Showing papers on "Langmuir published in 2015"
TL;DR: In this paper, the simultaneous removal of Methylene blue (MB) and Safranin-O (SO), as most together hazardous dye in wastewater, from aqueous solution by ultra-sonic-assisted adsorption onto the developed adsorbent i.e. Fe3O4 NPs were synthesized, by using central composite design (CCD).
551 citations
TL;DR: It is concluded that rice husk and wood biochar have potential to adsorb NH4(+)-N from piggery manure anaerobic digestate slurry, and thus can be used as nutrient filters prior to discharge into water streams.
400 citations
TL;DR: In this paper, the Zeolitic imidazolate framework-8 (ZIF-8) nanosorbent was successfully synthesized via a facile method at room temperature.
389 citations
TL;DR: In this article, the authors used the Langmuir, Freundlich and Temkin isotherms to describe the behavior of equilibrium adsorption of the studied mercury ions.
Abstract: Nanocomposites of silica incorporated with carbon nanotubes (silica/CNT) and activated carbon (silica/AC) were synthesized and characterized by scanning electron microscopy (SEM), element mapping, energy dispersive X-ray spectroscopy (EDX), thermogravimetric analyzer (TGA) and Fourier transform infrared spectroscopy (FTIR). Silica/CNT and silica/AC were investigated for efficient removal of mercury ions from aqueous solutions. The adsorbents have been analyzed on the basis of adsorption capacity, reusability, and their application in packed columns. The effects of experimental parameters, like pH, contact time and initial concentrations on the adsorption of mercury ions, were optimized. The kinetic data for the adsorption process obeyed a pseudo-second-order kinetic model with R2 of 0.999. Fitting the data to an intraparticle diffusion model indicated that surface adsorption and intraparticle diffusion were concurrently operating. In addition, this study used the Langmuir, Freundlich and Temkin isotherms to describe the behaviour of equilibrium adsorption. The equilibrium adsorption of the studied mercury ions is best fitted using the Freundlich isotherm, with silica/CNT of higher capacity than silica/AC. The silica/CNT showed better performance than silica/AC indicating silica/CNT has better efficiency.
377 citations
TL;DR: Three isotherm models are employed, namely: Langmuir, Freundlich, and Dubinin-Radushkevich, to correlate four sets of experimental adsorption isotherms data, which were obtained by batch tests in lab and showed that non-linear LangmuIR model could fit the data better than others, with relatively higher r2 values and smaller S.E. errors.
Abstract: Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained by batch tests in lab. The linearized and non-linearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the correlation coefficient (r2) and standard errors (S.E.) for each parameter were used to evaluate the data. The modeling results showed that non-linear Langmuir model could fit the data better than others, with relatively higher r2 values and smaller S.E. The linear Langmuir model had the highest value of r2, however, the maximum adsorption capacities estimated from linear Langmuir model were deviated from the experimental data.
360 citations
TL;DR: In this article, a novel adsorbent, copper oxide nanoparticle loaded on activated carbon (CuO-NP-AC), was synthesized by a simple, low cost and efficient procedure.
343 citations
TL;DR: These magnetite nanospheres with hollow interiors successfully remediated Cr(6+) and Pb(2+) from water and can be used to isolate and regenerate the used adsorbent.
292 citations
TL;DR: In this article, the longan seed activated carbon (LSAC) was used as an adsorbent for Cr(VI) removal from aqueous solutions in batch adsorption experiments.
285 citations
TL;DR: Pine wood biochar was used as a 3-dimensional adsorbent to remove salicylic acid and ibuprofen from aqueous solutions as mentioned in this paper, and the results showed that the biochar can adsorb far more adsorbate compared to commercial activated carbons.
284 citations
TL;DR: In this paper, polyaniline grafted chitosan (PGC) was employed as an adsorbent for the removal of Pb(II) and Cd(II), respectively, from aqueous solution.
277 citations
TL;DR: In this paper, 1H-pyrrole-2,5-dione derivatives were synthesized and their inhibitive action against the corrosion of carbon steel in 1 M HCl solution were investigated at 308 K by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods.
TL;DR: Water-insoluble β-cyclodextrin-based electrospun fibers synthesized by electrospinining followed by thermal cross-linking exhibited high adsorption capacity for cationic dye methylene blue with good recyclability and potential applications in the dye wastewater treatment field were suggested.
Abstract: Water-insoluble β-cyclodextrin-based fibers were synthesized by electrospinining followed by thermal cross-linking. The fibers were characterized by field-emission scanning electron microscopic (FE-SEM) and Fourier transformed infrared spectrometer (FT-IR). The highly insoluble fraction obtained from different pH values (3-11) indicates successful cross-linking reactions and their usability in aqueous solution. After the cross-linking reaction, the fibers' tensile strength increases significantly and the BET surface area is 19.49 m(2)/g. The cross-linked fibers exhibited high adsorption capacity for cationic dye methylene blue (MB) with good recyclability. The adsorption performance can be fitted well with pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacity is 826.45 mg/g according to Langmuir fitting. Due to electrostatic repulsion, the fibers show weak adsorption toward negatively charged anionic dye methyl orange (MO). On the basis of the selective adsorption, the fiber membrane can separate the MB/MO mixture solution by dynamic filtration at a high flow rate of 150 mL/min. The fibers can maintain good fibrous morphology and high separation efficiency even after five filtration-regeneration cycles. The obtained results suggested potential applications of β-cyclodextrin-based electrospun fibers in the dye wastewater treatment field.
TL;DR: The supramolecular isomerism of [ Zn(eim)2] is thoroughly studied using a rapid solution mixing reaction of [Zn(NH3)4](OH)2 and Heim, which enables MAF-6 with high crystallinity, purity, and thermal/chemical stabilities to be synthesized in large quantity.
Abstract: Porous materials combining high hydrophobicity, large surface area, as well as large and uniform pore size are very useful but rare. The nanoporous zeolitic metal azolate framework, RHO-[Zn(eim)2] (MAF-6, Heim = 2-ethylimidazole), is an attractive candidate but thought to be unobtainable/unstable. In this work, the supramolecular isomerism of [Zn(eim)2] is thoroughly studied using a rapid solution mixing reaction of [Zn(NH3)4](OH)2 and Heim, which enables MAF-6 with high crystallinity, purity, and thermal/chemical stabilities to be synthesized in large quantity. Gas and vapor adsorption isotherms, gas chromatography, and water contact angle measurements, as well as transient breakthrough and molecular dynamics simulations show that MAF-6 exhibits large surface area (langmuir surface area 1695 m2 g–1), pore volume (0.61 cm3 g–1), pore size (d = 18.4 A), and aperture size (d = 7.6 A) with high hydrophobicity on both the internal pore and external crystal surfaces. It can barely adsorb water or be wetted by ...
TL;DR: In this paper, the byproduct (bio-char) from liquefaction of rice husk with water, water/ethanol (V/V, 5:5), or ethanol as the solvent at 260-340°C was characterized in terms of its elemental composition, thermogravimetric characteristics, surface area and pore size distribution, morphology, and oxygen-containing functional group composition.
TL;DR: The usefulness of ultrasonic power as a dispersion and mixing tool to accelerate the adsorption of Safranin O, methylene blue, Pb(2+) ions and Cr(3+) ions onto the novel composite Fe3O4-NPs-AC adsorbent was investigated.
Abstract: In the present work, the usefulness of ultrasonic power as a dispersion and mixing tool to accelerate the adsorption of Safranin O (SO), methylene blue (MB), Pb2+ ions and Cr3+ ions onto the novel composite Fe3O4-NPs-AC adsorbent was investigated. This new material was extensively characterized and analyzed by different techniques such as XRD, FESEM, Raman spectroscopy and FT-IR. Central composite design (CCD) based on designed runs revealed that adsorbent mass, sonication time, MB concentration, SO concentration, Pb2+ ion and Cr3+ ion concentration and some of their interactions have significant contributions to the target compounds removal percentages. A combination of response surface methodology and Design-Expert software was used to qualify and estimate the influence and magnitude of each terms contribution to the response. An optimization study using the following investigated increments of the effective variables, adsorbent mass (0.01–0.03 g), sonication time (2–6 min), initial dye concentration (5–25 mg L−1), and initial metal ion concentration (20–60 mg L−1), revealed that fixing the experimental variables at 0.025 g of Mn–Fe3O4-NPs-AC, with a 3 min sonication time, and 20 mg L−1 of MB, 10 mg L−1 of SO, 38 mg L−1 of Pb2+ ions and 42 mg L−1 of Cr3+ ions at room temperature lead to the achievement of the best characteristics and performance. Conduction of 32 experiments according to the limitations of CCD and a subsequent analysis of variance (ANOVA) gave useful information about the significant and also approximate contributions of each term (main and interaction of variables) in an empirical equation for the expected response. The results indicate that the R2 values are more than 0.988 and the adjusted R2 values are in reasonable agreement with R2. Under the optimal conditions, the MB, SO, Pb2+ ion and Cr3+ ion removal efficiencies reached 99.54%, 98.87%, 80.25% and 99.54% after 3 min, while their equilibrium data with high performance can be represented by Langmuir isotherms and a pseudo second-order kinetic model. The maximum adsorption capacities for the single component system, 229.4 mg g−1 for MB, 159.7 mg g−1 for SO, 139.5 mg g−1 for Pb2+ ions and 267.4 mg g−1 for Cr3+ ions, support the high efficiency of Mn–Fe3O4-NPs-AC as a new adsorbent.
TL;DR: In this article, the adsorption process was found to be exothermic in nature in the case of methylene blue (MB) and malachite green (MG) for textile dyes.
TL;DR: In this article, an Australian zeolite with (ICZ) and without (Z) iron-coating, was used to remove five heavy metals from aqueous solutions using adsorption in batch and column experiments.
TL;DR: In this article, the potential of a low-cost Nigerian montmorillonite for the adsorption of Ni(II) and Mn(II), from aqueous solution was investigated by batch mode.
Abstract: The potential of a low-cost Nigerian montmorillonite for the adsorption of Ni(II) and Mn(II) ions from aqueous solution was investigated by batch mode. XRD, SEM and BET analysis were used to characterize the adsorbent. The experiments were performed as a function of pH, particle size, adsorbent dose, initial metal ion concentration, contact time, ligands and temperature. The process was found to be dependent on all the parameters investigated, with a pH of 6.0 obtained for optimum removal of both metal ions. The Langmuir monolayer adsorption capacity of 166.67 and 142.86 mg/g was obtained for Ni(II) and Mn(II) ions respectively. The Freundlich isotherm gave the best fit to the experimental data than the Langmuir, Temkin and Dubinin–Radushkevich isotherms. The scatchard plot analysis indicated the existence of more than one type of active site on the montmorillonite which corroborates the good fit of the Freundlich model. The pseudo-first order, pseudo-second order and intraparticle diffusion models were applied to the kinetic data. The best fit was achieved with the pseudo-first order model and the existence of intraparticle diffusion mechanism was indicated. Thermodynamic studies showed an endothermic, dissociative, spontaneous and a physical adsorption process between the metal ions and the montmorillonite. Desorption studies revealed over 90% desorption of both metal ions from the metal loaded adsorbent.
TL;DR: In this article, an iron oxide activated red mud (IOARM) was used effectively to adsorb Cd(II) from aqueous solution, and the optimized adsorption parameters were: pH-6.0, dose 6.0, contact time 90min, initial concentration 400μg/L and temperature 300 K.
TL;DR: In this paper, a linear combination approach has been developed to predict the Langmuir capacity of shales based on the mass fractions of their organic and inorganic components, which can be used to estimate the in situ sorption capacity of shale layers as a function of burial depth (formation pressure and temperature), and composition.
TL;DR: In this article, the effect of biosorption experimental parameters such as initial metal concentration, contact time, temperature and adsorbent dose has been discussed and discussed in details, and the equilibrium data for the removal of copper, nickel, chromium and zinc ions from synthetic waste water by using Moringa aptera Gaertn (MAG) was analyzed by using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models.
Abstract: The investigation of the effectiveness of the removal of copper, nickel, chromium and zinc ions from synthetic waste water by using Moringa aptera Gaertn (MAG) was studied. The effect of biosorption experimental parameters such as initial metal concentration, contact time, temperature and adsorbent dose has been presented and discussed in details. The equilibrium data for biosorption were analysed by using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models to define the best correlation for each metal. Among the four isotherm models, both Freundlich and Temkin models were fitted with the equilibrium isotherm for copper, while Temkin and Dubinin–Radushkevich models best correlated for nickel and Langmuir isotherm model best describe the experimental data for chromium. The adsorption capacity for each studied heavy metals is reported as follows: copper qe = 6.07 mg Cu/g MAG, nickel qe = 5.53 mg Ni/g MAG and chromium qe = 5.497 mg Cr/g MAG with a removal percentage of 90%, 68% and 91%, respectively for each ion at 1 g dose of biosorbent. Results also show that MAG pods are not a good biosorbent for the removal of zinc from wastewater. Kinetics results were best described by pseudo-second order model for all metals.
TL;DR: In this paper, a single-step solvothermal process was used to synthesize reduced graphene oxide and metal oxide based binary and ternary nanocomposites with enhanced photocatalytic and adsorption properties for removing methylene blue dye under UV and visible light irradiation.
Abstract: Reduced graphene oxide (rGO) and metal oxide based binary (rGO–TiO2/rGO–Fe3O4) and ternary (rGO–Fe3O4–TiO2) nanocomposites with enhanced photocatalytic and adsorption properties are successfully synthesized by a simple one-step solvothermal process. The microscopy images of the nanocomposites show that the ferric oxide (Fe3O4) and titania (TiO2) nanoparticles are firmly anchored over rGO, which enhances the surface area of the resultant nanocomposites. The as-synthesized nanocomposites are evaluated for the removal of methylene blue dye under UV and visible light irradiation as well as for the adsorption of As(III) from aqueous solution. Compared to binary, the ternary (rGO–Fe3O4–TiO2) nanocomposite exhibits the highest dye degradation efficiency (∼100% within 5 minutes). This enhancement is attributed to the synergetic interaction and increase in the surface area of rGO–Fe3O4–TiO2. For As(III) adsorption, the adsorption data are obtained by Langmuir and Freundlich adsorption isotherms. Compared to binary nanocomposites, the maximum monolayer adsorption capacity (147.05 mg g−1) is observed for rGO–Fe3O4–TiO2. These results reveal that the rGO–Fe3O4–TiO2 nanocomposite has potential application in water/wastewater treatment.
TL;DR: In this article, the intrinsic parameters of the Langmuir and Freundlich adsorption isotherms were experimentally obtained and subsequently utilized to predict removal efficiencies for other sets of initial solute concentrations, solution volumes, and adsorbent masses.
TL;DR: Hydrated ferric oxide, hydrated zirconium oxide and hydrated copper oxide were immobilized within a microporous anion exchange resin, forming hybrid media for enhanced phosphate removal from aqueous systems, suggesting that such hybrid media have the potential for application at full scale.
TL;DR: In this article, a metal-organic framework based on copper-benzenetricarboxylates was applied to the adsorption of hexavalent chromium from aqueous solution.
TL;DR: In this article, the authors demonstrated the potential of using pineapple waste biomass as cheap and efficient raw materials to produce activated carbon for dye removal from wastewaters, which was evaluated for its dye removal efficiency using methylene blue (MB) taking into consideration the following parameters; contact time, initial concentration of MB and adsorbent dosage.
TL;DR: Kinetics evaluation of experiments at various time intervals reveals that adsorption processes can be well predicated and fitted by pseudo-second-order and Elovich models.
TL;DR: In this paper, a nanocomposite of multi-walled carbon nanotubes (MWCNT) functionalized with chitosan (CS) and poly-2-hydroxyethyl methacrylate (pHEMA) was prepared and characterized.
TL;DR: Easy preparation, remarkable removal efficiency and firmly adsorptive ability make the MgO nanoparticles to be an efficient material in the treatment of heavy metal-contaminated water.
TL;DR: In this article, a detailed analysis of the Langmuir isotherm model is presented along with a quantitative analysis of a level of error that can arise in derived parameters when the model is inappropriately applied to characterize a protein adsorption process.
Abstract: The Langmuir adsorption isotherm provides one of the simplest and most direct methods to quantify an adsorption process. Because isotherm data from protein adsorption studies often appear to be fit well by the Langmuir isotherm model, estimates of protein binding affinity have often been made from its use despite that fact that none of the conditions required for a Langmuir adsorption process may be satisfied for this type of application. The physical events that cause protein adsorption isotherms to often provide a Langmuir-shaped isotherm can be explained as being due to changes in adsorption-induced spreading, reorientation, clustering, and aggregation of the protein on a surface as a function of solution concentration in contrast to being due to a dynamic equilibrium adsorption process, which is required for Langmuir adsorption. Unless the requirements of the Langmuir adsorption process can be confirmed, fitting of the Langmuir model to protein adsorption isotherm data to obtain thermodynamic properties, such as the equilibrium constant for adsorption and adsorption free energy, may provide erroneous values that have little to do with the actual protein adsorption process, and should be avoided. In this article, a detailed analysis of the Langmuir isotherm model is presented along with a quantitative analysis of the level of error that can arise in derived parameters when the Langmuir isotherm is inappropriately applied to characterize a protein adsorption process.