Adsorption of Methylene Blue Dye on Pure and Carbonized Water Weeds

The influence of process variables in batch adsorption has been used to assess the removal of methylene blue dye from aqueous solution using pure and carbonized biomasses of water hyacinth and water spinach. Dried leaves of the water weeds were carbonized at temperature up to 750°C. The optimum removal of dye was achieved at pH 10, 30°C, and 55 min at a dye concentration of 10 mg/L. In an attempt to describe the adsorption process, the equilibrium isotherm for each adsorbent was determined using Langmuir and Freundlich adsorption isotherm models. Maximum adsorption capacities based on the Langmuir model for pure and carbonized water hyacinth were (mg/g) 7.05 and 2.07, respectively, whereas those of pure and carbonized water spinach were 1.25 and 5.32, respectively. It was observed that the equilibrium data were well fit by both the Freundlich and Langmuir isotherms as R ² > .97. This study demonstrates that the two waterweeds are effective, environmentally friendly, and inexpensive biomaterials for the removal of color from industrial effluents.     

Model for the adsorption of cytochrome c at the water-mercury interface

The effect of cytochrome c on the redox behavior of 1,4-benzoquinone and cystine has been investigated by differential pulse polarography. The adsorption of cytochrome c on mercury surface produces a lowering of the reduction peak of 1,4-benzoquinone and of the cystine prepeak. When the covering of the drop is maximal, no variation in peak height is observed. By using the Koryta equation, values between 1500 and 2300 Ų for the surface area of one adsorbed cytochrome c molecule were obtained. The capacitance dependences on concentration and time have been determined by alternating-current polarography, and lead to the surface area values of 2800 and 2700 Ų, respectively. Results are interpreted on the basis of an unfolding of cytochrome c molecules during the adsorption process. It is likely that a rather compact covering is obtained, but about 10% of the mercury surface seems to be unoccupied and corresponds to the accessible interstices between adjacent molecules.     

Adsorption kinetics,isotherm, and thermodynamics studies of acetyl-11-keto-β-boswellic acids (AKBA) from Boswellia serrata extract using macroporous resin

An acetyl-11-keto-β-boswellic acid (AKBA) is potent anti-inflammatory agent found in Boswellia serrata oleogum resin. Adsorption characteristics of AKBA from B. serrata were studied using macroporous adsorbent resin to understand separation and adsorption mechanism of targeted molecules. Different macroporous resins were screened for adsorption and desorption of AKBA and Indion 830 was screened as it showed higher adsorption capacity. The kinetic equations were studied and results showed that the adsorption of AKBA on Indion 830 was well fitted to the pseudo first-order kinetic model. The influence of two parameters such as temperature (298, 303, and 308?K) and pH (5–8) on the adsorption process was also studied. The experimental data was further investigated using Langmuir, Freundlich, and Temkin isotherm models. It was observed that Langmuir isotherm model was found to be the best fit for AKBA adsorption by Indion 830 and highest adsorption capacity (50.34?mg/g) was obtained at temperature of 303?K. The values of thermodynamic parameters such as the change of Gibbs free energy (ΔG*), entropy (ΔS*), and enthalpy (ΔH*), indicated that the process of adsorption was spontaneous, favourable, and exothermic.     

Adsorption of cellulase fromTrichoderma viride on microcrystalline cellulose

Summary The adsorption behaviour of cellulase fromTrichoderma viride on microcrystalline celluloses with different specific surface areas was studied. The adsorption was found to fit a Langmuir isotherm. There was an increase in the maximum adsorption amount (A_max) as the specific surface area of microcrystalline cellulose increased. The values of A_max and adsorption equilibrium constant (K) decreased with increasing temperature. Thermodynamic parameters in adsorption were calculated from K. It was found from the enthalpy of adsorption, that van der Waals-Type interaction was responsible for adsorption of cellulase on microcrystalline cellulose. The adsorption process was exothermic and an adsorption enthalpy-controlled reaction.     

Hydrolysis of acrylonitrile by nitrile-converting bacterial cells immobilized on fibrous carbon adsorbents

Cells of the Pseudomonas fluorescens strain C2 containing nitrilase and Rhodococcus ruber strain gt1 with nitrile hydratase activity have been immobilized by the use of adsorption on fibrous carbon materials. It has been shown that the maximum adsorption value of Rhodococcus cells is higher than that in pseudomonades, reaching 21 mg of dry cells/1 g of the carrier vs. 6 mg, respectively. Cell adsorption, compared to cell suspension, gives a significant rise in nitrilase activity (by 7.4 times, using Ural TM-4 as the carrier) and in the stability of nitrile hydratase activity (5 reaction cycles without loss of activity, using Carbopon-B-active). Immobilized biocatalysts were also obtained by cell growth from Ps. fluorescens strain C2 and Rhodococcus ruber strain gt1 on fibrous carbon adsorbents. Biocatalyst productivity was higher for both strains when the carbonized material Ural TM-4 was used as the carrier.     

Immobilization of Candida rugosa lipase on sporopollenin from Lycopodium clavatum

Sporopollenin is a natural polymer obtained from Lycopodium clavatum, which is highly stable with constant chemical structure and has high resistant capacity to chemical attack. In this study, immobilization of lipase from Candida rugosa (CRL) on sporopollenin by adsorption method is reported for the first time. Besides this, the enzyme adsorption capacity, activity and thermal stability of immobilized enzyme have also been investigated. It has been observed that under the optimum conditions (Spo-E_(0.3)), the specific activity of the immobilized lipase on the sporopollenin by adsorption was 16.3 U/mg protein, which is 0.46 times less than that of the free lipase (35.6 U/mg protein). The pH and temperature of immobilized enzyme were optimized, which were 6.0 and 40 °C respectively. Kinetic parameters V_max and K_m were also determined for the immobilized lipase. It was observed that there is an increase of the K_m value (7.54 mM) and a decrease of the V_max value (145.0 U/mg-protein) comparing with that of the free lipase.     

Direct process integration of cell disruption and fluidised bed adsorption in the recovery of labile microbial enzymes

The practical feasibility and generic applicability of the direct integration of cell disruption by bead milling with the capture of intracellular products by fluidised bed adsorption has been demonstrated. Pilot-scale purification of the enzyme L-asparaginase from unclarified Erwinia chrysanthemi disruptates exploiting this novel approach yielded an interim product which rivalled or bettered that produced by the current commercial process employing discrete operations of alkaline lysis, centrifugal clarification and batch adsorption. In addition to improved yield and quality of product, the process time during primary stages of purification was greatly diminished. Two cation exchange adsorbents, CM HyperD LS (Biosepra/Life Technologies) and SP UpFront (custom made SP form of a prototype stainless steel/agarose matrix, UpFront Chromatography) were physically and biochemically evaluated for such direct product sequestration. Differences in performance with regard to product capacity and adsorption/desorption kinetics were demonstrated and are discussed with respect to the design of adsorbents for specific applications. In any purification of L-asparaginase (pI = 8.6), product-debris interactions commonly diminish the recovery of available product. It was demonstrated herein, that immediate disruptate exposure to a fluidised bed adsorbent promoted concomitant reduction of product in the liquid phase, which clearly counter-acted the product-debris interactions to the benefit of product yield.     

Quartz Sand as an Adsorbent for Purification of Extracellular Glucose Oxidase from Penicillium funiculosum 46.1

A procedure for purification of extracellular glucose oxidase (GO, EC 1.1.3.4) from a filtrate of culture liquid (CLF) of the fungus Penicillium funiculosum 46.1 has been developed using alluvial quartz sand as an adsorbent. Modifying the sand by changing the charge and polarity did not lead to a significant increase in its adsorption capacity towards GO. The effectiveness of sand and aluminum oxide used as adsorbents for GO isolation from CLF has been compared. Glucose oxidase isolated from CLF by adsorption on sand exhibited a greater catalytic activity than enzyme preparations obtained by column chromatography on CLF. Glucose oxidase from P. funiculosum 46.1 was adsorbed on sand more effectively than on aluminum oxide. It is concluded that sand may be used for fractionation of partially purified GO.     

Spent Rooibos (Aspalathus linearis) Tea Biomass as an Adsorbent for Organic Dye Removal

Spent rooibos (Aspalathus linearis) tea biomass can be used as an inexpensive biosorbent for xenobiotic removal. Seventeen dyes have been tested for their affinity to spent rooibos tea biomass. Eight dyes were used to study the adsorption process in detail. The dye adsorption has been described with the Langmuir isotherm. The calculated maximum adsorption capacities reached the value of over 200 mg of dye per gram of dried rooibos biomass for Bismarck brown Y. Spent rooibos tea biomass was also magnetically modified by contact with microwave-synthesized magnetic iron oxide nano- and microparticles. This new type of magnetically responsive biocomposite material can be easily separated by means of strong permanent magnets. Both native and magnetically modified spent rooibos biomass have shown excellent adsorption capacities for various types of organic dyes, so they are highly promising adsorbents in environmental technologies for selected xenobiotic removal.     

A theory of cell hydration governed by adsorption of water on cell proteins rather than by osmotic pressure

It is postulated that cell hydration is governed by adsorption of water on cell proteins in accord with the Bradley adsorption isotherm, and that the action of a solute in the surrounding solution is to lower the vapor pressure of the solution so that cell water adsorption is decreased by moving down the Bradley isotherm. From these concepts, it is derived that cell volume (V) should be related to solute concentration (x) by the equationV=−E log₁₀ x+F whereE andF are constants which are independent of type of solute. For a non-adsorbed solute this agrees well with experimental data. For solutes which are adsorbed by cell proteins, a correction in the above equation may be necessary at higher solute concentrations, which is shown to be compatible with various experimental data. The types of experiments which are generally used to support the osmotic pressure theory of cell hydration agree equally well with the adsorption theory. The virtue of the adsorption theory is that, unlike the osmotic pressure theory of cell swelling, it is compatible with permeability of the cell membrane to solutes, which has been experimentally observed for various solutes. The opinions and conclusions contained in this report are those of the author. They are not to be construed as necessarily reflecting the views or the endorsement of the Navy Department.     

A Promising Evaluation Method for Dead Leaves of Posidonia oceanica (L.) in the Adsorption of Methyl Violet

Posidonia oceanica (Linnaeus) Delile is an endemic species in the Mediterranean Sea. In the present study, dead leaves of P. oceanica (L.) which are accumulated on the beach seasonally were used as an alternative low cost biosorbent to remove methyl violet (MV) from aqueous solution. In order to explain the adsorption kinetics, pseudo first-order and pseudo second-order kinetic models were investigated. It was obtained that the pseudo second-order model was well in line with our experimental results. Equilibrium data were analyzed according to Langmuir, Freundlich, and Dubinin–Radushkevich equations. Langmuir isotherm model corresponded well with equilibrium data than the others, and the maximum adsorption capacity of the biomass was found to be 119.05 mg g⁻¹ at 45°C. Thermodynamic parameters, ΔG°, ΔH°, and ΔS°, were calculated according to van’t Hoff equation. Negative values of Gibbs free energy imply that the process is spontaneous. Consequently, dried biomass of this species can be an alternative and low cost material for the removal of MV from wastewaters. Moreover, since the remarkable adsorption capacity of these dead leaves compared to other low cost adsorbents has been observed, this beach waste could provide an economic contribution to the countries in the Mediterranean region.     

Microwave treated Salvadora oleoides as an eco-friendly biosorbent for the removal of toxic methyl violet dye from aqueous solution—A green approach

In the present study, microwave treated Salvadora oleoides (MW-SO) has been investigated as a potential biosorbent for the removal of toxic methyl violet dye. A batch adsorption method was experimented for biosorptive removal of toxic methyl violet dye from the aqueous solution. The effect of various operating variables, viz., adsorbent dosage, pH, contact time and temperature on the removal of the dye was studied and it was found that nearly 99% removal of the dye was possible under optimum conditions. Kinetic study revealed that a pseudo-second-order mechanism was predominant and the overall process of the dye adsorption involved more than one step. Hence, in order to investigate the rate determining step, intra-particle diffusion model was applied. Adsorption equilibrium study was made by analyzing Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) adsorption isotherm models and the biosorption data was found to be best represented by the Langmuir model. The biosorption efficiency of MW-SO was also compared with unmodified material, Salvadora oleoides (SO). It was found that the sorption capacity (q_max) increased from 58.5 mg/g to 219.7 mg/g on MW treatment. Determination of thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) confirmed the spontaneous, endothermic and feasible nature of the adsorption process. The preparation of MW-SO did not require any additional chemical treatment and a high percentage removal of methyl violet dye was obtained in much lesser time. Thus, it is in agreement with the principles of green chemistry. The results of the present research work suggest that MW-SO can be used as an environmentally friendly and economical alternative biosorbent for the removal of methyl violet dye from aqueous solutions.     

Isotherm and kinetic modelling of Toluidine Blue (TB) removal from aqueous solution using Lemna minor

The aim of this study was to investigate the ability of Lemna minor for Toluidine Blue (TB) removal. Influence of the initial concentration over the removal process was considered. Experimental data have been analyzed using Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Elovich isotherm models. In addition, several kinetic models, pseudo-first-, pseudo-second-order, intraparticle and film diffusion models were considered. Langmuir and Freundlich isotherm suggested a favorable adsorption of TB by Lemna minor plants. From the D–R the mean free energy was calculated to be 11.18 kJ/mol, which indicates that TB adsorption was characterized by a chemisorption process. Kinetic studies showed that liquid film diffusion plays an important role during the process. Adsorption capacities of up to 26.69 mg/g and a high capacity of adaptation indicated that phytoremediation using Lemna minor could be a valuable alternative for dyes removal from wastewaters.     

Effect of external electric current on adsorption of lead by Penicillium polonicum

Abstract

Lead is a major source of environmental pollution that has recently been the focus of a great deal of research. Bioremediation has been shown to be effective in remediation of lead pollution. Penicillium polonicum is a fungus with highly efficient adsorption of lead. In this study, the influence of electric current on the growth characteristics and adsorption of lead by the strain were investigated through applying different external voltages (1.5, 1.25, 1.0, 0.75, and 0.5?V). The results indicated that the electric current with voltage ranges from 1.0 to 1.25?V could promote the adsorption of lead. In addition, morphological characteristics and the quantity of lead-containing minerals formed on the surface of P. polonicum differed greatly under different experimental conditions. Further, the electric current intensity and electric energy consumption at voltages of 1.0, 1.25, and 1.5?V were higher than the blank control group, suggesting that the strain could utilize the energy supplied by an external electrochemical workstation to improve lead adsorption. After applying an external current, the lead adsorption of P. polonicum was affected by electric current changing the growth environment of the fungus and the electron transfer reaction between electrodes and P. polonicum.     

Ellipsometry as a tool to study the adsorption behavior of synthetic and biopolymers at the air–water interface

The application of ellipsometry of the study of the adsorption behavior of proteins and synthetic macromolecules at the air-water interface has been investigated. It is shown that for macromolecules the amount adsorbed per unit area, Γ, as determined by ellipsometry, only has a well-defined physical meaning if the refractive-index increment remains constant up to high concentrations present in the adsorbed layer. It has been found experimentally that this conditioned is fulfilled for proteins. The ellipsometric Γ values of some protein agree satisfactorily with those obtained by two independent techniques has been used to investigate the adsorption from solution of κ-casein, bovine serum albumin, and polyvinyl alcohol. For bovine serum albumin, Γ reaches a plateau value of 2.9 mg/m² for concentrations ≥ 0.05 wt%. The thickness of the adsorbed molecules. For κ-casein, Γ steadily increases with increasing centration and multilayers are formed. The technique provides interesting information on conformational changes in adsorbed macromolecules, on the rate of the process, and on the conditions under which these occur.     

The Suitability of Jatropha Seed Press Cake as a Biosorbent for Removal of Hexavalent Chromium from Aqueous Solutions

Jatropha seed press cake (JPC), a biodeisel waste, was investigated for its use as biosorbent for Cr(VI) removal from wastewater. The acid-pretreated biomass exhibited 1.9-fold higher biosorption efficiency for Cr(VI). The Cr(VI) biosorption efficiency was found to increase with decrease in pH of aqueous medium. The adsorption capacity of biosorbent for Cr(VI) increased with increasing concentration of Cr(VI). The biosorption of Cr(VI) by acid-treated JPC followed a pseudo-second-order kinetics. The results of equilibrium studies showed that the biosorption process fitted the Langmuir isotherm model, with a maximum adsorption capacity of 22.727 mg of Cr(VI)/g of biosorbent at 30°C. The activation energy was found to be 27.114 kJ/mol, suggesting that the adsorption process was mainly a physical process. The important thermodynamic parameters of adsorption (ΔG, ΔH, andΔS) were determined, which indicated that the Cr(VI) sorption by JPC is a spontaneous and endothermic process.     

柴达木沙漠链霉菌S10T阿糖腺苷的大孔树脂分离工艺优化与结构鉴定

为了获得具有药用价值的活性天然产物,采用4种大孔吸附树脂对柴达木沙漠链霉菌(Streptomyces qaidemensis)S10^T发酵液进行静态吸附和解吸实验,优化分离工艺。结果显示,AB-8型树脂具有良好的吸附和解吸性能,该树脂对柴达木沙漠链霉菌S10^T发酵液中的活性天然产物吸附工艺为发酵液pH值9,吸附时间4 h,洗脱液70%甲醇溶液。经正向硅胶、反相硅胶和葡聚糖凝胶Sephadex LH-20分离得到了一个化合物,¹H-NMR和¹³C-NMR结合高分辨质谱(LC-HR-MS)鉴定该化合物为阿糖腺苷(vidarabine),是一种具有抗病毒活性的核苷类抗生素,并简单探究了其在柴达木沙漠链霉菌中的生物合成过程。     

Optical absorption investigations for efficient crystal violet dye removal from wastewater via carbon nanotubes:Montmorillonite-based nanocomposite

The current study reports a facile method to fabricate functionalized multi-walled carbon nanotubes and montmorillonite clay mineral-based nanocomposite matrix and its detailed characterization using spectroscopic and morphological techniques. The nanocomposites have been studied for their potential applications in the treatment of contaminated water using batch adsorption studies. The investigations conducted using optical absorption spectroscopic measurements for the adsorption process indicate that the nanocomposite matrix can effectively remove almost 98% of the dye from aqueous solution. The nanocomposites have showed fast and strong adsorption behaviour for the dye with the maximum adsorption capacity (q_m) of ~467.3 mg g⁻¹ in 25 min. The experimental data at equilibrium were also correlated with the theoretical adsorption isotherm and kinetic models. The results demonstrate that the experimental data fits well to the Freundlich adsorption isotherm model and conforms to second-order kinetics. Furthermore, the nanocomposite exhibits good recyclability without any marked decrease in the adsorption performance even after five adsorption cycles of usage which indicates its potential application as reusable adsorbent for the efficient removal of hazardous dyes from contaminated water.     

An evaluation of the rate constants for the adsorption of the defective phage PBS Z to Bacillus subtilis

The adsorption of the defective phage PBS Z of Bacillus subtilis has previously been assumed to proceed in two steps, a reversible adsorption of extended phages followed by contraction of the adsorbed particles (Steensma, 1981a). This model, also used for other phages, explained the biphasic character of the adsorption curve, but a discrepancy was found between the calculated and observed concentrations of adsorbed, extended phages. Computer simulations indicated that this might be caused by inhomogeneity of the phage preparations with respect to their adsorption properties and that in that case other models would also fit the experimental data. Discrimination between the models was not possible on the basis of the available information on PBS Z and it was therefore concluded that the values reported previously for the rate constants (Steensma, 1981a) should be used with caution.