High Levels Of Adsorption Research Articles

Observation of metal ions adsorption on novel polymeric chelating fiber and activated carbon fiber

In this study, polymeric chelating fiber with good adsorbing capacity (11.4 mequiv./g) and activated carbon fiber with high specific area (1560 m 2/g) were synthesized to compare the adsorption of heavy metal ions on these materials. The adsorption isotherm of various cations on activated carbon fiber and poly(acrylo-amidino diethylenediamine) showed similar adsorption behavior. High adsorptions were found at high pHs. At low pHs, adsorbed H +s on the benzene (in the case of activated carbon fiber) and amine groups (in the case of poly(acrylo-amidino diethylenediamine)) blocked activated carbon fiber–metal complex and poly(acrylo-amidino diethylenediamine)–metal complex formations. Metal ion adsorption on activated carbon fiber was lower than that on poly(acrylo-amidino diethylenediamine) due to metal crystal growth on poly(acrylo-amidino diethylenediamine) although activated carbon fiber has high specific area. In the case of anions adsorption, much higher levels of adsorption were observed at lower pHs, but not at higher pHs due to H +s. In conclusion, the results suggest that metal crystal growth using functional group on the surface is more effective to remove metal ions in aqueous solution than high specific area.

Smooth Model Surfaces from Lignin Derivatives. II. Adsorption of Polyelectrolytes and PECs Monitored by QCM-D

For the first time to the knowledge of the authors, well-defined and stable lignin model surfaces have been utilized as substrates in polyelectrolyte adsorption studies. The adsorption of polyallylamine (PAH), poly(acrylic acid) (PAA), and polyelectrolyte complexes (PECs) was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The PECs were prepared by mixing PAH and PAA at different ratios and sequences, creating both cationic and anionic PECs with different charge levels. The adsorption experiments were performed in 1 and 10 mM sodium chloride solutions at pH 5 and 7.5. The highest adsorption of PAH and cationic PECs was found at pH 7.5, where the slightly negatively charged nature of the lignin substrate is more pronounced, governing electrostatic attraction of oppositely charged polymeric substances. An increase in the adsorption was further found when the electrolyte concentration was increased. In comparison, both PAA and the anionic PEC showed remarkably high adsorption to the lignin model film. The adsorption of PAA was further studied on silica and was found to be relatively low even at high electrolyte concentrations. This indicated that the high PAA adsorption on the lignin films was not induced by a decreased solubility of the anionic polyelectrolyte. The high levels of adsorption on lignin model surfaces found both for PAA and the anionic PAA-PAH polyelectrolyte complex points to the presence of strong nonionic interactions in these systems.

Effect of drying time, ambient temperature and pre-soaks on prion-infected tissue contamination levels on surgical stainless steel: concerns over prolonged transportation of instruments from theatre to central sterile service departments

Iatrogenic transmission of prions through use of surgical instruments has been shown both experimentally and clinically. In addition, recent discoveries of prion protein accumulation in peripheral tissues such as appendix and muscle, and evidence suggesting human-to-human blood-borne transmission, have led to a concern that any residual soiling containing this agent may remain infectious even after sterile service processing. Removal of all proteinaceous material from surgical devices is extremely important for effective sterilization. This removal can be severely hampered if the contaminant is allowed to dry onto the instrument surface for any length of time. The current move to centralize sterile service centres and the inevitable lengthening of transport time between theatres and re-processing makes it necessary to minimize the amount of residual soiling adhering to an instrument before sterilization. This investigation simulates the period between the application of surgical instruments in theatre and their initial pre-wash by a washer/disinfector. The aim was to investigate the kinetics of drying at different temperatures, and the application of different commercially available pre-soak solutions in situ. The findings show that all pre-soaks significantly reduce (by up to 96%) the prion-infected tissue contamination, and that controlling the temperature whilst in transit between theatres and cleaning facilities may allow an increase in time before high protein adsorption levels occur.

Selective Adsorption and Steric Recognition by Molecularly Imprinted Polymers: a Study on Molecular Self-Assembly and its Effect on Selectivity

This article presents an interesting study on molecular self-assembly and its effect on steric recognition by molecularly imprinted polymers. With S-naproxen as the template and acrylamide as the functional monomer, the self-assembly appears to play important roles in the selective adsorption, affecting not only the adsorption amount but also the enantioselective recognition. Both of them become evident by the change of monomer–template ratio. An increase in the monomer–template ratio will result in a higher level of adsorption. The best selectivity for steric recognition is, however, shown at an optimal composition (corresponding to the saturation interaction of monomer and template). A higher or lower monomer–template ratio leads to a dramatic decrease in this selectivity. Related information indicates that this may be a result from the matched arrangement between the binding sites and the template, which makes the binding sites capable of selectively recognizing the imprint species.

Interaction of Chlorhexidine With Smooth and Rough Types of Titanium Surfaces

Chlorhexidine (CHX) digluconate exerts plaque inhibitory efficacy in the natural dentition environment due to a superior degree of persistence at the tooth surface. The purpose of the present study was to assess the interaction of CHX with titanium surfaces to estimate its antiplaque potential in the peri-implant environment. Saliva-coated machined smooth (S) and sand-blasted acid-etched rough (R) titanium disks were soaked in either 0.1% or 0.2% CHX solution. After 24 hours, CHX amounts that were adsorbed, washed out, and desorbed from the titanium surfaces were determined spectrophotometrically at 230 nm. The antibacterial activity of CHX-treated titanium disks was assessed by measuring bacterial inhibition zones on Streptococcus mutans lawns. Titanium disks adsorbed 3% to 8% of the available CHX, which was significantly higher with 0.2% CHX (P<0.001) than with 0.1% CHX and two-fold higher on the R titanium disks compared to S titanium surface (P<0.001). After rinsing with water, 2.2% of the adsorbed CHX was washed out. Over 24 hours, S- and R-type disks released 1.1% and 0.6% of the adsorbed agent, respectively. Larger bacterial inhibition zones were obtained with 0.2% CHX and in R disks compared to S disks. CHX displayed persistence at the titanium surface. The adsorption level and bacterial growth inhibition were affected by CHX concentration and titanium surface characteristics, with higher levels of adsorption and antibacterial activity with 0.2% CHX and rough titanium surface. The slow CHX release rate suggests persistence of this agent at the titanium-pellicle surface, which can provide a long-term antiplaque effect.

Nitric Oxide Biosensors Based on the Immobilization of Hemoglobin on Mesoporous Titania Electrodes

A nanocrystalline TiO2 film is an electrode material with large surface area which allows high levels of protein adsorption without loss of protein structure or activity. As an optically transparent semiconductor, titania can be used to carry out direct spectroelectrochemistry of proteins such as hemoglobin. We demonstrate that the high protein loading and the optical transparency and electrical conductivity of the Hb/TiO2 films allow the optical and/or electrochemical sensing of nitric oxide. In particular we demonstrate the nitric oxide cycle of oxyhemoglobin immobilized on TiO2 films and use it to electrochemically measure micromolar levels of nitric oxide.

Selective adsorption and recovery of precious metal ions from geological samples by 1,5,9,13-tetrathiacyclohexadecane-3,11-diol anchored poly( p-CMS-DVB) microbeads

Poly( p-chloromethylstyrene-divinylbenzene) polymeric microbeads, poly( p-CMS-DVB), were synthesized and 1,5,9,13-tetrathiacyclohexadecane-3,11-diol was attached chemically to the polymeric microbeads. Characterizations of all microbeads were carried out using FT-IR, TGA, DSC and an elemental analyzer. The amount of 1,5,9,13-tetrathiacyclohexadecane-3,11-diol attached to the polymer was found to be 2.76 mmol/g polymer. These microbeads were used for recovery, preconcentration and the selective adsorption of precious metal ions by changing the pH and the initial metal ion concentrations. Au(III), Ag(I), Pt(II) and Pd(II) from single and competitive solutions were recovered and preconcentrated. High levels of metal ion adsorption were found below pH = 2, even when the pH fell as low as pH = 0.5. Preconcentration factors for the precious metal ions studied were found to be more than 1000-fold and recovery was between 96% and 102%. Selectivity of the modified microbeads followed the order Au(III) > Ag(I) > Pd(II) > Pt(II). In the geological samples and in some samples from water-lands, the ultra-trace precious metal ion concentration was determined easily by using modified microbeads after preconcentration. For the desorption of the precious metal ions, HCl (3 M) containing thiourea (0.8 M) was used and desorption ratio obtained was more than 96%.

Preparation of inert magnetic nano-particles for the directed immobilization of antibodies

Various activated supports (cyanogen bromide, glutaraldehyde, epoxy-chelates, primary amino) were evaluated for the immobilization of IgG anti-horseradish peroxidase. Cyanogen bromide and glutaraldehyde supports greatly reduced the recognition capacity of the antigen, probably due to the incorrect orientation of the antibody on the support. Hetero-functional epoxy-chelate and immobilization by the sugar chain on primary amino groups had little effect on high recognition of the antigen (near to the theoretically expected value). However, the immobilization by the sugar chain resulted in a higher adsorption rate of horseradish peroxidase, possibly due to a favourable orientation on a flexible spacer arm). Antibodies immobilized on aminated surfaces showed two major drawbacks. Firstly, the biological activity of the immobilized antibody sharply decreased over several days when stored at low ionic strength, although this effect could be partially reversed by incubation at high ionic strength. Secondly, a high level of non-specific proteins adsorption on the support surface was observed. Both problems could be successfully resolved by controlling the coating of the support with aldehyde-aspartic-dextran. We propose that the loss of biological activity was related to the ionic adsorption of the immobilized antibody on the support surface, leading to a blocking of the recognition areas. This optimized protocol was applied to the immobilization of IgG anti-horseradish peroxidase from rabbit on magnetic nano-particles. A 10 μg preparation of nanoparticles was able to capture more than 75% of the 0.1 microgram of recombinant horseradish peroxidase present in 10 L of crude protein extract (1 g/L) from Escherichia coli.

Interactions of corneal cells with transforming growth factor beta 2-modified poly dimethyl siloxane surfaces.

The downgrowth of corneal epithelial cells at the interface of an artificial cornea and the host eye tissue poses a significant problem to be overcome in developing a successful implant. As a means of inhibiting the proliferation of corneal epithelial cells on the stromal surface of the implant, we examined the immobilization of transforming growth factor beta-2 (TGF-beta2) via a bifunctional poly ethylene glycol (PEG) spacer to poly dimethyl siloxane (PDMS) surfaces. Growth factor immobilization was confirmed by modification with (125)I-labeled TGF-beta 2. The modified surfaces were also characterized by advancing water contact angles, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Although the amount of growth factor covalently bound to the surface was difficult to quantify apparently due to strong interactions between the growth factor and the PEG layer and high levels of adsorption, differences in the modified surfaces, suggestive of the presence of a significant amount of TGF-beta 2, were found. In vitro interactions of the modified surfaces with human corneal epithelial and stromal cells were examined. Growth factor surface concentrations as well as culture in the absence and presence of serum and other adhesive proteins were examined. Corneal stromal and epithelial cells cultured on the TGF-beta 2-modified surfaces consistently gave results opposite to those expected. Likely, the most notable and surprising result was the almost complete lack of adhesion of the stromal cells, with coverage averaging between 3 and 5%. In comparison, corneal epithelial cell growth appeared to be promoted by the presence of the immobilized growth factor, with cell coverage averaging 50-60% at 7 days of culture. A TGF-beta 2 concentration effect was noted with both cell types in the absence of serum, with increases in the coverage at higher TGF-beta 2 concentrations. The observed cell growth appeared to be the result of interactions between the cells and active growth factor, because the addition of anti-TGF-beta 2 to the culture medium reduced cell coverage to levels similar to those noted on control surfaces. Therefore, although TGF-beta 2-modified surfaces may not be suitable as corneal epithelial cell inhibiting surfaces, interactions of surface immobilized growth factor and corneal cells are complex and should be further examined.

Adsorption and desorption of triasulfuron by soil.

The adsorption and desorption of the herbicide triasulfuron [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide] by three soils, soil organic matter (H(+) and Ca(2+)-saturated), and an amorphous iron oxide were studied. Adsorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the adsorption in all of the systems. Indeed, the adsorption on soils was negatively correlated with pH. The highest level of adsorption was measured on soils with low pH and high organic carbon content. Moreover, it was found that humic acid is more effective in the adsorption compared with calcium humate (the pH values of the suspensions being 3.5 and 6, respectively). Experiments on amorphous iron oxide confirmed the pH dependence. Desorption was hysteretic on soils having high organic carbon content.

Evaluation of the Susceptibility to Staining of Artificial Teeth and the Influence of Surface Texture on Staining

Purpose : This study established a method of evaluating the susceptibility to staining of artificial teeth and clarified whether the surface texture of artificial teeth influences this staining tendency.Materials and Methods : Conventional resin teeth (R), resin teeth with a special acrylic polymer (FX), conventional composite resin teeth (EF), and composite resin teeth with an enhanced amount of fluor monomer (PX) were used. To evaluate the influence of surface texture on the staining tendency, the following polishing methods were used : no polishing, barrel-polishing and buff-polishing. The surface texture was examined using a scanning electron microscope. To evaluate direct staining, the artificial teeth were immersed for 1 week in curry and fuchsin basic solutions. To assess protein adsorption, they were immersed for 1 week in a human parotid saliva solution and a solution containing bovine serum albumin. They were subsequently immersed in a plaque-disclosing agent for 24 hours and washed in water. Color changes after direct staining and protein adsorption testing were evaluated. Multiple comparison of the color difference values (ΔE*ab) were evaluated using a Bonferroni test (p<0.01).Results : Protein adsorption testing showed that EF was remarkably stained for all surface textures. The barrel-polished surfaces were coarser than the other surfaces. EF was remarkably stained compared to the other teeth.Conclusion : It was demonstrated that the staining tendency of the conventional composite resin teeth is due to their high level of protein adsorption and that protein adsorption testing is a useful evaluation method. Also, it was recognized that surface roughness is an influencing factor on the staining tendency.

Modulation of adenosine 5'-monophosphate adsorption onto aqueous resident pyrite: potential mechanisms for prebiotic reactions.

The adsorption of adenosine 5'-monophosphate (5'-AMP) onto pyrite (FeS2) and its modulation by acetate, an organic precursor of complex metabolic pathways, was studied in aqueous media that simulate primitive environments. 5'-AMP adsorption requires divalent cations, indicating that a cationic bridge mediates its attachment to negatively charged sites of the mineral surface. The isotherm of 5'-AMP adsorption exhibits a strong cooperative effect at low nucleotide concentrations in acetate-rich medium, whereas high levels of adsorption were only found at high nucleotide concentrations in a model of primitive seawater (acetate free). The modulating role of acetate is also evidenced in the presence of high dipolar moment molecules: dimethyl sulfoxide (Me2SO) and dimethyl formamide (DMF) strongly inhibit 5'-AMP adsorption in acetate-rich media, whereas no effect of DMF was found in artificial seawater. The observation that exogenous divalent cations are not needed for acetate attachment onto FeS2 reveals that organic acids can interact with the Fe2+ atoms in the mineral surface. All considered, the results show that complex and flexible ironsulfide/biomonomers interactions can be modulated by molecules that accumulate in the interface layer.

Different methods for extracting bacteria from freshwater sediment and a simple method to measure bacterial production in sediment samples

The efficiency of different treatments was tested to extract bacterial cells from freshwater sediment samples. The influence of sonication, density gradient centrifugation, fixation by formalin and centrifugation speed on bacterial recovery was investigated. The method developed by Smith and Azam [Mar. Microb. Food Webs 6 (1992) 107] to measure microbial activity on bacterioplankton ( 3H-leucine incorporation), was also evaluated in sediment samples. After 1 min of sonication bacterial abundance was reduced by about 47% in diluted sediments with tetrasodium pyrophosphate. With the addition of Percoll after sonication, bacterial counts were not significantly different ( P<0.05). Fixation by formalin increased bacterial counts using sonication. However, higher bacterial abundance was estimated in non-sonicated samples. Bacterial abundance in samples centrifuged at 7000× g with and without Percoll was not significantly different ( P<0.05). Highest bacterial abundance was obtained after centrifugation at low speed (750× g). Bacterial abundance decreased with higher centrifugation speed (750, 1500 and 3000× g), the difference, however, was not significant. Bacterial production ranged from 0.10 μg C cm −3 d −1 in autoclaved sediment to 0.27 μg C cm −3 d −1 in untreated sediment. The radioactivity measured in controls of both untreated and autoclaved sediment was high (70 and 91%, respectively), indicating a high level of leucine adsorption in sediment particles. In contrast, radioactivity in control samples previously centrifuged was markedly lower (6%). Despite the high values of radioactivity in the controls, bacterial production in untreated sediment was significantly higher than in centrifuged sediment ( P<0.05).

Adsorption of copper(II) and EDTA-chelated copper(II) onto granular activated carbons

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA-chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA-chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell-based carbon exhibited a greater adsorption capacity for copper(II) than the coal-based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4–6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA-chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA-chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA-chelated copper(II) species. © 2000 Society of Chemical Industry

The role of surfactant adsorption in the improved dewatering of fine coal

Abstract This paper describes the adsorption kinetics and isotherms for cationic and anionic surfactants on coal surfaces. Both types of surfactants adsorb significantly rapidly; although the cationic surfactant achieved much higher levels of adsorption than the anionic one. The adsorption isotherms are of typical Langmuir type and employed for calculation of free energies. The results indicate that adsorption occurs through hydrophobic interaction in addition to electrostatic attraction between the surfactant molecules and the coal surface. Surfactant adsorption is shown to be a significant factor in the improved dewatering of coal particles. These improvements have been attributed to the changes which surfactant adsorption causes in the wetting characteristics of the coal surfaces. The results obtained are evaluated in terms of surface effects and by reference Laplace–Young equation. Furthermore, this equation has been used to quantify dewatering phenomena.

Protein and platelet interactions with thermally denatured fibrinogen and cross-linked fibrin coated surfaces

In this work the hypothesis that a mature, cross-linked fibrin clot, pre-formed on a biomaterial, may be relatively nonthrombogenic was investigated. A cross-linked fibrin layer was formed on polyethylene which had been precoated with thermally denatured fibrinogen. Plasma protein adsorption and platelet interactions with the cross-linked fibrin and denatured fibrinogen surfaces were investigated. The adsorption of albumin, fibrinogen, and fibronectin from plasma was measured. For all three proteins, the cross-linked fibrin surface exhibited much higher levels of adsorption than either the thermally denatured fibrinogen or the polyethylene surface. Vroman peaks were observed for fibrinogen and fibronectin on polyethylene but not on the cross-linked fibrin and thermally denatured fibrinogen materials. In dilute plasma the thermally denatured fibrinogen surface showed considerable resistance to protein adsorption. However, at plasma concentrations greater than about 5% normal, this protein resistance was apparently lost. Platelet interactions (adhesion and release of granule constituents from adherent platelets) using suspensions of washed platelets in the presence of red cells were investigated at shear rates of 50, 300, and 525 s -1 using a cone and plate apparatus. The levels of platelet adhesion on the different surfaces were in the order: adsorbed fibrinogen>cross-linked fibrin>thermally denatured fibrinogen=polyethylene. Platelets on the cross-linked fibrin surface also showed high levels of release indicating significant platelet activation. Scanning electron microscopic observations were in agreement with the platelet adhesion and release data, showing only a few (but well-spread) adherent platelets on the cross-linked fibrin surface.

Volatile organic compounds in the surface waters of a British estuary. Part 2. Fate processes

The fate of volatile organic compounds (VOC) in the Southampton Water estuary, presented in Part 1 of this paper, are described. The principal processes responsible for removing VOC from the water column include dilution and net transport, volatilisation and adsorption onto sediments. Volatilisation is the most important removal mechanism, and is significantly influenced by temporal and spatial changes in aqueous concentration and by the proximity of sources. Using surface renewal models, volatilisation rates ranging from 300 kg day −1 in summer months to 2000 kg day −1 in winter months were estimated. Within the water column, net transport rates were 3 to 5 times higher in winter relative to summer, reflecting the influence of enhanced input rates and increased dilution flows. Adsorption processes varied widely in their efficiency, and were dependent upon the availability of adsorbing solid surfaces within the water column and VOC affinity for sorption processes. The highest levels of adsorption were identified for chloroform in wastewater effluents where the organic matter content of suspended solids approached 100%. Within the estuary as a whole, not more than 5% of VOC such as aromatics and organohalogens was predicted to be adsorbed under the most favourable environmental conditions.

Site accessibility and the pH dependence of the saturation capacity of a highly cross-linked matrix Immobilized metal affinity chromatography of bovine serum albumin on chelating superose

Immobilized metal ion affinity chromatography has shown promise for isolating desired proteins from a mixture based on their affinity for chelated metal ions. Using frontal analysis, the pH dependence of the saturation capacity of chelating Superose matrix for bovine serum albumin (BSA) is examined over a broad pH ranage. A significant increase in the capacity was observed near the elution pH of BSA (pH 4.5) from a Cu-imminodiacetic acid column. The results of several experiments indicated that this apparently abnormal variation may reflect the low degree of accessibility of a large portion of copper sites inside chelating Superose. In a broader sense, these results suggest that during frontal analysis, the assumption of column saturation based on a plateau in the exit concentration that is almost at the same level as the input concentration could be misleading for highly cross-linked matrices and relatively large sized proteins. That is, the relatively less accessible copper sites may become difficult to be reached due to high level of protein adsorption in the more accessible regions and thus give the appearance of a plateau in the breakthrough curve prior to complete column saturation. This is likely to be the case at high pH where BSA demonstrates very high affinity for immobilized copper or a high input concentrations where the equilibrium coverage is expected to be high. The results demonstrate that the estimated saturation capacity could be significantly smaller than the actual capacity.

Elucidation of the DNA synthetic cycle of Entamoeba spp. using flow cytometry and mathematical modeling.

We developed a method to study the DNA synthetic cycles of Entamoeba histolytica and Entamoeba invadens by flow cytometry (FCM) based on a preparative procedure to reduce both high levels of natural fluorescence and non-specific adsorption of fluorochromes. We modeled G1, S, and G2 phases as a series of overlapping Gaussian curves. Both E. histolytica and E. invadens displayed G1, S, and G2 proportions that are consistent with eukaryotic cell populations in exponential or stationary growth phase. Exponential phase E. histolytica populations contained a hypodiploid subset with a mass of about 20% less than the diploid value which we estimate by FCM to be 24 x 10(-14) g DNA/cell. Exponential phase E. invadens populations contained a hypodiploid subset with a mass of about 6% less than the diploid value which we estimate by FCM to be 30 x 10(-14) g DNA/cell.

Adsorption of Aniline on Layer Silicate Clays and an Organic Soil

AbstractAdsorption isotherms of organic pollutants such as aniline on soil colloidal materials have generally not been described for a wide range of solution concentrations. The characteristics of isotherms for aniline adsorption on Ca‐saturated kaolinite, montmorillonite, vermiculite, and an organic soil were determined for a wide range of aqueous concentrations at acid and neutral pH. Aniline adsorption was greater at acid than neutral pH for all adsorbents, an indication of preferred adsorption of anilinium. Adsorption on montmorillonite, vermiculite, and kaolinite across the aniline concentration range of 1 × 10−4 to 2 × 10−2 M was best described by a sigmoid (S‐type) isotherm, an equation for which was derived from a model of cooperative adsorption, in which aniline was assumed to adsorb in molecular “clusters”. Adsorption on the organic soil across the same wide range of aqueous concentration was not described adequately by the S‐type isotherm, but rather by the Brunauer‐Emmett‐Teller (BET) function. Within the restricted range of low aniline adsorption, the adsorption isotherms were linear for all adsorbents. At somewhat higher (intermediate) aniline adsorption, the isotherms remained linear for kaolinite and vermiculite, but curvilinear (L‐type) isotherms were obtained for montmorillonite and the organic soil. Generally, the equation best describing adsorption data was different in form for each range of adsorption being considered. Fourier‐transform infrared (FTIR) spectroscopy indicated that, at least at low pH and high adsorption levels, aniline‐anilinium complexes adsorbed on all of the adsorbents. Adsorption on clay and organic matter had characteristics of both electrostatic and weak physical bonding.