Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Photocatalysis is an efficient and cost-effective method for removing toxic dyes from wastewater. Indeed, a large part of the research work carried out in the field of green chemistry has been devoted to the design and development of new photocatalysts with good photocatalytic activities. Incorporation of supports constitutes a strategy to improve the photocatalytic activity of photocatalysts by reducing the aggregation of nanoparticles during the photocatalytic process. Intercalated clays can be used as supports for oxide-based photocatalysts because they have high adsorption capacity. The goal of the present study consists of using SrCo2O4 nanoparticles as photocatalyst immobilized on natural Algerian clay modified by polyaniline (Clay/PANI/SrCo2O4). Spinel oxide (SrCo2O4) was synthesized through a sol–gel method. Then, polymer modified clay were ‎fabricated by in situ polymerization. The as-prepared composites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR) and Scanning electron microscopy (SEM). The photocatalytic performances of the synthesized materials were evaluated by studying the photocatalytic degradation of congo red dye under UV light irradiation.

ABSTRACT In an urban commune of Santiago, Chile, a monitoring campaign for dew and PM10 atmospheric particulate matter was implemented during 2022. The pH, conductivity, cation and anion concentrations of dew water, and the water-soluble fraction of PM10, were analyzed.   In the water-soluble fraction of PM10, the average cation concentrations were: 4.19 µgm3 for ammonia; 1.40 µgm-3  for  calcium; 0.46 µgm-3  for potassium; 0.36   µgm-3  for sodium; and 0.17 µgm-3  for  magnesium. In a decreasing order, concentrations were: NH4 ˃ Ca ˃ K ˃ Na ˃ Mg ˃ Zn ˃ Ba ˃ Cu ˃ Mn ˃ Al ˃ As ˃ V.   Among anions, the nitrate ion showed concentrations within the 4.49 to 20.09 µgm-3  range. The concentration of the carbonate ion ranged between 0 and 6.7 µgm-3 ; the sulphate ion ranged from 2.65 to 6.13 µgm-3  ; the chloride ion from 2.21 to 3.43 µgm-3 M; the phosphate ion varied between 2.08 and 2.33 µgm-3 ; the nitrite ion between 1.21 and 1.33 µgm-3 ; and the fluoride ion between 0.14 and 0.18. Simultaneously, 60 water dew events were collected during working days, with a total volume of 6465 mL, and 20 events on weekends. This volume was similar to the total level of rainfall in Santiago during 2022 (8217mL). In the dew water, the mean pH was 7.47, and the mean concentrations were: ammonia:13300 µgL-1, calcium: 12040 µgL-1 , potassium: 2600 µgL-1 , sodium 1530 µgL-1 , magnesium: 669 µgL-1 , zinc: 65 µgL-1, manganese: 50 µgL-1 , and copper:19 µgL-1. Among anions, mean concentration values were: chlorides: 8720 µgL-1 ; sulphates: 28938 µgL-1; nitrates: 32538 µgL-1: nitrites: 7556 µgL-1; and carbonates: 14540 µgL-1. Simple linear correlations between cations and anions present in dew water and PM10 showed values of 0.788 and 0.81, indicating a key removing role from the dew water in this city. In Santiago, dew water has a cleansing or removal effect as important as that of rain water

Studies carried out in different native Chilean plants demonstrate that compounds found in both fruits and leaves have the capacity to decrease oxidative cellular damage in humans, thus contributing to the prevention of chronic illnesses such as diabetes, cancer, and arterial hypertension. Information on native Chilean medicinal plants was extracted from the Scopus, Science Direct, Google Scholar, and PubMed databases. Plants with relevant antioxidant activity were selected based on their chemical compounds and their use as native-flora research materials in Chile. Provitamin A, carotenoids and vitamins C and E are the main compounds found in the studied species. Several analyses also show the presence of polyphenolic and alkaloid compounds with proven capacity to increase antioxidant activity. Therefore, such native species should be of interest for the food, cosmetic, and pharmaceutical industries, as safer natural antioxidant compounds are crucial for the prevention of human illnesses and for replacing the synthetic antioxidants currently in use (BHT, BHA). The present review aims to provide up-to-date information on the traditional uses of native plants in popular medicine, and to present evidence concerning the antioxidant activity of the studied plant species and their relationship with the active principles found.  

Traditional chemical methods, such as HPLC and AAS, are sensitive and selective for arsenic speciation but require complex sample preparation and are costly. In contrast, electrochemical methods, like voltammetry, offer a faster, more sensitive, and cost-effective analysis with a simpler sample preparation, highlighting their sample size and portability. The choice between both approaches depends on the specific needs of the analysis and the available resources.

The direct conversion of solar energy using a photocatalyst in a degradation of a pollutant reaction is a source of a sustainable and clean environment remediation.  In general, photocatalyst are semiconductors that possess valence and conduction bands. These energy bands permit the absorption of photon energy to excite electrons in the outer orbitals of the photocatalyst. Photoexcited electron and hole pairs can subsequently induce a reaction that degrade organic pollutant molecules. Photocatalyst degradation of pollutants is affected by the band level and crystallinity of the photocatalyst among others, therefore, band engineering using chemical modifications as particle size, morphology and physical as band gap could create photocatalyst suitable for the large-scale photodegradation of organic pollutant. In this Review, different factors of the photocatalyst obtained by solid-state, such as size, morphology, band gap and others are analyzed in the photocatalyst efficiency of the degradation of organic contaminant. This review involves binary metal oxide photocatalyst of the MxOy type, prepared from a solid-state route. The photocatalytic degradation of blue methylene using our  the solid-state TiO2, Fe2O3, NiO, ReO3, IrO2, Rh2O3, Rh/RhO2, and the actinide ThO2 prepared nanostructured metal oxides by a solid state method  is described and discussed. Also, other studies of photocatalysis also prepared in solid state for the degradation of methylene blue and reported in the literature are shown and analyzed.  With regard the photocatalytic efficiency, factors such as the particle size and morphology, the crystalline phase and the pyrolysis temperature used in the solid-state preparation method are very important. A multifactorial equation that summarizes the main factors that govern the photocatalytic efficiency of a photocatalyst is proposed. A parameterization of these factors is discussed through an equation of the photocatalytic efficiency as a function of these parameters. The importance of each of these parameters/factors in the photocatalytic efficiency against methylene blue degradation is discussed.

Antibiotics have improved the quality of life of human society due to their applications in medicine and food production. Nevertheless, antibiotics are also considered emerging pollutants because they have been found in the environment, water sources, and tap water. Their chemical stability and the excessive usage of these substances are the main causes of their presence in the environment. Antibiotics can be removed from water using adsorbent materials, in which activated charcoal has been extensively used for removing organic pollutants. Concerns about the environmental impact of producing activated charcoal are placing the interest in new eco-friendly materials for organic pollutant removal from water such as biochar and lignocellulosic materials. Those materials have desirable properties that allow them to remediate water in the presence of antibiotics. In this study, the use of activated carbon, biochar, and lignocellulosic materials for removing antibiotics from water is reviewed. Here we discuss the advantages and limitations of each material for the aforementioned purpose, comparing their efficiency in the removal of common antibiotics used in healthcare and agroindustry, and considering new approaches and alternatives to the technologies used for antibiotic removal from water.

The products of 1H-benzotriazole-1-methanol 1 O-acetylation, and their corrosion inhibition capabilities are reported. The O-acetylation of 1 led to the formation of 1-acetyl-1H-benzotriazole 4 as the major product and minor quantities of the O-acetylated isomeric acetates 2 and 3. Molecular structures were determined by NMR Spectroscopy, HRMS, and Single crystal X-ray diffraction. STM D1275-06 test was used to assess the corrosion inhibition capabilities. Compound 1 was the most active inhibitor. Substitution at N2 position is not recommended when looking for inhibition capabilities, the electron attracting capacity and the substituent’s size are important for an effective interaction with the copper surface.

In the realm of analytical chemistry, transition metal complexes especially the platinum group metals (PGMs) are often used compounds. Strong chromophores, inflexible luminous structures, biological potential and electrochemical activity are characteristics of the platinum metal complexes. These features have prompted the creation and study of analytical techniques based on these metal complexes for the identification of different analytes in a variety of analytical applications. Even if there are a few broad recommendations accessible to forecast a reagent's potentialities for the given goal, these studies show that sensitivity and selectivity imparted by the reagent to the metal in respective complex must be established. The quest for novel reagents is an ongoing effort to the wide and varied need for new ways to identify and analyze the metal ions under the peculiar conditions. In light of the frightening and complicated issue of environmental contamination, the endeavor of developing new and innovative reagents as well as techniques for inorganic analysis of PGMs have particular relevance. Of the numerous methodologies, the UV/VIS spectrophotometric determination technique of the PGM complexes is of interest being reliable, easy to handle, quick, cost effective, selective and sensitive. The technique relies on the process of interaction between an analyte and the metal, which are then determined analytically. In light of the enrichment of platinum group metals, the purpose of this article is to outline current research in the methods of spectrophotometric determination of PGMs. The review will assist researchers in formulating and refining PGMs as workable candidates for applications in medicine, pharmacology, analysis and catalysis.

Lichens (a symbiotic association of fungi and algae) and mosses are capable of accumulating heavy metals in their tissues. The retention of ecotoxic metals may take place in the functional groups that contain oxygen and nitrogen atoms, most likely carboxylic groups that form part of the cell wall of the fungus, through an ion exchange process. In this work, the study of carbon-lichen paste electrodes and carbon-moss paste electrodes has been carried out. Eighteen species of lichens and two species of mosses were used as sensitive agents. Additionally, the response of each of them with nine metal ions such as Cu, As, Pb, Hg, Zn, Cd, Al, Mo and Cr was studied. Being the electrode that is most sensitive to the lichen Protousnea Magallánica and the mosses Hypnum Cupresiforme and Ortotrichum Assimile, it presents better signals with the lead (II), Copper (II) and Mercury (II) ion.      

In the present work we apply a semiempirical method capable of calculating the pka and pkb values of a series of organic acids and bases through their electronic properties. This multilinear model, analogous to the one introduced by Kamlet-Taft, relates acid-base properties such as HBA and HBD to the regional electrophilicity and nucleophilicity derived from cDFT. To test the model, it was applied to a series of mono and dicarboxylic acids, as well as aliphatic/cyclic and heterocyclic amines, showing us that the model is only functional when the series of compounds present similar characteristics such as functional groups. Based on the regionalization of the electrophilicity and nucleophilicity, it can be observed that the acid-base characteristics are not exclusive to limited regions of the molecules, but that these present a bifunctional character that shifts to the relative characteristics of acid and/or base according to the global distribution of the electronic density.