Showing papers on "Langmuir published in 2002"
TL;DR: Based on the adsorption capacity, it was shown that banana peel was more effective than orange peel and intraparticle diffusion of dyes within the particle was identified to be rate limiting.
1,534 citations
TL;DR: In this paper, the adsorption of Congo Red by coir pith carbon was carried out by varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature.
1,357 citations
TL;DR: Sugar beet pulp generated by sugar-refining factories has been shown to be an effective adsorbent for the removal of heavy metals from aqueous solutions and Ion exchange with Ca2+ ions neutralizing the carboxyl groups of the polysaccharide was found to be the predominant mechanism.
Abstract: Sugar beet pulp generated by sugar-refining factories has been shown to be an effective adsorbent for the removal of heavy metals from aqueous solutions. The structural components related to the metallic adsorption being determined, batch adsorption studies were performed for several metal ions, namely, Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ cations. Two simple kinetic models, that is, pseudo-first- and pseudo-second-order, were tested to investigate the adsorption mechanisms. The kinetic parameters of the models were calculated and discussed. For an 8 x 10(-4) M initial metal concentration, the initial sorption rates (v0) ranged from 0.063 mmol x g(-1) x min(-1) for Pb2+ to 0.275 mmol x g(-1) x min(-1) for Ni2+ ions, in the order Ni2+ > Cd2+ > Zn2+ > Cu2+ > Pb2+. The equilibrium data fitted well with the Langmuir and Freundlich models and showed the following affinity order of the material: Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+. The metal removal was strongly dependent on pH and, to a lesser extent, ionic strength. Ion exchange with Ca2+ ions neutralizing the carboxyl groups of the polysaccharide was found to be the predominant mechanism, added with complexation for Pb2+, Cu2+, and Zn2+ metals.
1,147 citations
TL;DR: Activated carbon derived from bagasse, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing heavy metals from wastewater and it was concluded that the adsorption occurs through a film diffusion mechanism at low as well as at higher concentrations.
1,122 citations
TL;DR: In this article, the adsorption of Cu(II) ions onto chitosan and cross-linked chittosan beads has been investigated and the results showed that the results correlated well with the Langmuir isotherm equation.
Abstract: The adsorption of Cu(II) ions onto chitosan and cross-linked chitosan beads has been investigated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to obtain sorbents that are insoluble in aqueous acidic and basic solution. Batch adsorption experiments were carried out as a function of pH, agitation period, agitation rate and concentration of Cu(II) ions. A pH of 6.0 was found to be a optimum for Cu(II) adsorption on chitosan and cross-linked chitosan beads. Isotherm studies indicate Cu(II) can be effectively removed by chitosan and cross-linked chitosan beads. Adsorption isothermal data could be well interpreted by the Langmuir equation. Langmuir constants have been determined for chitosan and cross-linked chitosan beads. The experimental data of the adsorption equilibrium from Cu(II) solution correlated well with the Langmuir isotherm equation. The uptakes of Cu(II) ions on chitosan beads were 80.71 mg Cu(II)/g chitosan, on chitosan-GLA beads were 59.67 mg Cu(II)/g chitosan-GLA, on chitosan-ECH beads were 62.47 mg Cu(II)/g chitosan-ECH and on chitosan-EGDE beads were 45.94 mg Cu(II)/g chitosan-EGDE. The Cu(II) ions can be removed from the chitosan and cross-linked chitosan beads rapidly by treatment with an aqueous EDTA solution and at the same time the chitosan and cross-linked chitosan beads can be regenerated and also can be used again to adsorb heavy metal ions.
898 citations
TL;DR: In this article, the removal of poisonous Cr(VI) from industrial wastewater by different low-cost abundant adsorbents was investigated, including wool, olive cake, sawdust, pine needles, almond shells, cactus leaves and charcoal were used at different adsorbent/metal ion ratios.
884 citations
TL;DR: In this paper, methylene blue was adsorbed on kaolin from a local deposit and the adsorption data could be fitted by the Freundlich and Langmuir equations.
757 citations
TL;DR: In this article, the authors show that carbon nanotubes (CTNs) show exceptional adsorption capability and high adorption efficiency for lead removal from water and suggest that CNTs can be good Pb2+ adsorbers and have great potential applications in environmental protection.
647 citations
TL;DR: In this article, a batch system with respect to temperature and initial metal ion concentration was studied and the activation energy of biosorption (E A ) was determined as 25.92 kJ mole −1 using the Arrhenius equation.
640 citations
TL;DR: The experimental data fitted well to the second-order kinetic model, which indicates that the chemical sorption is the rate-limiting step, instead of mass transfer, in the reactive dye adsorption system.
625 citations
TL;DR: The Dubinin-Kaganer-Radushkevick model was adopted to describe the single-solute sorption isotherms and the kinetics of metal ions sorption was examined and the pseudo-first-order rate constant was finally evaluated.
TL;DR: In this article, 3,5-bis(4-methylthiophenyl)-4H-1,2,4-triazole (4-MTHT) has been studied for corrosion inhibition of mild steel in 1 M HCl and 0.5 M sulphuric acid (H 2 SO 4 ).
TL;DR: A fundamental investigation on the removal of cadmium ions from aqueous solutions by chitin was conducted in batch conditions and indicated that the Langmuir model gave a better fit to the experimental data than the Freundlich equation.
TL;DR: In this article, a new sorbent system for removing heavy metal ions, such as Zn, Cu, and Pb, from aqueous solutions has been investigated and the experimental results were fitted to the Langmuir, Freundlich and Redlich/Peterson isotherms to obtain the characteristic parameters of each model.
TL;DR: In this paper, the effect of the adsorbent concentration on the adsorption was studied and the dependence of the adaption of fluoride on the pH of the solution has been studied to achieve the optimum pH-value.
TL;DR: The error function method provided the best parameters for the isotherm equations in this system and is demonstrated for error comparison purposes.
TL;DR: The lead uptake capacity of Sargassum biomass was constantly retained (98%) and no significant biomass damage took place after 10 sorption-desorption cycles, and the applicability of the Langmuir and Freundlich models for the different biosorbents was tested.
TL;DR: The bagasse fly ash, obtained from the local sugar industry, has been used as inexpensive and effective adsorbent for the removal of lindane and malathion from wastewater and the adsorption was found to be exothermic in nature.
TL;DR: Raw bagasse and fly ash, the waste generated in sugar mills and boilers respectively have been used as low-cost potential adsorbents for the removal of chromium and nickel from an aqueous solution to study the kinetics and extent of adsorption at equilibrium.
TL;DR: In this paper, the removal of fluoride from aqueous solution by using the original and activated red mud forms was studied in batch equilibration technique and the effect of pH, adsorbent dose and contact time on the adsorption were investigated.
TL;DR: The studies showed that these cation exchange resins can be used as efficient adsorbent material for the removal of Co(II) from aqueous solutions.
TL;DR: The FTIR spectroscopic analysis of the native, Cr bound and the other types of chemically modified biomass indicated the involvement of amino groups of Rhizopus cell wall in Cr binding, which improved the biosorption efficiency to exceptionally high levels.
TL;DR: In this article, the effect of contact time, pH, initial metal concentration and fly ash origin on the adsorption process at 20 +/-2 degrees C were studied and it was found that an equilibrium time of 2h was required for the adsorbption of Ni(II), Cu(II) and Zn(II).
TL;DR: The 2-mercaptobenzimidazole loaded natural clay was prepared for the removal of Hg(II) from aqueous media and it was found that the values of isosteric heat of adsorption were varied with surface loading.
TL;DR: It was seen that the mono-component adsorption equilibrium data fitted very well to both the Mono-component Langmuir and Freundlich adsorbption models for both the components and the pH values studied while the multi-component Freundlic adsorptive model adequately predicted theMulti- component adsorbent equilibrium data at moderate ranges of initial mixture concentrations forboth the studied pH values.
TL;DR: In this article, a mixture of 3-mercaptopropyltrimethoxysilane (MPTMS) and TEOS was used to produce spherical mercury ion adsorbents with uniform mesopore channels.
Abstract: Microspherical mercury ion adsorbents with uniform mesopore channels were prepared by fluoride-catalyzed surfactant-directed co-condensation of tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) using mildly acidic nonionic surfactant solutions. Using batch adsorption methods, mercury(II) adsorption isotherms and kinetic uptake profiles for these adsorbents were obtained. The mercury(II) isotherms of the microspheres with low thiol group loadings did not fit the Langmuir expression and were indicative of weak interactions between the mercury(II) ions and the adsorbents. With increasing thiol group loading, the isotherms approached type-I in appearance, indicating improved binding energetics of the ions with the adsorbents. The adsorption kinetics of the adsorbents suggested that the uptake of mercury ions by the microspheres was rather slow, with diffusion coefficients ranging between 10-14 and 10-15 m2 s-1. The coefficients were found to increase as a function of the thiol group densit...
TL;DR: In this paper, the adsorption of fluoride ion in aqueous solution by using alumina was studied and the experimental results indicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH was found to be in the range of 5 to 7.
Abstract: The adsorption of fluoride ion in aqueous solution by using alumina was studied in this research. The experimental resultsindicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH wasfound to be in the range of 5 to 7. For neutral and acidic solutions, the adsorption capacities of fluoride by alumina wasinterfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well describe the equilibrium behaviorsof the adsorption processes. The experimentally determined lowvalues of activation energy indicate nonspecific adsorption isthe predominant mechanism. The surface reaction-limiting batchkinetic model can adequately describe the removal behaviors offluoride ion by alumina adsorption in the batch system.
TL;DR: The adsorption isotherm of p-nitrophenol onto granular activated carbon in 25 degrees C aqueous solution was experimentally determined by batch tests and a correlation was proposed to predict the volumetric mass-transfer coefficient in the liquid phase successfully.
TL;DR: Thermodynamical parameters revealed that the adsorption of Ni(II) is exothermic in nature.
TL;DR: Pelletized peanut hulls could gain use as a low-cost, once-through biomass filter medium for copper-bearing waste streams due to their demonstrated ability for Cu(II) uptake and favorable structural characteristics.