Search Results (77)

Bis(2-ethylhexyl) phosphate (P204) is widely used in extraction processes in the nuclear and rare earth industries. However, its high solubility in water results in high levels of total organic carbon and phosphorus in aqueous environments, and may also lead to radioactive contamination when it is used to combine with radionuclides. In this paper, we characterized a coconut shell activated carbon (CSAC) and a coal-based activated carbon (CBAC) for the adsorption of P204 and then evaluated their adsorption performance through batch and column experiments. The results found that, except for the main carbon matrix, CSAC and CBAC carried rich oxygen-containing functional groups and a small amount of inorganic substances. Both adsorbents had porous structures with pore diameters less than 4 nm. CSAC and CBAC showed good removal performance for P204 under low pH conditions, with removal efficiencies significantly higher than those of commonly used adsorption resins (XAD-4 and IRA900). The adsorption kinetics of P204 conformed to the pseudo-second-order kinetic model, and the adsorption isotherms conformed to the Langmuir model, indicating a monolayer chemical reaction mechanism. Both adsorbents exhibited strong anti-interference capabilities; their adsorption performance for P204 did not change greatly with the ambient temperature or the concentrations of common interfering ions. Column experiments demonstrated that CSAC could effectively fix dissolved P204 with a removal efficiency exceeding 90%. The fixed P204 could be desorbed with acetone. The findings provide an effective method for the recovery of P204 and the regeneration of spent activated carbon, which shows promise for practical applications in the future. Full article

Olive mill wastewater (OMW), a byproduct of the olive oil industry, is a potential source of natural bioactive phenolic polymers. In this work, a column chromatography technique was used for the isolation of a new complex polymer (named OMW-2000XAD) from OMW via fractionation on Amberlite^® XAD16 resin. The developed procedure was simple and proved to be reproducible using OMW from two different sources. OMW-2000XAD was further characterized by elemental, glycosidic, and amino acid composition analysis, as well as spectroscopic techniques. The polymer’s molecular size, which was estimated via gel filtration chromatography, was 1960 kDa, which is significantly larger than other high-molecular weight fractions previously isolated from OMW or other agro-industrial wastes. OMW-2000XAD was mainly composed of phenolic compounds (89.8%). It also contained polysaccharides (16.1%) and proteins (10.3%), with glucose (12.25%) and cysteine (1.71%) being the most abundant sugar and amino acid, respectively, as well as metals (1.29%, primarily potassium). However, due to its low solubility, complexity, and heterogeneous composition, it was not possible to identify all phenolic compounds or elucidate a definitive structure via MS, FTIR, and NMR. OMW-2000XAD exhibited strong radical scavenging antioxidant capacity (ABTS^•+, DPPH^• and peroxyl radicals), with results up to 7415 µmol Trolox equivalent/mol (ORAC method), but showed no antiproliferative effects, highlighting the need for further research. Full article

Cocoa is a rich source of health-promoting polyphenols such as flavanols. These compounds can be separated from other matrix constituents using various adsorbents or resins. Seven different macroporous resins (Amberlite^® XAD-2, XAD-4, XAD-7, XAD-7HP, XAD-16, Sepabeads^TM SP207, and Diaion^® HP2-MG) were evaluated for their adsorption and desorption properties for the enrichment of flavonoids from an aqueous cocoa (Theobroma cacao L.) extract. The influence of adsorption and desorption temperatures and the concentration of the desorption solvent (a hydroalcoholic solution) were investigated by static adsorption and desorption methods. The results of the resin comparison showed that the adsorbent XAD-7HP had the best adsorption characteristics, with an adsorption capacity of 39.8 mg ECE/g. XAD-7HP was found to be the most suitable adsorbent, and 70% ethanol was the best desorbing solvent, based on static experiments. In addition, the optimal conditions for the adsorption of flavonoids were obtained at a temperature of 30 °C, where equilibrium was reached after 80 min. The static adsorption process was well-described by a pseudo-second-order kinetics model, while the adsorption isotherm data were fitted well by the Freundlich isotherm model. Further dynamic adsorption and desorption characteristics were evaluated on a packed glass column, and it was shown that XAD-7HP could enrich the flavanol content by 5.03-fold, with a dry matter content of 456.05 mg/mL (as estimated by the degree of DP1–DP7 procyanidin polymers using ultra-pressure liquid chromatography). Full article

Berberine, palmatine, and coptisine are bioactive alkaloids commonly found in medicinal plants, including Coptis chinensis Franch. (Ranunculaceae). To address the limitations of conventional volatile organic solvents, this study employed eco-friendly solvents—aqueous solutions of surfactants, carboxylic acids, and deep eutectic solvents—to extract these alkaloids. Among the solvents tested, lactic acid, malic acid, and pyruvic acid exhibited the highest extraction efficiencies. Optimal extraction conditions for ultrasound-assisted extraction were determined via response surface methodology. For lactic acid, optimal conditions included a concentration of 96% (w/w), a liquid-to-solid ratio of 30.0 mL/g, and a temperature of 60.0 °C, yielding 139.6 ± 0.2 mg/g of total alkaloids. Malic acid at 40.0% (w/w), 30.0 mL/g, and 80.0 °C produced 133.0 ± 0.5 mg/g, while pyruvic acid at 88.0% (w/w), 30.0 mL/g, and 75.0 °C resulted in 146.3 ± 0.4 mg/g. The recovery efficiencies of these alkaloids were further enhanced using macroporous resins. The XAD-8 and AB-8 resins achieved recovery rates of 80.11 ± 0.78% and 79.00 ± 1.06%, respectively, for lactic acid extracts. The LSA-40 resin yielded efficiencies of 95.58 ± 1.40% and 89.86 ± 0.90% for malic and pyruvic acid extracts, respectively. Notably, the combination of malic acid as an extraction solvent and the HPD-400 resin achieved an impressive alkaloid recovery yield of 79.52% from C. chinensis. This work represents the first reported application of this approach and highlights the potential of green solvents and macroporous resins for sustainable and efficient alkaloid extraction from C. chinensis. Full article

In this study, polyphenols in the crude extract (CE) from red onion peel were recovered by macroporous resin, and their antioxidant and anti-inflammatory activities were evaluated. Among the four resins screened (SP850, XAD2, XAD7HP, and XAD16N), XAD7HP showed the highest desorption and recovery ratios, and it was used to optimize polyphenol recovery through single-factor experiments. The optimal conditions were established as 1 g resin, pH 4, 25 °C, 7 h for adsorption, followed by desorption with 70% ethanol for 1 h at 25 °C. These conditions achieved 85.00% adsorption ratio, 87.10% desorption ratio, and 20.9% yield of the macroporous resin-recovered extract (MRE) from the CE. HPLC analysis revealed that rosmarinic acid, quercetin, and myricetin were major compounds in the MRE, with the content of these compounds higher (about 7-fold) compared to the CE, confirming enhanced recovery of polyphenols by macroporous resin. Moreover, FT-IR and ¹H-NMR analysis confirmed the successful recovery of these polyphenol compounds in the MRE. Furthermore, the MRE displayed significantly improved antioxidant activities (DPPH, ABTS, and FRAP) and anti-inflammatory activities (inhibition of nitric oxide synthesis and reactive oxygen species production) compared to the CE. In summary, our findings suggest that macroporous resin can effectively recover polyphenol compounds from red onion peel extract and enhance their biological activities. Full article

Background/Objectives: Plants species of the Epilobium genus are traditionally used to treat prostatitis and other urinary tract disorders and are particularly rich in ellagitannins and flavonol 3-O-glycosides. The aim of this work was to evaluate the inhibitory activity of different extracts from E. angustifolium L. and E. parviflorum Schreb. and their major bioactive compound, oenothein B, against a panel of Gram-positive (Enterococcus faecalis ATCC 29212, Enterococcus faecalis BS, Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 29213, and Staphylococcus aureus ATCC 43300) and Gram-negative (Escherichia coli ATCC 25922, Escherichia coli ATCC 35218, Escherichia coli BS, Klebsiella pneumoniae ATCC 13883, Klebsiella pneumoniae ATCC 70063, Klebsiella pneumoniae BS, Proteus mirabilis BS, and Pseudomonas aeruginosa ATCC 27853) bacteria responsible for prostatitis. Methods: Aqueous and ethanolic raw extracts were prepared, and the latter were further purified using the resin Amberlite^TM XAD7HP. Then, an HPLC-MS/MS method was developed for the quantification of the marker bioactives and their levels were correlated with the antimicrobial activity. Results: Purified extracts were richer in polyphenols (330.80 and 367.66 mg/g of dry extract for E. angustifolium and E. parvifolium, respectively) than the raw extracts. Oenothein B was the predominant compound in all the extracts (119.98 to 327.57 mg/g of dry extract). The minimum inhibitory concentrations (MICs) in the range of µg/mL indicated significant antibacterial activity, which was higher for the purified extracts and oenothein B (MIC values from 4 to 16 and 8 to 1024 µg/mL on Gram-positive and Gram-negative strains, respectively). Conclusions: These results outline the outstanding potential of E. angustifolium and E. parviflorum extracts and oenothein B as therapeutic alternatives or complementary agents to conventional antibiotic treatments of prostatitis and other urinary tract infections. Full article

This study evaluated the antioxidant efficacy of ellagitannins from a pomegranate husk in preventing vegetable canola oil (VCO) oxidation during French fry preparation. Ellagitannins were extracted using 80% acetone, purified via Amberlite XAD-16 resin chromatography, and incorporated into VCO at 0.05%, 0.1%, and 0.2% concentrations. VCO oxidation was assessed at 145 °C, 160 °C, and 190 °C, with frying experiments conducted at 160 °C for five 10 min cycles. Primary lipid oxidation (peroxide values) was measured using the AOCS Cd 8-53 method, and molecular structural changes were analyzed by infrared spectroscopy. Results showed that ellagitannins significantly mitigated VCO oxidation across all temperatures, with 0.05% identified as the optimal concentration. This concentration reduced peroxide values to 4.66 ± 1.15 meq O/kg, remaining stable and below acceptable limits during frying. Infrared spectroscopy confirmed no significant structural changes in VCO. These findings highlight ellagitannins as effective antioxidants for enhancing VCO oxidative stability during frying, offering a natural, sustainable solution for improving oil quality and extending its usability in the food industry. Full article

Owing to the intensive development of electrical and electronic equipment, there is an increasing demand for precious metals, which are often used for its production. Due to their scarce supply, it is important to recover them from secondary sources. A promising way to recover precious metals are impregnated resins. In this research, Amberlite XAD-16 was impregnated with TBP at the weight ratios of 1:2 and 1:3 using the ‘warm impregnation’ method. Studies were carried out on the sorption of Au(III), Pd(II), Pt(IV), and Rh(III) ions from the model chloride solutions as well as the real solution formed after leaching the smart card chips. Only Au(III) ions were efficiently sorbed on the prepared impregnated sorbents. The best results were obtained at 6 M HCl and the sorbent mass: 0.1 g/25 mL. The maximum sorption capacity for the impregnated sorbents was: 147.91 mg/g (ratio 1:2) and 149.66 mg/g (ratio 1:3). Recovery of Au(III) ions from the real leaching solution was: 97.36% and 97.77%, respectively. The Langmuir isotherm was the best-fit model for the experimental results. Thermodynamic studies proved that the investigated sorption process is spontaneous and exothermic. The desorption process can be easily carried out with 1 M HCl/1 M TU. Full article

This paper proposes a simple, environmentally friendly, and efficient procedure for preparing natural water samples for the voltammetric determination of trace amounts of Se(IV). The method is based on premixing a sample with Amberlite XAD-7 resin at 50 °C. The composition of the 10 mL solution consists of the sample to be analysed, 0.1 mol L⁻¹ of acetate buffer at pH = 4.0, and 0.5 g of Amberlite XAD-7. After 2 min of stirring, a voltammetric measurement is carried out using a fixed bismuth microelectrode using the following potentials: −2.5 V for 2 s and −0.55 V for 30 s. The voltammetry is recorded by varying the potential from −400 mV to −1000 mV. An undisturbed Se(IV) signal is obtained in the presence of 10 mg L⁻¹ of Triton X-100, 5 mg L⁻¹ of SDS, 10 mg L⁻¹ of CTAB, 5 mg L⁻¹ of Rhamnolipid, 5 mg L⁻¹ of HA, 10 mg L⁻¹ of FA, and 2 mg L⁻¹ of NOM. The validity of the developed procedure is checked by analysing the certified reference materials SPS-SW1 (surface water) and TM-25.5 (Lake Ontario water) additionally enriched with surfactants and humic substances. Full article

The objective of this study was to investigate the umami characteristics of soy sauce using electronic tongue evaluation and amino acid composition and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI−TOF MS) analysis. The soy sauce peptides were isolated from soy sauce using XAD−16 macroporous resin combined with ethanol solution. The results showed that the soy sauce peptide fraction eluted by 60% ethanol (SS−60%) exhibited a prominent umami taste, and the umami scores were highly positively correlated with the amino acid nitrogen contents of soy sauces. The umami scores of SS−60% were significantly positively correlated with the contents of free amino acids. Especially, Phe showed the highest positive correlation with the umami scores. In addition, five characteristic ion peaks with m/z at 499, 561, 643, 649, and 855 were identified in the peptide mass fingerprinting. Therefore, this study provides new insights into the umami characteristics for the taste evaluation and reality identification of soy sauce. Full article

The aim of this paper was to investigate the effect of temperature on the removal efficiency of surfactant-induced interferences. Surfactants were removed as a result of mixing with XAD-7 resin. The study was carried out using the example of Cr(VI) determination by adsorption stripping voltammetry (AdSV). Measurements were carried out using a solution containing Cr(VI), acetate buffer (pH = 6.2), DTPA, KNO₃, and different surfactants. Ten mL of the solution was mixed with 0.5 g of XAD-7 resin at different temperatures for 5 min prior to voltammetric measurement. The effect of the mixing temperature of the sample with the resin on the voltammetric Cr(VI) signal in the presence of different surfactants was studied in the range from 20 to 60 °C. The proposed method of removing interference from surfactants by mixing the sample with the XAD-7 resin at 60 °C was used for the determination of trace amounts of Cr(VI) in river water containing non-ionic, anionic, cationic surfactants, and biosurfactants. Full article

This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box–Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples. Full article

An endophytic symbiont P. aeruginosa-producing anticandidal siderophore was recovered from mangrove leaves for the first time. Production was optimal in a succinate medium supplemented with 0.4% citric acid and 15 µM iron at pH 7 and 35 °C after 60 h of fermentation. UV spectra of the acidic preparation after purification with Amberlite XAD-4 resin gave a peak at 400 nm, while the neutralized form gave a peak at 360 nm. A prominent peak with RP-HPLC was obtained at RT 18.95 min, confirming its homogeneity. It was pH stable at 5.0–9.5 and thermally stable at elevated temperatures, which encourages the possibility of its application in extreme environments. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against Candida spp. Were in the range of 128 µg/mL and lower. It enhanced the intracellular iron accumulation with 3.2–4.2-fold (as judged by atomic absorption spectrometry) with a subsequent increase in the intracellular antioxidative enzymes SOD and CAT. Furthermore, the malondialdehyde (MDA) concentration due to cellular lipid peroxidation increased to 3.8-fold and 7.3-fold in C. albicans and C. tropicalis, respectively. The scanning electron microscope (SEM) confirmed cellular damage in the form of roughness, malformation, and production of defensive exopolysaccharides and/or proteins after exposure to siderophore. In conclusion, this anticandidal siderophore may be a promising biocontrol, nonpolluting agent against waterborne pathogens and pathogens of the skin. It indirectly kills Candida spp. by ferroptosis and mediation of hyperaccumulation of iron rather than directly attacking the cell targets, which triggers the activation of antioxidative enzymes. Full article

In an actual economic context, the demand for scandium has grown due to its applications in top technologies. However, further development of new technologies will lead to an increase in the market for Sc related to such technologies. The present study aims to improve and upgrade existing technology in terms of efficient scandium recovery, proposing a new material with selective adsorptive properties for scandium recovery. To highlight the impregnation of Amberlite XAD7HP resin with tri-n-octylphosphine oxide extractant by the solvent-impregnated resin method, the obtained adsorbent material was characterized by physico-chemical techniques. Further, the specific surface of the adsorbent and the zero-point charge of the adsorbent surface have been determined. Different parameters, such as initial concentration, adsorbent amount, contact time, or temperature, have been studied. The initial pH effect was investigated when a maximum adsorption capacity of 31.84 mg g⁻¹ was obtained at pH > 3, using 0.1 g of adsorbent and a contact time of 90 min and 298 K. An attempt was made to discuss and provide a clear representation of the studied adsorption process, proposing a specific mechanism for Sc(III) recovery from aqueous solutions through kinetic, thermodynamic, and equilibrium studies. Adsorption/desorption studies reveal that the prepared adsorbent material can be reused five times. Full article

Given the ever-increasing demand for gallium(III) as a crucial precursor in the fabrication of advanced materials, there arises an imperative to devise efficient recovery processes from primary and secondary sources. In the present investigation, the retrieval of gallium(III) from aqueous solutions through the mechanism of adsorption was investigated. Materials with superior adsorbent properties play an important role in the dynamics of the adsorption process. To enhance these properties, select materials, such as Amberlite-type polymeric resins, are amenable to functionalization through impregnation with extractants featuring specialized active groups, designed for the selective recovery of metal ions—specifically, Ga(III). The impregnation method employed in this study is the Solvent-Impregnated Resin (SIR) method, utilizing the amino acid DL-valine as the extractant. The new material was characterized through Scanning Electron Microscopy (SEM), Elemental Analysis via X-ray energy-dispersive spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) to elucidate the presence of the extractant on the resin’s surface. Concurrently, the material’s pH_PZC was determined. The adsorptive prowess of the synthesized material was investigated through kinetic, thermodynamic, and equilibrium studies. The influence of specific parameters in the adsorption process—namely, pH, contact time, temperature, and Ga(III) initial concentration—on the maximal adsorption capacity was determined. The optimal adsorption conditions were established using the Taguchi method. Full article