Journal of the Chilean Chemical Society

SYNTHESIS AND WOUND HEALING PROPERTIES OF POLYVINYL ALCOHOL FILMS DOPED WITH METAL NANOPARTICLES OF Cu AND Ag

2023-01-10T19:04:01+00:00

The skin recovery (wound healing) properties of materials based on polyvinyl alcohol (PVA) doped with metal nanoparticles (PVA-MNPs) and their chemical and physical characterization is reported. The synthesis of copper and silver metal nanoparticles supported in PVA was performed by Solvated Metal Atom Dispersed (SMAD) method using 2-ethoxyethanol as solvent. The average size of metal nanoclusters (PVA-Cu = 77 nm, PVA-Ag = 72 nm) was determined by TEM and the distribution of the inorganic phase in the hybrid material was analyzed by SEM-EDX. TGA performed in synthetic air atmosphere shows an improvement in the thermal stability by addition of nanometals to pure polymer, with the copper composite showing a higher thermo resistive capacity than the rest. Antibacterial activity against ATCC bacterial strains of Escherichia coli (E.C.), Staphylococcus aureus (S.A.), Staphylococcus epidermidis (S.E.) and Pseudomonas aeruginosa (P.A.) was determined. The silver compound showed antibacterial activity against all tested microorganisms, while the copper compound was active against S.E. Toxicological and wound healing tests were performed in Sprague Dawley rats with infested injuries on the back which were treated with PVA films doped with copper and silver. The recovery of injures infested with S. aureus is reported. This type of material could be used for biomedical applications, such as skin recovery processes in infected wounds or type I and II burns.

HEAVY METALS RISK ASSESSMENT OF TAILINGS COLLECTED FROM ANDACOLLO CITY, NORTHEN CHILE

2023-01-10T19:04:01+00:00

Throughout human history, passive mining residues have increased the levels of heavy metals or metallic trace elements in different environmental matrices. These elements, having the ability to accumulate, generate potentially toxic sites, and sometimes affecting people's health.

In Chile, metal mining is concentrated between the Administrative Regions IV and VI. Mine tailings constitute the toxic residues composed of heavy metals, which in many occasions are deposited in areas neighboring human settlements and are a health hazard for the inhabitants. When the entire mineral is extracted from a copper mine, only 2 % is used; the rest is cast off as different types of waste: 50 % sterile, 44 % tailings and 4 % slag.

In this work, the concentrations of metallic trace elements such as: Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Zn were studied in 6 sites of the largest tailings located within Andacollo city, Northern Chile.

The sampling points were recorded using GPS geographic coordinates and, in the laboratory, they were characterized determining: pH, electrical conductivity, soluble organic carbon, total organic carbon, available phosphorus, boron, total nitrogen and capacity cation exchange. The concentrations of metallic trace elements in the tailings were quantified through the analysis of two of its fractions, total fraction and soluble fraction. Metals in both fractions ware determined by atomic absorption spectrophotometry (AAS).

The physicochemical characterization of the tailings allowed establishing a profile of the environmental conditions of the sampled sites.

The sites that presented a higher concentration of metals in the total fraction correspond to sites 4 and 6, while the sites that presented a higher concentration of metals in the labile fraction correspond to sites 2 and 6.

Cu, Hg and Mo where the metals with the mayor Environmental risks assessment in all of sites.

THIONE-THIOL TAUTOMERIC EQUILIBRIUM IN A DIHYDROPYRIMIDINE-THIONE: X RAY DIFFRACTION HELPED BY NMR, FTIR AND THEORETICAL CALCULATIONS

2023-01-10T19:04:01+00:00

The solid state thione-thiol equilibrium in 4,6-diphenyl-3,4-dihydropyrimidine-2(1H)-thione (C₁₆H₁₄N₂S) is analyzed through three different techniques, viz: Single Cristal X-Ray Diffraction (SCXRD), Nuclear Magnetic Resonance (NMR) and Fourier Transformed Infra-Red spectroscopy (FTIR), each one providing complementary information to the solution of the problem. The existence of thione-thiol equilibrium is firmly established, both in solution (by HNMR techniques) as in the solid state (by FTIR methods), and even if no traces of the thiol form could be found via SCXRD, some hints about the way in which the coexistence of both forms could be structurally achieved are provided by the structural analysis. In order to confirm the existence of this equilibrium, theoretical calculations were carried out at the B3LYP/6-311G(d,p) level theory, and a double proton transfer reaction is proposed.

STUDY ON THE CORROSION RESISTANCE CHARACTERISTICS OF n-TiO2/Al2O3 REINFORCED HYBRID Mg COMPOSITES

2023-01-10T19:04:01+00:00

The Mg based composites with the element addition of 3Zn, 0.5Mn and the reinforcement of ceramic particles nanoTiO₂ and Al₂O₃ are added to form an Mg- hybrid composites through powder metallurgy method. The examination is mainly concentrated on the effect of multi ceramic particles such as nanoTiO₂ and Al₂O₃ inclusion in the composite matrix for the characteristics of hardness, tensile strength, wear and corrosion. Optical and scanning electron microscopy are used for the micro structural variation. X-ray diffraction is used to analysis the various phases available in the hybrid composites matrix. Many intermetallic phase are formed during heat treatment process which reduces the porosity and increases density and corrosion resistance of the composites. The hard ceramic particles inclusion, hot extrusion process and heat treatment or stress-relieving mechanism enhances the above said properties of the prepared hybrid composites.

DETERMINATION OF IBUPROFEN AND 1-HYDROXYIBUPROFEN IN AQUEOUS SAMPLES USING CORK AS A NATURAL PHASE IN ROTATING-DISK SORPTIVE EXTRACTION

2023-01-10T19:04:01+00:00

Ibuprofen is one of the most widely used nonsteroidal anti-inflammatory drugs due to its analgesic, anti-inflammatory and antipyretic properties, as well as its low cost and easy accessibility. A fraction of the compound and its metabolites are excreted in the urine, being eliminated in the wastewater reaching river waters in the range of ng L-1 to µg L-1. In this context, highly sensitive and selective analytical methods are required to quantify them, including these methods a pre-concentration step. In this work, the use of a microextraction technology based on rotating-disk sorptive extraction, involving a sorptive phase of laminar cork, was implemented for the extraction of ibuprofen and 1-hydroxyibuprofen from aqueous samples and their subsequent determination by gas chromatography coupled to mass spectrometry.
The optimal conditions for determination of the analytes were: 20 mL of sample volume, pH 2, 20 % w/v NaCl (to increase the ionic strength), 90 min of extraction time and 2000 rpm of rotation velocity of the disk. Recoveries of 118 and 39 % and relative standard deviations of 6 and 13 % for ibuprofen and 1-hydroxyibuprofen were obtained, respectively. The presence of both compounds in river waters (Mapocho River, Santiago de Chile) at a concentration of 2.56 to 4.08 µg L-1 were found. The use of laminar cork as a natural sorbent phase immobilized in the rotating-disk allowed to extract the analytes from water samples through its lipophilic-hydrophilic balance that favors the interaction with the compounds under study.

PRELIMINARY DETERMINATION OF ESSENTIAL AND TOXIC ELEMENTS IN BUCKWHEAT (Fagopyrum esculentum) BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

2023-01-19T21:20:05+00:00

This paper describes the preliminary determination of some element concentration in buckwheat and commercial buckwheat flour determined by ICP-MS. The results indicate how essential and toxic elements added in the soil were absorbed by the buckwheat seeds planted and how the elements concentration of the new seeds was affected by this intentional addition. Results showed limits of detection and quantification range from 0.008 to 1.085 µg/Kg. Correlation coefficients (r) were calculated in the range of 0.9920 to 0.9999. The data obtained described that some elements are far below LOD and LOQ in µg/Kg concentrations in the grains. and that ICP-MS was a very precise method to determinate simultaneously many elements at the same time.

PHYTOCHEMICAL STUDY ON ECTOMYCORRHIZAL FUNGI Cortinarius magellanicus: AN UNUSUAL BROMINATED SECONDARY METABOLITE ISOLATED

2023-01-10T19:04:01+00:00

Phytochemical analysis of the basidiomycete Cortinarius magellanicus (family Cortinariaceae) resulted in the isolation of eight secondary metabolites, where a brominated secondary metabolite was isolated for first time from a natural source. The structure elucidation of this compound was made using one- and two-dimensional NMR experiments, FT-IR, GC-MS, HRESIMS and chemical derivation. The disk diffusion assay of the brominated compound 4 and 8 revealed a low inhibition on Gram-positive and Gram-negative bacteria, respectively. No antifungal activities were detected for these compounds.

REMOVAL OF MERCURY AND LEAD BY BIOADSORBENTS. AN OVERVIEW

2023-01-10T19:04:01+00:00

Humanity and industrialization have led to ecosystems, in all their matrices, being compromised in terms ofpollution generated by different metals. Among them we find mercury and lead, both correspond to metals highlydangerous for all ecosystems and their trophic chains. In this review we will look at the dangers of these metals and theways in which they can be removed, ranging from more traditional processes to adsorption processes withmaterials derived from natural sources and how they can be an effective source of heavy metal removal.

DEVELOPMENT OF HIGH-PERFORMING NOVEL HETEROGENEOUS FENTON-LIKE CATALYSTS FOR THE ABATEMENT OF ORGANIC POLLUTANTS: AN OVERVIEW

2023-01-10T19:04:01+00:00

Fenton reagent is known for over a hundred years and the role of homogeneous and heterogeneous Fenton degradation in wastewater treatment in removing recalcitrant organic contaminants is well appreciated and extensively explored. Limitations and shortcomings of homogeneous and heterogeneous Fenton degradation hinder the large-scale application of heterogeneous Fenton reactions in environmental remediation. Thus, the development of Fenton-like reagents is considered as a need of the hour.

Most of the drawbacks of Fenton degradation have been taken care of by these novel reagents were dramatically increased catalytic degradation rate of contaminants was observed due to high surface area. Good mechanical stability, improved electron transfer, magnetically separability, and the possibility of widening the scope are the additional features of Fenton-like reagents.

In this review, recent trends in the synthesis, strategies for enhancing its catalytic activity, and various applications of heterogeneous Fenton-like catalysts for the abatement of organic pollutants are discussed. This review describes the recent development of other transition metals, Graphene oxide/Carbon/CNT, MIL/MOF, and oxides as Fenton like catalysts in environmental remediation procedures even at ambient conditions.

This review aims to encourage the fabrications of novel and efficient heterogeneous Fenton-like systems and assist the readers in the selection of the best suitable Fenton-like systems for industrial applications by unfolding the various properties and applications of these catalysts.

A SHORT REVIEW ON BIOLOGICAL APPLICATIONS OF MACROCYCLIC COMPLEXES OF CHROMIUM

2023-01-10T19:04:01+00:00

ABSTRACT: The main intent of the article is to lay out a brief valuation of biological significance of latest macrocyclic complexes of chromium metal with highlighting the synthesis of these complexes and their applications as antimicrobial agents. Antibiotic ministration is the leading perspective of current medical science which is used to resist infections. But nowadays, power of established drugs against microorganisms is persistently decreased due to bacterial resistivity, which creates a serious issue related to public health. Extensive work has been disclosed on macrocyclic complexes of first row transition metals performing as remedy for copious microbial infections and these reports express their equal or higher capacities to resist the infection as compared to other clinically useable drugs. So here in this review, the synthesized complexes of chromium metal, their precursors and their reported biological activities have been discussed.

REMOVAL OF MACROLYDES FROM WATER. ANALYTICAL REMOVAL TECHNIQUES. AN OVERVIEW.

2023-01-10T19:04:01+00:00

Water is an essential substance to ensure the survival of human beings has been contaminated over the years, which has been reflected in the increase of contamination by substances from industry and domestic waste, deteriorating its quality and turning it into a risk for those who consume it or live in it. However, in recent years the interest of researchers to remedy this problem has led to the study of different techniques applied to remove these contaminants since the traditional methods used in water treatment plants do not satisfactorily fulfill this purpose. Among the contaminants of greatest interest and to which this review is directed are the emerging contaminants, substances at trace level of a large number of chemical compounds of different origin and nature, which accumulate in aquatic environments causing cardiac affections, psychiatric reactions, liver disorders, genetic mutation, ecotoxicological risks as well as bacterial resistance, such as macrolides. These compounds belong to the group of antibiotics used to treat mainly respiratory affections, but whose consumption has increased in the last couple of years due to their possible action for the prevention of contagion or reduction of symptoms in patients with the COVID-19 virus. Therefore, the objective of this review is to compile the techniques used for their removal, such as sonochemical treatment and continuous ozonation, from which removal percentages higher than 70% have been obtained for macrolides such as azithromycin, clarithromycin, and erythromycin, representative drugs of this type of antibiotics, this in order to conduct research and experimental work for the removal with techniques such as polymer-assisted liquid phase retention, ultranofiltration membranes, which have had high percentages of efficiency for different types of antibiotics and thus establish different ways of removal for these contaminants of interest.