RESUMO

The preparation of a functional device based on a functionalized MIL-100(Fe) metal-organic framework for the solid-phase extraction of heavy metals is reported. By a simple and easy straightforward grafting procedure, a thiol-functionalized MIL-100(Fe) material (MIL-100(Fe)-SH) with a S/Fe ratio of 0.80 and a surface area of 840 m2 g-1 was obtained. MIL-100(Fe)-SH exhibited a higher Hg(II) extraction (96 ± 5%) than that of MIL-100(Fe) (78 ± 4%) due to the interaction between thiol groups and Hg(II) ions. For practical applications, the obtained MIL-100(Fe)-SH was integrated by a simple method to a 3D printed support based on a matrix of interconnected cubes using poly(vinylidene fluoride) as binder, obtaining a functional device that simultaneously acts as stirrer and sorbent. The developed device showed high efficiency for the removal of Hg(II), good reusability, and excellent performance for the simultaneous preconcentration and further detection and quantification of Hg(II), Pb(II), and As(V) in tap, well, and lake water samples.

RESUMO

A solid-phase extraction methodology using a MIL-101(Fe)/PVDF membrane was proposed as a useful alternative for the simultaneous determination of naproxen, diclofenac, and ibuprofen, three anti-inflammatory drugs (NSAIDs), in wastewater samples by HPLC-CCD analysis. The MIL-101(Fe) was prepared by a rapid microwave-assisted method and supported in a polymeric PVDF membrane. The prepared material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). The factors that affect the extraction of the NSAIDs using the MIL-101(Fe)/PVDF membrane as the sample volume, the solution pH and the elution solvent were studied in detail. The selected conditions were 50 mL of sample solution at pH 3 and 5 mL of methanol: acetone (30:70, v v-1) acidified with formic acid at 2% as elution solvent. The analytical method was linear with determination coefficients (r2 ≥ 0.998) in the calibration ranges from 2 to 100 ng mL-1 for naproxen, 20-200 ng mL-1 for diclofenac, and 100-300 ng mL-1 for ibuprofen. The intra and inter-day precision (repeatability and reproducibility, respectively) of the method (RSD%, n = 5) were lower than 4.8% and 7.1%, respectively. The accuracy reported as recovery percentages ranged from 82 to 118%, and the limits of detection were between 1.8 and 32.3 ng mL-1. Moreover, MIL-101(Fe)/PVDF membrane exhibited improved adsorption efficiency compared to that of its analog MIL-101(Cr)/PVDF and the pristine PVDF membranes, obtaining in an easy and rapid (60 min) way a low-cost and low-toxic adsorbent with excellent stability, reusability, mechanic resistance, and simple operation which shows excellent performance.

Assuntos

Estruturas Metalorgânicas , Preparações Farmacêuticas , Adsorção , Ferro , Reprodutibilidade dos Testes , Extração em Fase Sólida , Espectroscopia de Infravermelho com Transformada de Fourier

RESUMO

In this work, the dispersive solid-phase extraction of sulfonamide antibiotics was evaluated using magnetic porous carbons derived from cobalt(ii)-based metal-organic frameworks. By direct carbonization under the inert atmosphere of Co-SIM-1, Co-MOF-74 and Co-DABCO MOFs, different magnetic porous carbons were prepared and characterized to study their structural, morphological, chemical and textural properties. Their performance for the simultaneous extraction of three sulfonamides (sulfadiazine, sulfamerazine and sulfamethazine), prior to HPLC analysis, was also evaluated, obtaining the best results (>95%) in the case of C/Co-SIM-1 carbon, probably due to its bimodal pore structure, high surface area and large amount of surface defects. Using this adsorbent, the effect of the solution pH and contact time on the adsorption of the sulfonamides, and the reusability of the carbon were studied.

RESUMO

A fully automated on-line system for monitoring the TiO2-based photocatalytic degradation of dimethyl phthalate (DMP) and diethyl phthalate (DEP) using sequential injection analysis (SIA) coupled to liquid chromatography (LC) with UV detection was proposed. The effects of the type of catalyst (sol-gel, Degussa P25 and Hombikat), the amount of catalyst (0.5, 1.0 and 1.5 g L-1), and the solution pH (4, 7 and 10) were evaluated through a three-level fractional factorial design (FFD) to verify the influence of the factors on the response variable (degradation efficiency, %). As a result of FFD evaluation, the main factor that influences the process is the type of catalyst. Degradation percentages close to 100% under UV-vis radiation were reached using the two commercial TiO2 materials, which present mixed phases (anatase/rutile), Degussa P25 (82%/18%) and Hombikat (76%/24%). 60% degradation was obtained using the laboratory-made pure anatase crystalline TiO2 phase. The pH and amount of catalyst showed minimum significant effect on the degradation efficiencies of DMP and DEP. Greater degradation efficiency was achieved using Degussa P25 at pH 10 with 1.5 g L-1 catalyst dosage. Under these conditions, complete degradation and 92% mineralization were achieved after 300 min of reaction. Additionally, a drastic decrease in the concentration of BOD5 and COD was observed, which results in significant enhancement of their biodegradability obtaining a BOD5/COD index of 0.66 after the photocatalytic treatment. The main intermediate products found were dimethyl 4-hydroxyphthalate, 4-hydroxy-diethyl phthalate, phthalic acid and phthalic anhydride indicating that the photocatalytic degradation pathway involved the hydrolysis reaction of the aliphatic chain and hydroxylation of the aromatic ring, obtaining products with lower toxicity than the initial molecules.