RESUMEN
We herein have developed a mild approach for the fabrication of glauconite clay (G)-modified chitosan (CS) nanocomposites by the combination of a simple blending and crosslinking method. The chitosan was modified with ethylenediaminetetraacetic acid (EDTA), glutaraldehyde (GL), sodium dodecyl sulfate (SDS), and cetyltrimethyl ammonium bromide (CTAB). The as-prepared composites were identified using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), nitrogen physical adsorption (BET), atomic absorption spectrophotometry (AA), and thermal gravimetric analysis (TGA). The adsorption activities of the as-prepared materials were assessed for the removal of fluoride ions from aqueous media using a batch technique. Raw glauconite (G), GL-CS/G, SDS-CS/G, EDTA-GL-CS/G, and CTAB-CS/G adsorbents displayed maximum adsorption capacity values of 1.15, 4.31, 4.55, 6.90, and 9.03 mg g-1, respectively. The adsorption results were well described by employing the pseudo-second-order kinetic and Langmuir isotherm models. The estimated thermodynamic constants indicated that the F- ion adsorption was a spontaneous, physisorption process. Furthermore, the modified chitosan adsorbents are good candidates for the adsorptive elimination of F- ions from aqueous solutions, according to their reusability, high stability, good adsorption capacity, and applicability for actual field water samples.
RESUMEN
Polyurethane foam functionalized with 8-hydroxyquinoline has been prepared by coupling the foam matrix with 8-hydroxyquinoline (oxine) through an azo spacer. The oxine-bonded foam (Ox PUF) was characterized by use of different tools (UV-Vis spectra, IR spectra, density, and stability). Ox PUF was found to be very suitable for separation and preconcentration of trace metals, e.g. Zn(II), Cd(II), and Hg(II) ions, from wastewater in the pH ranges 2-12, 9-12, and 3-6, respectively. Various conditions influencing the sorption of these metal ions on to Ox PUF were optimized. Extraction of the metal ions was accomplished in 15 to 20 min. Study of the variation of the sorption of the tested metal ions with temperature yielded average values for DeltaH, DeltaS, and DeltaG of 41.99, 158.23, and -5.1 kJ mol(-1), respectively. The capacities of the foam material were 0.27, 0.16, and 0.09 mmol g(-1) for Zn(II), Cd(II), and Hg(II), respectively. Preconcentration factors >50 were achieved (RSD approximately 6.18). The quantitative results were obtained from experiments performed using certified reference materials.
Asunto(s)
Metales Pesados/química , Oxiquinolina/química , Poliuretanos/química , Cadmio/química , Concentración de Iones de Hidrógeno , Cinética , Mercurio/química , Solventes/química , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Temperatura , Zinc/químicaRESUMEN
The present work describes a novel method for the incorporation of Nile blue A into polyurethane foam matrix. This foam material was found to be very suitable for the extraction of metal ions from aqueous solutions. The characterization of Nile blue A grafted foam and the effect of halide concentration, pH, shaking time, extraction isotherm and capacity have been investigated. This foam material was found to be suitable for the separation and preconcentration of iron (III), zinc (II), cadmium (II) and mercury (II) from waste water. The extraction was accomplished in (15-20) minutes. Iron was separated from acid medium (2-4 M HCl), zinc from (3-5 M HCl), cadmium from (4-6 M HCl) as thiocyanate complexes and mercury was separated from (1-2 M HCl) as chloride.
RESUMEN
Catechins, polyphenolic compounds belonging to flavanoid family, have been reported to posses insulin-like properties and their antidiabetic actions have also been documented. Recently catechins have received much attention as strong anti-oxidative agents. Since oxidative stress has been implicated in the development of diabetic complications and GSH plays an important role in protection against oxidative damages, we have studied the in vitro effect of (-)epicatechin and insulin on the reduced glutathione content in normal and type 2 diabetic erythrocytes. The GSH content was significantly lower (p < 0.001) in type 2 diabetic patients as compared to normal individuals. In vitro insulin treatment (10(-9) M) resulted in increase in the GSH content in both normal and type 2 diabetic erythrocytes. (-)Epicatechin (1mM) also resulted in an increase in erythrocyte GSH content in both normal and type 2 diabetic erythrocytes. Insulin gave a pronounced dose-responsive effect: maximum increase in GSH content at physiological hormone concentration and a lower increase at higher and lower insulin concentrations. (-)Epicatechin did not show a similar dose-responsive effect. Although the exact mechanism by which (-)epicatechin causes elevation of erythrocyte GSH is not clear nevertheless this finding may have important therapeutic implications. A higher content of dietary flavanoids may thus protect diabetic patients against long-term complications.
Asunto(s)
Catequina/farmacología , Diabetes Mellitus Tipo 2/sangre , Eritrocitos/química , Glutatión/sangre , Insulina/farmacología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
1. Changes in the activity of acetylcholinesterase (AChE) have been reported in diabetes mellitus that have been linked to certain brain defects. The erythrocyte membrane AChE is reported to be similar to AChE present in the brain. 2. Epicatechin, a member of a group of polyphenolic compounds collectively known as "catechins" that are present in tea and belong to the flavonoid family, has been reported to possess insulin-like activity. 3. In the present study, the in vitro effect of (-)epicatechin and/or insulin was tested on erythrocyte membrane AChE in normal and type 2 diabetic patients. The aim of the study was to test the efficacy of (-)epicatechin to mimic insulin in its effect on erythrocyte membrane AChE. 4. Acetylcholinesterase activity was significantly lower in type 2 diabetic patients than in normal controls and in vitro insulin treatment restored this activity to normal levels. Epicatechin (1 mmol/L) also caused an elevation in AChE activity in diabetic erythrocytes, an effect that was similar to the effect of insulin. 5. Epicatechin has a pronounced insulin-like effect on erythrocyte membrane-bound AChE in type 2 diabetic patients; however, the mechanism of action of epicatechin remains speculative.
Asunto(s)
Acetilcolinesterasa/efectos de los fármacos , Catequina/farmacología , Diabetes Mellitus Tipo 2/enzimología , Membrana Eritrocítica/efectos de los fármacos , Insulina/farmacología , Acetilcolinesterasa/metabolismo , Adulto , Diabetes Mellitus Tipo 2/sangre , Relación Dosis-Respuesta a Droga , Membrana Eritrocítica/enzimología , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
The antimicrobial potential of eight phenolic compounds isolated from olive cake was tested against the growth of Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Aspergillus flavus and Aspergillus parasiticus. The phenolic compounds included p-hydroxy benzoic, vanillic, caffeic, protocatechuic, syringic, and p-coumaric acids, oleuropein and quercetin. Caffeic and protocatechuic acids (0.3 mg/ml) inhibited the growth of E. coli and K. pneumoniae. The same compounds apart from syringic acid (0.5 mg/ml) completely inhibited the growth of B. cereus. Oleuropein, and p-hydroxy benzoic, vanillic and p-coumaric acids (0.4 mg/ml) completely inhibited the growth of E. coli, K. pneumoniae and B. cereus. Vanillic and caffeic acids (0.2 mg/ml) completely inhibited the growth and aflatoxin production by both A. flavus and A. parasiticus, whereas the complete inhibition of the moulds was attained with 0.3 mg/ml p-hydroxy benzoic, protocatechuic, syringic, and p-coumaric acids and quercetin.