Adsorption of phenols onto macroreticular resin particles

Experimental uptake curves wore collected by a shallow bed technique at 298.2 K. Adsorbent particles employed were macroreticular (MR) resins and adsorbates were phenol and its derivatives. From the uptake curves and equilibrium data obtained by the so-called, batch bottle technique, equilibrium and kinetic parameters were determined and the effects of functional groups within both adsorbate molecules and adsorbent particles on those parameters are discussed. From the results, it became clear that physical and chemical properties, surface area of adsorbent functional group, and solubility of adsorbates affected adsorption equilibria. Also, nitro-functional groups seemed to hinder adsorption equilibria and kinetics. Results can be explained by the resonance effects of functional groups.     

Adsorption of phenols in a fixed-bed adsorber charged with polymeric sorbents

Adsorption of phenols onto a polymeric sorbent, SP206, was carried out in a fixed-bed adsorber and the saturated bed was regenerated by using 0.05 N sodium hydroxide solution to get information for a cyclic adsorption process as an alternative for the activated carbon process. Furthermore, a simple dynamic model for simulating the dynamic behavior of multicomponent adsorption systems was proposed based on both the ideal adsorbed solution theory (IAST) for multicomponent equilibria and the linear driving force approximation (LDFA) for intraparticle mass transport. In spite of its simplicity, the proposed dynamic model successfully simulated breakthrough curves up to a three-species mixture.     

Adsorption and desorption of phenylalanine and tryptophane on a nonionic polymeric sorbent

Adsorption equilibrium of two amino acids — Phenylalanine (Phe) and Tryptophane (Trp) — onto nonionic polymeric sorbent, SP850 was studied under various pH values and temperatures. Adsorption equilibrium data of two amino acids on SP850 were fitted well with the Langmuir and Freundlich equations. Thermodynamic parameters such as Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were evaluated by applying the Van’t Hoff equation. Besides, adsorption kinetic of Phe was also investigated. Adsorption kinetic data were analyzed using the models of pseudo-first-order, pseudo-second-order and intraparticle diffusion. The results indicated that the pseudo-second-order model was more successful in simulating the adsorption kinetic data and the adsorption rate was mainly controlled by the diffusion rate in adsorption process. On the other hand, desorption studies were conducted by employing different organic solvents such as isopropyl alcohol (IPA), ethanol, and methanol. It was found that IPA was the best material for desorbing amino acid on the polymeric sorbent.     

Adsorption and desorption dynamics of amino acids in a nonionic polymeric sorbent XAD-16 column

A separation technique for amino acids, phenylalanine and tryptophan, from aqueous solution was studied in a column that was packed with a polymeric resin, XAD-16. This technique is based on a cyclic operation that has three typical steps such as adsorption, desorption, and washing. In particular, the desorption step for amino acids from the resin was carried out by using organic solvents, isopropyl alcohol and methanol. The desorption mechanism was assumed to be a competitive adsorption between amino acids and solvents, and the ideal adsorbed solution theory (IAST) based on the Langmuir equation as a single component isotherm was used in describing multicomponent equilibria. Adsorption and desorption breakthrough curves of the two amino acids were measured under various experimental conditions such as concentration, flow rate, and column length, in order to check the feasibility of the resin as a medium for the separation of amino acids. It was found that this separation technique could be a promising one for this purpose. Also, a simple dynamic model was formulated to describe both adsorption and desorption breakthrough curves of amino acids.     

Adsorption/desorption of phenols onto granular activated carbon in a liquid–solid fluidized bed

The adsorption/desorption of phenols in aqueous solution onto coconut‐shell granular activated carbon (GAC) in a liquid–solid fluidized bed adsorber approaching saturation capacity was investigated. Experiments were carried out using a 20 mm id adsorber under a variety of operating conditions including GAC particle sizes (0.937, 1.524 mm), GAC mass (12, 24 g), influent phenol concentration (0.367–1.071 mmol dm⁻³), surface loading of GAC (2.0, 2.5 mmol g⁻¹) and liquid flow rate (0.15, 0.2, 0.35 dm³ min⁻¹). The effect of repetitive adsorption/desorption cycles on the adsorption capacity has also been examined for phenol/GAC systems. The model based on the external mass transfer with film‐surface diffusion, surface adsorption equilibrium and internal mass transfer was proposed to simulate the breakthrough curves of the phenol adsorption/desorption process. Using the experimentally measured Langmuir isotherm equilibrium parameters in the model has been found to describe reasonably well the experimental results. © 1999 Society of Chemical Industry     

三种阴离子聚合物分散剂在吡虫啉颗粒表面的吸附热力学和动力学

通过振荡吸附实验研究了三种阴离子聚合物分散剂Morwet D-425、GYD-1252和LG-3在农药吡虫啉颗粒表面的吸附热力学和动力学,对比分析了三种分散剂吸附性能的差异。吸附等温线符合Langmuir和Freundlich吸附等温方程,前者拟合程度较高。由ΔG<0、ΔH<0、ΔS>0可知该吸附为自发、放热、熵增过程,高温不利于吸附进行,|ΔH|<40 kJ·mol^-1表明该吸附为物理吸附。通过对比可知Morwet D-425吸附稳定性最高,受温度影响最小;LG-3吸附稳定性最低,受温度影响最大;GYD-1252吸附稳定性介于两者之间。吸附动力学曲线最符合伪二级动力学方程,吸附过程包括颗粒外传质扩散和表面吸附两个步骤,不包括颗粒内微孔扩散。吸附速率由大到小的顺序为Morwet D-425、GYD-1252、LG-3.通过XPS测定不同温度下分散剂吸附层厚度可知Morwet D-425在吡虫啉颗粒表面的吸附致密,吸附层厚度较低但随温度升高变化很小;GYD-1252和LG-3在吡虫啉颗粒表面吸附疏松,低温下吸附层厚度较高但随温度升高明显降低。     

A simple model for regeneration of a polymeric sorbent saturated with phenol

Regeneration of spent resin particles is a crucial step in a cyclic adsorption process for removal of phenolic species from wastewater. A simple: model is developed for simulating the regeneration behavior in finite batch adsorbers. It is then applied to the regeneration by sodium hydroxide solutions, of a polymeric sorbent, SP206, saturated with phenol. Analytic solutions of the model are obtained based on both the reaction front assumption and the quasi-steady state approximation in the resin particle, considering the fact that sodium hydroxide reacts with phenol very quickly.     

Adsorption of copper on specifically modified polyamide sorbent

A novel, specific sorbent based on polyamide covalently immobilized with dead yeast cells by glutaraldehyde was prepared and characterized. This sorbent exhibits a high capacity for metal complexation based on multifunctional groups of dead cells, as well as a good stability for reuse based on the crosslinking agent, glutaraldehyde. The Cu²⁺ sorption characteristics of the polyamide modified with immobilized dead cells were studied and compared to those of the polyamide chemically modified without cells. The adsorption capacity of specifically modified polyamide was about 19‐fold higher than the chemically modified polymer. The adsorption isotherms of Langmuir and Freundlich for the new specific sorbent were determined. The effect of pH, temperature and co‐ions (Zn²⁺, Pb²⁺, Co²⁺, Ca²⁺ and Mg²⁺) on the Cu²⁺ sorption capacity were studied. The effectiveness of heavy metal desorption and the coefficient of recovery of sorption ability were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 80–85, 2003     

Immobilization of glucose oxidase and acetylcholinesterase onto modified polyamide sorbent

Two types of polyamide (PA) sorbents with high specific area were prepared. The effects of solvent type, concentrations of formic acid, and polymer on the porosity characteristics were studied. The sorbent with the highest specific area was obtained by using C₂H₅OH—HCOOH solvent (60% HCOOH) and the rest of the experiments were carried out with this type of sorbent. The possibility of applying the PA sorbent as carrier for immobilization of glucose oxidase (GOD) and acetylcholinesterase (AChE) was investigated. In order to increase the active groups content (necessary for enzyme immobilization), the sorbent was modified with dimethylaminoethylmethacrylate (DMAEM) and 2-acrylamido-2-methylpropensulfonic acid. The amount of the active groups introduced during the modification and the degree of hydrophilicity were determined. The quantity of bound protein and relative activity of GOD and AChE immobilized onto unmodified and modified sorbents were studied. Optimum pH and temperature of the immobilized GOD and AChE were also determined. The influence of three phosphoroorganic compounds on the activity of the immobilized AChE was investigated. Tetrachlorvinvos was found to be the strongest inhibitor, while AChE immobilized onto PA sorbent modified with DMAEM showed the highest stability. The possibility of using immobilized GOD and AChE in a flow-injection system for determination of the concentrations of glucose and phosphoroorganic compounds was studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:323–329, 1998     

Adsorption of Rhodamine B onto O-Carboxymethylchitosan-N-Lauryl

The adsorption of a cationic dye (rhodamine B; RB) on O-carboximethyl-N-acetylated (L-CMCh) in aqueous solution was investigated. The effect of the process parameters such as the contact time, pH, and temperature are reported. Both temperature and pH influence dye adsorption. To determine the adsorption capacity, the equilibrium adsorption data were analyzed by the Langmuir, Langmuir-Freundlich, and Redlich-Peterson isotherm models. The results showed better agreement with the Langmuir-Freundlich model than the other models. The maximum adsorption capacity of RB for L-CMCh was determined as 38.5 mg g^?1 at pH 8.5 and 25°C. The kinetic results follow a pseudo-second-order rate equation. The activation energy value for adsorption of RB on L-CMCh was found to be 52.0 kJ mol^?1. The negative values of Gibbs free energy and enthalpy show the adsorption to be spontaneous and exothermic. The negative value of the enthalpy for adsorption of RB onto L-CMCh shows the adsorption to be exothermic.     

Macroporous polymeric sorbents with high selectivity for separation of phenols

A polymeric sorbent with high selectivity and capacity for phenols in aqueous stream was synthesized based on 5-amino-2-methoxyphenol functionalized poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate), P(GMA-TRIM)-AMP. In addition to sorption, the materials were studied using solid-stated NMR, Fourier transform infrared (FT-IR), elemental analysis, and scanning electron microscopy (SEM). Well-defined internal micrometer-sized spheres of P(GMA-TRIM)-AMP have stable macropore inner structures surrounded by a thin outer shell. The sorbent has functional groups that are similar in chemical structure to 4-propyl-2-methoxyphenol, PMP, and show high selectivity in removal of PMP from glucose- and xylose-containing monosaccharides solutions in bioethanol production without the loss of the saccharides. The sorbent could also be used to separate phenol and 4-chlorophenol from waste water that contained concentrations of phenols in the ppm range. The sorbent is easily regenerated, has good durability and reusability. It was regenerated and reused at least 10 times without loss in sorption behavior.     

Application of ductile polymeric coatings onto graphite fibers

Thin, high molecular weight copolymers have been applied to the surfaces of commercial, 8 micron diameter, graphite fibers by electropolymerization. Random copolymers were obtained, and the process appears to be consistent with the rules of standard free radical copolymerization. Coating thickness, T_g, and modulus can be systematically controlled. Very preliminary mechanical property measurements indicate a substantially improved impact strength and reduction in the interlaminar shear strength. These effects may be related to poor adhesion between the interlayer and the epoxy resin, however, which may be corrected by use of a “top layer” of appropriate composition.     

Nitrogen Adsorption onto Silane-Derived Silicon Powders

Nitrogen chemisorption onto silane-derived silicon powder was studied at atmospheric pressure in N₂, using thermogravimetric analysis (TGA) to examine the reaction kinetics and using Fourier transform infrared (FTIR) spectroscopy to characterize the surface chemistry. Above 700°C the initial Si—H surface is transformed to an Si—N surface; the latter is characterized by a broad infrared absorption band at 830 to 840 cm⁻¹. Isothermal TGA data exhibit a sigmoidal shape which is apparently caused by simultaneous hydrogen desorption and nitrogen adsorption. By holding samples under vacuum at 900°C before nitridation the adsorption reaction was isolated. The kinetics of this reaction are well described by a simple first-order model with an activation energy of 140 kJ/mol, and with very low sticking probabilities (between 10⁻¹³ and 10⁻¹⁰).     

Adsorption of pesticides on porous polymeric adsorbents

The adsorption of herbicides alachlor, amitrole, trifluralin and prometryn on porous polymeric adsorbents has been studied. Two adsorbent resins were investigated, the highly hydrophobic Amberlite XAD-4 (polystyrene-divinylbenzene copolymer) and the functionalized more hydrophilic XAD-7 (nonionic aliphatic acrylic polymer). Equilibrium adsorption experiments using buffered aqueous solutions were conducted to estimate the types of isotherms and their parameters. The effect of chemical composition and structure of the herbicides, was investigated. The pH range studied was 3-6.5, the temperature range was 288-303 K and the ionic strength was maintained at 0.01 M. Adsorption isotherms seemed generally to approach the Langmuir or Freundlich isotherm model and can be characterized by temperature and pH dependent apparent adsorption equilibrium constants, characteristic of the adsorbent-adsorbate system. By studying the dependence of temperature of this adsorption constant, heats of adsorption have been estimated from van’t Hoff law. In the case of trifluralin and prometryn adsorption on both resins and amitrole adsorption on XAD-4 resin, the heats of adsorption were negative (8.1-33.6 kcal/mol). On the contrary, in alachlor adsorption on both resins and amitrole adsorption on XAD-7 resin, the estimated heats of adsorption were positive.     

Adsorption of humic acid onto pillared bentonite

Pillared bentonite, a clean and cost-effective adsorbent with high specific areas of 111.3 m²/g and high basalspacing of 1.98 nm, was prepared for the removal of humic acid from water. It is effective for the removal of humic acid with a high adsorption capacity of 537 mg/g, and adsorption is favored under acid conditions. Adsorption is dependent on ionic strength and dissolved NaCl enhanced adsorption. Over 97% removal was observed under natural pH conditions from humic acid solutions containing 10 mg/L Ca²⁺ or Mg²⁺, which suggests that pillared bentonite can be an effective adsorbent for the removal of humic acid for drinking water purification. Pillared bentonite can be regenerated with NaOH, and the regeneration efficiency reaches 83% and 85% when the concentration of NaOH reaches 0.025 and 0.05 mol/L. The mechanism for adsorption of humic acid to pillared bentonite is discussed.     

阴-阳离子有机膨润土对甲基橙的吸附性能

以阴、阳离子表面活性剂--十六烷基三甲基溴化铵(CTMAB)和十二烷基硫酸钠(SDS)复配改性膨润土,制备出了阴-阳离子有机膨润土;研究了甲基橙在阴-阳离子有机膨润土上的吸附行为.结果表明,阴-阳离子有机膨润土吸附染料甲基橙的速率和吸附量均较大,其吸附动力学行为遵循Langmuir方程所描述的规律.平衡吸附量qe与平衡浓度Ce之间的关系符合Freundlich和Langmuir等温吸附方程.阴-阳离子有机膨润土对染料甲基橙的吸附效果要好于活性炭,可代替活性炭用于染料废水的吸附脱色处理.     

Adsorption Equilibrium and Kinetics of Toxic Dye-Erythrosine B Adsorption onto Montmorillonite

Erythrosine B is extensively used in the textile and food industry. It is reported to be a neurotoxicant and is carcinogenic in nature. It can induce DNA damage in the gastrointestinal organs even at low doses. In this study, adsorption efficiency of montmorillonite (MMT) has been investigated for the removal of erythrosine B (EB) from aqueous solution. The batch adsorption model was developed to predict the equilibrium adsorption capacity with respect to the pH of the dye solution, contact time, initial dye concentration, and adsorbent dosage. A maximum monolayer adsorption capacity of 578.03 mg/g was obtained at the original pH (7.5) of the aqueous dye solution within 5 minutes of contact time. It was found that the Langmuir adsorption isotherm yielded the most favorable representation of the adsorption behavior of EB. The dye was found to be chemisorbed on the adsorbent as confirmed by the FTIR spectral analysis. Although anionic in nature, the dye was found to be intercalated into the clay interlayers as suggested by the X-ray diffraction studies.     

Adsorption of casein onto alkali treated bentonite

The adsorption measurements of casein onto alkali treated bentonite were performed at room temperature and fixed pH (11.8) with an object to study the mode of casein adsorption at the alkali treated bentonite surfaces. The adsorption isotherm was found to have a Langmuir nature. The adsorption was pH dependent and increased with a decrease in temperature. The adsorption was quite sensitive to the presence of Cl⁻, SO, and PO ions and showed many interesting variations with increasing concentrations of the added anions. Various kinetic and adsorption parameters such as the adsorption coefficient, rate constants for adsorption and desorption, diffusion constant, and penetration rate constant were calculated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1656–1663, 2000     

改性海泡石对亚甲基蓝的吸附性能

对海泡石进行了硫酸改性、高温改性、硫酸/高温改性,以亚甲基蓝为吸附对象,研究了改性方法对海泡石吸附性能的影响,对各改性海泡石进行了孔径、孔体积等表征. 结果表明,3种改性方法中,硫酸/高温改性对海泡石吸附性能的提高效果最好,吸附量比改性前提高47.8%,达41 mg/g,吸附等温线符合Langmuir方程. 硫酸/高温复合改性后的海泡石平均孔径达9.74 nm,孔体积达7.064′10-2 cm3/g,分别提高117%和92.6%. 对改性海泡石对亚甲基兰的吸附机理进行了探讨.