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Magnesium acetate, magnesium oxalate and magnesium oxide were employed to prepare waste polyester textiles-based activated carbons with well-developed mesoporous structures. TG analysis was conducted to explore the pyrolysis process and pore-forming mechanism. N 2 adsorption/desorption isotherms, EA, XRD, SEM and FTIR were performed to investigate the influences of different Mg-containing compounds on the physicochemical properties of activated carbons. The results indicated that the samples prepared by two organic magnesium salts exhibited higher specific surface area and porosity than that by magnesium oxide. Diversity in pore structure, morphology and surface groups of the carbons were owing to the differences in grain size of MgO and pyrolysis pathway of Mg-containing compounds. The adsorption isotherm of Cr(VI) for the activated carbons fitted well with Freundlich model, indicating that the adsorption process accorded with the theory of multilayer adsorption. The maximum adsorption capacity of Langmuir model of the sample prepared from magnesium acetate was the highest, and the main adsorption mechanisms were confirmed as electrostatic interaction and reduction reaction. [ABSTRACT FROM AUTHOR]

Adsorption of uranium (U) from real mine contaminated water (U 1.652 mg/L) by phosphate rock apatite (PRA) was investigated in the batch experiment and flow column test system. In batch experiment, the equilibrium adsorption amount is 0.1133 mg/g with the highest uranium removal efficiency of 76.89% under the ratio of solid to liquid (1:100) in 15 h. And the pH of wastewater became neutral (pH 7.51) from acidic (pH 3.88) after adsorption equilibrium. The saturated adsorption amount (0.2021 mg/g) in batch experiment is higher than the maximum accumulative adsorption amount (0.0684 mg/g) in column experiment. Langmuir model and pseudo-second order kinetic model are fitted well and, indicating that PRA is a favorable adsorbent with monolayer coverage and a chemisorption for uranium. Moreover, the surface morphology of the adsorbent by SEM confirmed the surface changes after uranium adsorption. XRD spectra showed that two new mineral phase of Metaankoleite [K(UO 2 )(PO 4 )·3H 2 O], Chernikovite [H 2 (UO 2 ) 2 (PO 4 ) 2 ·8H 2 O] have been generated on PRA after uranium adsorption, but which were trace for relatively low uranium concentration in tested polluted water. In addition, the FT-IR spectra results confirmed the uranium in contaminated water was adsorbed onto the PRA in the form of (O = U = O) 2+ with the participation of the PO 4 3– in binding of it. [ABSTRACT FROM AUTHOR]

A novel bimetallic metal–organic gel (JLUE-MOG-Fe/Y) was fabricated through solvothermal method and employed for adsorptive removal of chlortetracycline hydrochloride (CTC) from aqueous solution. JLUE-MOG-Fe/Y, with outstanding stability, wide adaptability and excellent recyclability, showed strong CTC adsorption capacity as high as 584.83 mg·g−1 at 25 °C. The process of CTC adsorption on JLUE-MOG-Fe/Y was exothermic and spontaneous, and fitted well with the pseudo-second-order kinetic model and Freundlich isotherm model. Based on the adsorption experiments and characterization results, pore filling, coordination bonds, electrostatic interactions, π-π interactions, hydrogen bonds and hydrophilic/hydrophobic interaction participated in the adsorption process. [Display omitted] • Bimetallic metal organic gel used for CTC adsorption. • JLUE-MOG-Fe/Y showed strong stability, excellent recyclability and outstanding anti-interference ability. • The maximum adsorption capacity of CTC could reach 584.83 mg·g–1 at 25 ℃. • Adsorption mechanism involved coordination bonds, π-π interactions, hydrogen bonds, electrostatic interactions, etc. [ABSTRACT FROM AUTHOR]

The adsorption kinetics, isotherms and thermodynamics of Cr(III) on graphene oxide (GO) were studied. The adsorption kinetic data were well described with pseudo-second-order model and the equilibrium data were well fitted by Langmuir model. The calculated thermodynamic parameters indicated that the adsorption of Cr(III) on GO was spontaneous and endothermic. The maximum adsorption capacity of Cr(III) on GO at pH 5.0 and T = 296 K was about 92.65 mg g-1, which was higher than other reported adsorbents. It was found that the adsorption of Cr(III) on GO was strongly dependent on solution pH, but weakly dependent on ionic strength. Fourier transform infrared (FTIR) spectra suggested that Cr(III) was adsorbed on GO mainly through the formation of inner-sphere complexes with the O-containing functional groups on GO surface. Results in this study suggested that GO was a suitable material for the preconcentration and removal of Cr(III) from water. [ABSTRACT FROM AUTHOR]

Dyes released from different industries are one of the major pollutants in the water system. So removal of dye before disposal to the main water stream is necessary. In this study, adsorption technique was adopted for removal of the cationic dye from aqueous system using reduced graphene oxide (rGO) as adsorbent material. The kinetic study of adsorption shows that the present system follows pseudo second order kinetic (linear) model. Adsorption isotherm investigation indicates that the adsorption of methyl green onto rGO nanosheets follows the isotherm models in the order Toth > Sips > Dubinin--Radushkevich (D--R) > Scatchard > Langmuir > Temkin > Freundlich model in the pH range 4--6. However, the order changes to D--R > Scatchard > Toth > Sips > Langmuir > Temkin > Freundlich model at pH 7 and 9. The adsorption capacity of methyl green onto the rGO nanosheets increases with increasing pH of the medium due to the change in the surface properties. Presence of other ions like Na+, Ca2+, Mg2+ and SO42- also influenced on adsorption due to the change in the surface properties. The magnitude of ΔG° values are found to be in the characteristic range of physisorption nature of adsorption. Further, the mechanism of the adsorption process was investigated by FTIR spectroscopy and it indicates that the adsorption is due to electrostatic interaction between methyl green dye molecule and rGO nanosheets. X-ray radial distribution function (RDF) analysis revealed the formation regular molecular packets of graphene. X-ray diffraction (XRD) analysis of the rGO nanosheets before and after adsorption of the dye molecule indicates that some textural changes occur in the rGO nanosheets upon adsorption of the methyl green dye molecule. [ABSTRACT FROM AUTHOR]

Highlights: [•] Activated carbon treated by KOH exhibited better adsorption properties than untreated one. [•] Thermodynamic parameters demonstrated the adsorption process was spontaneous and favorable. [•] It was probable to deduce adsorption mechanisms and design adsorption systems by the study of adsorption kinetics, isotherms and thermodynamics. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different shapes and sizes of hysteresis loop have been observed for a set of pore with different sequences of connectivity. [•] The adsorption in one section of the pore is affected significantly by the state of the adjacent pores. [•] The presence and the position of the closed ends affect significantly the shape and size of the hysteresis loop. [•] Pore size distribution calculated using kernel of isotherms of independent open pores may be incorrect for connected pores. [Copyright &y& Elsevier]

Abstract: The paper presents the numerical analysis based on the low temperature N2 adsorption isotherms of carbon foam microporous structures prepared by various methods from furfuryl alcohol by employment of the fast multivariant fitting procedure of the thermodynamical LBET class models. Various techniques, including chemical vapor polymerization, were employed to produce microporous carbons. To perform the analysis of the porous structure, the fast multivariant fitting procedure with the new adsorption numerical models of the LBET class was used. The results of the analyses carried out with the use of the fast multivariant fitting procedure of the LBET class models have provided valuable information concerning the microporous structure of the analyzed materials, with the determination of the reliability of the defined parameters of the LBET class models. Those studies have been completed by microscopic research aimed at visualization of the macroporous structure as a framework for the formation of micropores. [Copyright &y& Elsevier]

Abstract: Surface and interfacial tension measurements have been performed at the water/air and water/hexane interface by drop profile analysis tensiometry for a series of alkyl trimethylammonium bromides with different chain lengths (C10, C12, C14 and C16). The effect of neutral phosphate buffer (10mM, pH 7) has been investigated and the results have been compared with literature data obtained for the same surfactants in the absence of salt. The use of a modified Frumkin isotherm (Ionic Compressibility) taking into account the mean activity of all ions in solution leads to a real improvement of the data interpretation, while the classical Frumkin Compressibility model yields similar results but overestimates the adsorption parameters. At the water/hexane interface, the hexane molecules are incorporated in the surfactant layer and it results a kind of competitive adsorption for the shortest chain surfactant (10 carbons). For the longest chains, the attractive interactions between the hydrophobic chains of the adsorbed surfactants are strong enough to replace the solvent molecules from the interface. [ABSTRACT FROM AUTHOR]

Abstract: A model for the selective adsorption phenomenon in an isotropic liquid considering a localized adsorption energy is proposed. The fundamental equations governing the adsorption phenomena are established, by considering the mass balance equation in a limited region close to the interface. The electric field distribution inside the sample and the behavior of the chemical potential are determined as a function of the initial concentration of the fluid phase. This model allows us to obtain isotherms that lie outside the Langmuir approximation, because the effective potentials relevant to the adsorption process are determined in a self-consistent manner. [Copyright &y& Elsevier]

Abstract: We applied the model of adsorption of ionic and non-ionic surfactant mixtures, being an extension of previously developed model of adsorption of ionic surfactants, for the description of the pH regulated surface activity of alkanoic acids. We determined the surface tension isotherms for aqueous solutions of octanoic acids and its sodium salt – sodium octanoate, with various additions of NaOH and HCl. A very peculiar shape of isotherms, which was the result of acid–base equilibrium and a large difference of surface activity of octanoate ions and neutral octanoic acid molecules, could be well described by the theoretical model. Additional measurements of surface potential isotherms were correlated with the surface tension and could also be described by our theoretical model. [Copyright &y& Elsevier]

Abstract: A novel glutaraldehyde cross-linked epoxyaminated chitosan (GA-C-ENCS) prepared through chemical modification was used as an adsorbent for the removal and recovery of Cu(II) from aqueous media. The adsorbent was characterized by FTIR, SEM-EDS, ESR, TG/DTG, BET-surface area and potentiometric titration. The Cu(II) adsorption process, which was pH dependent showed maximum removal at pH 6.0. Adsorption equilibrium was achieved within 3h. The adsorption of Cu(II) followed a reversible-first-order kinetics. The equilibrium data were evaluated using the Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. The best interpretation for the equilibrium data was given by the Dubinin–Radushkevich isotherm. The adsorption capacity of the adsorbent increased from 3.11 to 3.71mmolg−1 when the temperature was increased from 20 to 50°C. The complete removal of 20.7mgL−1 Cu(II) from electroplating industry wastewater was achieved by 0.4gL−1 GA-C-ENCS. Regeneration experiments were tried for four cycles and the results indicate a capacity loss of <7.0%. [Copyright &y& Elsevier]

Abstract: The adsorption of Cu(II) from aqueous solution to GMZ bentonite was studied using batch technique under ambient conditions. Removal percentage (%) and distribution coefficient (K d) were determined as a function of contact time, pH, ionic strength and temperature. The adsorption of Cu(II) on GMZ bentonite increased with increasing pH gradually at pH<6.5, and maintained high level at pH>6.5. At pH<6.5, the removal percentage of Cu(II) was the highest at ionic strength of 0.001M NaNO3 and was the lowest at ionic strength of 0.1M NaNO3. The presence of complementary cations depressed the adsorption of Cu(II) on bentonite in the order of Li+ >Na+ >K+ at pH<6.5. The adsorption isotherms were simulated by the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) models very well. The thermodynamic parameters (i.e., ΔH 0, ΔS 0 and ΔG 0) for the adsorption of Cu(II) were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15K, respectively, and the results indicated that the adsorption reaction was favored at higher temperature. The results suggest that GMZ bentonite is a suitable material as an adsorbent for preconcentration and immobilization of Cu(II) from aqueous solution. [Copyright &y& Elsevier]

Abstract: The Azizian–Volkov (AV)-isotherm is a general isotherm for gas adsorption with two different states of an adsorbate. It has been derived previously by a classical thermodynamic approach. The new AV-isotherm gives the possibility to analyze multi and single centered adsorption and the interfacial structure in a general case. The AV-isotherm takes into account the interaction between adsorbed molecules and adsorbent and provides information about the orientation of adsorbates. Traditional isotherms (Henry, Langmuir, and Frumkin) for homogeneous adsorption can be derived from the AV-isotherm. In the present work the AV-isotherm is derived using statistical thermodynamics. This derivation provides a stronger basis for this isotherm. A new concept of the important parameter (η) of AV-isotherm is obtained. Finally, the AV-isotherm was simplified and its application was justified by analysis of the equilibrium data of a numerically generated and experimental systems. [Copyright &y& Elsevier]

Abstract: The adsorption isotherms of phenol, 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, and 3,5-dichlorophenol onto natural zeolite were obtained at pH values of 4.0, 6.0, pK a of phenols, and 10.5. A simple two-site Langmuir model was used to fit the experimental data where two types of interaction were quantified by the model. The first is the pH independent interaction of phenols with hydrophobic sites of zeolite. The second is the pH-dependent phenolate complexation with hydrophilic sites of zeolite (metal ions). The adsorption was enhanced with increasing pH values due to the increase of phenolates complexation with metal ions on zeolite surface. The number of hydrophobic sites of zeolite available for phenols (Q m1) was found to be greater than that of the hydrophilic sites (Q m2). On the other hand, the affinity constants of the hydrophilic sites (K 2) were found to be much greater than those of the hydrophobic sites (K 1). Moreover, the adsorption process of phenols onto zeolite was found to be independent on the ionic strength. [Copyright &y& Elsevier]

Abstract: Polymeric adsorbents have been widely studied for the removal of organic pollutants from waste streams. In this research, a hypercrosslinked polymeric adsorbent (NDA-150) and a macroporous polymeric adsorbent (XAD-4), which have the same matrix of poly(styrene-divinylbenzene) and similar surface area, were chose as model adsorbents to investigate their adsorption characteristics. The adsorption isotherms and kinetics of naphthalene onto two adsorbents from aqueous solutions were investigated. The equilibrium data were correlated with Polanyi–Manes–Dubinin equation, and the adsorption enthalpy changes (ΔH meas) were determined. The good fits of Polanyi–Manes–Dubinin equation and high-exothermic adsorption enthalpies indicated that micropore filling was involved during the adsorption of naphthalene onto two adsorbents. The superior adsorption capacity of hypercrosslinked adsorbent compared to macroporous adsorbent was mainly due to its larger micropore volume. The adsorption of naphthalene onto two polymeric adsorbents was a pseudo-second-order process, controlled by intra-particle diffusion. The kinetic data also demonstrated that the adsorption rate of macroporous adsorbent (XAD-4) was faster than that of hypercrosslinked adsorbent (NDA-150) because it has more suitable porous structure for transporting the adsorbate into the adsorption sites. [Copyright &y& Elsevier]

Abstract: Adsorption isotherms and kinetics of methylene blue (MB) onto mesoporous carbons prepared by using acid- and alkaline-treated zeolite X as the template and furfuryl alcohol as carbon source through vapor-deposition polymerization method were determined. Adsorption isotherm models, Langmuir and Freundlich were used to simulate the equilibrium data of MB. It was found that equilibrium adsorption capacities of MB at 20°C onto the carbons prepared using acid- and alkaline-treated zeolite X as the template were 223 and 380mg/g, respectively. Adsorption isotherm data could be better described by Langmuir model than Freundlich model. Water treatment of the carbon for 2h resulted in the increase of adsorption velocity without changing the equilibrium adsorption capacity. The adsorption capacity increased with temperature increased in the range of 20–40°C. The adsorption kinetics of MB on mesoporous carbons could be well depicted by using pseudo-second-order kinetic model. [Copyright &y& Elsevier]

Abstract: Alpha olefin sulfonate (AOS) surfactants have shown outstanding detergency, lower adsorption on porous rocks, high compatibility with hard water and good wetting and foaming properties. These properties make AOS an excellent candidate for foam applications in enhanced oil recovery. This paper summarizes the basic properties of foam films stabilized by an AOS surfactant. The foam film thickness and contact angle between the film and its meniscus were measured as a function of NaCl and AOS concentrations. The critical AOS concentration for formation of stable films was obtained. The critical NaCl concentration for formation of stable Newton black films was found. The dependence of the film thickness on the NaCl concentration was compared to the same dependence of the contact angle experiments. With increasing NaCl concentration the film thickness decreases gradually while the contact angle (and, respectively the free energy of film formation) increases, in accordance with the classical DLVO theory. The surface tension isotherms of the AOS solutions were measured at different NaCl concentrations. They coincide on a single curve when plotted as a function of mean ionic activity product. Our data imply that the adsorption of AOS is independent of NaCl concentration at a given mean ionic activity. [Copyright &y& Elsevier]

Abstract: The interaction between N,N-disubstituted hydrophobically modified polyacrylamide (HMPAM) and kaolin particle in aqueous suspension was investigated by determining the adsorption isotherms and the flocculation behaviors. HMPAMs with different structures varying in hydrophobic distribution degree, N H (the initial number of hydrophobic monomers per micelle during the preparation) 4.45, 2.55 and 1.79, were used in the experiment. Compared with polyacrylamide (PAM), the HMPAMs have very high-adsorbed amount that correspond to a thick adsorbed layer. These surface loads correlate positively with the effective flocculation of HMPAMs, which are attributed to the affinity and association behavior. Additionally, in the test, the HMPAMs with blocky hydrophobic distribution were better than the ones with short hydrophobic sequences. NaCl was used to detect the effect of electrolyte. As a result of the change of environment property with addition of NaCl, association behavior is promoted; consequently, adsorption and flocculation efficiency are enhanced. [Copyright &y& Elsevier]

Abstract: Removal of silica from aqueous solution by industrial solid ‘waste’ Fe(III)/Cr(III) hydroxide was investigated. Initial pH has no effect on the adsorption of silica in the pH range 4.0–10.0 studied. First, second order and Elovich kinetic models were used to study the adsorption process. The adsorption system followed second order and Elovich kinetics. Langmuir and Freundlich isotherms have been employed to analyze the adsorption equilibrium data. Adsorption process followed Langmuir isotherm. The Langmuir adsorption capacity (Q 0) was found to be 12.25mgg−1. Freundlich constants k f and n were found to be 2.44 and 2.74, respectively. Silica adsorption in the presence of vanadate, phosphate and selenite was decreased whereas molybdate, thiocyanate, chloride, nitrate and sulfate have shown negligible effect. [Copyright &y& Elsevier]

Abstract: The aim of this work was to study the problems related to the description of the heterogeneous structures of the microporous carbonaceous adsorbents. Special attention was focused on comparison of the evaluation reliability of microporous structure parameters by employing single and double adsorption isotherms. The single and double isotherm identification reliability were analysed, for different values of the system parameters. In this context, legitimacy of simultaneous analysis of two isotherms was also studied. The adsorption isotherm used in calculations were generated by the LBET class models for different values of the system parameters relating to real adsorption systems. [Copyright &y& Elsevier]

Abstract: In the present study, natural sepiolite was used as an adsorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of an acid dye (Acid Blue 193, AB193) from aqueous solution at various pHs, temperatures and concentrations. Two simplified kinetic models, first-order and pseudo-second-order, were used to predict the adsorption rate constants. It was found that the kinetics of the adsorption of AB193 onto natural sepiolite at different operating conditions was the best described by the pseudo-second-order model. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated and compared to identify the adsorption mechanisms. Adsorption isotherms and equilibrium adsorption capacities were determined by the fittings of the experimental data to three well-known isotherm models including Langmuir, Freundlich and Dubinin-Radushkevich (D-R). The results showed that the D-R model appears to fit the adsorption better than other adsorption models for the adsorption of AB193 onto natural sepiolite. The equilibrium constants were used to calculate thermodynamic parameters, such as the change of free energy, enthalpy and entropy. [Copyright &y& Elsevier]

Abstract: The difference of phosphate adsorption on the different trophic lake sediments was investigated, including adsorption isotherms, adsorption kinetics, effect of temperature on adsorption, effect of pH on adsorption, thermodynamic parameters of adsorption and adsorption–desorption equilibrium concentration. Three isotherm models were used to characterize the adsorption behavior. The results indicate that the Linear model was the best to describe the adsorption behavior of phosphate on the heavily contaminated sediment with high phosphorus concentration, while for the slightly contaminated sediments the Freundlich model was the best. The adsorption kinetic data were fitted with three kinetic models, while the power function equation was the best kinetic equation, and there was no obvious difference between the different trophic sediments. The phosphate adsorption–desorption equilibrium concentration had a positive correlation with the nutrient level. The slightly contaminated sediment was the sink for phosphate. However, the heavily eutrophic sediment was the source for phosphate, and had the trend to release phosphate to the overlying water. The pH values were different for the various trophic sediments when the phosphate adsorption rates were in maximum and minimum, which may be attributed to the phosphate release. The adsorption process of phosphate on sediments was the endothermic reaction. The phosphate adsorption ability of the heavily contaminated sediments was stronger, and was less affected by temperature than that of the slightly contaminated sediments. [Copyright &y& Elsevier]

Abstract: Kinetics of adsorption of benzoate and salicylate onto the natural hematite surfaces have been carried out at pH 5 and at a fixed ionic strength (I=1×10-4moldm-3). The state of equilibrium was attained at 144 and 70h for benzoate and salicylate, respectively. Adsorption behaviour of benzoate and salicylate onto the natural hematite was studied over a wide range of pH at a fixed I=5×10-4moldm-3 NaCl and at different temperatures. The adsorption isotherms for both the adsorbates were Langmuir type up to pH 8. The Γmax for benzoate is ≉2.7–13.7 times more than that of salicylate depending on the pH of the suspension. Unlike benzoate, salicylate is not only adsorbed at one surface site but also covers around three or more surface sites of hematite surface. The rate constant for adsorption, K1 for salicylate onto the natural hematite is greater than that of benzoate and increases with the increase in temperature and ≉4 times greater at a fixed temperature. The activation energy for the adsorption of salicylate onto the natural hematite is 2.9 times more than that of benzoate on the same adsorbent resulting in lower Γmax. [Copyright &y& Elsevier]

Abstract: Adsorption behavior of phenol, ortho-nitrophenol (ONP), meta-nitrophenol (MNP) and para-nitrophenol (PNP) on a kaolinite-type clay has been investigated by means of spectrophotometric method at 298K. Adsorbability of the phenolic compounds in aqueous solution decreases in the following order; ONP>phenol>MNP≅PNP. Influence of an anionic surfactant, sodium dodecylsulfate (SDS), on adsorption behavior of phenol and nitro-substituted phenols onto kaolinite is studied by determining their adsorption isotherms. Experimental evidence has shown that phenol does not adsorb to the surface of kaolinite in the presence of SDS due to large repulsive, electrostatic barrier between negatively charged phenol and negatively charged adsorptive SDS micelles or hemimmicelles. The adsorption capacity of kaolinite for the aromatic nitro compounds in the SDS system is markedly increased compared with the adsorption onto bare kaolinite surface especially at high-concentration region. Adsorption results were interpreted by comparing isotherms of phenolic compounds and SDS. It is shown that bilayer structure of SDS forms even at low SDS concentrations. In this region, PNP molecules are adsorbed via adsolubilisation whereas penetration of ONP and PNP is difficult because of their structural properties and electrical interactions. However, adsolubilisation phenomenon dominates adsorption process of all nitrophenol compounds at higher concentrations. Data show that adsorption capacities of the adsorbates in the presence of SDS follow the order ONP>MNP>PNP. The differences in the adsorption capacities depending on position of nitro group on phenol ring are correlated with the capacity of SDS. The equilibrium isotherms of phenols have been analyzed using Freundlich and Langmuir equations. [Copyright &y& Elsevier]

Abstract: Measurements of the amount adsorbed of an anionic surfactant from aqueous solutions on activated carbons and carbon blacks, together with zeta potential determinations of the suspended particles, have been carried out. Changes in adsorption isotherms and zeta potential curves with the equilibrium concentration in solution present a similar behavior. Although the solids have different zeta potential when they are suspended in pure water, it has been found that the relative change of the zeta potential at the maximum adsorption for each solid is proportional to the areal amount adsorbed, this proportion being similar for all the samples despite of their surface area or porosity. These results indicate that adsorption of the anionic surfactant has to take place on parts of the surface which allow the ionic head to be exposed to the solution, probably the more inner parts of the surface being not allowable to the adsorbate. [Copyright &y& Elsevier]

Hexane adsorption on mesoporous silicas has been studied in the temperature range 260 up to 350K. Classical models for the textural characterization of MCM-41 by hexane were employed and confirmed analyses using nitrogen as a probe whereas energetic parameters such as CBET were found to be dramatically low. This has been discussed in terms of balance of wall/adsorptive interaction and dispersive interaction leading to unusual adsorption processes, capillary condensation commencing before the monolayer completion. Isosteric heats of adsorption could be derived. Specific confinement effects could be evidenced and the heat of adsorption was found to be strongly dependent on the pore size. [Copyright &y& Elsevier]

Adsorption isotherms of dimethyldodecylamine-N-oxide (DDAO) onto laponite were determined by potentiometry, using a surfactant-specific electrode. The isotherms were obtained at pH 7; 8 and 9, and at various NaCl concentrations. The stability of laponite in these conditions was evidenced. All isotherms are mingled in these conditions and the level of adsorption of the non-ionic surfactant is found to be much higher than that of its cationic homologue, dodecyltrimethylammonium (DTA+). [Copyright &y& Elsevier]

Studies have been made of the sorption equilibria of chlorinated anilines in aqueous solution on ligand exchange resin. The chlorinated anilines used included 2-chloroaniline, 3-chloroaniline, 4-chloroaniline and 2,5-dichloroaniline. A mini-column apparatus was used to study sorption of chlorinated anilines onto ligand exchange resin. The experiments were conducted in a constant temperature at 25±0.1 °C. The sorption behaviour of these chlorinated anilines on Co(II)-loaded carboxylated diaminoethyl sporopollenin (CDAE-sporopollenin) can be expressed by the Langmuir and Freundlich isotherms. The characteristics of the sorption process were also investigated using Scatchard plot analysis (q/C vs. q). When the Scatchard plot showed a deviation from linearity, greater emphasis was placed on the analysis of the adsorption data in terms of the Freundlich model, in order to construct the adsorption isotherms of the ligand(s) at particular concentration(s) in solutions. Equilibrium binding data for ligands gave rise to a linear plot, indicating that the Langmuir model could be applied. Ligand adsorption constants, dissociation constant (Kd) and correlation coefficients for the ligands were calculated from Langmuir and Freundlich isotherms. [Copyright &y& Elsevier]

The synthesis of a novel triazine based resin (TRIAZ-PA) has been accomplished for the ultrahigh and efficient removal of Methyl orange (MO), Eriochrom Black T (EBT) and Acid Blue 92 (AB92) from aqueous solution. At room temperature, the mesoporous TRIAZ-PA exhibited excellent adsorptive performance, displaying maximum adsorption capacities (Q max) of 620.5 mg g−1, 198.3 mg g-1 and 239.6 mg g−1 for MO, EBT and AB92, respectively. Examination of the experimental adsorption data by non-linear curve fitting of four isotherm models suggested that Langmuir and Freundlich isotherms were the best-fit models in describing the adsorption of these dyes. The kinetics studies revealed faster rate of adsorption, as the equilibrium was achieved within the first 4 h. Moreover, thermodynamics calculations suggested that adsorption was spontaneous, exothermic and physical in nature. The adsorptive performance of the resin at varied pH indicates that beside electrostatic forces and hydrogen-bonding, other adsorption mechanism such hydrophobic interaction or π-π stacking interaction are also involved. The thermal stability of the resin was deduced by thermogravimetric analysis (TGA) (T d < 300 °C) whereas its mesoporous nature was ascertained by Brunauer-Emmett-Teller (BET) analysis. The X-ray photoelectron spectroscopy (XPS) analysis of dye-loaded resins revealed two new peaks due to O 1s and S 2P at around 529.5 eV and 161.2 eV, hinting the adsorption of the sulfur-based dyes onto the resin. The resin exhibits good reusability, retaining adsorption efficiency of 70 % after four cycles of adsorption-desorption process. [ABSTRACT FROM AUTHOR]