A novel approach of the deposition of two-component coating consisting of TiO₂ and CuO on polymer membranes by MS-PVD method was presented in this work. This confirmed the possibility of using thin functional coatings for the modification of polymer membranes. The influence of technological parameters of the coating deposition on the membrane’s structure, chemical composition and functional properties (hydrophilic, photocatalytic and bactericidal properties) were analyzed using SEM. Model microorganism such as Escherichia coli and Bacillus subtilis have been used to check the antibacterial properties. The results indicated that doping with CuO highlights the potential of bactericidal efficiency. The surface properties of the membranes were evaluated with the surface free energy. For evaluating photocatalytic properties, the UV and visible light were used. The filtration tests showed that polymer membranes treated with two-component TiO₂ + CuO coatings have a permeate flux similar to the reference material (non-coated membrane). The obtained results constitute a very promising perspective of the potential application of magnetron sputtering for deposition of TiO₂ + CuO coatings in the prevention of biofouling resulted from the membrane filtration of dairy wastewater.

According to the idea of sustainable development, humanity should make every effort to care for the natural environment along with economic development. Decreasing water resources in the world makes it necessary to take action to reduce the consumption of this resource. This article presents the results of research conducted to improve the use of recyclable materials in line with the circular economy model. The research focused on the development of a technological solution for the recovery of raw materials from galvanic wastewater. The concept of a galvanic wastewater treatment system presented in the article includes wastewater pre-treatment in the ultrafiltration (UF) process and water recovery in the reverse osmosis (RO) process. In addition, the purpose of the work was to manage post-filtration waste (RO retentate) containing high concentrations of zinc in the process of galvanizing metal details. The obtained results indicate that it is possible to reduce the amount of sewage from the galvanizing industry by reusing the recovered water as technical water in the process line. The carried-out model tests of galvanizing confirmed the possibility of using RO retentate for the production of metal parts. The achieved results are a proposal to solve the problem of reducing the impact of galvanic wastewater on the environment and to improve the profitability of existing galvanizing technologies by reducing the consumption of water and raw materials.

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, I_D/I_G coefficients are calculated to assess the organisation of the materials’ structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work.

The possibility of using pyrolysis for the valorisation of leather and textile wastes constituting post-consumer clothes is analysed in this paper. The effect of gas type was investigated on the physico-chemical properties, composition, structure, and formation of the specific surfaces of carbonised materials produced by the pyrolysis process. The differences in the elemental composition of the carbonised materials derived from textile and leather wastes may be due to the specific chemical compositions. Both textile and leather wastes are rich in organic compounds, but their structural and compositional differences significantly influence the element content of carbonised materials. The characteristic feature of carbonised material made from leather waste is a relatively high nitrogen content (approx. 9 wt. %). In turn, in the case of carbonised material made from textile waste, a high carbon content is characteristic (75–80 wt. %). Moreover, G- and D-bands were detected in all the analysed carbonised materials. The presence of these bands confirms the transformation of leather and textile wastes into carbon materials. It was found that maintaining a high degree of order in the structure (calculated as I_D/I_G ratios based on the D and G peak intensities) of carbonised materials is advantageous to conducting the pyrolysis process on textile materials in N₂ and on leather materials in CO₂. The carbonised materials produced using these gases are characterised by an I_D/I_G ratio at a level of 0.05. Pyrolysis carried out in these gases also has a positive effect on the size of the BET surface area. However, it was shown that the carbonised products from textile materials are characterised by a higher BET surface area than that of carbonised products from leather materials regardless of the type of gas used during the pyrolysis process. Furthermore, all the carbonised materials are characterised by a high percentage content of mesopores in the carbon structure. These types of carbon materials have widespread application potential. The presented studies contribute data about the pyrolytic processing of post-consumer clothes (such as leather and textile waste) into carbonised materials to reuse, according to the circular economy model.

This paper presents the basic assumptions of the concept of a new technology for the valorisation of chromium tannery waste. It assumes the use of an integrated system of the thermal pressure hydrolysis process and membrane filtration techniques for the recovery of chromium compounds and the use of a separated organic matter during anaerobic fermentation. According to the assumptions of the developed technological concept, at the first stage, the crushed mixture of chromium tannery waste is decomposed in the process of thermal pressure hydrolysis using appropriate process conditions in an alkaline environment. Then, the liquid product of this process (the so-called hydrolysate) is processed using centrifugal force separation and ultrafiltration. Such activities enable the recovery of chromium compounds for rawhide currying and concentration of organic matter (fats, proteins) with energy potential. Research carried out under conditions similar to real operating conditions proved that chromium compounds recovered from waste can be successfully used in the processing of cowhides intended for the production of footwear. The industrial implementation of the developed technology for valorising chromium tannery waste would enable the transition from a linear to a circular economy.

This paper presents the results of research on a new method of chromium recovery from solid waste generated during the tanning of raw hides. In the first stage, the shredded mixture of useless leather scraps is decomposed through thermal pressure hydrolysis (TPH) in nitric acid in appropriate process conditions. Then, the liquid product of this process (hydrolysate) is fractionated using membrane separation techniques. The microfiltration (MF) process enables the initial purification of the hydrolysate by concentrating the organic matter. On the other hand, the nanofiltration (NF) process enables a three-fold concentration of total chromium in the pre-purified hydrolysate. The total chromium concentrate prepared in the above manner was successfully used in the model tanning processes. These processes were carried out on pickled bovine hides, using a mixture of a commercial chromium tanning agent and chromium concentrate after nanofiltration. The reference sample was bovine hide traditionally tanned with a commercial chromium tanning agent. Based on the results of the physical and chemical analyses, it was found that the properties of hides tanned using chromium recovered from waste are similar to those of hides tanned traditionally using a commercially available chromium tanning agent. The industrial implementation of the developed tannery waste valorisation technology would enable transition from a linear economy to circular economy.