Showing papers on "Freundlich equation published in 2001"
TL;DR: In this article, the kinetics and mechanism of methylene blue adsorption on commercial activated carbon and indigenously prepared activated carbons from bamboo dust, coconut shell, groundnut shell, rice husk, and straw, have been studied.
1,762 citations
TL;DR: Red mud, an aluminium industry waste, has been converted into an inexpensive and efficient adsorbent and used for the removal of lead and chromium from aqueous solutions and the data follow both Freundlich and Langmuir models.
743 citations
TL;DR: In this paper, a batch system with respect to the temperature, initial pH, and initial metal ion concentration was studied, where Freundlich and Langmuir isotherm models were tried to represent the equilibrium data of cadmium(II) biosorption depending on temperature.
647 citations
TL;DR: It was found that more than 95% removal was achieved under optimal conditions and ion exchange resins investigated showed reversible uptake of chromium and, thus, have good application potential for the removal/recovery of Chromium from aqueous solutions.
641 citations
TL;DR: The effectiveness of orange peel in adsorbing Acid violet 17 from aqueous solutions has been studied as a function of agitation time, adsorbent dosage, initial dye concentration and pH.
575 citations
TL;DR: The adsorption of Cr(VI) was pH dependent and maximum removal was observed in the acidic pH range and was calculated from the Langmuir isotherm.
547 citations
TL;DR: Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation of basic dyes from aqueous solution onto granular activated carbon and natural zeolite.
544 citations
TL;DR: The agreement among the models and experimental data indicated that the adsorption and diffusion of arsenate and arsenite can be simulated by the proposed model.
534 citations
TL;DR: The ability of bentonite clay to remove Pb(II) from aqueous solutions and from nitric acid, hydrochloric acid and perchloric Acid solutions has been studied at different optimized conditions of concentrations, amount of adsorbent, temperature, concentration of electrolyte and pH.
519 citations
TL;DR: In this article, the adsorption capacity (Q 0 ) calculated from Langmuir isotherm was 62.5 mg Ni(II) g −1 at initial pH of 5.0 at 30°C for the particle size 250-500 μm.
417 citations
TL;DR: Attention was focused on the adsorption of rhodamine-B and acid violet by coir pith carbon using a variety of parameters such as agitation time, dye concentration, adsorbent dose and pH.
TL;DR: The results showed that the equilibrium data for all the mono-chlorinated phenol-sorbent systems fitted the Redlich-Peterson model best within the concentration range studied.
TL;DR: The study aimed to quantify the Cr sorption ability of powdered biomass of Rhizopus nigricans at the best operating conditions and the adsorption rate constant values (Kad) were calculated and the sorption was found to be higher at lower concentration of metal ion.
TL;DR: In this paper, the ability of crab shell to remove heavy metals from aqueous solution was evaluated by comparing with that of several sorbents (cation exchange resin, zeolite, granular activated carbon, powdered activated carbon).
TL;DR: The results showed that both the dyes uptake processes followed the second-order rate expression and the equilibrium data fitted very well to both the Freundlich and Langmuir adsorption models.
TL;DR: The Langmuir model appears to fit the isotherm data better than the Freundlich model and the physical properties of these adsorbents were consistent with the parameters obtained from theIsotherm equations.
TL;DR: The results indicate the potentially practical value of this method in industries and also provide strong evidence to support the adsorption mechanism proposed.
TL;DR: In this article, the adsorption of phenol and chlorophenols on four commercial granular activated carbons (GACs) was investigated by batch experiment to correlate with the structure of activated carbon.
TL;DR: In this article, the adsorption of water-soluble dye reactive brilliant blue KN-R onto the functionalized resin NKY has been dynamically and thermodynamically investigated, and the rate constant is obtained from the first-order expression log( Q e − Q )=log Q e−k ad t /2.303.
TL;DR: It is concluded that the adsorption trends of SNBs on K-SAz-1 can be explained without recourse to hypothetical electron donor-acceptor complexes.
Abstract: To more fully understand the potential for transport of nitroaromatic compounds in soils and subsoils, the adsorption of a series of para- and meta-substituted nitrobenzenes (SNBs) by K-smectite clay was measured. Adsorption isotherms were fit to the Freundlich equation, and the resultant Freundlich adsorption coefficients (log(Kf)) were positively correlated with the Hammett substituent constant (r2 = 0.80). This relationship and a positive reaction constant (ρ = 1.15) indicate that the adsorption reaction is favored by electron-withdrawing substituents. These results are consistent with an electron donor (smectite)−acceptor (substituted nitrobenzene) mechanism offered previously. However, quantum calculations did not reveal any systematic relationship between the Hammett constant and the electron density on the aromatic ring, which would explain a donor−acceptor relationship. Rather, electron density donated by a second substituent on nitrobenzene appears to be appropriated by the nitro group leaving ri...
TL;DR: In this paper, a survey of systems from the literature revealing that the Freundlich isotherm gives a good mathematical approximation of the binding characteristics for non-covalently imprinted polymers.
TL;DR: In this paper, the removal of acid dyes (acid violet and acid brilliant blue) and basic dyes using coir pith as adsorbent was carried out using "waste" coirpith as a substitute.
Abstract: Removal of acid dyes (acid violet and acid brilliant blue) and basic dyes (rhodamine B and methylene blue) was carried out using ‘waste’ coir pith as adsorbent. Parameters like agitation time, adsorbent dosage and pH effect were studied. Adsorption followed the first-order rate expression. The equilibrium data fit well with both Langmuir and Freundlich models of adsorption. Desorption experiments confirmed that major mode of adsorption is ion-exchange for the dyes acid brilliant blue and methylene blue whereas acid violet showed mainly physical adsorption. Chemisorption seems to be the major mode of adsorption for rhodamine B.
TL;DR: In this article, a detailed comparison between experimental measurements and the excess adsorption predicted by the Ono−Kondo lattice model was performed for high-pressure adsorptio...
Abstract: We present a detailed comparison between experimental adsorption measurements and the excess adsorption predicted by the Ono−Kondo lattice model. The study was performed for high-pressure adsorptio...
TL;DR: In this article, a heavily-weathered Tertiary soil from Xinzhou, China was used as a sorbent for defluoridation of high-fluoride drinking water.
TL;DR: In this article, 19 samples of calcareous soil and subsurface limestone bedrock were collected from the southern Everglades wetland, pineland, and nearby farmland, and the results showed that the sorption in these soils fit the linear isotherm.
Abstract: The understanding of P sorption and desorption by soils is important for safeguarding water quality and for fertilizer management. Little is known about the P-sorption characteristics of the calcareous soils and limestone bedrocks in southern Florida. In this study, 19 samples of calcareous soil and subsurface limestone bedrock were collected from the southern Everglades wetland, pineland, and nearby farmland. At very low P concentrations. P sorption in these soils fit the linear isotherm. The equilibrium P concentration at zero-net P sorption (EPCo) of soils correlated positively with P saturation. Phosphorus-sorption data of soils at medium P concentrations fit the Freundlich and Langmuir equations up to a point at high P concentrations where the slope of the isotherm changed abruptly. In bedrock samples the sorption-isotherm-inflection point, which is caused by P precipitation, occurred at much lower solution P concentrations than in the case of soils (4-18 vs. 400-600 mg mL -1 ). Also bedrock samples had significantly lower Freundlich values, K f, Than soils. The sorption of P in soils occurred at relatively low solution P concentrations (as indicated by Freundlich value, K f ), and appears to be caused by strong affinity of the noncarbonate clay, while the P sorption at relatively high solution concentrations (as indicted by Langmuir maximum sorption, S max ) appears to be caused by the affinities of both the noncarbonate clay and carbonate clay. Phosphorus-sorption values (P sorption ) estimated from the one-point isotherm were comparable with the S max values calculated from the Langmuir isotherm. Phosphorus saturation and the P-retention capacities (S max of P sorption ) were correlated strongly to the percentage of P desorption.
TL;DR: Since the biosorption capacities were relatively high for both entrapped live and dead forms, those fungal forms could be considered as suitable biosorbents for the removal of cadmium in wastewater-treatment systems.
TL;DR: In this article, the removal of acid dyes from a single component solution by adsorption on activated carbon and bone char has been investigated using Langmuir and Freundlich isotherm analyses.
TL;DR: In this article, the surface charge of commercial nanofiltration (NF) membranes through streaming potential measurements was determined by using the Gouy-Chapman equation, and the results showed a logarithmic relationship between the membrane surface charge and the feed solution concentration.
TL;DR: Sorption isotherms of 13 apolar liquids and solids and polar solids used to evaluate a polymer- based model for natural organic matter show linear-scale inflection consistent with the presence of flexible (deformable) porosity as predicted by the glassy polymer-based Extended Dual-Mode Model (EDMM).
Abstract: Sorption isotherms of 13 apolar liquids and solids and polar solidssix in unprecedented detailare used to evaluate a polymer-based model for natural organic matter. While all isotherms are nonlinear, the “running” Freundlich exponent n varies markedly with concentration. The isotherms show linear-scale inflection consistent with the presence of flexible (deformable) porosity as predicted by the glassy polymer-based Extended Dual-Mode Model (EDMM). The EDMM assumes dissolution and hole-filling domains in the organic solid, with provision for sorbate-caused plasticization of the solid and “melting” of the holes. Features of the EDMM are illustrated for chlorinated benzenes in poly(vinyl chloride). The solutes fall into categories of “hard” (aliphatics and 2,4-dichlorophenol) and “soft” (chlorinated benzenes, 2-chloronitrobenzene) according to their ability to plasticize organic matter. Comparison of domain coefficients at infinite dilution reveals that organic solutes have a modestly greater affinity for ho...
TL;DR: The characteristics of polyvinyl alcohol (PVA) and calcium alginate as immobilization matrices were examined and compared for the uptake of gold by a fungal biomass and revealed a much more rapid uptake phenomenon by the former.