Showing papers on "Freundlich equation published in 2003"
TL;DR: In this paper, an acid dye, acid yellow 36, was used as the adsorbate for the removal of acid dyes from aqueous solution and the results showed that a pH value of 3 is favorable for the adsorption of acid dye.
926 citations
TL;DR: The adsorption mechanism is shown to be the electrostatic interactions between the dye and chitosan beads and the dynamical data fit well with the second-order kinetic model, except for the dry beads fitting better with the first-order model.
803 citations
TL;DR: The thermodynamics of copper ion/tree fern system indicates spontaneous and endothermic nature of the process and various thermodynamic parameters, such as Delta G(0), Delta H(0) and Delta S(0, have been calculated.
646 citations
TL;DR: In this article, the suitability of granular activated carbon for granular carbon production is not determined by material specific (elemental composition) but type-specific features, such as physical, chemical, surface and adsorption properties.
615 citations
TL;DR: The study indicated that electrostatic interactions play an important role in the adsorption of dyes onto diatomite and a model of the advertisersorption mechanism of methylene blue onto di Atomite is proposed.
609 citations
TL;DR: The amount of adsorption increased with increasing pH and reached a plateau at pH > 7, which was confirmed by the variations of zeta potentials.
561 citations
TL;DR: It was found that the intraparticle diffusion model could be used to well describe the adsorption of two basic dyes on modified peat-resin particle and the kinetics experiment indicated that initial dye concentrations, particle dose and particle size could affect the adsOrption processes ofbasic dyes.
537 citations
TL;DR: A comparison of the results of the present investigation with those reported in the literature showed that chitosan coated on alumina exhibits greater adsorption capacity for chromium(VI), while the ultimate capacity obtained from the Langmuir model is 153.85 mg/g chitan.
Abstract: A new composite chitosan biosorbent was prepared by coating chitosan, a glucosamine biopolymer, onto ceramic alumina. The composite bioadsorbent was characterized by high-temperature pyrolysis, porosimetry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Batch isothermal equilibrium and continuous column adsorption experiments were conducted at 25 degrees C to evaluate the biosorbent for the removal of hexavalent chromium from synthetic as well as field samples obtained from chrome plating facilities. The effect of pH, sulfate, and chloride ion on adsorption was also investigated. The biosorbent loaded with Cr(VI) was regenerated using 0.1 M sodium hydroxide solution. A comparison of the results of the present investigation with those reported in the literature showed that chitosan coated on alumina exhibits greater adsorption capacity for chromium(VI). Further, experimental equilibrium data were fitted to Langmuir and Freundlich adsorption isotherms, and values of the parameters of the isotherms are reported. The ultimate capacity obtained from the Langmuir model is 153.85 mg/g chitosan.
484 citations
TL;DR: Ion exchange resins 1200H, 1500H and IRN97H show a remarkable increase in sorption capacity for chromium, compared to other adsorbents and can be used for the efficient removal of chromium from water and wastewater.
464 citations
TL;DR: In this article, activated carbon prepared from coirpith, an agricultural solid waste byproduct, has been used for the adsorption of Cd(II) from aqueous solution.
447 citations
TL;DR: The thermodynamic data indicate that Co(II) adsorption onto sepiolite is entropically driven and characterized by physical adsOrption.
TL;DR: In this article, the authors investigated the Cr(VI) biosorption potential of immobilized Rhizopus nigricans and to screen a variety of non-toxic desorbing agents, in order to find out possible application in multiple sorption-desorption cycles.
TL;DR: The experimental result inferred that chelation ion exchange is one of the major adsorption mechanisms for binding metal ions to the maple sawdust.
TL;DR: It was shown that the first-order model could best describe the sorption kinetics of hexavalent chromium removal by calcined Mg-Al-CO(3) hydrotalcite, and was evaluated to fit the experimental data.
TL;DR: In this article, a process of competitive biosorption of Cr(VI) and Fe(III) ions on Streptococcus equisimilis, Saccharomyces cerevisiae and Aspergillus niger is described and compared to single metal ion adsorption in solution.
TL;DR: The adsorption of basic red was found to be endothermic and first-order in nature and the effect of pH, temperature, initial absorbate concentration, particle size of the adsorbent, and solid-to-liquid ratio was delineated.
TL;DR: Kudzu was found to be an effective adsorbent for basic dye colour removal; though its capacity for colour removal was not as high as an activated carbon, the potential appeared to exist to use it as an alternative to activated carbon where carbon cost was prohibitive.
TL;DR: In this paper, the experimental equilibrium data for the single component dye−chitosan systems have been analyzed using the linearized forms of Langmuir, Freundlich, and Redlich−Peterson isotherms.
Abstract: The ability of chitosan as an adsorbent for the removal of acid dyestuff, namely, acid green 25, acid orange 10, acid orange 12, acid red 18, and acid red 73, from aqueous solution has been studied. The experimental equilibrium data for the single component dye−chitosan systems have been analyzed using the linearized forms of Langmuir, Freundlich, and Redlich−Peterson isotherms. The Langmuir isotherm was found to provide the best theoretical correlation of the experimental data for the adsorption of all five acid dyes. On the basis of the Langmuir analysis, the monolayer adsorption (saturation) capacities were determined to be 645.1, 922.9, 973.3, 693.2, and 728.2 mg of dye per gram of chitosan for acid green 25, acid orange 10, acid orange 12, acid red 18, and acid red 73, respectively. The differences in adsorption capacities may be due to the effect of molecular size and the number of sulfonate groups of each dye. The results demonstrated that monovalent and/or smaller dye molecules have superior adsor...
TL;DR: In this article, the adsorption equilibria and kinetics of three dyes and three phenols (phenol, 3-chlorophenol, and o-cresol) from aqueous solutions on such carbons were examined at 30°C.
TL;DR: An activated carbon was developed from coconut shell fibers, characterized and used for the removal of methylene blue (basic) and methyl orange (acidic) dyes from wastewater successfully.
Abstract: An activated carbon was developed from coconut shell fibers, characterized and used for the removal of methylene blue (basic) and methyl orange (acidic) dyes from wastewater successfully. Adsorption studies were carried out at different temperatures, particle size, pH, and adsorbent doses. The adsorption data are correlated with both Langmuir and Freundlich models. The results indicate that the Freundlich model fits the data better as compared to the Langmuir model in terms of regression coefficients. Isotherms have been used to obtain the thermodynamic parameters such as free energy, enthalpy, and entropy of adsorption. The kinetic studies were also conducted, and the adsorption of methylene blue and methyl orange follow the first-order rate equation. Various kinetic parameters such as the mass-transfer coefficient, effective diffusion coefficient, activation energy, and entropy of activation were evaluated to establish the mechanisms. It was concluded that methylene blue adsorption occurs through a film diffusion mechanism at low as well as at higher concentrations, while methyl orange adsorption occurs through film diffusion at low concentration and particle diffusion at high concentrations. The sorption capacity of the developed carbon is comparable to the other available adsorbents, and costwise it is quite cheaper.
TL;DR: The metal ions removal was lower at neutral and generally the initial adsorption rate was rapid and reached equilibrium after 10 min and the process of uptake obeys both Langmuir and Freundlich isotherms.
TL;DR: In this paper, a fine powder of Neem leaves was used to remove the dye Brilliant Green from aqueous solution, in a batch process with different concentrations of the dye and different adsorbent doses, at a range of pH values and temperature.
TL;DR: The objective of this paper was to examine the main aspects of a possible strategy for the removal of arsenates, employing P. chrysogenum biomass, and promising results were obtained in laboratory experiments.
TL;DR: It is confirmed that PAC treatment is feasible for >99% removal of three estrogenic compounds from raw drinking waters that may be at risk for containing such compounds, at least at initial concentration of 500 ng/l and higher.
TL;DR: The Langmuir model suggests that, in order to sustain a long-term P-removal in subsurface flow constructed reed beds, precipitation reactions of insoluble P-salts should be promoted.
TL;DR: It is hypothesized that the sorption of polycyclic aromatic hydrocarbons to natural sediments and soils should consider both absorption into a biogenic/diagenetic organic carbon (OC) fraction and adsorption onto a combustion-derived, black carbon (BC) fraction.
Abstract: We hypothesized that the sorption of polycyclic aromatic hydrocarbons (PAHs) to natural sediments and soils should consider both absorption into a biogenic/diagenetic organic carbon (OC) fraction and adsorption onto a combustion-derived, black carbon (BC) fraction. Here, two sets of literature data were reevaluated to illustrate that an OC absorbent and a BC adsorbent together can (1) account for sediment−pore-water distribution coefficients observed in the field that are greater than predicted by a simple focKoc partitioning model and (2) explain a group of nonlinear phenanthrene isotherms observed in the laboratory with a single value for the BC-normalized distribution coefficient (log KBC = 6.1 ± 0.04) and a Freundlich exponent (n ≈ 0.6 if log Koc = 4.0) that is strongly dependent on the Koc value selected.
TL;DR: F Fourier transform infrared spectra of Ce-Fe adsorbent before and after As(V) adsorption demonstrated that M-OH groups plays an important role for As(v) ions removal in the adsorptive mechanisms of Ce/O/H groups.
TL;DR: In this paper, the effect of initial dye concentrations, adsorbent particle size and concentration, and agitation speed on adsorption was investigated, and two simplified kinetics models, pseudo-first order and pseudo-second order, were tested to investigate the adaption mechanisms.
TL;DR: In this paper, a batch adsorption test was carried out to remove phenol from aqueous solution using the above-mentioned bentonites, and it was found that the amount of phenol removal was seriated in the following order: CTAB/Al-Bentonite>Al-bentonite >CTAB bentonite>thermal-treated bentonite >cyclohexane-treated bendonite>natural bentonite.
TL;DR: The sorption of lead ions from aqueous solution onto chitosan has been studied and error functions have been used to determine the alternative single component equilibrium isotherm parameters by non-linear regression due to the inherent bias in using the correlation coefficient from the linearization.