Papers by Keyword: Freundlich Isotherm

Abstract: Sulfuric acid cross-linked chitosan/pectin polyelectrolyte complex (CPS) film was prepared as sodium dodecyl sulfate (SDS) adsorbent. CPS films were prepared in various compositions of chitosan/pectin and cross-linked by immersion in 0.1 M H₂SO₄ solution. CPS films were characterized using FTIR and SEM. CPS film was used for SDS adsorption with parameters of film composition, contact time, pH, initial SDS concentration. FTIR spectra showed characteristic peaks for chitosan, pectin and their interaction with sulfuric acid. The surface of the CPS film changed to become smoother after being used for SDS adsorption. CPS film composition 70:30 showed the highest percent swelling and was stable at the overall pH. The optimum conditions for SDS adsorption by sulfuric acid cross-linked chitosan/pectin CPS film occurred at a contact time of 120 minutes, pH 5, initial concentration of SDS 100 mg L^–1 with a film composition of 70:30. Adsorption followed the pseudo-second-order kinetic and Freundlich isotherm models with K_F and n of 0.0297 and 0.377, respectively. The highest SDS desorption of 97.6% was achieved using 0.1 M NaClO₄ solution.

Abstract: The environmental problem that often occurs in coal mining is acid mine drainage which can pose a serious threat to human health, animals and ecological systems. Acid mine drainage contains heavy metal contaminants such as iron and manganese. The purpose of this study was to determine the adsorption equilibrium carried out using natural zeolite adsorbents type mordenite from Klaten, Central Java. The application of natural zeolite with a volume of 100 mL synthetic acid mine drainage with concentrations of Fe 41.97 mg/L, Mn 21.75 mg/L and variations in dose of natural zeolite (2, 4, 6, 8, and 10 grams). The highest percent removal was at a dose of 10 grams of zeolite resulted in % removal of 97.94 % for Fe and 67.81 % for Mn. The results obtained using Langmuir and Freundlich adsorption isotherms. The results followed the Freundlich isotherm model with an adsorption parameters K_f = 0.427 mg/g, R² = 0.991, n = 1.610 Fe metal and Mn metal adsorption parameters are K_f = 0.006 mg/g, R² = 0.9971, and n = 0.578

Abstract: The aim of the study was to make known of the adsorption property of several materials which would be the component of a type of green sorption media blends having advantages in cost, availability, permeability, environmental benefit, and strong removal efficiency to the nutrient from surface runoff. The media blends were suitable for the substrate in the retention ponds, bio-swales, rainwater garden, river side pond, and helpful to control the non-pointed nutrient pollution in the surface runoff. The sand-loam, sawdust, tire crumb, limestone, and ceramic sand were selected to study the adsorption property of ammonia, nitrates, total phosphorus (TP) in the static adsorption test. Langmuir and Freundlich isotherm were used to fit the adsorption property. The experimental results showed that it was the combined action of physical and chemical adsorption to the removal of ammonia, nitrate, TP by the five kinds of adsorption materials. The adsorption property to the ammonia of the five materials were sand-loam>sawdust>ceramic sand>limestone>tire crumb, to the nitrate were sand-loam>tire crumb>sawdust>ceramic sand>limestone, to the TP were tire crumb>sand-loam>ceramic sand> limestone>sawdust. The sand-loam and sawdust were the prior materials to remove nitrogen, while the tire crumb had the great advantages to remove phosphorus.

Abstract: The adsorption of bacteria onto minerals is the premise for bioleaching and plays an important role in minerals oxidation. Understanding of the adsorption kinetics onto the surface will give information on the effectiveness of bioleaching. Three kinds of mixed bacteria (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, Sulfobacillus) were cultured in different substrates - copper concentrate, elemental sulfur and ferrous iron and adsorbed onto different solid surface of elemental sulfur, silica and copper concentrate. Adsorption kinetics was examined and surface properties were investigated by Zeta-potential and FT-IR spectroscopy. Bacterial adsorption equilibrium data for bacteria grown on three different substrates were well fitted to Freundlich isotherms, indicating inhomogeneous and selective adsorption. Microorganisms grown on copper concentrate and S⁰ showed similar adsorption kinetics whereby cell adsorptions proceeded rapidly and reached equilibrium within 30 mins of interaction. With the average K_F value of 46.2, most copper concentrate-grown cells were strongly adsorbed to three solid surfaces. Microorganisms grown on copper concentrate and S⁰ also showed higher hydrophobicity and higher isoelectric point (IEP) (pH 3.4-3.8) as compared to the soluble Fe²⁺-grown cells (pH 2.1), indicating higher amount of EPS and proteins on the surfaces. The FT-IR spectra indicated the presence of COOH, NH₂, OH and PO₄ groups on all cell surfaces. However, more proteinaceous compounds were found on cells grown on copper concentrate and S⁰ substrates.

Abstract: Due to the potential of kaolin as an adsorbent for removal of heavy metals from solution, the competitive adsorption of Lead (Pb) and Copper (Cu) by kaolin was investigated to provide further understanding on the binding behaviors and capacities of these two metals onto kaolin. The Langmuir and Freundlich isotherms were applied to further explain the competition between the metals. Three different solutions were used, each at concentrations 10, 20, 30, 45, 60 and 75mg/L: single-metal solution of Pb (Pb-Only), single-metal solution of Cu (Cu-Only), and solution of both metals at the same concentrations (Binary solution). The kaolin adsorbed Pb about twice more than Cu, both for the binary solution and for the single-metal solutions. This correlated well with predictions of maximum adsorption capacity (Q) for kaolin, where Q for Pb was about twice as much as that for Cu, both in the binary solution and in the single-metal solution. Competition from Cu in binary solution reduced Pb adsorption by 9%, while Cu rather increased by 4.1%, relative to their respective adsorptions in Pb-Only and Cu-Only, respectively. However, during competitive adsorption in the binary solution, the relative proportions of adsorbed Pb increased by 11.4% as the initial metals concentration increased from 10 – 75mg/L, while that of Cu reduced by the same proportion. This was explainable by their respective separation factors (R_L), which indicated higher favorability of kaolin for Pb than for Cu. Furthermore, bonding energy (K_L) of Pb unto kaolin during competition was about 2.5 times that of Cu, and was likely able to cause Pb to displace Cu from kaolin surface. This study reveals greater adsorption capacity of kaolin for Pb than for Cu, and could provide the basis for future projects/studies that would employ kaolin in Pb and Cu removal.

Abstract: The capability for the adsorption of Cu (II) ion with mesoporous material SBA-15, amino-functionalized SBA-15 and mercaptopropyl-functionalized SBA-15 was investigated. XRD, FT-IR and FESEM were used for characterizing the structure and surface properties of adsorbent prepared. Effects of initial concentrations and pH on adsorption process were studied. Amino-functionalized SBA-15 was found to show the highest percentage removal of Cu (II) ion from aqueous solution compared to mercaptopropyl-functionalized SBA-15. Adsorption isothermal model was also examined. Langmuir isothermal model was found to be better fitted with adsorption process compared to Freundlich isotherm model.

Abstract: In this study, we modified the surface of nanoporous carbons with carboxymethylated polyethyleneimine (CM-PEI) of a high charge density in order to increase the Pt loading on the nanoporous carbons in an aqueous solution. We carried out equilibrium adsorption tests of Pt(IV) on the pure nanoporous carbon and the CM-PEI-coated carbons and evaluated the adsorption isotherm on the CM-PEI-coated carbon using various isotherm models. It was found that the adsorption of Pt(IV) onto the CM-PEI-coated carbons obeys the Langmuir isotherm model.

Abstract: We present the preparation and Cu(II) adsorption characteristics of a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of Cu(II) on the CM-PEI/F400 composite and evaluated the adsorption data using three kinds of isotherm models (Langmuir, Freundlich, and Temkin isotherms). It was found that the adsorption of Cu(II) on the CM-PEI/F400 composite obeys the Langmuir isotherm model. Furthermore, The Cu element mapping results showed that Cu was well distributed throughout all the surface of the composite particle, suggesting that the surface of the F400 particle was uniformly covered with CM-PEI.

Abstract: We applied a polymer-based surface modification technique to the surface treatment of a microporous activated carbon. We used a new chelating polymer, carboxymethylated polyethyleneimine (CM-PEI), as a functional polymer to modify the carbon surface. In this study, we examined the adsorption phenomena of the CM-PEI on an activated carbon with a nanopore less than 2 nm in diameter and evaluated the adsorption mechanism using three kinds of models; Langmuir, Freundlich, and Redlich-Peterson isotherm. It was found that the adsorption of CM-PEI on the F400 follows the Freundlich isotherm model. Furthermore, desorption experiments of the CM-PEI were carried out to examine the stability of the CM-PEI adsorption on the F400 and to estimate the applicability of the CM-PEI-coated F400 to the adsorbents. It was observed that most of the CM-PEI remains on the F400 for 7 days in the pH range of 3 to 7. Especially, the adsorption amount of CM-PEI on the F400 did not change after 3 days at the pH range of 5 to 7, indicating that the CM-PEI strongly adheres to the F400.