Temperature Dependence Of Adsorption Research Articles

Th(IV) Adsorption onto Oxidized Multi-Walled Carbon Nanotubes in the Presence of Hydroxylated Fullerene and Carboxylated Fullerene.

The adsorption of Th(IV) onto the surface of oxidized multi-walled carbon nanotubes (oMWCNTs) in the absence and presence of hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) has been investigated. C60(OH)n, C60(C(COOH)2)n and oMWCNTs have been chosen as model phases because of their representative in carbon nano-materials family. Adsorption experiments were performed by batch procedure as a function of contact time, pH, ionic strength, and temperature. The results demonstrated that the adsorption of Th(IV) was rapidly reached equilibrium and the kinetic process could be described by a pseudo-second-order rate model very well. Th(IV) adsorption on oMWCNTs was dependent on pH but independent on ionic strength. Adsorption isotherms were correlated better with the Langmuir model than with the Freundlich model. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Th(IV) adsorption on oMWCNTs was spontaneous and endothermic. Compared with the adsorption of Th(IV) on the same oMWCNTs free of C60(OH)n or C60(C(COOH)2)n, the study of a ternary system showed the inhibition effect of C60(OH)n at high concentration on the adsorption of Th(IV) in a pH range from neutral to slightly alkaline; whereas the promotion effect of C60(C(COOH)2)n, even at its low concentration, on Th(IV) adsorption was observed in acid medium.

Adsorption of Cu(II) on oxidized multi-walled carbon nanotubes in the presence of hydroxylated and carboxylated fullerenes.

The adsorption of Cu(II) on oxidized multi-walled carbon nanotubes (oMWCNTs) as a function of contact time, pH, ionic strength, temperature, and hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) were studied under ambient conditions using batch techniques. The results showed that the adsorption of Cu(II) had rapidly reached equilibrium and the kinetic process was well described by a pseudo-second-order rate model. Cu(II) adsorption on oMWCNTs was dependent on pH but independent of ionic strength. Compared with the Freundlich model, the Langmuir model was more suitable for analyzing the adsorption isotherms. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Cu(II) adsorption on oMWCNTs was spontaneous and endothermic. The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration. The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5. The presence of C60(C(COOH)2)n inhibited the adsorption of Cu(II) onto oMWCNTs at pH 4–6. The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

Organo-bentonite-Fe3O4 poly(sodium acrylate) magnetic superabsorbent nanocomposite: Synthesis, characterization, and Thorium(IV) adsorption

Novel magnetic organo-bentonite-Fe3O4 poly(sodium acrylate) (OB-Fe3O4 PSA) superabsorbent nanocomposites were synthesized in aqueous solution through the copolymerization of partially neutralized acrylic acid (SA) on OB-Fe3O4 nanoparticle by using N,N′-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. This new superabsorbent was characterized by FTIR, TGA, FE-SEM and XRD. Its iron content and magnetic properties were studied by using inductively coupled plasma (ICP) and a vibrating sample magnetometer (VSM), respectively. The water retention test of OB-Fe3O4 PSA was also performed. The introduced OB-Fe3O4 could form a loose and coarse surface and improve the water absorbency of OB-Fe3O4 PSA superabsorbent. The effects of pH, ionic strength, and humic substances (HS) on the adsorption of Th(IV) were investigated in detail through batch experiments. The maximum adsorption capacity (Qmax) of Th(IV) on OB-Fe3O4 PSA 3.6 superabsorbent at pH 3.0±0.05 and T=298K was about 6.55mmol/g, higher than any value previously reported. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Th(IV) adsorption on OB-Fe3O4 PSA superabsorbent was an endothermic and spontaneous process. Furthermore, OB-Fe3O4 PSA superabsorbent could be regenerated through the desorption of Th(IV) using 0.1mol/L HCl solution and the adsorption capacity was still higher than 3.6mmol/g after five consecutive adsorption–desorption processes.

Assembly of Poly(dopamine)/Poly(N-isopropylacrylamide) Mixed Films and Their Temperature-Dependent Interaction with Proteins, Liposomes, and Cells

Many biomedical applications benefit from responsive polymer coatings. The properties of poly(dopamine) (PDA) films can be affected by codepositing dopamine (DA) with the temperature-responsive polymer poly(N-isopropylacrylamide) (pNiPAAm). We characterize the film assembly at 24 and 39 °C using DA and aminated or carboxylated pNiPAAm by a quartz crystal microbalance with dissipation monitoring (QCM-D), X-ray photoelectron spectroscopy, UV-vis, ellipsometry, and atomic force microscopy. It was found that pNiPAAm with both types of end groups are incorporated into the films. We then identified a temperature-dependent adsorption behavior of proteins and liposomes to these PDA and pNiPAAm containing coatings by QCM-D and optical microscopy. Finally, a difference in myoblast cell response was found when these cells were allowed to adhere to these coatings. Taken together, these fundamental findings considerably broaden the potential biomedical applications of PDA films due to the added temperature responsiveness.

Temperature-dependent adsorption of surfactant molecules and associated crystallization kinetics of noncentrosymmetric Fe(IO3)3 nanorods in microemulsions

Aggregation-induced crystallization of iron iodate nanorods within organic–inorganic aggregates of primary amorphous precursors is probed by time-dependent hyper-Rayleigh scattering measurements in Triton X-100 based-microemulsions. In the context of a growing interest of noncentrosymmetric oxide nanomaterials in multi-photon bioimaging, we demonstrate by a combination of X-ray diffraction and electron microscopy that an increase in the synthesis of temperature results in faster crystallization kinetics and in a better shape-control of the final Fe(IO3)3 nanorods. For initial microemulsions of fixed composition, room-temperature synthesis leads to bundles of 1–3μm long nanorods, whereas shorter individual nanorods are obtained when the temperature is increased. Results are interpreted in terms of kinetically unfavorable mesoscale transformations due to the strong binding interactions with Triton molecules. The interplay between the nanorod crystallization kinetics and their corresponding unit cell deformation, evidenced by lattice parameter refinements, is attributed to a temperature-dependent adsorption of surfactants molecules at the organic–inorganic interface.

Activation and Catalytic Dehydrogenation of Methane on Small Pdx+ and PdxO+ Clusters

The temperature-dependent adsorption as well as the possible activation and dehydrogenation of methane mediated by small free palladium Pdx+ (x = 2–4) and palladium mono-oxide PdxO+ (x = 2–4) clusters have been studied in an ion trap experiment under multicollision conditions. The smallest clusters Pd2+ and Pd3+ are found to readily dehydrogenate methane, while Pd4+ is completely nonreactive within the whole investigated temperature range between 220 and 300 K. In the case of the oxides PdxO+, a critical number of at least three coadsorbed CD4 is required before methane dehydrogenation can be observed. Temperature-dependent kinetic studies of the reaction of Pd2+ and Pd2O+ with methane allow for the determination of catalytic reaction mechanisms that involve C–D bond cleavage and C–C bond formation processes. The catalytic activity of these two clusters is compared in terms of active species, cooperative effects, and activation barriers. Finally, the possible methane oxidation on PdxO+ is discussed.

On Equilibrium Ga Intergranular Films in Cr2GaC

The presence of equilibrium intergranular films (IGFs) in metallic systems has long been postulated; compelling evidence for this idea, however, is still lacking. Herein differential scanning calorimetry, in the−60°C to 70°C temperature range, on bulk and Cr2GaC powders was carried out. A sharp endothermic trough, roughly 50°C below the melting point of bulk pure Ga, in the powdered samples was taken to be strong evidence for the presence of IGFs in the latter. The troughs for the sintered body were much more diffuse suggesting that in this case, a distribution of grain boundary thicknesses exists. A temperature dependent adsorption energy is postulated to explain the reversible extrusion and resorption of 100 μm thick Ga micro-pillars.

Effect of environmental parameters on the sequestration of radionickel by Mg2Al layered double hydroxide

In this work, sequestration of Ni(II) from aqueous solution to Mg2Al layered double hydroxide (Mg2Al LDH) by adsorption process as a function of various water quality parameters and temperature was investigated. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The adsorption of Ni(II) on Mg2Al LDH was strongly dependent on pH and ionic strength. The presence of humic acid (HA)/fulvic acid (FA) enhanced the adsorption of Ni(II) on Mg2Al LDH at low pH, whereas reduced Ni(II) adsorption at high pH. The Langmuir model fitted the adsorption isotherms of Ni(II) better than the Freundlich model at three different temperatures of 298, 318 and 338 K. The thermodynamic parameters (ΔHo, ΔSo and ΔGo) calculated from the temperature dependent adsorption isotherms indicated that the adsorption process of Ni(II) on Mg2Al LDH was endothermic and spontaneous. The results show that Mg2Al LDH is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.

Adsorption of phenol and 1-naphthol onto XC-72 carbon

XC-72 carbon (XC-72) was characterized by SEM, XPS, N2 adsorption-desorption, particle size distribution analysis and potentiometric acid-base titration. The adsorption of phenol and 1-naphthol on XC-72 was studied as a function of contact time, pH, adsorbent content and temperature. The kinetic adsorption data were described well by the pseudo-second-order model. The adsorption isotherms of phenol were described well by Freundlich model, while the adsorption isotherms of 1-naphthol were fitted well by Langmuir model. The results demonstrated that XC-72 had much higher adsorption capacity for 1-naphthol than for phenol. The adsorption thermodynamic data were calculated from the temperature-dependent adsorption isotherms at T=293, 313 and 333 K, and the results indicated that the adsorption of phenol was an exothermic process, whereas the adsorption of 1-naphthol was an endothermic process. XC-72 is a suitable material for the preconcentration of phenol and 1-naphthol from large volumes of aqueous solutions.

Adsorption of uranium from aqueous solution by PAMAM dendron functionalized styrene divinylbenzene

A new polymeric chelating resin was prepared by growing third generation poly(amido)amine (PAMAMG3) dendron on the surface of styrene divinylbenzene (SDB) and characterized by FTIR, TGA and SEM. The ideal branching of dendron in the chelating resin was determined from potentiometric titration. Adsorption of uranium (VI) from aqueous solution using PAMAMG3-SDB chelating resin was studied in a series of batch experiments. Effect of contact time, pH, ionic strength, adsorbent dose, initial U(VI) concentration, dendron generation and temperature on adsorption of U(VI) were investigated. Kinetic experiments showed that U(VI) adsorption on PAMAMG3-SDB followed pseudo-second-order kinetics model appropriately and equilibrium data agreed well with the Langmuir isotherm model. Thermodynamic parameters (ΔH°, ΔS°, ΔG°) were evaluated from temperature dependent adsorption data and the uranium adsorption on PAMAMG3-SDB was found to be endothermic and spontaneous in nature. The sticking probability value (5.303×10−9), kinetic and isotherm data reveal the chemisorption of uranium on PAMAMG3-SDB and adsorption capacity of the chelating resin was estimated to be 130.25mgg−1 at 298K. About 99% of adsorbed U(VI) can be desorbed from PAMAMG3-SDB by a simple acid treatment suggesting that the chelating resin is reusable.

Microscopic insights into the temperature-dependent adsorption of Eu(III) onto titanate nanotubes studied by FTIR, XPS, XAFS and batch technique

This work investigated the effects of reaction temperature on Eu(III) interaction mechanism and microstructure at the titanate nanotubes (TNTs)/water interface by batch and spectroscopic (FTIR, XPS, XAFS) technique. Batch adsorption results showed that the adsorption of Eu(III) onto TNTs is promoted at higher temperature, and is an endothermic and spontaneous interfacial process. The adsorption isotherms at three different temperatures can be described by the Freundlich model better than the Langmuir model did. The spectroscopic analysis results suggested that Eu(III) interaction with TNTs is mainly controlled by outer-sphere surface complexation at T=293K, which is a reversible adsorption process, whereas Eu(III) interaction is mainly controlled by inner-sphere surface complexation at T=313K and T=343K, which is an irreversible adsorption process. The findings in this work can help us to better understand the physicochemical behavior of Eu(III) and related radionuclides in natural environment. The results of this work also show the great potential importance of TNTs as novel nanomaterials in the near future of nuclear waste management.

Oxygen Vacancy-Assisted Coupling and Enolization of Acetaldehyde on CeO2(111)

The temperature-dependent adsorption and reaction of acetaldehyde (CH(3)CHO) on a fully oxidized and a highly reduced thin-film CeO(2)(111) surface have been investigated using a combination of reflection-absorption infrared spectroscopy (RAIRS) and periodic density functional theory (DFT+U) calculations. On the fully oxidized surface, acetaldehyde adsorbs weakly through its carbonyl O interacting with a lattice Ce(4+) cation in the η(1)-O configuration. This state desorbs at 210 K without reaction. On the highly reduced surface, new vibrational signatures appear below 220 K. They are identified by RAIRS and DFT as a dimer state formed from the coupling of the carbonyl O and the acyl C of two acetaldehyde molecules. This dimer state remains up to 400 K before decomposing to produce another distinct set of vibrational signatures, which are identified as the enolate form of acetaldehyde (CH(2)CHO¯). Furthermore, the calculated activation barriers for the coupling of acetaldehyde, the decomposition of the dimer state, and the recombinative desorption of enolate and H as acetaldehyde are in good agreement with previously reported TPD results for acetaldehyde adsorbed on reduced CeO(2)(111) [Chen et al. J. Phys. Chem. C 2011, 115, 3385]. The present findings demonstrate that surface oxygen vacancies alter the reactivity of the CeO(2)(111) surface and play a crucial role in stabilizing and activating acetaldehyde for coupling reactions.

Removal of simulated radionuclide Ce(III) from aqueous solution by as-synthesized chrysotile nanotubes

Chrysotile nanotubes (ChNTs) were synthesized under hydrothermal conditions for removing simulated radionuclide Ce(III). The prepared samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and N2 adsorption and desorption which show that as-synthesized ChNTs possess hollow structured, whose inner and outer diameters are ca. 8–15nm and 30–50nm respectively with inner aspect ratio to 20. The BET surface area and total pore volume were calculated to be 144.1m2g−1 and 0.39cm3g−1, respectively. In addition, the effects of contact time, solid content, pH and temperature were also investigated by batch technique. The adsorption kinetics and isotherms of ChNTs for Ce(III) indicate that the kinetic adsorption is well described by the pseudo-second-order model and the adsorption isotherm is fitted well by Langmuir model (Qmax=1.21×10−3molg−1 at 348±1K). The thermodynamic parameters (i.e., ΔG∘, ΔS∘ and ΔH∘) of the adsorption for Ce(III) were determined from the temperature dependent adsorption isotherms at 298, 323 and 348±1K, respectively. The results indicate that the adsorption process of Ce(III) on ChNTs is spontaneous and endothermic.

Application of PRSV2 equation of state and explicit pressure dependence of the Langmuir adsorption constant to study phase behavior of gas hydrates in the presence and absence of methanol

In this study, we present a simple thermodynamic model that predicts equilibrium pressures as a function of temperature of hydrates with CH4, C2H6, C3H8, N2, CO2 and their mixtures as guests in the presence and absence of methanol. The model is based on equality of water fugacity in the liquid water and hydrate phases. The van der Waals and Platteeuw model is applied for calculating the fugacity of water in the hydrate phase. The Stryjek and Vera modification of Peng–Robinson (PRSV2) equation of state is used to evaluate the fugacity of water in the vapor and liquid phases. To achieve more accurate results, binary interaction parameters are adjusted as a linear function of temperature. In this work, we used a new pressure- and temperature-dependent Langmuir adsorption constant proposed by Hsieh. Acceptable agreement between the model predictions and experimental data exhibits its reliability.

Removal of radiocobalt from aqueous solution by Mg2Al layered double hydroxide

The adsorption behavior of radiocobalt by Mg2Al layered double hydroxide (Mg2Al LDH) was studied as a function of contact time, pH, ionic strength, foreign ions, FA and temperature under ambient conditions. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The adsorption of Co(II) on Mg2Al LDH was strongly dependent on pH and ionic strength. The presence of FA enhanced the adsorption of Co(II) on Mg2Al LDH at low pH, whereas reduced Co(II) adsorption at high pH. The Langmuir model fitted the adsorption isotherms of Co(II) better than the Freundlich and D–R model at three different temperatures of 303, 323 and 343 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent adsorption isotherms indicated that the adsorption process of Co(II) on Mg2Al LDH was endothermic and spontaneous. The results show that Mg2Al LDH is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.

Interaction between Eu(III) and Graphene Oxide Nanosheets Investigated by Batch and Extended X-ray Absorption Fine Structure Spectroscopy and by Modeling Techniques

The interaction mechanism between Eu(III) and graphene oxide nanosheets (GONS) was investigated by batch and extended X-ray absorption fine structure (EXAFS) spectroscopy and by modeling techniques. The effects of pH, ionic strength, and temperature on Eu(III) adsorption on GONS were evaluated. The results indicated that ionic strength had no effect on Eu(III) adsorption on GONS. The maximum adsorption capacity of Eu(III) on GONS at pH 6.0 and T = 298 K was calculated to be 175.44 mg·g(-1), much higher than any currently reported. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Eu(III) adsorption on GONS was an endothermic and spontaneous process. Results of EXAFS spectral analysis indicated that Eu(III) was bound to ∼6-7 O atoms at a bond distance of ∼2.44 Å in the first coordination shell. The value of Eu-C bond distance confirmed the formation of inner-sphere surface complexes on GONS. Surface complexation modeling gave an excellent fit with the predominant mononuclear monodentate >SOEu(2+) and binuclear bidentate (>SO)(2)Eu(2)(OH)(2)(2+) complexes. This paper highlights the application of GONS as a suitable material for the preconcentration and removal of trivalent lanthanides and actinides from aqueous solutions in environmental pollution management.

Explicit pressure dependence of the Langmuir adsorption constant in the van der Waals–Platteeuw model for the equilibrium conditions of clathrate hydrates

In this work, we propose a new pressure- and temperature-dependent Langmuir adsorption constant for the modeling of the phase boundary of clathrate hydrates over a wide range of conditions. The proposed Langmuir adsorption constant is designed to produce a reduced free volume available to the encapsulated gas molecules as the pressure increases. We show that the combination of a cubic equation of state and the van der Waals–Platteeuw model with this new Langmuir model can be used to describe various types of three phase coexisting conditions of gas hydrates, from vapor–ice–hydrate equilibrium (VIHE) at low temperatures, to vapor–liquid–hydrate equilibrium (VLHE) at higher temperatures, and to liquid–liquid–hydrate equilibrium (LLHE) at high pressures, using a single set of parameters. The average relative deviations in the equilibrium pressure are found to be 4.57% for 12 pure gas hydrates over a large range of temperatures (148.8–323.9K) and pressures (5.35×102Pa to 8.27×108Pa). Furthermore, the retrograde behavior observed in CH4, CO2, C3H8, and i-C4H10 pure gas hydrate systems can all be successfully modeled by the change of free volume at high pressures. We believe that this method is useful for many gas hydrates related the multiple three-phase regions.

Experimental and Theoretical Insight of Nonisothermal Adsorption Kinetics for a Single Component Adsorbent–Adsorbate System

A theoretical framework is proposed to describe the temperature-dependent adsorption kinetics and their interpretation of measured uptake curves of four types of adsorbate, namely, methane and halogenated refrigerants (R134a, R410a, and R507a) onto a pitch-based activated carbon, Maxsorb III. The model requires only two measurable data from the experiments, that is, the adsorbent temperature and system pressure during the adsorption dynamics. We have demonstrated that the temperature dependency adsorption has significant influence on the intrapellet diffusion coefficients of the linear driving force (LDF) model. A modified LDF model is proposed in this paper, and it is validated using the uptake behavior of these adsorbates; good agreement is found between the proposed kinetics model and the experimental uptake. The parameters postulated in the model are consistent and reproducible and agree well with a priori estimates. The model provides a useful theoretical basis for the analysis of rapid sorption proc...

Study on adsorption behavior and separation efficiency of naturally occurring clay for some elements by batch experiments

This paper describes the versatile nature of clay that was obtained from Suez Gulf, Suez city, Egypt, as a new low cost natural resource which is non toxic to ecosystem and highly effective adsorbent material. The properties of the natural clay and its significance in removing Th(IV) and Ce(IV) as a representative of tetravalent actinides and lanthanides, respectively, La(III) as a representative of trivalent lanthanides as well as homologues of americium and Sr(II) as one of the fission products, in aqueous solutions have been studied, in order to consider its application for nuclear waste treatment. Batch experiments have been carried out to determine the effect of various factors such as initial metal ion concentration, clay dose, pH, contact time, and temperature on the adsorption process. The results have dictated that, the adsorption efficiency of the natural clay was significantly high at pH = 4. Maximum metal ion uptake capacity of clay has been obtained from batch studies was 99.24, 98.21, 77.76 and 57.94% for Th(IV), Ce(IV), La(III) and Sr(II), respectively. The thermodynamic parameters (Δ H o , Δ S o and Δ G o ) have been calculated from the temperature dependent adsorption isotherms. Furthermore, separation factors (α) have been calculated in order to separate these elements from each other at pH = 4.

Diffusion of Chlorin-p6 Across Phosphatidyl Choline Liposome Bilayer Probed by Second Harmonic Generation

We have investigated the diffusion of the photosensitizer Chlorin-p(6) (Cp(6)) across a egg lecithin lipid bilayer at different pH by the Second Harmonic Generation (SHG) method. Cp(6) has three ionizable carboxylic acid groups, and consequently, neutral and several ionic forms of Cp(6) are expected to be present in the pH range 3-8. The absorption spectra of Cp(6) get considerably modified in the presence of liposomes as the pH is decreased indicating that the drug liposome binding is pH dependent. The first pK(a) of interconversion (D-C) has been identified at pH ~7.0 by fluorescence measurement in an earlier work. In this work, the second pK(a) of interconversion (C-B) has been identified at pH ~4.8 by the hyper-Rayleigh scattering method. At acidic pH (3, 4, and 5), where species A, B, and C are dominant, the addition of liposomes to a Cp(6) solution generates an instantaneous rise (less than 1 s) in the second harmonic (SH) signal followed by decays whose time constants ranged from ten to hundreds of seconds. The instantaneous rise is attributed to the adsorption of Cp(6) to the outer lipid bilayer, and the decay is attributed to the diffusion of the neutral and charged (A and B) species of the drug. The observed fast and slow time constants for diffusion in the pH range 3-5 are attributed to the neutral (A) and ionic form (B) of Cp(6), respectively. At pH 6, the intensity of the generated SH signals on the addition of liposome reduced, and at physiological pH, it was too weak to be detected. These results are consistent with previous studies that show that the interaction between Cp(6) and egg-PC liposomes is pH dependent. At lower pH due to the presence of the hydrophobic species (A and B) of Cp(6), its interaction with liposomes is strong, and at higher pH, the abundance of the negatively charged hydrophilic species (C and D) decreases the interaction with the like charged liposomes. We have also studied the effect of increasing the bilayer rigidity by decreasing the temperature of the medium or by incorporating 50 mol % cholesterol in the lipid bilayer and observed that lowering of temperature has more profound effect on the diffusion rates. The characteristics of the SH signal changed significantly when liposomes incorporating 50 mol % cholesterol were used at a low (3 °C) temperature. Under these conditions, the SH signal consisted of an instantaneous (<1s) followed by a slower rise (10-90s), and then, it decayed on a much longer time scale. This slow rise of the SH signal at pH 3 and 4 may be attributed to the temperature dependent adsorption of the anionic species (B) of Cp(6) with the liposomes. Further investigations are required in order to understand clearly the pH dependent diffusion of this drug across lipid bilayers.