Showing papers on "Langmuir published in 2009"
TL;DR: Distinctive adsorption equilibria and kinetic models are of extensive use in explaining the biosorption of heavy metals, denoting the need to highlight and summarize their essential issues, which is the main purpose of this paper.
1,471 citations
TL;DR: In this paper, it was shown that for a dilute solution of charged adsorbates or for a solution of uncharged adsorates at any concentration, the thermodynamic equilibrium constant of adsorption would be reasonably approximated by the Langmuir equilibrium constant.
Abstract: In the study of adsorption, changes in free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) have been most frequently calculated from the Langmuir equilibrium constant. In a strict theoretical sense, the Langmuir equilibrium constant with units of liters per mole and the thermodynamic equilibrium constant without units are not the same. Moreover, the equilibrium constants for thermodynamic calculation have also been derived in different ways in the literature, for example, Frumkin isotherm, Flory−Huggins isotherm, distribution constants, and so on. As a result, values of ΔG°, ΔH°, and ΔS° of adsorption reported in the literature are very confusing. This study shows that for a dilute solution of charged adsorbates or for a solution of uncharged adsorbates at any concentration, the thermodynamic equilibrium constant of adsorption would be reasonably approximated by the Langmuir equilibrium constant, and thus the use of the Langmuir equilibrium constant for calculation of ΔG° and subsequent determination of ...
900 citations
TL;DR: In this article, the adsorption capability of clay minerals of bentonite, kaolin, and zeolite to remove Congo red from aqueous solution was evaluated using pseudo-first order and second order kinetic equations, and Freundlich and Langmuir models.
841 citations
TL;DR: The results indicated that the garlic peel could be an alternative for more costly adsorbents used for dye removal, and was fitted well with the Freundlich isotherm.
690 citations
TL;DR: In this article, the inhibition ability of benzimidazole and its derivatives against the corrosion of mild steel in 1M HCl solution was studied, and the change of impedance parameters observed by variation of inhibitors concentration within the range of 50-250ppm was an indication of their adsorption.
633 citations
TL;DR: The present investigation assesses the applicability of waste materials--bottom ash and deoiled soya--for the removal of the colorant Congo red from wastewaters by evaluating the adsorption characteristics and dye removal efficiency of adsorbents.
624 citations
TL;DR: Adsorption, as an efficient process to remove contaminants from water was chosen; in particular with bentonite and activated carbon as adsorbents, with several possible mechanisms for these adsorption systems elaborated further.
619 citations
01 Apr 2009
TL;DR: The results indicate that montmorillonite clay adsorbs MB efficiently and could be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes.
Abstract: In this study, montmorillonite clay (MC) has been utilized as the adsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solution by the batch adsorption technique under different conditions of initial dye concentration, adsorbent concentration, contact time, solution pH, and temperature. Attempts were made to fit the isothermal data using Langmuir and Freundlich equations. The experimental results have demonstrated that the equilibrium data are fitted well by a Langmuir isotherm equation. Thermodynamic parameters such as the changes in enthalpy, entropy, and Gibbs' free energy were determined, showing adsorption to be an endothermic yet spontaneous process. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were considered to evaluate the rate parameters. The experimental data fitted the pseudo-second-order kinetic model, with an activation energy of +28.5 kJ mol(-1). The results indicate that MC adsorbs MB efficiently and could be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes.
617 citations
TL;DR: Nano-sized zero-valent iron was supported onto activated carbon (NZVI/AC) by impregnating carbon with ferrous sulfate followed by chemical reduction with NaBH(4) and ferrous iron (Fe(2+)) was found to suppress arsenite adsorption.
612 citations
TL;DR: The amino-functionalized magnetic nano-adsorbent shows a quite good capability for the rapid and efficient adsorption of metal cations and anions from aqueous solutions via the chelation or ion exchange mechanisms.
546 citations
TL;DR: The biomass used in this work proved to be effective materials for the treatment of chromium bearing aqueous solutions and the pseudo-first-order kinetic model adequately describe the kinetic data in comparison to second-order model.
TL;DR: In this article, the adsorption behavior of natural zeolite (clinoptilolite) has been studied in order to determine its applicability in treating acid mine drainage.
TL;DR: Performance of Dowex HCR S/S cation exchange resin was evaluated for removal of nickel and zinc from aqueous solutions and it was determined that removal of Ni (2+) and Zn(2+) was well-fitted by second-order reaction kinetic.
TL;DR: The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature.
TL;DR: In this paper, the application for the removal of Ni, Cd, and Pb(II) ions from aqueous solution by using mesoporous silica materials was investigated.
TL;DR: Spent tea leaves, being waste, have the potential to be used as a low-cost adsorbent for the removal of methylene blue from aqueous solutions.
TL;DR: In this paper, bottom ash and deoiled soya were used for removal and recovery of hazardous phenol red dye from wastewaters, and the results showed that the column regeneration characteristic has been also investigated and recovery percentage greater than 90% was obtained for both adsorbents by utilizing acidic eluent.
TL;DR: The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorptive mechanism and not involving a mass transfer in solution.
TL;DR: Fundamental results demonstrate that the montmorillonite-supported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of hexavalent chromium from aqueous solution.
TL;DR: The adsorption of dye on neem sawdust was found to follow a gradual process and the dimensionless factor, R(L) of the malachite green, neemsawdust isotherm revealed that the adsorptive process is favourable in nature.
TL;DR: In this paper, the feasibility of using waste iron hydroxide-eggshell as an adsorbent for the removal of phosphate under different experimental conditions was explored and the results showed that the sorption capacity increases with an increase in solution temperature from 20 to 45 C at the initial phosphate solution concentration.
TL;DR: The correlation coefficients and the normalized standard deviation Deltaq (%) were determined showing globally, that the recently derived fractal kinetic equation could best describe the adsorption kinetics for the adsorbates tested here, indicating a complex Adsorption mechanism.
TL;DR: In this article, the acid corrosion inhibition process of mild steel in 1-M HCl by 1-butyl-3-methylimidazolium chlorides (BMIC) and 1- butyl- 3methyloridazolate hydrogen sulfate ([BMIM]HSO4) has been investigated using electrochemical impedance, potentiodynamic polarization and weight loss measurements.
TL;DR: In this paper, a low-cost adsorbent is developed from the naturally and abundantly available sawdust which is biodegradable, and the maximum adsorption of Cr(VI) on sawdust is obtained at an initial pH value of 1.
TL;DR: The ability of activated alumina as synthetic adsorbent was investigated for adsorptive removal of Cd (II) and Pb(II) ions from aqueous solutions and showed the suitability ofactivated alumina in waste water treatment plant operation.
TL;DR: In this paper, the effect of contact time at different temperatures and initial concentration were fitted to pseudo-second-order kinetic model to obtain the relative parameters, and error analysis was conducted to find whether linear method or nonlinear method was better to predict the experimental results.
TL;DR: The apparent temperature independence and the strong pH dependence of the amount of metal ions adsorbed along with moderate mean free energies of biosorption altogether indicate that bios orption of Cd(2+) and Cu(2+ by wheat straw might follow a chemisorption mechanism.
TL;DR: Overall, the study demonstrated that MWCNTs can effectively remove Cr(VI) from aqueous solution under a wide range of experimental conditions, without significant Cr(III) release.
TL;DR: The present study shows that the coniferous pinus bark powder (CPBP) can be used as a potential adsorbent for the removal of crystal violet (basic dye) from aqueous solutions.
TL;DR: Adsorption of IC on RHA was favorably influenced by an increase in the temperature of the operation, and the positive values of the change in entropy and heat of adsorption and the negative value of change in Gibbs free energy indicate feasible and spontaneous adsorbent dose on to RHA.