Effects Of Adsorption Conditions Research Articles

Removal of Cu(II) by loofah fibers as a natural and low-cost adsorbent from aqueous solutions

As a natural and low-cost material, loofah fibers were applied as an adsorbent to remove Cu(II) from aqueous solutions. The effect of adsorption conditions, such as pH, foreign ions, humic substances (HS), contact time and temperature on the Cu(II) removal, was investigated intensively. The adsorption of Cu(II) on loofah fibers was strongly dependent on pH and foreign ions, and the adsorption of Cu(II) was increased in the presence of humic acid (HA) at pH<8.0 but decreased at pH>8.0. The Langmuir and Freundlich isotherm models were used to simulate the adsorption isotherms. The simulated adsorption isotherms, which were obtained from Langmuir and Freundlich isotherm models, showed that both of the two models were applicable to this system. On the basis of the experimental data, the Langmuir isotherm model could fit it better according to linear correlation coefficient (R2). The optimum kinetics of adsorption was found to fit the pseudo-second-order kinetic model. The values of ΔΗ° and ΔG° indicated that the adsorption process was exothermic and spontaneous.

Sorption Behavior of Methyl Violet onto Poly(acrylic acid-co-acrylamide)/Kaolin Hydrogel Composite

Poly(acrylic acid-co-acrylamide)/kaolin hydrogel composite was synthesized and characterized. Sorption behavior of methyl violet (MV) onto the composite was studied. Effect of adsorption conditions, including contact time, initial concentration of MV, pH values, adsorbent dosage and ionic strength, on the adsorption capacity and removal percentage was investigated in detail. The equilibrium adsorption capacity reached 908.0 mg/g as the initial concentration of MV was 1000 mg/L. Adsorption mechanisms were also speculated. Further studies showed that the adsorption process was spontaneous and satisfied the Redlich–Peterson model. The kinetic data showed that the adsorption was in accordance with the Lagergren pseudo–first-order kinetic model.

Removal of Cu(II) by loofah fibers as a natural and low-cost adsorbent from aqueous solutions

As a natural and low-cost material, loofah fibers were applied as an adsorbent to remove Cu(II) from aqueous solutions. The effect of adsorption conditions, such as pH, foreign ions, humic substances (HS), contact time and temperature on the Cu(II) removal, were investigated intensively. The adsorption of Cu(II) on loofah fibers was strongly dependent on pH and foreign ions, and the adsorption of Cu(II) was increased in the presence of humic acid (HA) at pH<8.0 but decreased at pH>8.0. The Langmuir and Freundlich isotherm models were used to simulate the adsorption isotherms. The simulated adsorption isotherms, which were obtained from Langmuir and Freundlich isotherm models, showed that both of the two models were applicable to this system. On the basis of the experimental data, the Langmuir isotherm model could fit it better according to linear correlation coefficient (R2). The optimum kinetics of adsorption was found to fit the pseudo-second-order kinetic model. The values of ∆H° and ∆G° indicated that the adsorption process was exothermic and spontaneous.

Effect of Adsorption Conditions on Effective Diffusivity and Textural Property of Dry Banana Foam Mat

Foamed banana product, a crispy snack, can quickly adsorb the moisture from the moist air, leading to loss of textural property. The main purpose of this research was therefore to study moisture adsorption kinetics of dry banana foam mat and its texture quality change. The adsorption isotherm experiments were carried out with a standard static method using saturated salt solutions over a wide range of relative humidities from 32 to 82% and temperatures of 35, 40, and 45°C. Three dry banana foam densities of 0.21, 0.26, and 0.30 g/cm3 adsorbed water vapor under controlled conditions. Fick's second law coupled with an optimization technique was used to estimate the effective moisture diffusivity at sorption conditions. Empirical equations with two and three constant parameters for describing the dependence of the effective moisture diffusivity on moisture content were tested. The two constant parameters could suitably describe the variation of the effective moisture diffusivity with moisture content. The initial foam density, relative humidity, and temperature significantly affected the effective moisture diffusivity. The banana foam mats for all densities lost their crispy texture at moisture content of 0.078 kg/kg db.

Adsorption of polyallylamine to lignocellulosic fibres: effect of adsorption conditions on localisation of adsorbed polyelectrolyte and mechanical properties of resulting paper sheets

Cationic polyallylamine (PAH), was adsorbed onto lignocellulosic fibres, and a fluorescent label on the polyelectrolyte enabled its location to be shown by confocal fluorescence microscopy. The ads ...

Poly(Styrene‐Hydroxyethyl Methacrylate) Monodisperse Microspheres as Specific Sorbent in Dye Affinity Adsorption of Albumin

In this study, human serum albumin (HSA) adsorption properties of reactive green HE‐4BD‐attached monodisperse poly(styrene‐2‐hydroxyethyl methacrylate) [poly(St‐HEMA)] microspheres were investigated. Poly(St‐HEMA) microspheres with an uniform size of 4.0 µm in diameter were produced by the dispersion copolymerization of St and HEMA in an ethanol–water medium. Reactive green HE‐4BD was covalently attached onto the poly(St‐HEMA) microspheres via a nucleophilic substitution reaction between the hydroxyl groups of HEMA and triazinyl chloro groups of dye with the equilibrium coupling capacity of 45.8 µmol dye (g polymer)−1. The poly(St‐HEMA) monodisperse microspheres were characterized by scanning electron microscopy. The effect of concentration of HSA, medium pH, and ionic strength on the adsorption efficiency of dye‐attached microspheres were studied in a batch system. The nonspecific adsorption of HSA on the poly(St‐HEMA) microspheres was 2.1 mg g−1. Reactive green HE‐4BD attachment significantly increased the HSA adsorption up to 221 mg g−1. The langmuir adsorption model was found to be applicable in interpreting HSA adsorption by reactive green HE‐4BD attached microspheres. Significant amount of the adsorbed HSA (up to 92%) was eluted in 1 hr in the elution medium containing 1.0‐M NaCl. To determine the effects of adsorption conditions on possible conformational changes of HSA structure, fluorescence spectrophotometry was employed. We resulted that poly(St‐HEMA) dye‐affinity microspheres can be applied for HSA adsorption without causing any significant conformational changes. Repeated adsorption/elution processes showed that these dye‐attached monodisperse microspheres are suitable for HSA adsorption.

Effects of Adsorption Conditions on Kinetics of Protein Adsorption and Conformational Changes at Ultrafine Silica Particles

Human hemoglobin (HHb, a very soft protein) was adsorbed on ultrafine silica particles. Effects of various adsorption conditions on the kinetics of adsorption and conformational changes in HHb were studied. The conformational changes in HHb upon adsorption were monitored by both circular dichroism and absorbance spectra. The adsorption rates were measured using an aqueous two-phase system to very quickly separate the ultrafine silica particles. The rate of conformational changes upon adsorption was significantly affected by pH, ionic strength, and temperature. At high temperature, large conformational changes in HHb were accomplished soon after attachment to the surfaces. On the other hand, at low temperature and/or high ionic strength, the extent of conformational changes accompanying attachment to the surfaces was small, and slow conformational changes occurred after adsorption. Moreover, the rate of conformational changes upon adsorption decreased with increasing adsorption. Renaturation of HHb during desorption was also measured and found to be accomplished within a short time. The percentage of desorbed HHb decreased with increasing adsorption time, because the extent of conformational changes in adsorbed HHb increased. Based on these results, the general tendency of the kinetics of conformational changes in proteins upon adsorption on the solid surfaces are discussed.

The growth of two togaviruses in cultured mosquito and vertebrate cells.

SUMMARY In cultured Aedes albopictus cells at 28 °C, Semliki Forest virus (SFV, an alphavirus; Wildy, 1971) shows a latent period, growth rate and yield per cell similar to that obtained with the same virus in three vertebrate cell lines at 37 °C. SFV and the flavivirus Kunjin both grow more slowly and to lower titre in A. aegypti cells (Peleg, 1968) than in A. albopictus cells. Kunjin grows more slowly than SFV in both mosquito and vertebrate cell lines. No replication of either virus occurred in another A. aegypti cell line (Grace, 1966). The effect of adsorption conditions on the percentage of Aedes albopictus cells infected by SFV is examined. In both mosquito and Vero cells the temperature giving the shortest latent period of SFV growth is close to the optimal temperature for cell growth. No c.p.e. were visible in infected mosquito cells; this contrasts with the invariant destruction of vertebrate cells.