Adsorption and controlled release of Chlortetracycline HCl by using multifunctional polymeric hydrogels

Adsorption and controlled release of Chlortetracycline HCl to and from multifunctional polymeric materials (HEMA/MAA) hydrogels were investigated. P(HEMA/MAA) hydrogels were synthesized by gamma radiation-induced copolymerization of 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA) in aqueous solution. The influence of copolymer composition and pH value of the surrounding medium on the type of water diffusion into the glassy polymer were discussed. Drug, Chlortetracycline HCl containing hydrogels, with different drug concentration to polymer ratios, was loaded by direct adsorption method. The influence of MAA content in the gel on the adsorption capacities of hydrogel was studied. Chlortetracycline HCl adsorption capacity of hydrogels was found to increase from 8 to 138 mg Chlortetracycline HCl per gram dry gel with increasing amount of MAA in the gel system and drug concentration. The effect of pH on the releasing behavior of Chlortetracycline HCl from gel matrix was investigated. In vitro drug release studies in different buffer solutions show that the basic parameters affecting the drug release behavior of hydrogel are the pH of the solution and MAA content of hydrogel.     

Use of poly(N,N-dimethylacrylamide-co-sodium acrylate) hydrogel to extract cationic dyes and metals from water

Poly(N,N-dimethylacrylamide-co-sodium acrylate) hydrogel, which bears negatively charged –COO⁻ groups was used to extract organic or inorganic solutes from water. Some model dyes and metal ions have been studied. Cationic dyes are strongly adsorbed and retained by the polymer while adsorbance of hydrophobic dyes was very low and that of anionic dyes was negligible. Both maximum adsorption and equilibrium binding constant varied from one cationic species to the other depending on the chemical structure of the dye, the presence of functional chemical groups and the hydrophobic–hydrophilic balance. In the case of metal cations, adsorption depended on valence. The hydrogel can be regenerated in an aqueous phase of low pH and thus be reused in several adsorption procedures.     

Kinetics of copper dissolving in the water solution of polyacrylic acid or its copolymers with acrylonitrile and hydrogen peroxide

During the coating of metal plates by carboxyl-containing polymers from their solutions or dispersions, adsorption of the polymer onto the surface and oxidation of the metal by oxygen take place. Adsorption of polyacrylic acid and its copolymers with acrylonitrile at the copper surface and kinetics of copper dissolving in the presence of carboxyl-containing polymers and hydrogen peroxide have been investigated. The adsorption of polymers at the surface of the copper powder passes through a maximum when the content of acrylonitrile in copolymers rises. The rate at which copper dissolves increases with increased polymer concentration in solution, reaching a constant value, and does not depend on the hydrogen peroxide concentration. The rate at which copper dissolves depends on the rate of copper oxidation by hydrogen peroxide in the adsorption layer and the rate of polymer desorption. The increase of the solution pH leads to a decrease in the adsorption of polyacrylic acid at the copper surface and the rate at which copper dissolves in the presence of hydrogen peroxide.     

PREPARATION OF SURFACE ION-IMPRINTED ATTAPULGITE-SUPPORTED POLYMER AND ITS ADSORPTION BEHAVIORS OF Sr（II）

The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the preparation of a new attapulgite-supported organic-inorganic hybrid polymer for selective separation of Sr（II） from aqueous solution. The prepared polymer was characterized with SEM, IR and XRD. The results showed that as a sorbent, it had good configuration and binding sites. Its adsorption behaviors for Sr（II） was investigated by FAAS and ICP-AES. The effects on adsorption capacities, including pH, quiescent time, and adsorbent amount were discussed, and the adsorption isothermal curve was obtained. Then the Kd a parameter estimating relative adsorbability, was conducted to study the selectivity towards Sr（II） of the prepared polymer. Under the optimum conditions, the ion-imprinted polymer offered a fast kinetics for the adsorption of Sr（II） and the maximum capacity was 12.9mg/g. The Kd and K parameters estimating relative adsorbability towards target ion, suggested that selective recognition of the ion-imprinted polymer towards Sr（II） was much higher than that of the non-imprinted polymer and attapulgite. Furthermore, the ion-imprinted polymer is of great regeneration capacity. The prepared functional polymer was shown to be promising for selective preseparation and enrichment of trace Sr（II） in environmental samples.     

Adsorption of block polyampholyte micelles in monolayers at the silicon water interface

 The adsorption of the diblock polyampholyte poly (methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate) from aqueous solution on silicon substrates was investigated as a function of polymer concentration and pH. Dynamic light scattering and electrokinetic measurements were used to characterize the polyampholyte in solution. The amount of polymer adsorbed was determined by ellipsometry and lateral structures of the polymer layer were investigated by scanning force microscopy. The amount of polymer adsorbed was found to be strongly influenced by the pH of the polymer solution, while the size of the polyampholyte micelles adsorbed on the surface was hardly affected by pH during adsorption. From investigations by scanning force microscopy well-seperated micelles were seen in the dried monolayers adsorbed directly from solution. The structures at the surface are correlated to structures in solution, and the adsorbed amount depends on the relative charge of the micelles and the surface. Received: 13 September 1999 Accepted in revised form: 8 December 1999     

Studies of 85Sr adsorption on grain fractions of soil

Summary The adsorption of ⁸⁵Sr on grain fractions isolated from four different types of soil was studied. The influence of pH, concentration and presence of calcium ions on the process was investigated. The adsorption process depends mainly on pH, grain size of the solidandthe type of soil. Ca²⁺in the system is lowering the adsorption of ⁸⁵Sr.     

Adsorption of Anionic Dyes onto Chitosan-modified Diatomite

The purpose of this work is to study the possibility of anionic dyes Reactive Red M-8B(RR) and Direct Green B(DG) adsorbed on chitosan-modified diatomite. The characteristics of adsorbent, adsorption isotherms and the influence of adsorption time, temperature and pH were researched in this work. The results show that the mo- dified diatomite had a much better adsorption capability than the natural diatomite. The adsorption capacities of chitosan-modified diatomite for RR and DG were 94.46 and 137.0 mg/g, respectively. Both adsorption time and adsorption temperature provided a positive effect on the dye adsorption. Within the experimental pH range, the adsorbance was enhanced at lower pH but reduced sharply at high pH. On the basis of the experimental results and discussion, electrostatic attraction is considered as the main mechanism of this chemisorption.     

Preparation of a novel lysozyme molecularly imprinted polymer using uniformly sized functionalized poly(glycidyl methacrylate) microspheres as the matrix and its application to lysozyme purification

A novel lysozyme imprinted polymer based on uniformly sized functionalized poly(glycidyl methacrylate) microspheres has been synthesized in aqueous solution using the surface imprinting technique. The microspheres were modified with hydroxyl ethyl methacrylate to allow for the introduction of polymerizable double bonds, with β‐cyclodextrin and acrylamide being grafted onto the surface as functional monomers. The selective recognition properties of the resulting molecularly imprinted polymers (MIPs) were investigated by HPLC. Various factors were also investigated in terms of their influence on the retention behaviors of the imprinted polymers, including the pH and salt concentration of the mobile phase. The binding capability properties of the MIPs were evaluated, and the P_GMA/EDMA‐MIPs showed a high adsorption capacity for lysozyme. Furthermore, this MIP was used to separate and enrich lysozyme from egg whites. The results revealed that the lysozyme surface‐modified MIP could be used to efficiently separate and purify lysozyme from egg whites. Copyright © 2013 John Wiley & Sons, Ltd.     

微塑料富集金属铅元素的能力与特征分析

以微塑料为载体,考察了其对溶液中铅离子的富集能力。首先利用2%HNO_3为解吸溶液,并用超声波仪进行辅助解吸,然后用电感耦合等离子体质谱仪(ICP-MS)测定其吸附的铅含量,从而研究微塑料吸附铅离子的能力。对微塑料的材质、吸附时间、粒径、离子浓度、选择性以及共存离子等进行了考察,分析了微塑料吸附铅离子的特征。实验结果表明:不同材质的微塑料对铅离子的吸附能力不同,其中聚氯乙烯(PVC)、聚丙烯(PP)吸附量最高,分别达到1.32μg/g和0.63μg/g。微塑料粒径越大,其对铅离子的吸附量越低。随着吸附时间和铅离子浓度的增加,微塑料对铅离子的吸附效率出现先升后降的趋势。共存离子实验表明,当溶液中存在其他离子时,不同材质的微塑料对铅离子的吸附能力受到不同程度的影响,当铅离子和铜离子共存时,2种离子存在竞争性吸附现象。该文探索了微塑料对铅离子的吸附特性,可为深入研究海洋中微塑料富集重金属及其环境行为提供理论基础。     

Development of molecularly imprinted polymeric nanofibers by electrospinning and applications to pesticide adsorption

Novel polystyrene‐based molecularly imprinted polymer nanofibers were synthesized through the electrospinning technique. The molecularly imprinted polymers were prepared using a non‐covalent approach and atrazine as template. For comparison, nonimprinted polymer nanofibers were also synthesized. The morphology of the synthesized nanofibers was characterized using scanning electron microscopy. The adsorption of pesticides, atrazine, atrazine desisopropyl, atraton, carboxin, linuron, and chlorpyrifos was studied under equilibrium (batch) conditions. To describe the adsorption capability of the synthesized polymers, Langmuir and Freundlich models were used. The Freundlich model provided a better mathematical approximation of the sorption characteristic for polymers nanofibers. To evaluate the adsorption capacity in the presence of interferents experiments on river water samples spiked with a mixture of six pesticides were also performed. The results obtained for the highest concentration levels investigated, show a greater amount of pesticide adsorbed on molecularly imprinted polymers and non‐imprinted polymers compared to those obtained using commercial stationary phases used as reference.     

Sorption behavior of acidic herbicides on carbon nanotubes

Carbon nanotubes and graphitized carbon are investigated as adsorbents for solid phase extraction of dicamba and 2,4,5-T, two phenoxyalkanoic acid herbicides. These adsorbents have much greater adsorption capability than that of C₁₈ bonded silica, which was also tested for comparison studies. The adsorption capacity increases remarkably at lower pH of the sample solution. Freundlich isotherms were applied to analyze the data. Our studies suggest that carbon nanotubes have great potential applications in environmental analysis.     

氨基功能化纳米Fe3O4磁性高分子吸附剂对废水中Cr(VI)的吸附研究

采用分散聚合法通过共聚、开环反应, 对纳米Fe3O4进行表面功能化修饰, 得到富含NH2官能团的纳米磁性高分子复合材料. 通过透射电镜(TEM)、振动样品磁强计(VSM)、热重差热分析(TGA)、X射线衍射(XRD)、红外光谱(IR)等对其进行表征, 着重研究了其作为吸附剂对Cr(VI)的吸附性能. 结果表明: 该吸附剂对Cr(VI)的吸附能在10 min内达到平衡; 废水溶液pH值能显著影响吸附剂对Cr(VI)的吸附效果, pH为2.5时效果最佳. 废水中Cr(VI)的初始浓度、吸附时间、温度等因素对吸附效果均有不同程度的影响. 结合相应pH值下Cr(VI)的形态分布, 探讨了这种新型材料对Cr(VI)的吸附机理. 结果表明: 其吸附机理及吸附容量与废水中Cr(VI)的离子形式有关; 吸附过程以离子交换与静电引力为主. 等温吸附数据符合Langmuir模型, T＝308 K, pH＝2.5, V＝40 mL时, 吸附剂的饱和吸附容量qm＝25.58 mg/g. 吸附为吸热过程, 焓变ΔH＝8.64 kJ/mol.     

Adsorption of an amphipatic copolymer on a kidney dialysis membrane

We have studied the adsorption of a copolymer of acrylonitrile and methacrylate of nonaethyleneglycol on a kidney dialysis membrane, which contains mostly nitrile groups. The kinetics study reveals at first a rapid increase of the adsorbance, followed by slow variations suggesting rearrangements at the interface. The isotherms do not present a true plateau at high concentration. The high adsorbance observed at low pH or high salt concentration could be related to the ability of polyethyleneoxide to form a complex with cations.     

胺化木质素对水中硝基苯吸附性能的研究

含硝基苯的工业废水对环境造成了严重的污染.本文用环氧氯丙烷、乙二胺对碱木质素进行改性制备胺化木质素,详细研究了溶液pH、接触时间、温度、浓度等因素对胺化木质素吸附水溶液中硝基苯性能的影响.结果表明:溶液pH对吸附有较大的影响,吸附的最佳pH为8,胺化木质素对硝基苯吸附3h后达到平衡,与准一级吸附动力学模型有较好的拟合;...     

Polydispersity effects and the interpretation of polymer adsorption isotherms

In many cases, polymer adsorption is studied by measuring adsorption isotherms. Quite often it is found that the results are at variance with theoretical predictions. However, usually these adsorption isotherms are interpreted in terms of a single polymeric solute. Most polymers used in experimental studies are polydisperse and should be treated as mixtures. It is well established that the larger molecules in such mixtures adsorb preferentially over the smaller ones. In this paper we show that many discrepancies between polymer adsorption theory and experiment (e.g., the rounded shape of isotherms, the dependence of the adsorbance on adsorbent concentration, and the lack of desorption upon dilution) can be attributed to polydispersity. A quantitative analysis enables us to calculate isotherms for a polymer of arbitrary molecular weight distribution, provided the dependency of the plateau adsorbance on molecular weight is known. Experiments supporting the theory are reported. The fact that polymers do not desorb upon dilution with solvent is often regarded as a proof that polymer adsorption is irreversible. We show that, if a polydisperse sample is in equilibrium with an adsorbing surface, no detectable desorption may take place upon dilution. Therefore, the adsorption of polymers might well be reversible, even if desorption experiments would indicate apparent irreversibility.     

pH shifting effect on anionic dye removal by surfactant-modified sugar beet pulp: Modeling of column studies

pH shifting effect on the adsorption of anionic RBB dye was tested by using untreated and CTAB-treated SBP as adsorbent in both batch and continuous systems. Characterization of the sorbents revealed the effects of surface modification. Enhanced binding sites and more porous surface structure resulted in improved adsorption capability. Flow rate and initial RBB concentration effects were tested in packed bed column. Optimum pH value of the adsorption, which was determined as 2.0 in the batch studies with untreated SBP, shifted to 8.0 with 20 g/L CTAB treated SBP. Experimental data in column studies showed the decreasing capacity with increasing flow rate and enhanced performance with increasing inlet RBB concentration for both sorbents. Maximum capacities of the columns were found as 36.9 and 2.6 mg/g with dried SBP at pH 2.0 and 8.0, respectively, at a maximum inlet RBB concentration of 500 mg/L and a minimum flow rate of 0.8 mL/min. The highest capacity value at pH 8.0 was found as 140.0 mg/g under the same operating conditions, which reveals positive effect of the treatment on adsorptive performance. Langmuir isotherm was found to be most convenient model for the all equilibrium cases in the column. Moreover, Thomas model accurately predicted the breakthrough curves of each system. This is the first study reporting the modeling data of an anionic dye adsorption in a packed bed column by using modified SBP.     

弱碱性大孔吸附树脂对腐殖酸的吸附

研究了腐殖酸分子量对弱碱性大孔树脂吸附腐殖酸的影响, 阐明了溶液中小分子芳环化合物(苯酚)及盐含量对树脂吸附腐殖酸的影响机制. 结果表明, 树脂对低分子量腐殖酸的吸附效果要优于高分子量腐殖酸; 低浓度苯酚在溶液中可以促进树脂吸附腐殖酸, 但溶液中苯酚浓度过高会对树脂吸附腐殖酸产生抑制作用; 溶液中的盐对树脂吸附腐殖酸的影响取决于溶液的pH值.     

Factors affecting drug adsorption on beta zeolites

The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO₂/Al₂O₃ ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X‐ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity.     

ADSORPTION CHARACTERISTICS OF L-HISTIDINE ON ACTIVE CARBON

Adsorption properties of L-histidine on active carbon were studied in the paper, which are affected by the main parameters, such as the quantity percent of active carbon, pH value of the solution, the time of adsorption equilibrium and adsorption temperature. The results indicate that adsorption equilibrium time of L-his on active carbon is about 80 minutes. With the increasing of the quantity percent of active carbon, the adsorbance of L-his decreases sharply, and increases lighter after that. When the quantity percent of active carbon is 10%, the adsorbance reaches the minimum.pH value of solution and extraction temperature have great affection on the adsorption. When the pH value is higher or lower than the pI of L-his, the adsorbance is small, even zero. It is proven that the experimental equilibrium data which are obtained under the conditions of 80 ℃and pH=1.0, are fitted with the Freundlich equation: q=2.5914c0.8097. The results can provide certain references in L-his adsorption process of industrial operation.     

Interactions of quinine with polyacrylic and poly-L-glutamic acids in aqueous solutions

Drug-loaded polymers provide an attractive form for controlled drug delivery systems. A proper knowledge of polymer-drug interactions can aid in the designing of polymers for various drug-delivery applications. In this paper we have investigated the interaction of a drug such as quinine, with synthetic macromolecules such as poly(acrylic acid), PAA, and poly(L-glutamic acid), PGA, at pH 7 and 37 °C by fluorescence spectroscopy and viscometry. The analysis of the binding isotherms revealed that the association process is positive cooperative up to a threshold concentration and then it is negative. In addition, the thermodynamic parameters vary along the isotherm. Results also suggest that there is an optimum polymer to quinine ratio. Based on the viscometry results a mechanism of the interaction in which the polymer conformation plays a determinant role is proposed. Since the conformation depends on the molecular size, the architecture of the macromolecule, the effective charge and ergo the ionic strength, all these variables have been taken into account and their effect on the binding discussed.