Journal of the Chilean Chemical Society

Comparative Ion Exchange Performance of Iminodiacetate and Aminophosphonate Resins for Efficient Cadmium Removal from Aqueous Solutions

2026-04-15T04:04:55+00:00

The removal of cadmium ions (Cd²⁺) from aqueous media was systematically investigated using two commercial chelating ion-exchange resins: Puromet MTS9300, functionalized with iminodiacetic acid groups, and Puromet MTS9500, containing aminophosphonic acid groups. The effects of resin dosage, solution pH, temperature, and contact time on Cd²⁺ removal were evaluated through batch experiments. The results revealed that both resins exhibited high Cd²⁺ removal efficiencies, achieving complete removal under optimized conditions. Ion exchange performance was strongly influenced by solution pH, as both resins possess weakly acidic functional groups that undergo protonation in acidic media, thereby reducing Cd²⁺ uptake. Kinetic data fitted well to the pseudo-second-order model. The equilibrium data correlated closely with the Langmuir model, with maximum exchange capacities of 201.33 mg/g for MTS9300 and 191.44 mg/g for MTS9500 at 30 °C. Thermodynamic analysis confirmed the spontaneous nature of Cd²⁺ removal for both resins, with ΔG° values ranging from –26.37 to –30.09 kJ/mol. MTS9500 exhibited an endothermic exchange process, while MTS9300 displayed exothermic behaviour. Regeneration experiments demonstrated excellent reusability with both HCl and H₂SO₄ solutions, maintaining nearly 100% regeneration efficiency. These findings highlight the high potential of MTS9300 and MTS9500 resins as efficient, regenerable materials for the removal of cadmium ions from contaminated water.

ECOTOXICOLOGICAL EVALUATION OF Lippia alba Mill PLANT RESIDUES ON TERRESTRIAL ECOSYSTEM REPRESENTATIVES

2026-04-15T04:04:55+00:00

Lippia alba is a medicinal plant commonly used in Cuba and the Caribbean for thedevelopment of herbal formulations against skin inflammatory illnesses thus generating residual biomass whose environmental impact remains unassessed. This study aimed to evaluate the ecotoxicological effects of L. alba residues and their aqueous extract fractions on key terrestrial ecosystem organisms. Soil microbial community activity was analyzed through CO₂ emissions and ammonium (NH₄⁺) quantification, as well as degradation and toxicity tests on earthworms (Eisenia andrei). Phytotoxicity was assessed using Phaseolus vulgaris seeds to determine germination rates and radicle length. Results showed that CO₂ emissions increased in the groups treated with L. alba residues, suggesting enhanced microbial respiration, whereas NH₄⁺ levels remained unchanged across all treatments. Seed germination rates remained above 75% at all tested extract concentrations except at 75%. Radicle length, however, was significantly reduced at higher concentrations (75% and 100%).No toxic effects were observed in E. andrei (earthworms). These findings indicate that L. alba residues are not toxic to soil macro- or microfauna and may contribute to soil organic enrichment, although higher concentrations of aqueous extracts exhibit moderate phytotoxic effects. The study supports the potential incorporation of L. alba waste into sustainable soil management strategies, such as composting and vermicomposting.

ANALYSIS OF CARILITE OLIGOMERS AND THEIR FUNCTIONALIZATION WITH FURFURYLAMINE AT LOW CONVERSION BY GPC, NMR AND ESI-MASS SPECTROSCOPIES

2026-04-15T14:50:45+00:00

Background/Objectives: Carilite oligomers may be easily functionalized with primary amines, such as furfuryl amine, through the Paal-Knorr reaction, converting polymeric 1,4-diketone groups into N-substituted pyrroles with pendant furanyl groups. The resulting oligomers allow producing polymer and polymer composites materials by adding a bifunctional dienophile, leading to reversible crosslinking through the Diels-Alder reaction. The extent of conversion in the Paal Knorr reaction should determine the amount of polymer chains showing two or more furanyl dienes, condition necessary for extended crosslinking. Thus, the objectives of this work consisted of i) to characterize a sample of Carilite oligomers (PK₃₀), ii) to calculate the probabilistic distribution of the N-substituted pyrroles in the oligomer chains as a function of the diketone conversion, and iii) to compare the prediction with experimental data of a sample obtained after reaction between PK₃₀ and furfuryl amine aiming at 20 % of conversion. Methods: GPC, NMR, and ESI mass spectroscopies are used for the analysis of the polymers. Poisson distribution and one-dimensional hard-dimer exclusion models have been applied for probabilistic calculations. Results: Carilite oligomers are a polydisperse mixture where the most abundant molecules present 1 – 16 ketone moieties. After functionalization, the most abundant derivatized molecules consist of oligomers functionalized with only one furfuryl amino residue. Good matching with the predictions were found. Conclusions: The use of NMR combined with ESI-mass spectroscopy has served to understand the molecular structure of Carilite oligomers and their furfuryl amine-functionalized derivatives. This allows determining refined molecular weights that allow calculating effective conversion aimed and, in combination with the probabilistic predictions, obtaining insights of the expected Fu content per chain, contributing to the improvement of design, handling, and control strategies for reversibly crosslinked polymer matrices.

REMOVAL OF LEAD, CADMIUM, COPPER, ZINC, AND MERCURY FROM WATER ON BANANA PEEL RESIDUES

2026-04-15T04:04:56+00:00

Industrial activities, inadequate waste disposal, and poor control of discharges generated by mining and domestic activities are the primary causes of water pollution with numerous chemical substances, including heavy metals. Several methods have been proposed for removing metals from water, such as precipitation, membrane separation, ion exchange, solid phase extraction, flocculation, and others to address this issue. The metal bio-adsorption using biomass from crops is an alternative that has shown excellent results in recent years. In this work, We studied the bio-adsorption of five metals present in water on biomass from ground banana peel. We evaluated the retention capacity of copper, lead, cadmium, zinc, and mercury on the bio-adsorbent material subjected to acid hydrolysis, basic hydrolysis, and the material without treatment. The material with the best-obtained results was selected to execute a 2^k experimental design. The factors were pH, adsorbent dose, and contact time between the adsorbent and the metal ion solution. We used the anodic stripping square wave voltammetry for the mercury determination and adsorptive stripping by square wave voltammetry for copper, zinc, cadmium, and lead quantification. The maximum adsorption capacity ranged from 20 to 30 mg for each gram of material used for the five studied metals. The optimum pH value for mercury was 3.0 while for copper, zinc, cadmium, and lead was 5.0. The optimum contact time was 15 minutes. Mercury is captured differently from the other metals. The materials were characterized using the techniques of Infrared Spectroscopy, Scanning Electron Microscopy, energy-dispersive X-ray Spectroscopy, and thermogravimetric analysis.

Thermal Degradation Kinetics and In Vitro Gastrointestinal Stability of 10-Hydroxy-2-Decenoic Acid in Royal Jelly-Based Functional Formulations

2026-04-15T04:04:56+00:00

Royal jelly (RJ) is a bee-derived secretion rich in 10-hydroxy-2-decenoic acid (10-HDA), a fatty acid responsible for its antimicrobial, antioxidant, and neuroprotective effects. However, 10-HDA is sensitive to heat and digestive conditions, which limits its stability in functional formulations. This study investigated the thermal degradation kinetics and in vitro gastrointestinal stability of 10-HDA in pure RJ and its mixtures with honey, pollen, and propolis. Samples were thermally treated at 30, 50, 70, and 90 °C for 0–20 minutes. LC-MS/MS analysis showed that in pure RJ, 10-HDA content decreased from 1.905 g/100 g to 0.149 g/100 g at 90 °C, following first-order kinetics with an activation energy of 29,27. In contrast, all mixtures followed zero-order kinetics, suggesting that matrix components provided thermal protection. Calculated activation energies and Q₁₀ values confirmed the compound’s thermal sensitivity. Gastrointestinal stability was assessed using simulated salivary, gastric, and intestinal fluids. The highest degradation occurred in the oral and intestinal phases. The soft candy formulation showed the highest intestinal loss (57.14%), while the RJ- honey-propolis mixture retained the most 10-HDA (31.19 g/100 g). Propolis-containing formulations consistently performed better. In conclusion, 10-HDA degradation is strongly affected by temperature, digestion time, and formulation composition. Propolis and honey enhanced 10-HDA retention, especially under digestive conditions. These findings offer practical insights for developing heat-stable and bioaccessible RJ-based functional products for food, supplement, and apitherapy applications.

Unlocking the Biocatalytic Efficiency of Factor-Independent Urate Hydroxylase from Bacillus subtilis in Petrochemical Hydrocarbon Detoxification

2026-04-15T04:04:56+00:00

Petrochemical hydrocarbons are toxic, persistent environmental pollutants that pose serious ecological and health risks. Bioremediation using microbial enzymes offers a sustainable and effective alternative for their degradation. This study presents an in-silico analysis of Factor-independent urate hydroxylase from Bacillus subtilis to evaluate its potential in hydrocarbon biodegradation. The enzyme’s physicochemical properties revealed moderate stability and hydrophilicity, favoring activity in aqueous environments. Post-translational modification analysis predicted multiple regulatory sites, suggesting adaptability to environmental conditions. Structural modeling and validation confirmed a high-quality 3D structure suitable for molecular docking. Nine petrochemical hydrocarbons were selected for virtual screening. Docking results showed strong binding affinities, particularly with 1,2,3,4,7,8-hexachlorodibenzofuran (-7.4 kcal/mol), crystal violet (-7.3 kcal/mol), and dioxins, with key residues (e.g., ARG207, VAL211, PHE289) mediating interactions. Toxicity predictions indicated high neurotoxicity and hepatotoxicity among the compounds, highlighting the urgency for effective remediation tools. The study concludes that Factor-independent urate hydroxylase demonstrates promising interaction with harmful hydrocarbons and play a key role in microbial bioremediation. These computational findings provide a foundation for future experimental validation and potential application in cleaning up petrochemical-contaminated environments.

Organometallic Aminomethyl 1,2,3-Triazoles: Synthesis, Characterization and Reactivity

2026-04-15T04:04:56+00:00

In search of new organometallic-1,2,3-triazoles, this work describes a convenient synthesis to obtain ferrocenyl and cyrhetrenyl 1,2,3-triazole derivatives containing aminomethyl fragment. On this regard, the compounds of general formulae [(η⁵-C₅H₄-(1)-1,2,3-triazole-(4)-CH₂NH₂)MLn] [where MLn =Fe(η⁵-C₅H₅) (1a), Re(CO)₃ (1b)] were obtained via tert-butoxycarbonyl (BOC) deprotection under acid conditions of the corresponding protected triazoles [(η⁵-C₅H₄-(1)-1,2,3-triazole-(4)-CH₂NH(C=O)OC(CH₃)₃)MLn] with MLn = Fe(η⁵-C₅H₅) (P1), Re(CO)₃ (P2)], with good yields (89–95%). In addition, the reactivity of aminomethyl compounds (1a–b) was evaluated in condensation reactions with 4-(1H-1,2,4-triazol-1-yl)benzaldehyde, isolated the Schiff bases [(η⁵-C₅H₄-(1)-1,2,3-triazole-(4)-CH₂N=CH-(1)-C₆H₄-(4)-1H-1,2,4-triazole)MLn] (2a–b) [where MLn =Fe(η⁵-C₅H₅) (2a), Re(CO)₃ (2b)] under mild reactions conditions. All compounds were characterized by FT-IR, ¹H NMR spectroscopy and elemental analysis. Moreover, the molecular structure of 2a was determined by single-crystal X-ray diffraction.

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THREE NOVEL 23,24-DINORCHOLANE BRASSINOSTEROID ANALOGS BEARING BENZOATE GROUPS AND HALOGEN SUBSTITUENTS.

2026-04-15T04:04:56+00:00

Brassinosteroids are an important family of plant hormones involved in various processes of plant growth and development. They also play a crucial role in plant stress responses, improving tolerance to abiotic factors such as temperature extremes, drought, and salinity, and contributing to resistance against biotic stresses. This work describes the synthesis and full structural characterization of three new 23,24-dinorcholane-type brassinosteroid analogs bearing benzoate groups at C-22 and substituted with fluorine and chlorine atoms, while maintaining the structural features of the A/B rings present in active natural brassinosteroids such as castasterone. The synthesis was achieved in two steps: an esterification reaction with acyl chlorides, followed by a stereospecific Sharpless dihydroxylation. Both reactions proceeded with good yields.

Methodological Scope of Standard NCh0765 for the Determination of Total Impurities by Washing in Algae of the Genus Gracilaria

2026-04-15T04:04:56+00:00

Due to contradictory experimental results obtained in the determination of impurities by washing in algae of the genus Gracilaria, compared to sieving and manual
separation, the methodological basis described by the Instituto Nacional de Normalización (INN) to the normative NCh0765 was analyzed. Our results show that for
the same sample, 2.4 ± 0.9% of impurities were determined by sieving and manual separation analysis, while 31.9 ± 2.9% was detected by the washing methodology.
This difference would be mainly due to the exudation of organic compounds, principally the phycocolloid Agar, during the washing procedure which loss can range
from 10 - 20%. The differences in impurities according to the methodology could have consequences for the export restrictions of algal resources due to current
Chilean regulations and buyers' demands.