A kinetics,isotherms, and thermodynamic study of diclofenac adsorption using activated carbon prepared from olive stones

The objective of this work was to study the efficiency of activated carbon prepared from agricultural waste (olive stones; OS) on diclofenac (DCF) adsorption in aqueous solutions. The prepared charcoals were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM)/Energy Dispersive X-Ray Analyser (EDX), and Brunauer–Emmett–Teller (BET) analysis techniques. The results show that DCF adsorption is favorable in acid medium and low temperature. The adsorption kinetics follows a pseudo-second-order kinetic model. The adsorption was found to be spontaneous (ΔG°?相似文献   

Nonuniform microporous structures and adsorption properties of carbon adsorbents 11. Physical adsorption equations based on a normal distribution of micropore volume

The fundamental properties of three parameter equations for physical adsorption of vapors on nonuniform microporous structures based on the slit type model and having a normal micropore volume distribution have been considered. The widely applied two parameter Dubinin-Radushkevich equation provides for the special case of standard uniform microporous structures. Various threeparameter equations can be differentiated according to their energy coefficient k, which can be expressed as the product of the characteristic adsorption energy E_o and the maximum micropore dimension x_o, taken from the distribution curve. The coefficient k requires an independent determination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2691–2699, December, 1990.The authors would like to thank M. V. Degtyarev for the experimental investigations.     

Standard thermodynamic properties of H3PO4(aq) over a wide range of temperatures and pressures

The densities and heat capacities of solutions of phosphoric acid, 0.05 to 1 mol kg-1, were measured using flow vibrating tube densitometry and differential Picker-type calorimetry at temperatures up to 623 K and at pressures up to 28 MPa. The standard molar volumes and heat capacities of molecular H3PO4(aq) were obtained, via the apparent molar properties corrected for partial dissociation, by extrapolation to infinite dilution. The data on standard derivative properties were correlated simultaneously with the dissociation constants of phosphoric acid from the literature using the theoretically founded SOCW model. This made it possible to describe the standard thermodynamic properties, particularly the standard chemical potential, of both molecular and ionized phosphoric acid at temperatures up to at least 623 K and at pressures up to 200 MPa. This representation allows one to easily calculate the first-degree dissociation constant of H3PO4(aq). The performance of the SOCW model was compared with the other approaches for calculating the high-temperature dissociation constant of the phosphoric acid. Using the standard derivative properties, sensitively reflecting the interactions between the solute and the solvent, the high-temperature behavior of H3PO4(aq) is compared with that of other weak acids.     

Simulation of the supramolecular organization and permittivity of methanol over a wide range of state parameters, including the supercritical region

Supramolecular structure models were suggested to describe the permittivity of methanol over a wide range of state parameters from the melting point to the supercritical region. The models were based on the quasi-chemical model of a nonideal associated solution. The permittivity and dipole correlation factor of methanol were calculated over the temperature range 177–593 K at pressures from 0.1 to 20 MPa for two supramolecular structure models. Methanol molecules formed chain associates according to the first model and chain and cyclic aggregates according to the second one. Both models successfully described the experimental data on pure methanol, but the inclusion of cyclic aggregates was necessary for consistency with models of methanol solutions in various solvents over the entire composition range. The thermodynamic and structural parameters of supramolecular aggregates were calculated. The particle-size distributions of aggregates and other integral and differential characteristics of association over the whole range of fluid methanol state parameters were determined for the first time.