Jose Alfredo Hernandez

The evolution of coke deposits during propane dehydrogenation.

Concerns have increased significantly in recent years due to the presence of microplastics in different environmental compartments given that this pollutant can cause adverse effects on the environment and human health. The present review integrates representative studies of Mexican researchers proposing solutions to these concerns, addressing ecological risk and the human food chain, microplastic ingestion by animals, water and sediment pollution, physical/chemical methods for microplastic removal from water, and chemical recycling as a research direction in plastic waste management. Several publications from Mexican institutions are limited to the occurrence and identification of polymers, and a smaller number of documents are focused on solutions to microplastic pollution. Fibers, fragments, spheres, films, and foams have been found in aquatic compartments, sediment, and animals. High ecological risk has been documented in some aquatic compartments. There is a lack of standardized protocols for sampling, extraction, identification, and reporting. Flocculation is a cost-effective approach and may be one of the most promising options for removing microplastics from fresh water. Bioremediation using microorganisms and chemical recycling appear to be the two most widely considered approaches to reverse plastic pollution. National databases, permissible limits, and mandatory monitoring programs should be developed, as these are essential components of an effective regulatory framework.

Polymers in Medicine – a peer-reviewed scientific journal published by Wrocław Medical University, focusing on research on the application of polymers in medicine, pharmacy, and biomaterials.

The discharge of metal-containing effluents into aquatic systems remains a major environmental concern because metal ions can persist in water bodies and accumulate in biological systems, potentially affecting ecosystem and human health. Among these contaminants, Cr(III) is frequently encountered in waste streams generated by industrial activities, making its removal an important objective in water quality management. This study investigated the adsorption behavior of Cr(III) using lignocellulosic biosorbents obtained from tamarind shell (Tamarindus indica) after water, H₂O₂, and HCl pretreatments, with particular emphasis on equilibrium behavior, thermodynamic characteristics, and pretreatment-induced physicochemical modifications. Batch adsorption experiments were conducted to evaluate equilibrium behavior. The highest adsorption capacity (41.6 mg g⁻¹) was obtained with the water-treated biosorbent at 60 °C. The equilibrium data were best represented by the Sips model, suggesting that Cr(III) adsorption occurred on surfaces containing adsorption sites with different energetic characteristics. Thermodynamic analysis revealed that the adsorption process was spontaneous, while the enthalpy changes indicated predominantly endothermic behavior for the pretreated biosorbents. ATR-FTIR, SEM, EDS, and XRD analyses were performed to characterize the biosorbents before and after adsorption. The characterization results indicated that oxygen-containing functional groups, particularly hydroxyl and carbonyl functionalities, were associated with the adsorption process. SEM images showed morphological changes associated with pore occupation, while EDS confirmed chromium adsorption and suggested possible ion-exchange mechanisms. XRD patterns indicated a mainly amorphous structure. The results demonstrated that pretreatment-induced modifications strongly influenced the adsorption performance of tamarind shell. Water pretreatment produced the most favorable adsorption behavior, yielding the highest adsorption capacity among the evaluated biosorbents. The combined interpretation of equilibrium, thermodynamic, and characterization results revealed a close relationship between surface properties and Cr(III) uptake.

At present, human activity is the main source of water pollution. The tanning industry is a primary source of water contamination with Cr(III), which can cause various diseases if ingested. A circular economy approach proposes an effective, low-cost solution. The utilization of waste from the food industry is used for the removal of Cr(III) through biosorption. This study evaluated the adsorption capacity of orange peel (OP) and pineapple crown (PC) pretreated with H₂O₂ and NaOH was evaluated under different operating conditions. The physicochemical properties of the biosorbents were characterized using techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results show that treatment with NaOH at 60 °C obtained an adsorption capacity of 61.63 mg/g and 64.19 mg/g for OP and PC, respectively. The combined biosorbents resulted in an approximately 50% increase in the adsorption capacity of Cr(III) compared to individual biosorbents. The isotherms that best fit the experimental data were Sips and Redlich–Peterson (RP) models, suggesting heterogeneous adsorption behavior in biosorbents. Thermodynamic parameters indicated that biosorption process was spontaneous and endothermic.

Calcium phosphate (CaP) materials are biocompatible and non-toxic to the body. However, they lack biointegration, exhibit a low resorption rate and can cause fibrous encapsulation throughout the implant material. A promising approach for dental or orthopedic regeneration is the use of dicalcium phosphate dihydrate (DCPD) and octacalcium phosphate (OCP), as they are well-suited to bone components. From a novel perspective, these apatites can be used as drug carriers for individuals with low tolerance to common excipients. In this study, the transformation of DCPD into different morphologies in DMEM was investigated using an induced dissolution and reprecipitation reaction solution. The DCPD transformation time was observed to be morphology-dependent and can occur between 48 and 168 h. In the interaction with simulated body fluid (SBF), simulated gastric fluid (SGF) and a combination of both (BFS/SGF), a higher mass loss was observed in SGF (~80%) than in the other fluids (~35%). The structural changes presented in DCPD and OCP before and after immersion in physiological fluids were analyzed by ATR-FTIR, SEM, XRD and EDS. The obtained OCP showed low stability in SGF compared to SBF and SBF/SGF, which indicates that it may be a suitable candidate for drug delivery in the digestive tract.

Currently, chalcopyrite is the world’s largest copper reserve. Commonly, the copper contained in chalcopyrite is obtained by pyrometallurgical processes. Still, in recent years, due to the environmental problems generated by this route, more environmentally friendly techniques have been proposed, such as hydrometallurgy; but chalcopyrite has the drawback of passiveness. A promising alternative to minimize this phenomenon is using polar organic solvents in an acidic medium, obtaining copper extraction percentages of 90% in five h. A solvent that has significant functionality is methanol. Moreover, a topic barely studied in depth is the characterization of the gases emitted in the leaching of minerals such as chalcopyrite. In this sense, one gas generated through chalcopyrite leaching is molecular hydrogen, which would increase the economic viability of the process. In this work, the gases formed during the leaching of chalcopyrite concentrate are analyzed, and the formation of only molecular hydrogen by gas chromatography was detected. The hydrogen production was 0.24 µmol in 300 min, and the copper extraction was around 65%, using a concentration of 0.5 M of H₂SO₄, 60 mL of methanol, and 20 mL of H₂O₂. Thus, based on the detected chemicals in solid residues of the leaching of chalcopyrite concentrate, the thermodynamic analysis supports the spontaneous formation of hydrogen with a value of ΔG = −119.66 kJ/mol.

The potential of king grass biomass as a precursor for carbon-based materials was evaluated through comprehensive physicochemical characterization. The biomass showed high fixed carbon content, reactive oxygenated groups, and favorable atomic ratios, supporting its suitability for conversion into porous carbon structures. This study focused on the synthesis of graphene-like materials via high-temperature pyrolysis (~1000 °C), employing FeCl₃ and potassium ferricyanide (K₃[Fe(CN)₆]) as catalytic agents. Although FeCl₃ is widely studied, it showed limited capacity to promote graphitic ordering. In contrast, K₃[Fe(CN)₆] exhibited a synergistic effect, combining iron-based catalytic species (Fe, Fe₃C) and potassium-derived activating compounds (K₂CO₃), which significantly enhanced graphitization and porosity. Characterization by Raman spectroscopy, XRD, and SEM confirmed that materials synthesized with K₃[Fe(CN)₆] presented improved crystallinity, lower defect densities (I_D/I_G = 0.37–1.11), and distinct 2D bands (I_2D/I_G = 0.32–0.80), indicating the formation of few-layer graphene domains. The most promising structure was obtained from cellulose treated with alkaline peroxide and deoxygenated prior to pyrolysis with K₃[Fe(CN)₆], showing properties comparable to commercial graphene. BET analysis revealed surface areas up to 714.50 m²/g. While non-catalyzed samples yielded higher mass, the catalytic approach with K₃[Fe(CN)₆] demonstrates a sustainable and efficient pathway for producing graphene-like carbon materials from lignocellulosic biomass.

The advancement of science and technology has helped humans solve different problems related to their health. Among these applications are biomaterials, which are materials synthesized by humans for medical or biological use, representing a market and innovation with potential. The best known biomaterials are calcium phosphate cements (CPCs) that are used as bone substitutes, which show a similarity to bone minerals such as apatites such as dicalcium phosphate dihydrate, and it was synthesized and tested in previously prepared simulated intestinal and body fluids to analyze its stability under specific physiological conditions. Purity was determined by the ash method, giving an average of 73% and 85% in the different tests carried out. The characterization study was involved using ATR‐FTIR, XRD, SEM, and EDS where changes were observed in the crystalline structure, in the bonds of the functional groups present on the surface and the morphology of Brushite causing the interaction with the different simulated fluids transformation into monetite, amorphous dicalcium phosphate, and hydroxyapatite.

Currently, water pollution caused by dyes is a serious problem since they are toxic and carcinogenic to living beings. To reduce the presence of these contaminants, natural adsorbents have been considered as they are easy to obtain, inexpensive, and have high removal efficiency. In this work, the adsorption process using natural brushite (nDCPD) was studied for the removal of phenol red (PR), achieving a removal rate of 99.15% and an adsorption capacity of 82.24 mg/g, and gentian violet (GV), achieving a removal rate of 97.03% and an adsorption capacity of 74.22 mg/g. Equilibrium adsorption occurs for both dyes in multiple layers on the surface. The adsorption process is spontaneous for both dyes. The kinetics of the adsorption process involve using a single active site on the surface for PR adsorption, while for GV, two active sites on the surface are required. Analysis via FTIR, EDS, and XRD revealed various mechanisms that intervene in the adsorption process of both dyes on the surface of nDCPD, such as electrostatic forces, functional groups, physisorption, and ion exchange.