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It is well known that corrosion inhibition performance of organic compounds in acidic media depend on their concentration and molecular structures. Therefore, the comparative study of inhibition efficiency of eugenol as aromatic and linalool as linear molecules on aluminium corrosion in 0.5 M HCl solution was performed. The study was done by weight loss, potentiodynamic polarization and EIS methods, while surface morphology of aluminium was examined by SEM method. All used methods confirmed inhibition efficiency of both investigated compounds on aluminium corrosion in acidic medium. From the obtained potentiodynamic polarization curves is evident that presence of eugenol and linalool in acid media cause a prominent decrease in current densities, and shift of the Ecorr values to more cathodic direction in comparison with 0.5 M HCl without inhibitors. EIS method confirmed that the maximum inhibition was achieved with addition of 0.012 mol L-1 eugenol (92.4%) and 0.035 mol L-1 linalool (85.1%) in HCl solution. Thus, these concentrations can be assumed as optimum for corrosion inhibition of aluminium. SEM results are in accordance with the results obtained by weight loss and electrochemical measurements, confirming the existence of protective inhibitor film on the Al surface.

Considering the fact that corrosion of metals and alloys presents a significant problem all over the world, the one of most recently utilized approaches to combat this problem necessitates the researches for employment of new materials, which satisfied the green chemistry idea. In this connection, the development of sustainable corrosion inhibitors is highly demanded due to the increasing of awareness of green chemistry principles not only in corrosion discipline, but also in all branches of science and technology. Due to natural and biological origin as well as their eco-friendly extraction, the plant materials and biomass derived from various waste sources could be applied as beneficial substances for metals and alloys protection in different corrosion environment. Therefore, this work reports the main findings regarding their employments as green anticorrosion substances.

In this study, for the first time, the adsorption/desorption characteristics of carnosic acid and carnosol from deep eutectic solvent extract of Salvia officinalis on five macroporous resins (HP20, XAD7HP, XAD16N, HP21, HP2MG) were evaluated. The high adsorption and medium desorption capacities of carnosic acid and carnosol as well as antibacterial and antiradical activity from the extract obtained with choline chloride:lactic acid (1:2) on XAD7HP resin indicated that resin was appropriate. To get the optimal separation process, the influence of factors such as adsorption/desorption time and volume of desorbent was further investigated. The results showed that the extract with high antiradical and antibacterial activity was obtained via adsorption and desorption on XAD7HP resin. The extraction efficiencies of the deep eutectic solvents (DESs) recycled once, twice, and thrice were 97.64% (±0.03%), 93.10% (±0.66%), and 88.94% (±1.15%), respectively, for carnosic acid, and 96.63% (±0.04%), 94.38% (±0.27%), and 91.19% (±0.36%), respectively, for carnosol, relative to the initial solvent efficiency. Based on that, this method is a promising basis for the large-scale preparation of extracts from Salvia officinalis with further application in the pharmaceutical or food industry, especially for maintaining the “green” character of the whole process to obtain the appropriate extract.

Chocolate is considered as both caloric and functional food. Its nutritional properties may be improved by addition of fiber, however, this may reduce polyphenols content. The aim of this research was to determine the influence of cocoa shell addition (as a source of fiber) and its combination with different ingredients (cocoa butter equivalents (CBE), emulsifiers, dairy ingredients) on polyphenols of dark and milk chocolates. Total polyphenol (TPC) and total flavonoid (TFC) contents were determined spectrophotometrically, identification and quantification of individual compounds by high pressure liquid chromatography and antioxidant capacity by ferric reducing antioxidant power (FRAP) assay. Results showed that even though addition of cocoa shell to chocolate results in reduced contents of TPC, TFC, and individual compounds, it is not significant compared to ones reported by other authors for commercial chocolates. Other ingredients influence determined values for all investigated parameters, however, additional research is needed to reveal exact mechanisms and implications.

The pectin from tomato peel waste (TPP) was employed as tin corrosion inhibitor with the aim to enhance the knowledge regarding the application of natural inhibitors, instead synthetic, and reducing the waste disposal for value-added biopolymers production. To evaluate the TPP anticorrosion activity the commercial apple pectin (CAP) was also utilised. The gravimetric tests show that the highest inhibitive impact (η) of 75.9 % (CAP) and 73.9 % (TPP) are gained at concentration of 20 g L−1. By electrochemical, potentiodynamic polarization and impedance spectroscopy measurements, the maximum η (60.05–65.5 %) are reached at lower concentration (4 g L−1), due to tendency of pectins to form viscous solution. The prominent decreases in current density with the shifts of potential in the cathodic direction revealed that pectins provided cathodic protection of tin surface. Similar inhibition impact of pectins, and fine agreement between applied methods confirmed their suitability against tin corrosion.

The application of dye sensitized photocatalysis for the degradation of surfactant in the model wastewater has been studied. The aim was to explore the possibility of the photocatalytic activity enhancement by introducing the waste toner powder in the photocatalytic films. The development and a partial characterization of the supported catalyst were described within this study. Waste toner and commercial TiO2 powder (AEROXIDE® P25) were integrated within the matrix of chitosan molecules as a thin layer films. The developed films contain the high amount of the TiO2 (approx. 90%) which structure appeared to be intact. The efficiency of the photocatalytic films for the oxidation of the anionic surfactant dodecylbenzene sulfonate (SDBS) has been evaluated. Preliminary experiments were performed in an annular batch reactor using UVC lamp. Photocatalytic films were supported on the glass, stainless steel and waste offset printing plates. Support was made in a form of plates or rings. Further experiments were performed under artificial and natural solar irradiation whereby photocatalytic films were fixed at the bottom of reaction cell (boat shaped flow reactor). In order to estimate the reaction rate constant for SDBS degradation over irradiated photocatalytic films and to evaluate the effects of photon absorption under different irradiation conditions, a detailed kinetic model was developed. The sensitization effect of the components in toner powder due to the visible light absorption for the photocatalytic oxidation of SDBS under solar irradiation was quantified.