Optical second harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of copolymer vinylidene fluoride with trifluorethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of LB films and a thickness independent (almost 2D) transition in the bulk of these films are observed in temperatur...

the aim of the present work was to investigate the ability of cocopeat to remove of lead (ii) from aqueous solutions. the effects of different parameters such as particle size, adsorbent dosage, ph, contact time, agitation speed and concentration on the removal process has been investigated. the maximum removal of lead ion (92.5%) took place in the ph range of 4 contact time in 30 minutes and i...

The adsorption of Pb (II) ions onto chitosan beads and cross-linked chitosan beads has been investigated. The epichlorohydrin (ECH) was used as a cross-linking agent. Experiments were carried out as a function of pH, stirring time, adsorbent dosage and concentration of Pb (II) ions. The experimental data of the adsorption equilibrium from Pb (II) solution correlated well with the Langmuir isoth...

The present study proposes a model to explain the adsorption process through ionexchange membrane adsorbers. The model is defined by the continuity equation, expressed as a differential mass balance of the solute over a section of the membrane, and the Langmuir isotherm. The proposed model uses dimensionless variables that were defined by characteristic times of the global process. To examine t...

Activated carbon honeycomb-monoliths with different textural properties were prepared by chemical activation of African palm shells with H(3)PO(4), ZnCl(2) and CaCl(2) aqueous solutions of various concentrations. The adsorbents obtained were characterized by N(2) adsorption at 77 K, and their carbon dioxide adsorption capacities were measured at 273 K and 1 Bar in volumetric adsorption equipmen...

Removal of fluoride ions was investigated using a new adsorbent of yttrium alginate biocomposite (YALG). Effect of various parameters such as pH, contact time, initial concentration of fluoride ions and temperature on the sorption capacity of adsorbent was studied. Performing a mathematical assessment of fluoride sorption, isotherm and kinetics models including Freundlich & Langmuir isotherms a...

An explanation ís put forward for the shape of adsorption envelopes found for phosphate adsorption by various metallic oxides. The equation x m '" C l (p.H PO. + 3 J.t¿;anions) is proposed, where J.tH 3 PO. is the chemícal potential of undissociated H3 PO.; J.t¿;anions is the chemical potential of all phosphate anions considered as one. component; CI is a constant that incIudes influences of su...

where the function u(x, t) denotes the fast time scale component of the electric field raised by electrons, and the function n(x, t) denotes the deviation of the ion density from its equilibrium. Here u(x, t) is a complex function, n(x, t) is a real function, α , β are two nonzero real parameters. This system describes the interaction of the Langmuir wave and the ion acoustic wave in a high fre...

A balance is described with Langmuir binding of weights to each side. This simple physical system, when coupled with a previously derived equation for the equivalent displacement of weight that perturbs the equilibrium of a balance, models twostate, receptor systems in pharmacology for receptor activation. Surprisingly, this system also shows desensitization similar to many drug-receptor system...

We use a newly developed set of boundary conditions to revisit the problem of an evaporating thin liquid film. In particular, instead of the conventional Hertz–Knudsen– Langmuir equation for the evaporation mass flux we impose a more general equation expressing the balance of configurational momentum. This balance, which supplements the conventional conditions enforcing the balances of mass, mo...