Valorization of high-volume mine tailings could be achieved by the development of new geopolymers with a low CO₂ footprint. Materials rich in aluminum and silicon with appropriate solubility in an alkaline medium can be used to obtain a geopolymer. This paper presents a study of copper mine tailings from Bulgaria as precursors for geopolymers. Particle size distribution, chemical and mineralogical composition, as well as alkaline reactivity, acidity and electroconductivity of aqueous slurry are studied. The heavy metal content and their mobility are studied by leaching tests. Sequential extraction was applied to determine the geochemical phase distribution of heavy metals. The studied samples were characterized by high alkalinity, which could favor the geopolymerization process. The water-soluble sulphates were less than 4%. The Si/Al ratio in mine tailing was found to be 3. The alkaline reactivity depended more so on the time of extraction than on the concentration of NaOH solution. The main part of the heavy metals was found in the residual fraction; hence, in high alkaline medium during the geopolymerization process, they will stay fixed. Thus, the obtained geopolymers could be expected to exert low environmental impact. The presented results revealed that studied copper mine tailing is a suitable precursor for geopolymerization.

Today, environmental protection is one of the main goals in the strive to preserve the human existence. Development in this area requires invention of new materials, which can reduce the levels of pollution. Hybrid materials are suitable for this purpose, because they combine different desirable properties existing in separate sources into one unique and accessible structure. Most of the commonly used materials for the degradation of different kind of pollutants are based on titanium dioxide, because of its photocatalytic activity under UV irradiation. Innovative silica hybrid materials, containing an organic component (chitosan) and titanium nanoparticles, were successfully synthesized via the sol–gel method and tetraethyl orthosilicate was used as a silica source and network former. Interaction between the chitosan and titanium units, and their influence on the structure of final material, were observed and discussed. A homogeneous structure with an even distribution of titanium and chitosan particles was visible from scanning electron microscopy (SEM) micrographs and the particle size varied between 50 and 150 nm. The formed silica network, characteristic peaks of chitosan and titanium groups and possible interactions between them are observed from Fourier transform infrared (FTIR) spectroscopy spectra and nuclear magnetic resonance (NMR) spectroscopy results. The behaviour of the synthesized silica hybrids after thermal treatment was investigated via differential thermal/thermo-gravimetric analysis (DTA/TG) analysis and the sorption and degradation activities of the obtained hybrid materials were investigated using a solution of methyl orange as model pollutant. The structure and properties of the synthesized silica hybrid materials assert their potential application in environmental remediation due to their photocatalytic degradation and sorption activities against pollutants.

The cement industry is one of the most energy-intensive industries, which is why new energy-reducing and reducingCO2 emissions, additives are being sought. Grinding aid or grinding additives refer to substances that when mixed into the mill contents cause an increase in the rate of size reduction. These terms are very common in cement industries where it increases the throughput of the mill. Grinding aid also affects the cement flowability throughout the circuits. The grinding aid facilitates size reduction so that the mill has to apply less grinding power without hurting any of the properties of the resulting cement. The present research work aimed to investigate the influence of a chemical grinding aid ethylene glycol (EG) on cement properties and mill performance during the grinding of Portland cement beyond 500 ppm reaching up to 1200 ppm. The obtained results show increasing in initial compressive strength and increasing in the productivity of the cement mill.

In this study, amorphous nanoparticles were extracted from fly ash using a sol-gel method. The obtained nanoparticles were characterized using XRF spectroscopy, XRD, FT-IR and TEM. The XRD curves show the presence of both crystalline and amorphous phases. FT-IR analysis indicated the presence of silanol and siloxane groups. Upon analysis, the primary nanoparticles were found to exhibit a roughly spherical shape with an average size of approximately 65 nm. The findings of this study demonstrate the feasibility of applying the sol-gel method to synthesize nanoparticles derived from coal fly ash (CFA), thereby avoiding other expensive and energy-intensive methods of nanoparticle synthesis.

The presented study is dedicated to a “green” solution for hot beverage packaging—a biodegradable single-use cup. Product development follows a specifically elaborated methodology that involves initial material characterization, followed by adjusted product design. The research and design activities continue toward mold design development and testing. The study concludes with a cost analysis, in which an alternative material composition is also examined. The finalized product is ready for industrialization, reaching TRL 5, with assessed financial aspects. This study is a good demonstration of the application of modern technologies and tools for the development of an innovative product.