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Engineered Nanomaterials (ENMs) or products containing ENMs, known as nano-enabled products are commercialized globally by a large number of companies. Concern about the potential risks and negative impacts of releasing ENMs into the environment is under investigation. For this reason, methodologies to estimate the probable mass concentrations of ENMs released in different regions of the world have been developed. As a first attempt to estimate the probable mass flows of nanosized titanium dioxide (nano-TiO 2 ) released in Mexico, we developed a Probabilistic Material Flow Analysis (PMFA) for 2015. The model describes probabilistic mass flows of released nano-TiO 2 during the life cycle of sunscreens, coatings, ceramic, and other nano-enabled products, including the flows through the solid waste and wastewater management systems, as well as the transfer of nano-TiO 2 to three environmental compartments (atmosphere, topsoil, and surface water). The PMFA incorporates the uncertainty related to the input data. We observed that the most significant nano-TiO 2 flows occur to the surface water, landfill, and soil compartments, targeted as the main "hot-spots", where living organisms could be more exposed to this material. Further improvements in the model are needed due to some data gaps at some life cycle stages, for instance, solid waste management and reused wastewater manipulation for irrigation purposes. Finally, the model developed in this study can be adjusted to assess other ENM releases and can be beneficial for further investigation in fate modeling and environmental risk assessment., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Solar stills are an excellent option for providing freshwater to isolated communities living near the coast of Baja California, Mexico, and facing scarcity. Double-slope solar stills are simple and easy to operate; however, they normally produce low volumes of condensate. To overcome this, changes to the architecture of the still, implementation of mechanical items, or addition of nanoparticles to the water have been proposed. Since coupling the still with a solar water preheater and adding nanomaterials can be done without incurring in costly designs, and provided that using two types of nanoparticles simultaneously has the potential to further enhance the heat transfer capabilities, these options were investigated here. A spiral solar heater, utilized to increase the feedwater temperature, and combinations of TiO2, ZnO, and Al2O3 nanoparticles were implemented to augment the yield of a double-slope solar still. The nanostructures were specifically synthesized for this application and experiments were done at the climate of Ensenada, Baja California. Nanostructures whose shape allowed wide contact with the water and with adequate absorptivity were produced. Peak yields and efficiencies of 5.46 L/m2 and 59.9% were achieved combining TiO2 + Al2O3, and 4.72 L/m2 and 50.2% with TiO2 + ZnO at costs between 0.034 and 0.038 US$/L. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles (TiO2-NPs) have a wide range of industrial applications (paintings, sunscreens, food and cosmetics) and is one of the most intensively used nanomaterials worldwide. Leaching from commercial products TiO2-NPs are predicted to significantly accumulate in wastewater sludges, which are then often used as soil amendment. In this work, sludge samples from four wastewater treatment plants of the Chihuahua State in Mexico were obtained during spring and summer (2017). A comprehensive characterization study was performed by X-ray based (laboratory and synchrotron) techniques and electron microscopy. Ti was detected in all sludge samples (1810–2760 mg/kg) mainly as TiO2 particles ranging from 40 nm up to hundreds of nm. Micro-XANES data was analyzed by principal component analysis and linear combination fitting enabling the identification of three predominant Ti species: anatase, rutile and ilmenite. Micro-XANES from the smaller Ti particles was predominantly anatase (68% + 32% rutile), suggesting these TiO2-NPs originate from paintings and cosmetics. TEM imaging confirmed the presence of nanoscale Ti with smooth surface morphologies resembling engineered TiO2-NPs. The size and crystalline phase of TiO2-NPs in the sludge from this region suggest increased reactivity and potential toxicity to agro-systems. Further studies should be dedicated to evaluating this. [ABSTRACT FROM AUTHOR]

A palygorskite unit was discovered in a road cut of undifferentiated Tertiary limestone between the villages of El Pariso and San Roman (18°49.309N, 88°37.861W) in the southeastern Yucatán Peninsula, Mexico. This is the southern most locality of a clay-rich sedimentary unit reported in the literature for the Tertiary carbonates of the Yucatán Peninsula. This occurrence indicates a much wider range of palygorskite-rich clay deposition than previously recognized. The lithology is 99% clay and 1% sand to silt size diagenetic quartz grains. The clay consists of approximately 85% palygorskite, 15% montmorillonite and trace amounts of titanium oxides. EDS analyses on palygorskite are largely consistent with sedimentary palygorskites from other coastal marine settings, however palygorskite has a low total Fe content (average = 0.40 wt% expressed as Fe2O3) compared to many other sedimentary palygorskites. Montmorillonite chemical compositions are typical and compared to the palygorskite have substantially higher Fe2O3 concentrations (average = 3.90 wt%). The low percentage of coarse grains in the lithology combined with a high proportion of palygorskite and lack of detrimental trace minerals suggest the deposit is of industrial grade; however, it has limited reserves (6,000 m3). The unit could be potentially used in a wide array of environmental applications which are needed in the region including liners for landfills and constructed wetlands. The unit is in a geographic location which would serve the expanding economy of the region. This resource has the potential to have great impact on the quality of the local environment and the economy of a region under great environmental threat. [ABSTRACT FROM AUTHOR]

The Chemours Company has begun the commercial start-up of the new titanium dioxide (TiO 2 ) line at its Altamira plant in the Mexican state of Tamaulipas. Following mechanical completion of the line in December 2015, the company reports that it has now begun to run it using its proprietary chloride process, producing Ti-Pure TiO 2 pigments for customer qualification. [ABSTRACT FROM AUTHOR]