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Surface functionalization of graphene oxide (GO) is one of the best ways to achieve homogeneous dispersions of GO within polymeric matrices and composites. Nonetheless, studies regarding how the level of GO functionalization affects the macroscopic properties of three-dimensional (3D) printed nanocomposites are still few. Furthermore, the bifunctionalization of GO with the NH 2 /NH 3 + groups to obtain improved thermomechanical macroscopic properties at ultralow loads has not been reported. In this paper, fast and straightforward surface bifunctionalization of GO with a controlled ratio of NH 2 /NH 3 + groups at low, medium, and high functionalization levels (AGOL, AGOM, and AGOH) in a one-step microwave-assisted synthesis is reported for the first time. The functionalization mechanism was disclosed, wherein three graft densities (G φ ) were obtained. A plateau of maximum functionalization (G φ = 4.9 μmol/m 2 = 2.9 molecules/nm 2 ) was reached, suggesting that full coverage of the GO surface is achievable. Also, an increase in the exfoliation of functionalized layers was obtained, ranging from d 002 = 8.6 Å up to d 002 = 15.8 Å. X-ray photoelectron spectroscopy (XPS) reveals the successful functionalization of GO, as well as an atomic relationship NH 2 /NH 3 + of about 50/50% in all functionalized samples. Stereolithographic (SLA) 3D-printed nanocomposites (AGOL/R, AGOM/R, and AGOH/R) were obtained using ultralow loads (0.01 wt %) of each bifunctionalized material. This ultralow amount was sufficient to enhance thermal stability (up to 4 °C) and a significant increase in the glass transition temperature (93 °C ≤ T g ≤ 120 °C). Interestingly, we found that low and medium grafting density promotes a ductile material (ε > 5%); meanwhile, a high graft density produces brittle materials. Also, we observe that the toughness can be tuned as a function of the graft density (AGOH: 24 MPa, AGOM: 342 MPa, AGOL: 562 MPa) at ultralow loadings. The 3D-printed nanocomposites using GO with low graft density (AGOL) increase their tensile strain by 90% in comparison with the control sample (without filler). Finally, the underlying mechanisms were discussed to explain the findings.

Lactose is a disaccharide of importance in humans dietary, food products, and the pharmaceutical industry. From the existing isomeric forms, -lactose is rarely found in nature. Thus, in this work, a simple methodology to obtain anhydrous -lactose ( L) from -lactose monohydrate ( L⋅H 2 O) is presented. The L⋅H 2 O powder was dispersed into a basic alcoholic solution (72 hours), at controlled conditions of temperature (27, 29, 31, and 32 ∘ C), without stirring. The slurry was dried at room temperature and characterized. Fourier transform infrared spectroscopy showed the formation of L for the samples prepared at 29 and 32 ∘ C. Raman spectroscopy confirmed this result and suggested the occurrence of crystalline L. Rietveld refinement of the X-ray diffraction patterns was employed to identify and quantify the composition of the isomers. The samples prepared at 29 and 31 ∘ C showed the formation of pure L, while those at 27 and 32 ∘ C showed the presence of L⋅H 2 O and a mixture of the two isomers, respectively. The morphology of the powders was studied by scanning electron microscopy, observing the formation of irregular shape L⋅H 2 O particles and axe-like L particles. Clearly, with this methodology, it was possible to obtain pure, crystalline, and anhydrous L at mild temperature.

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A significant challenge in the photocatalysis field is getting selfsupporting three-dimensional (3D)-printable photocatalysts that preserve their photocatalytic activity. Herein, we disclose reusable 3D-printable photocatalysts based on binder-free TiO 2 nanoparticles (3DM-TiO 2 ) under an eco-friendly, affordable, and reliable methodology for the first time. Strong and mechanically stable 3DM-TiO 2 structures (compression strength = 16 MPa) were obtained under soft sintered conditions (∼400 °C), exhibiting an anatase/rutile ratio of 85/ 15% by the Rietveld refinement, a mesoporous structure with a surface area (S BET ) of 45.2 m 2 /g, and outstanding photocatalytic activity. 3DM-TiO 2 successfully demonstrated high recyclability and adaptability in the dust-free photodegradation experiments of emerging contaminants in the liquid phase (triclosan, TCS) and gas phase (liquefied petroleum gas, LPG). A TCS mineralization of ∼95% was obtained at 6 h of photodegradation. The reusability from the 3DM-TiO 2 was assessed during 12 cycles of TCS degradation, recovering its photocatalytic activity by 100% after reactivation at 400 °C. In the gas phase, the maximum conversion of LPG to CO 2 was 95.3% for n-butane, 93.7% for isobutane, and 52.9% for propane after 15 h of photodegradation. All photodegradation experiments were fitted to the Langmuir−Hinshelwood kinetic model. We believe that the technology proposed here could trigger applications of nanomaterial-based photocatalysts, replacing the powdered materials to achieve new reactor designs and process configurations on a large scale.

In this work, the particulate matter (PM) from three different monitoring stations in the Monterrey Metropolitan Area in Mexico were investigated for their compositional, morphological, and optical properties. The main aim of the research was to decipher the different sources of the particles. The methodology involved the ex situ sequential analysis of individual particles by three analytical techniques: scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), polarized light microscopy (PLM), and micro-Raman spectroscopy (MRS). The microanalysis was performed on samples of total suspended particles. Different morphologies were observed for particles rich in the same element, including prismatic, spherical, spheroidal, and irregular morphologies. The sequential microanalysis by SEM-EDS/PLM/MRS revealed that Fe-rich particles with spherical and irregular morphologies were derived from anthopogenic sources, such as emissions from the metallurgical industry and the wear of automobile parts, respectively. In contrast, Fe-rich particles with prismatic morphologies were associated with natural sources. In relation to carbon (C), the methodology was able to distinguish between the C-rich particles that came from different anthopogenic sources—such as the burning of fossil fuels, biomass, or charcoal—and the metallurgical industry. The optical properties of the Si-rich particles depended, to a greater extent, on their chemical composition than on their morphology, which made it possible to quickly and accurately differentiate aluminosilicates from quartz. The methodology demonstrated in this study was useful for performing the speciation of the particles rich in different elements. This differentiation helped to assign their possible emission sources.