This work studies the feasibility to employ a combination of volcanic ash (natural waste) with different raw materials in the production of geopolymers: fly ash and mining tailing (considered hazardous solid waste), natural pozzolan, and metakaolin. This study compares the properties of geopolymers based on volcanic ash with fly ash, pozzolan, metakaolin, and mining tailing in a relation of 1:1 with the addition of NaOH 15M and Na₂SiO₃ as alkali activators. FTIR and XRD assays and mechanical tests were employed to characterize the geopolymers. The results showed that those materials can be used as raw materials to produce geopolymers. Additionally, the results revealed that prime material composition and their mineralogical characteristics influence the geopolymerization reaction and compression strength, reaching values of 35 MPa for the volcanic ash-pozzolan mixture. The pozzolan is a good source of Al₂O₃ and SiO₂ and is highly reactive to the alkali activators resulting in a better geopolymerization in comparison to the mixtures of volcanic ash with metakaolin, fly ash, or mining tailing.

The physical, mechanical and microstructural properties of volcanic ash based geopolymer mortars by alkaline activation (with NaOH and Na(OH) + Na₂SiO₃ solutions) using different aggregates (Peruvian sand and standard sand) were studied. For the synthesis of geopolymers, a liquid:solid ratio of 0.1 and an ash:sand ratio of 1:1 were selected, and 25% of sodium silicate was added to the Na(OH) solution. The samples were compacted, toughened and cured at 80°C for 48 h. The dissolution of volcanic ash particles and the formation of the geopolymeric matrix increase with Na(OH)+Na₂SiO₃ solution and standard sand while the local sand promotes better geopolymerization with NaOH solution. The compression strength of volcanic ash based geopolymer mortar reported values from 18.93 MPa to 23.28 MPa at 6 months of curing, which determines the use of these geopolymers as a construction material.

In this research, the influence of natural zeolites obtained from the volcanic ash of the Ubinas volcano has been studied as synergistic agents in a flame-retardant system (composed of ammonium polyphosphate, pentaerythritol, and polypropylene). Four zeolites were synthesized from volcanic ash, including those that had been calcined and those that had not. These were then placed in an alkaline solution at three synthesis temperatures. Zeolites were characterized through X-ray diffraction, specific surface area by nitrogen adsorption analysis (Brunauer–Emmett–Teller) and scanning electron microscopy. Polypropylene matrix composites were prepared with ammonium polyphosphate, pentaerythritol and zeolites at 1, 5 and 9%. Its thermal stability and fire resistance were evaluated by thermogravimetric analysis, limiting oxygen index, vertical burning test and cone calorimeter and its morphological structure by scanning electron microscopy. It was determined that the synthesis temperature and the use of calcined and without calcined volcanic ash have an influence on the characteristics of the zeolites and on its synergistic action.

Cheese whey is a byproduct of the cheese industry that causes high levels of pollution in the environment, but its high lactose content means that it can be used as a source to obtain lactic acid. In this study, two strains, one belonging to a yeast and the other one to a bacteria (Kluyveromyces lactis and Enterococcus faecalis), were isolated from cheese whey and molecularly characterized, and the optimal growth conditions were determined. Then, using proteinized and deproteinized cheese whey, batch fermentation was carried out with the strains arranged in suspension and immobilized. The consumption of lactose and the production of lactic acid were measured through Brix degrees and acidity analysis. Afterwards, the lactic acid was purified, and its yield and physical and chemical characteristics were determined. It was proven that there were differences between each of the strains; arranged in free or encapsulated cells, the proteinized and deproteinized cheese wheys, under the same purification conditions, achieved different yields, colors, and densities of lactic acid. Immobilized Enterococcus faecalis had the highest yield (50.61 ± 34.94 g/L) using the deproteinized cheese whey compared to the immobilized Kluyveromyces lactis (35.70 ± 0.15 g/L) using the proteinized cheese whey.

The main purpose of this study is to evaluate the Buddleja species bioaccumulation capacity for the phytoremediation of soils contaminated with chromium produced by tannery effluents. The soils evaluated were collected from the Añashuayco stream, located in Arequipa region. The soil samples were collected from four different locations, in order to determine the presence of total chromium through the Environmental Protection Agency analytical technique, method 3050B acid digestion of sediment, sludge and soil. Three soil samples were analyzed for each collected location. Additionally, two non-contaminated soil samples (control group) were also analyzed. A Buddleja species seedling was placed in each sample to be monitored monthly for up to 90 days. Then, the plant tissue analysis was carried out by the analytical method of atomic absorption spectrophotometry in order to determine the amount of bioaccumulated total chromium. As a result, the Buddleja species bioaccumulated 30.45%, 24.19%, 34.55% and 40.72% of total chromium per each soil sample location in a period of 90 days. Therefore, the Buddleja species can be considered as an alternative to remediate soils contaminated with total chromium that comes from tannery effluents.

The valorization of volcanic ash as a raw material for advanced functional materials offers dual benefits for both the environment and technology. Firstly, it diverts waste from landfills, thereby reducing the environmental footprint of volcanic deposits. Secondly, it contributes to the circular economy by transforming an abundant natural residue into a high-value product. In this study, zeolites were synthesized from the ash of the Ubinas volcano via the hydrothermal method in an alkaline medium. A systematic investigation was conducted to ascertain the influence of NaOH concentration and reaction temperature on synthesis efficiency and final material properties. The crystalline phases and morphology of the products were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), while textural and thermal properties were evaluated through the Brunauer–Emmett–Teller (BET) method and Thermogravimetric Analysis (TGA). The results revealed that both temperature and NaOH concentration significantly affected the physicochemical properties of the zeolites. Four zeolite types were obtained; among them, Zeolite Z4 (synthesized with 3 M NaOH at 150 °C) exhibited the highest adsorption capacity, with a specific surface area of 35.60 m²/g, while Zeolite Z1 (synthesized at 120 °C with 1.5 M NaOH and 27.85 m²/g) displayed superior thermal stability and crystallinity. These variations in thermal and textural properties were reflected in the catalytic pyrolysis performance of polypropylene (PP). Zeolite Z3 (synthesized at 150 °C with 1.5 M NaOH) achieved the highest gaseous product yield (80.2%), despite lacking the expected zeolitic crystalline phases. In contrast, Zeolite Z2 (synthesized at 120 °C with 3 M NaOH) yielded 57.7% gaseous products and stood out for its predominant analcime phase, characteristic of zeolitic materials. In summary, this study demonstrates that volcanic ash-derived zeolites not only enhance synthesis efficiency and functional performance but also represent a sustainable strategy for waste valorization, closing material loops and enabling the recovery of high-calorific gaseous products from plastic waste.