Hydroxyapatite (HAp) and hydroxyapatite/multi-walled carbon nanotube (MWCNT) composites were obtained by the co-precipitation method, followed by ultrasound-assisted and microwave radiation and thermal treatment at 250 °C. X-ray diffraction (XRD) confirmed the presence of a hexagonal phase in all the samples, while Fourier-transform infrared (FTIR) spectroscopy elucidated the interaction between HAp and MWCNTs. The photoluminescent technique revealed that HAp and the composite with non-functionalized MWCNTs present a blue luminescence, while the composite with functionalized MWCNTs, under UV-vis radiation shows an intense white emission. These findings allowed presentation of a proposal for the use of HAp and HAp with functionalized MWCNTs as potential materials for optoelectronic and medical applications.

Applications of carbon-TiO₂ materials have attracted attention in nanotechnology due to their synergic effects. We report the immobilization of TiO₂ on carbon prepared from residues of the plant Manihot, commercial TiO₂ and glycerol. The objective was to obtain a moderate loading of the anatase phase by preserving the carbonaceous external surface and micropores of the composite. Two preparation methods were compared, including mixing dry precursors and immobilization using a glycerol slurry. The evaluation of the micropore blocking was performed using nitrogen adsorption isotherms. The results indicated that it was possible to use Manihot residues and glycerol to prepare an anatase-containing material with a basic surface and a significant S_BET value. The activities of the prepared materials were tested in a decomposition assay of indigo carmine. The TiO₂/carbon eliminated nearly 100% of the dye under UV irradiation using the optimal conditions found by a Taguchi L4 orthogonal array considering the specific surface, temperature and initial concentration. The reaction was monitored by UV-Vis spectrophotometry and LC-ESI-(Qq)-TOF-MS, enabling the identification of some intermediates. No isatin-5-sulfonic acid was detected after a 60 min photocatalytic reaction, and three sulfonated aromatic amines, including 4-amino-3-hydroxybenzenesulfonic acid, 2-(2-amino-5-sulfophenyl)-2-oxoacetic acid and 2-amino-5-sulfobenzoic acid, were present in the reaction mixture.

Five sulfonyl aromatic alcohols, namely 4-((2-hydroxyethyl)sulfonyl)phenol, 4-((2-(2-((4-hydroxyphenyl)sulfonyl)ethoxy)vinyl)sulfonyl)phenol, 4-(ethylsulfonyl)phenol, 4-(vinylsulfonyl)phenol and 5-((4-aminophenyl)sulfonyl)-2-penten-1-ol were identified by LC-ESI-Qq-TOF-MS as products formed by electrolysis of the bisazo reactive dye Reactive Black 5 (RB5). Since electrolyses were performed in an undivided cell equipped with Ni electrodes in alkaline medium, amines like 4-(2-methoxyethylsulfonyl)benzene-amine (MEBA) with m/z 216 were also suspected to be formed due to the plausible chemical reaction in the bulk or the cathodic reduction of RB5 and its oxidation by-products. Aiming to check this hypothesis, a method was used for the preparation of MEBA with 98% purity, via chemical reduction also of the dye RB5. The logP of the synthesized sulfonyl aromatic compounds was calculated and their logk_w values were determined chromatographically. These data were discussed in regard to the relationship between hydrophobicity/lipophilicity and toxicity.

Emerging pharmaceutical contaminants in wastewater are a significant concern, especially those extensively consumed during the COVID-19 pandemic. This study aims to identify in Nexapa River the following pharmaceuticals used in COVID-19 treatment: acetaminophen, albendazole, chloroquine, dexamethasone, diclofenac, hydroxychloroquine, and ivermectin. Solid Phase Extraction was used to extract and concentrate the target compounds from water samples. HPLC–DAD-MS was employed to identify and quantify some emerging pharmaceuticals. The ecological risk for three trophic levels was calculated: -algae, invertebrates, and fish- Two treatment scenarios were studied using the Estimation Programs Interface (EPI) Suite™ in a wastewater treatment plant, current operating conditions and hypothetical ideal operating conditions of an equivalent WWTP, in the state of Puebla, Mexico. The results indicate that treatment plant effluents are the primary source of the entry of these compounds into the aquatic environment. Among them, ivermectin was found to be the compound with the highest potential ecological risk despite its low concentration (6.17 μg L⁻¹), followed by diclofenac (25.75 μg L⁻¹) and paracetamol (132.89 μg L⁻¹).

Los complejos de gadolinio son los agentes de contraste más utilizados en estudios de imagenología por resonancia magnética. Estos compuestos son excretados sin metabolizar a través de la orina y circulan en el drenaje donde son propensos a experimentar cambios en su estructura química que propician la liberación del ion gadolinio, que es altamente tóxico. Sin embargo, en forma de complejo o de ion es considerado un contaminante emergente en los cuerpos de agua. El objetivo de esta contribución es evidenciar la problemática ambiental que representa la disposición inadecuada de los agentes de contraste basados en gadolinio.