 420 seconds of treatment (ј=10 mA/cm2). At the initial concentration of dye (γ=50 mg/L) and γNaCl= 8 g/L, the color removal efficiency of 96.01% was attained for 300 seconds of treatment (ј=10 mA/cm2)

In this study, corrosion behaviour of stainless steel in 0.5 M and 1 M hydrochloric acid was examined. Also, commercial corrosion inhibitor which contain 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) is examined as potential inhibitor for stainless steel EN 1.4301 in 0.5 M hydrochloric acid. For experimental research it was used DC-technique (Tafel extrapolation, linear polarization method and potentiodynamic polarization). The obtained results show that the inhibitor is effective in mentioned acid environment and the protection efficiency depends primarily on the concentration of the inhibitor. Based on the obtained results this inhibitor has moderate inhibition efficiency, since the highest efficacy was achieved Ei = 55.7%. According to the corrosion mechanism the inhibitor is behaved as a mixed inhibitor.

The electrooxidation (EO) of three important environmental contaminants, anticorrosive 1H-benzotriazole (BTA), plasticizer dibutyl phthalate (DBP), and non-ionic surfactant Triton X-100 (tert-octylphenoxy[poly(ethoxy)] ethanol, t-OPPE), was studied as a possible means to improve their elimination from wastewaters, which are an important emission source. EO was performed in a batch reactor with a boron-doped diamond (BDD) anode and a stainless steel cathode. Different supporting electrolytes were tested: NaCl, H₂SO₄, and Na₂SO₄. Results were analysed from the point of their efficacy in terms of degradation rate, kinetics, energy consumption, and transformation products. The highest degradation rate, shortest half-life, and lowest energy consumption was observed in the electrolyte H₂SO₄, followed by Na₂SO₄ with only slightly less favourable characteristics. In both cases, degradation was probably due to the formation of persulphate or sulphate radicals. Transformation products (TPs) were studied mainly in the sulphate media and several oxidation products were identified with all three contaminants, while some evidence of progressive degradation, e.g., ring-opening products, was observed only with t-OPPE. The possible reasons for the lack of further degradation in BTA and DBP are too short of an EO treatment time and perhaps a lack of detection due to unsuitable analytical methods for more polar TPs. Results demonstrate that BDD-based EO is a robust method for the efficient removal of structurally diverse organic contaminants, making it a promising candidate for advanced water treatment technologies.

Polar benzotriazoles are heterocyclic compounds widely used in industry, and as such are easily released into the environment. These compounds show harmful and toxic effects on plants and some aquatic organisms, biodegrade quite slowly, and some, depending on the structure, have the ability to bioaccumulate. They can only be partially removed by conventional wastewater treatment, and are therefore found in a variety of waters, as well as solid waste. In this paper, synthetic wastewater containing polar benzotriazole was treated by an electrooxidation process. The efficiency of the treatment was tested depending on various parameters, such as: anode material (mixed metal oxide - MMO and boron-doped diamond - BDD), applied current density (10 and 20 mA/cm2), type of supporting electrolyte (NaCl, Na2CO3, Na2SO4, H2SO4) and treatment time (0.5 - 2.5 h). Obtained results showed the treatment was more effective at higher current density and by using BDD anode. Also, the efficiency of the treatment increases with the prolongation of the electrolysis time. After 2.5 h of treatment, 97.9% of benzotriazole was removed, in the presence of sulfuric acid as supporting electrolyte.

The aim of this study is the development and characterization of a carbon-based electrochemical sensor, modified with TiO2 nanoparticles for potential application in electroanalytical techniques. The influence of binder and modifier contents on morphological, physicochemical and electrochemical characteristics of the electrode material was investigated in order to determine the optimal ratio of the carbon material/binder/modifier. Carbon pastes were prepared from mixtures containing graphite powder, TiO2 nanoparticles and liquid hydrocarbons. Scanning electron microscopy showed that the electrode material becomes more compact with the addition and the increase in the binder material content, while increasing the proportion of TiO2 nanoparticles did not have any significant effect on the material morphology showing fairly homogeneous nanoparticle distribution in the graphite electrode material. The test results indicate that the modified carbon paste with 40 vol.% paraffin oil (PO) and 6-8 wt.% TiO2 nanoparticles is characterized by the lowest value of specific resistance. By applying cyclic voltammetry, the most pronounced degree of reversibility was obtained in relation to the standard reversible redox system ([Fe (CN)]-3/-4) for the electrode material with 30-40 vol.% PO and 8-10 wt.% TiO2 nanoparticles. Characterization of the electrode material based on carbon modified with TiO2 nanoparticles indicated that the optimal composition contains 40 vol.% PO and 6-8 wt.% TiO2 nanoparticles, which is important for application in electroanalytical techniques.