Adsorption Of Phenobarbital Research Articles

Evaluation of Phenobarbital Adsorption Efficiency on Biosorbents or Activated Carbon Obtained from Adansonia Digitata Shells.

The removal of pharmaceutically active compounds present in relatively low concentration in wastewater is critical. This is because they have a severe, negative impact on life and the environment. To address this issue, adsorption was used, which is an effective wastewater treatment method for removing substances found in low concentrations in water. This study compared the adsorption performance of active carbon to three biosorbents derived from Adansonia digitata shells. The adsorbents were prepared and characterized using TGA, SEM, EDX, and FTIR analyses and pHPZC. To better understand the adsorption process, equilibrium and reaction kinetics studies were conducted. The effect of contact time, initial phenobarbital concentration, adsorbent mass, and pH was investigated in static conditions. The adsorption results revealed that the biosorbent B3 has a higher affinity for the eliminated compound, with an equilibrium time of 60 min and an adsorption capacity of 47.08 mg/g at an initial concentration of 50 mg/L. The experimental data are consistent with Langmuir and Sips adsorption isotherm models, and with the pseudo-second order and Elovich models for kinetics description. This indicates strong interactions between the adsorbent materials and the pharmaceutical micropollutant. Based on these findings, it appears that, among the tested materials, B3 biosorbent is the most efficient for removing phenobarbital present in low concentrations in water.

Disagreements Between Calorimetric and Van't Hoff Enthalpies of Adsorption II: Effect of pH and pH Buffers on Phenobarbital Adsorption to Activated Carbon

The reported inconsistencies between the van't Hoff equation and calorimetry hinder the utility of thermodynamics in biochemical and pharmaceutical research. A novel thermodynamic approach is developed herein for ligand adsorption with a focus on the interpretation of calorimetric data in the presence of concurrent proton exchange reactions. Such exchange reactions typically result in a pH-dependence of calorimetric measurements that obscures intrinsic binding enthalpies. It is shown that for the adsorption of phenobarbital to activated carbon, the measured calorimetric enthalpy is a result of three linked acid/base equilibria. A model was established to predict the intrinsic binding enthalpy using 1) the adsorbate's pKa and 2) the adsorbate's enthalpy of protonation. The observed calorimetric enthalpy of binding exhibited both pH and buffer-dependence and was between -5 and -42 kJ/mol. Meanwhile, the predicted intrinsic enthalpy (-25.1 kJ/mol) of binding was in excellent agreement with the measured intrinsic enthalpy (-25.6 kJ/mol). Corrections to the observed calorimetric enthalpies allowed comparisons with enthalpies obtained from the van't Hoff method. It is shown that the predicted intrinsic calorimetric enthalpy agrees well with the van't Hoff enthalpies in instances where observed enthalpies significantly deviated. This treatment is general and is not specific to phenobarbital or activated carbon.

Study of phenobarbital removal from the aqueous solutions employing magnetite-functionalized chitosan.

Due to its wide use in anticonvulsant pharmacotherapy, phenobarbital (PHEN) is an aquatic contaminant with a high prevalence in the environment. In this adsorption study, chitosan and chitosan-based magnetic adsorbents containing different amounts of incorporated magnetite (CS, CS·Fe3O4 1:1, CS·Fe3O4 1:5, and CS·Fe3O4 1:10) were used for phenobarbital removal. The magnetic adsorbents were synthesized by co-precipitation method and characterized through FTIR, XRD, MEV, and VSM analysis. In PHEN adsorption, the equilibrium and adsorption kinetic were better adjusted by the Sips and pseudo-second-order model, respectively. Among the four nanoadsorbents used, the maximum phenobarbital adsorption capacity was 94.60mgg-1 using 25mg of CS·Fe3O4 1:5, with a concentration of PHEN (50mg L-1), pH 7.0 at room temperature. The parameters of pH, adsorbent dosage, ionic strength, and thermodynamic study were tested for the adsorbent with the highest performance (CS·Fe3O4 1:5). The nanoadsorbent demonstrates efficiency in the removal of the contaminant for diverse adsorption cycles. Finally, the protocol employing magnetic adsorbents dispenses the subsequent steps of filtration and centrifugation.

Polyethersulfone-Activated Carbon Hybrid Particles for Phenobarbital Removal

Polyethersulfone-Activated carbon (PES-AC) hybrid particles are prepared using a liquid-liquid phase separation technique. The PES-AC hybrid particles are then used for the removal of phenobarbital (PB) from its aqueous solutions. The adsorption ability of the particles increased significantly when activated carbon was embedded into the particles, and with the increase of the activated carbon content in the hybrid particles, the PB adsorbed amount increased. Also when the PB concentration increased, the adsorbed amount increased. The adsorption of PB to the hybrid particles belongs to the Freundlich adsorption. To more effectively remove PB, PES-AC particle columns were prepared; and the particle column showed more high removal efficiency for PB. The results suggested that the PES -AC hybrid particles have a potential to be used for the removal of PB, and may be used in blood purification.

Phenobarbital interactions with derivatized activated carbon surfaces

The interactions between phenobarbital and activated carbon surfaces were studied in detail in this work. This was accomplished by utilizing different reagents to manipulate the surface polar functional group compositions of different activated carbons, and determining how those modifications changed phenobarbital adsorption. Oxidation of an activated carbon surface caused a systematic decrease in the basal carbon surface, resulting in a concurrent systematic decrease in the non-specific adsorption of phenobarbital. Even more interesting, it was shown for the first time that chemical reduction of some of the carbonyl-containing functional groups on the activated carbon surface caused a significant increase in the specific adsorption of phenobarbital without any significant effect on the non-specific adsorption. These results support the notion that the OH groups on activated carbon surfaces are the specific adsorption sites for phenobarbital from aqueous solutions, and that the basal carbon surface is the region where non-specific adsorption takes place.

In VitroAdsorption of Phenobarbital, Chlorpheniramine Maleate, and Theophylline by Four Commercially Available Activated Charcoal Suspensions

Four commercially available antidotal activated charcoal suspensions (Actidose Aqua, InstaChar, LiquiChar, and CharcoAid 2000) were evaluated with respect to their abilities to adsorb three test drugs in vitro from simulated gastric fluid. Different volumes of each suspension were added to glass vials containing 20 mL of stock solutions of each drug. The vials were shaken for a time more than sufficient to ensure adsorption equilibrium, then the charcoal was removed from the samples by filtration. The filtrates were analyzed by ultraviolet spectroscopy to determine the residual drug concentrations. The product containing a 2000 m2/g charcoal (CharcoAid 2000) adsorbed more drug per unit volume of suspension than did the other three products, which contained 900 m2/g charcoal and which were all similar in performance.

Surface characterization of activated charcoal by X-ray photoelectron spectroscopy (XPS): correlation with phenobarbital adsorption data.

X-ray photoelectron spectroscopy (XPS) was used to identify the functional states of carbon existing on the surfaces of various activated charcoals. The relative percentages of carbon, oxygen, and detectable trace elements comprising the activated charcoal surfaces were determined. Analysis of the carbon core-electron binding energy region revealed the existence of one hydrocarbon state (C-H, C-C are indistinguishable) and three oxygen-containing functional states. These states were hydroxyls or ethers (C-O), carbonyls (C = O), and carboxylic acids or esters (O-C = O). The C-O functional state contributed approximately 60-70% to the total percentage of oxygen-containing states. A very good correlation existed between the apparent areas occupied on the adsorbent surface per phenobarbital molecule and the relative percentages of the C-O functional state. Previously reported heat of displacement results for phenobarbital adsorption are now explained since the C-O state appears to be the primary site involved in the binding of phenobarbital by the activated charcoals.

Model selection for the adsorption of phenobarbital by activated charcoal.

Activated charcoal is known to adsorb a wide variety of substances from solution, and several equations have been used to fit the resulting adsorption data. The determination of the correct model to fit phenobarbital adsorption onto activated charcoal was made using a calorimetric method. The differential heats of displacement of water by phenobarbital for four activated charcoals were determined and found to be linearly related to the amount of phenobarbital adsorbed. The activated charcoals studied had statistically similar heats of displacement. The linear relationship between heat evolved and the amount of phenobarbital adsorbed is consistent with the assumptions implicit in the Langmuir model.