Sorption studies of chromate on weakly basic macroporous anion exchanger Amberlyst A-21 were performed as a function of pH (2 - 9), temperature (20 - 40 degrees C) and concentration (0.4 - 80 mmol.l(-1)). Chromate sorption was observed to decrease with the increase in initial pH of the solution, with a sorption maxima at pH 2 and increased with the increase in temperature. The changes in pH and in the ratio of choride ions released to chromate ions sorbed suggested that the anion exchange process was accomanied by hydrolysis and Donnan invasion. The FTIR spectra and isoeteric heat of sorption besides showing the hydrolysis / Donnan invasion of resin under different experimental conditions of concentration, pH and temperature also showed the dimerization of the chromate species inside the resin phase.
Due to the broad range uses of chromium for industrial purposes, besides its carcinogenic effect, an efficient, cost effective removal method should be obtained. In this study, cow bones as a cheap raw material were utilized to produce active carbon (CBAC) by physiochemical activation, which was characterized using: SEM to investigate surface morphology and BET to estimate the specific surface area. The best surface area of CBAC was 595.9 m2/gm which was prepared at 600 ᵒC activation temperature and impregnation ratio of 1:1.5. CBAC was used in aqueous chromium ions adsorption. The investigated factors and their ranges are: initial concentration (10-50 mg/L), adsorption time (30-300 min), temperature (20-50 ᵒC) and solution pH (2-11). Isotherm of adsorption and its kinetics were studied. The adsorption process was modeled statistically and was represented by an empirical model. Equilibrium data were fitted to the Langmuir and Freundlich isotherm models and the data best represented by Freundlich isotherm. Pseudo- first order and pseudo- second order kinetic equations were utilized to study adsorption kinetics, where chromium adsorption on CBAC fitted pseudo- second order fitted the data more adequately. The best removal efficiency was found to be 94.32%.
Alkali metal ion exchange (Li+, Na' and K') on irontlll) phosphate (FeP0 4) was studied potentiometricaIly as a function of temperature and metal ion concentration. The uptake behaviourof iron(llI) phosphate was inferred from a comparison of the K' ions sorbed and the loss of H' ions from the exchanger. Ff-IR spectroscopicstudiesand dissolutionstudiesof FeP0 4 confirmed the uptake mechanism of alkali metal cations as cation exchange. The potentiometric titrationdata were employedto evaluatethe apparentdissociationconstants of iron(lII) phosphate which were found to depend on the temperature of the system. The corresponding thermodynamic parameters i\Ho and i\So were also evaluated.
In this study, sawdust as a cheap method and abundant raw material was utilized to produce active carbon (SDAC). Physiochemical activation was utilized where potassium hydroxide used as a chemical activating agent and carbon dioxide was used as a physical activating agent. Taguchi method of experimental design was used to find the optimum conditions of SDAC production. The produced SDAC was characterized using SEM to investigate surface morphology and BET to estimate the specific surface area. SDAC was used in aqueous lead ions adsorption. Adsorption process was modeled statistically and represented by an empirical model. The highest specific surface area of SDAC was 688.3 m2/gm. Langmuir and Freundlich isotherms were used to fit the adsorption process, where equilibrium data was best represented by Langmuir isotherm model. Pseudo-first order and pseudo-second order equations were used to study adsorption kinetics, lead adsorption on SDAC fitted pseudo- second order more adequately. Best removal efficiency was found to be 99.63% with highest adsorption capacity of 19.92 mg/g.
Leflunomide is an isoxazole immunomodulating drug used to treat rheumatoid arthritis (RA). It is adopted as a metal-containing molecule to proceed with saturated salts of essential and detected metals; it amends the pharmacokinetic and pharmacodynamics activity of leflunomide to provide [M(Lef)4]X2-type complexes. Earlier it has been reported that after forming complexes with metals, leflunomide anti-arthritic activity was significantly altered in an acute arthritic model. In the present study, we evaluated the possible modification in anti-arthritic activities of leflunomide–metal complexes (Mg+2, Ca+2, Fe+2, Zn+2) with and without an anti-depressant drug, i.e., fluoxetine (10 mg/kg) in a chronic AIA model. Rats (n = 5) were administered with 0.1 mL of CFA into the right hind paw while treated groups received leflunomide and its metal complexes orally (3.2 mg/kg) for 24 days. On the final day of experiment, rats were sacrificed; a specific rat immunoassay ELISA kit was used to assess TNF-α in serum samples and read at 450 nm; a tissue sample of a paw was homogenized in a phosphate buffer using DCFH-DA dye for binding to assess ROS. A rat’s brain sample was homogenized and evaluated for tryptophan, serotonin (5-HT), and HIAA by RP-HPLC with EC detector. The overall TNF production was altered in treated rats. In addition, a decreased ROS was observed in all categories, except lef+Mg+2 group. Moreover, depletion in the brain indolamine levels were found in treated groups; an upraised level of these indolamines was observed when fluoxetine was added. It is concluded that metals affect leflunomide activity on complexation and simultaneous administration of fluoxetine cope up with the depression in arthritic-induced rats.
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