One of the key features of a nano catalyst for photocatalysis is the band gap, because, through its analysis, the potential of the catalyst can be determined. In this investigation, the impact on the band gap of different catalysts made by the sol–gel method, compared with TiO₂ P25 Sigma-Aldrich, showing the effect of using gold or ruthenium as a metal supported on TiO₂, with two different dosage percentages of 1 and 3 percent, was analysed. Additionally, two oxidation states of the catalyst, the reduced form and the oxidized form of the metal, were used to see the effect on the band gap. The experiments show that the gold addition has a higher beneficial effect on the band gap for the UV region (ultra violet region), and the ruthenium addition has a higher beneficial effect for the UV/visible region. The preferred oxidation state for the band gap was the oxidized state. The characterisation of the catalyst provided an insight into the relation between the band gap and the catalyst itself.

A composite membrane based on polycaprolactone (PCL) and cellulose nanofibers (CNF) with different compositions was prepared using the electro-spinning method, with the objective of developing organic membranes with good mechanical properties to remove contaminants from water. Water is a resource of primary importance for life and human activities. In this sense, cellulose obtained from agave bagasse and polycaprolactone nanofibers was used to prepare membranes that were tested by filtering tap water. The membranes obtained presented a porosity and structure on a nanometric scale. The water quality variables evaluated after filtration with the PCL/CNF membranes showed 100% turbidity removal, 100% conductivity, and heavy metal removal of the order of 75% to 99% for iron and chromium. CNF comprises biowaste derived from tequila production, and it has added value. Electro-spun CNF and PCL membranes can be applied as a “green” and eco-friendly filtration system for water purification.

The bagasse of Agave tequilana Weber is one of the most abundant agroindustrial wastes in the state of Jalisco. However, at the present time, there is no technical use for this waste, and its high availability makes it an environmental problem. The objective of this research was to take advantage of this waste and give it an added value to be used in the elaboration of advanced materials. In this sense, the agave bagasse cellulose was obtained using an organosolv method. To obtain the nanofibrils, the cellulose was passed through 6 cycles of a microfluidizer. The material was classified by FTIR, confirming the presence of the functional groups (O-H, C-H, C-C, and C-O-C), characteristics of cellulose, and the elimination of hemicellulose and lignin present in agave bagasse without treatment. The X-ray diffraction technique allowed the determination of the degree of crystallinity of the cellulose nanofibers, which was 68.5%, with a negative zeta potential of −42 mV. The images from the atomic force microscopy helped for the observation of the degree of fibrillation in the cellulose, and with the software ImageJ, the average diameter of the nanofibers was determined to be 75 ± 5 nm with a relatively uniform length of 1.0–1.2 μm. Finally, by means of thermogravimetric analysis, it was found that the obtained cellulose nanofibers (CNFs) supported high temperatures of thermal decomposition, so it was concluded that due to the diameter of the fibrils, the high resistance to pressure, and elasticity, the nanofibrils obtained in this investigation can be used in the elaboration of advanced materials.

Agave tequilana Bagasse as Source of Cellulose Nanocrystals via Organosolv Treatment

The pineapple fruit when harvested generates a large amount of residual biomass; this biomass can be used to generate value-added products such as cellulose nanofibers. This study was focused on the isolation of CNF from pineapple leaves after oxidation pretreatment with 2,2,6,6-tetramethylpireridine-1-oxyl, followed by mechanical deconstruction of the fibers via combination of grinding and microfluidization process. One and two microfluidization passes were applied to bleached and unbleached fibers, respectively. The implications of these findings are that during the production process it is possible to reduce the amount of chemicals needed for bleaching and the energy involved in the mechanical microfluidization process. Such process yielded corresponding fibril lengths and widths in the range of 481–746 nm and 16–48 nm. The respective electrostatic charges, as measured by zeta potentials, were −41 mV and −31 mV. As expected, the CNF crystallinity was higher than that of the starting material, especially for the cellulose. However, the thermal stability was reduced, showing two degradative processes due to the chemical modification of the fibers. The CNF produced from pineapple leaves has a potential to be used like biomaterial in diverse applications while representing a viable alternative to producers, which face serious environmental and health challenges given the large volume of biomass that is otherwise left in the fields as waste. Graphic Abstract

Tequila vinasse is a liquid waste generated during the production of tequila, an emblematic alcoholic beverage in Mexico. The objective of this study was to carry out an investigation on the tequila factories located in the state of Jalisco in order to know the location of the factories in the state, the characterization of the vinasses including factories of different sizes, the current treatment methods, and disposal practices as well as the impacts of common practices of vinasse disposal. Part of the information was collected by applying a questionnaire to the tequila factories previously contacted (and physically located). For the vinasse characterization, 24 tequila factories provided a composite sample of vinasse. To assess the impact of common vinasse disposal practices, a stream running through tequila factories, soil that has been used for vinasse discharge for 14 years, and a well located near the soil were evaluated. In two main regions (Valle and Altos Sur), 110 tequila factories distributed in 10 municipalities, were identified. Vinasse disposal and treatment problems are mainly related to micro-factories that do not treat their vinasse at all. The most common method of disposal is discharging on soils. Only in the Valle region is disposal in surface waters a common practice, as well as discharges into sewage systems. The monitored stream is totally degraded with low pH, high concentrations of organic matter, suspended solids, etc. Soil fertility has not been affected due to a method of vinasse discharge-soil rest. The texture of the soils (high content of clay and silt) has been decisive in protecting groundwater from the infiltration of vinasse. The results obtained in this study could help the authorities to develop adequate strategies for the management of vinasses (treatment and disposal), mainly in micro and small tequila factories.