Crosslinked Β-cyclodextrin Polymer Research Articles

A novel aminated Fe3O4/GO/carboxylated cross-linked β-CDP composite for effective sorption of cationic and anionic dyes from water

A novel adsorbent, aminated Fe3O4 (Fe3O4-NH2)/graphite oxide (GO)/carboxylated cross-linked β-cyclodextrin polymer (CDP-COOH) composite, was fabricated for influential removal of various types of dyes from waters. The morphology and structure of resulting Fe3O4-NH2/GO/CDP-COOH composite was studied by SEM, two-dimensional EDS map, FTIR, WAXD, XPS, TGA, and zeta potential meter, and its saturation magnetization was determined to be 46.3 emu/g by VSM. The maximal sorption capacities of Fe3O4-NH2/GO/CDP-COOH composite for methylene blue (MB, as a model of cationic dyes) and Congo red (CR, as a model of anionic dyes) at 303 K were 201.75 mg/g and 2211.05 mg/g, respectively, which can be mainly assigned to multiple adsorptive forces like electrostatic attractions, hydrogen bonds, host–guest self-assembly interactions, π-π electron cloud interactions, and Lewis acid-base interactions. The dye sorption by the Fe3O4-NH2/GO/CDP-COOH composite had a spontaneous nature according to the sorption thermodynamic calculation and can be well explained by pseudo-second-order model. The Langmuir and Freundlich models could explain the sorption isotherms of Fe3O4-NH2/GO/CDP-COOH composite for MB and GO, respectively. The Fe3O4-NH2/GO/CDP-COOH composite possessed many other advantages including the good sorption capability for different heavy metal ions (like Pb2+, Ni2+, and Cu2+) and organic compounds (like dichlorophenol and propranolol) as well as the good recyclability and reusability.

Cyclodextrin Polymer-Loaded Micro-Ceramic Balls for Solid-Phase Extraction of Triazole Pesticides from Water.

A citric acid cross-linked β-cyclodextrin (β-CD) polymer was synthesized and loaded on micro-ceramic balls to fabricate the solid-phase adsorbents (P-MCB) for adsorption and extraction of triazole pesticides from water. The stability of β-CD polymer and P-MCB was investigated in solutions with different pH values at different temperatures. The adsorption properties and the influence of kinetics, sorbent amount, pesticide concentration, and temperature on the adsorption capacity were evaluated. The results showed P-MCB had favorable adsorption of 15.98 mg/g flutriafol in 3.5 h. The equilibrium data followed the Freundlich equation, and the adsorption of flutriafol and diniconazole followed the second-order kinetics. The recovery rate of P-MCB for triazole pesticides in water was satisfactory, and the recovery rate was still 80.1%, even at the 10th cycle. The P-MCB had good stability, with a degradation rate of 0.2% ± 0.08 within 10 days, which could ensure extraction and recycling.

Cyclodextrin polymer networks decorated with subnanometer metal nanoparticles for high-performance low-temperature catalysis.

The synthesis of support materials with suitable coordination sites and confined structures for the controlled growth of ultrasmall metal nanoparticles is of great importance in heterogeneous catalysis. Here, by rational design of a cross-linked β-cyclodextrin polymer network (CPN), various metal nanoparticles (palladium, silver, platinum, gold, and rhodium) of subnanometer size (<1 nm) and narrow size distribution are formed via a mild and facile procedure. The presence of the metal coordination sites and the network structure are key to the successful synthesis and stabilization of the ultrasmall metal nanoparticles. The as-prepared CPN, loaded with palladium nanoparticles, is used as a heterogeneous catalyst and shows outstanding catalytic performance in the hydrogenation of nitro compounds and Suzuki-Miyaura coupling reaction under mild conditions. The CPN support works synergistically with the metal nanoparticles, achieving high catalytic activity and selectivity. In addition, the catalytic activity of the formed catalyst is controllable.

Interfacially crosslinked β-cyclodextrin polymer composite porous membranes for fast removal of organic micropollutants from water by flow-through adsorption

Persistent organic micropollutants have seriously damaged aquatic ecological equilibrium and affected human health. Conventional adsorbents are limited due to slow adsorption rate. Therefore, it’s significant to integrate adsorbent into porous membrane to develop a highly efficient continuous filtration method for water purification. Herein, β-cyclodextrin polymer (β-CDP) composite porous membranes were prepared via convenient interfacial cross-linking. The membranes combined the adsorption ability of β-CDP and the convective mass transport process of filtration membrane to quickly remove contaminants from water by flow-through adsorption. In optimized preparation conditions, the composite membrane exhibited a 100% of removal efficiency towards bisphenol A and a high treating capacity up to 440 mg m-2. The treating capacity kept nearly unchanged in acidic and neutral pH condition, while increased greatly with the addition of salts due to the salting-out effect. Also, the membrane could completely remove pollutants with ultrahigh flux up to 2500 L·m-2 h-1. In addition, the used membranes were fully regenerated by mild ethanol cleaning.

Adsorption behaviour of Eriochrome Black T from water onto a cross-linked β-cyclodextrin polymer

In this paper, a new β-cyclodextrin polymer (β-CDBEP) was successfully prepared by derivatizing with 1H-benzotriazole followed by cross-linking with epichlorohydrin. The adsorption behaviour of β-CDBEP for anionic Eriochrome Black T (EBT) was studied by batch experiments. The results showed that the highest adsorption capacity was obtained in acidic medium (pH = 5), and the pseudo-second-order model fitted well with the experimental data indicating the rate-determining step mainly determined by chemisorption. The adsorption equilibrium data followed better the Freundlich isotherm model with multi-layered adsorption compared to the Langmuir isotherm model. Thermodynamic parameters indicated that the adsorption of EBT onto β-CDBEP was an endothermic and spontaneous process, and a favorable adsorption happened at a relatively higher temperature. The combined electrostatic interactions, inclusion complexation, π-π interactions and intra-particle diffusion contributed to the adsorption of EBT onto β-CDBEP.

Characterization of EDTA-cross-linked β-cyclodextrin grafted onto Fe-Al hydroxides as an efficient adsorbent for methylene blue

The synthesis process of Fe-Al hydroxides coated with ethylenediaminetetraacetic acid (EDTA)-cross-linked β-cyclodextrin polymer (FA-ECD) and its utilization in the adsorption of methylene blue (MB) were investigated. The FA-ECD before and after adsorption was characterized by scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) analysis, Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, and X-ray diffraction (XRD). In addition, the EDTA and β-cyclodextrin contents were determined quantitatively. The optimization of several variables such as contact time, pH, initial concentration, and adsorbent dosage achieved the maximum removal percentages in mild conditions. The results revealed that the adsorption process mainly depended on the pH value and the optimal adsorption capacity of the MB was 60.71 mg/g at pH 8. Subsequently, the experimental equilibrium data at different temperatures were fitted with the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models; the Freundlich model provided the best results. In addition, the pseudo-second-order kinetic model best described the adsorption of the MB. The thermodynamic analysis proved that the adsorption process was endothermic and spontaneous.

A crosslinked β-cyclodextrin polymer used for rapid removal of a broad-spectrum of organic micropollutants from water

Organic micropollutants in aquatic environment such as plasticizer, pesticide and pharmaceuticals, have posed a serious threat to human health and are emerging as a great challenge to humanity. Traditional water treatment techniques fail to achieve high removal efficiency for low concentration of organic micropollutants. Here we demonstrate a water-insoluble crosslinked β-cyclodextrin (β-CD) polymer able to remove a broad-spectrum of organic micropollutants from water by rapid adsorption. A family of β-CD polymers (β-CDPs) were synthesized by nucleophilic aromatic substitution of β-CD hydroxyl groups and 4,4′-difluorodiphenylsulfone. The β-CDPs were used to adsorb various organic micropollutants in water by static or dynamic adsorption process. It was found that more than 99% micropollutants in water were removed by flowing the feed water through the column of β-CDPs. The results of static adsorption experiments indicated the adsorption process was fast and the adsorption capacity was very high (the maximal value was 113.0mg of bisphenol A per gram of β-CDP). The adsorption process was fitted well with the quasi-second-order kinetics and the Langmuir isothermal adsorption model, suggesting that it is mainly a chemical adsorption of monolayer. The water-insoluble characteristic of the β-CDPs is convenient for their separation from the treated solution after adsorption saturation for regeneration and reuse. The adsorption ability of β-CDPs was kept nearly unchanged after five filtration-regeneration cycles.

Facile synthesis, characterization, and adsorption properties of Cd (II) from aqueous solution using β-cyclodextrin polymer impregnated in functionalized chitosan beads as a novel adsorbent

This study explores the adsorption capacity of carboxymethyl-β-cyclodextrin (CMβ-CD) functionalized chitosan (CS) impregnated with water-insoluble epichlorohydrin cross-linked β-cyclodextrin polymer (β-CDP) to yield CS-β-CDP-CMβ-CD composite beads for the removal of toxic Cd (II) ions from aqueous solutions. Characterization of the adsorbent was performed with XPS, FTIR, NMR, BET and SEM. The synergistic effect was expected and found at removing Cd (II) with a sorption capacity exceeding 378mgg−1 (approximately 3.37mmolg−1), which is higher than any other existing technology. The removal of Cd (II) was found maximum at pH 6.5. The rate reduction can be expressed by pseudo-second-order reaction kinetics. Thermodynamic parameters such as the enthalpy (ΔH0), entropy (ΔS0), and free energy change (ΔG0) suggest the endothermic adsorption of Cd (II) in solution. The activation energy was calculated to be 65.62kJ mol−1 indicating a chemisorption process. The regeneration and reusability of the adsorbent were found suitable for in situ application of this technology for Cd remediation. The Langmuir isotherm model, which is effective for analyzing equilibrium data, indicated both monolayer adsorption and chemisorption. The intraparticle diffusion model indicated both film diffusion and intraparticle diffusion as the rate limiting steps. Thus, the synthesized CS-β-CDP-CMβ-CD beads showed good adsorption selectivity for Cd (II) having excellent regeneration and reusability.

Divinyl Sulfone Cross-Linked β-Cyclodextrin Polymer as New and Effective Corrosion Inhibitor for Zn Anode in 3.5 M KOH

The inhibition behavior of the divinyl sulfone cross-linked β-cyclodextrin polymer (βCDS-P) in 3.5 M KOH in the temperature range 25–55 °C on Zn anode was studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Results showed that, the inhibition efficiency increased with the increase in the concentration of inhibitor and the best inhibitor efficiency was reached with 250 ppm. The results also showed that the inhibition efficiency decreased with the increase in temperature. The inhibition was assumed to occur via adsorption of βCDS-P on the Zn surface which could be approximated by Langmuir adsorption isotherm model. On the other hand, the corrosion potential (E corr) slightly shifted to more negative values. This indicated that the presence of the inhibitor had a positive effect on charge efficiency and self-discharge. X-ray spectroscopy analysis (EDX) and scanning electron microscopy observations confirmed the presence of a good protective film on the Zn surface.

Adsorption kinetics and thermodynamics of water-insoluble crosslinked β-cyclodextrin polymer for phenol in aqueous solution

A water-insoluble β-cyclodextrin (β-CD) polymer was synthesized by reacting β-CD with hexamethyl- ene diisocyanate, and its adsorption kinetics and thermodynamics for phenol from aqueous solution was investi- gated. The kinetics of adsorption followed the pseudo-second-order model and the adsorption isotherms could be well fitted by the Freundlich adsorption equation. The values of thermodynamic parameters demonstrated that the adsorption was a physisorption in a spontaneous and exothermic process.

Adsorption Behavior of &lt;i&gt;β&lt;/i&gt;-Cyclodextrin Polymer to Phenol in Aqueous Solution

Removal of low concentration of phenol from aqueous solutions through the adsorption process by using crosslinked β-Cyclodextrin polymer (β-CD polymer) was investigated. The effects of contact time, sodium chloride content, contact temperature and initial concentration of phenol in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results show that β-CD polymer on the adsorption of phenol balanced after 6h. The adsorption process was apparently influenced by sodium chloride content, contact temperature and initial phenol concentration in aqueous solution. The adsorption behavior for phenol of β-CD polymer is fitted into the Freundlich isotherm.

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Lipase from Candida rugosa was immobilized on a β-cyclodextrin-based polymer by adsorption and subsequent cross-linking with epichlorohydrin (EP-CD). The ligand iminodiacetic acid (IDA) was then bonded with the cross-linked β-cyclodextrin (EP-CD-IDA). This affinity adsorbent was further chelated with Cu2 + for the purpose of binding affinity and stability. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. Results showed that 266 µg protein with an activity of 17.85 U was bound per gram of matrix, giving 188% of the specific activity of the free enzyme and a total recovered activity of 79.7% under the optimum conditions. The pH and thermal stabilities of lipase were improved after immobilization on the β-cyclodextrin-based polymer (EP-CD-IDA-Cu2 +). In addition, experimental results indicated that the residual activity of the immobilized lipase was 50% after eight cycles of reuse.

Adsorption of phenol, p-chlorophenol and p-nitrophenol onto functional chitosan

Functional chitosan, chemically modified by salicylaldehyde (CS-SA), β-cyclodextrin (CS-CD), and a cross-linked β-cyclodextrin polymer (EPI-CD) were prepared as adsorbents to remove phenol, p-nitrophenol and p-chlorophenol from aqueous solution. Langmuir and Freundlich models were applied to describe the adsorption isotherm of phenols, and adsorption parameters were evaluated. Functional chitosan displayed outstanding adsorption ability for phenols. To our surprise, CS-CD exhibited specific adsorption ability for p-chlorophenol. The possible adsorption interaction was discussed. Effects of pH and KCl on the adsorption suggested that the adsorption of phenols was predominated by hydrogen bonding, hydrophobic interaction and π–π interaction not electrostatic interaction. Effect of temperature indicated that the low temperature was favorable for the adsorption of phenols. Separation of phenols and adsorbent regeneration were carried out by simple washing with ethanol and filtrating.

Studies of a Disposable Biosensor Based on the β-Cyclodextrin Inclusion Complex as Mediator

This paper reports the use of a disposable voltammetric biosensor based on a screen-printed basal electrode and highly efficient mediators, the β-cyclodextrin inclusion complexes tetramethylbenzidine and ferrocene. The polyphenol oxidase, contained in the crude extract of mushroom, was immobilized in the membrane of the cross-linked β-cyclodextrin polymer. The resulting biosensor gave excellent analytical performance due to the supramolecular complexation for mediators. It responded to the concentration of dopamine with high selectively in the range from 1.0 × 10 −9 to 1.0 × 10 −6 M with a detection limit as low as 5 × 10 −10 M. The response time for reaching 90% of its steady-state value was less than 60 s, and the activity was retained for at least 15 days.

Novel composite adsorbent for adsorption of urea

A urea adsorbent with an aldo structure was obtained by the oxidation of a crosslinked β-cyclodextrin polymer. The highest urea adsorption capacity reached 50.6 mg/g in 0.05 M aqueous phosphate buffer at 37°C and pH = 7.4, and decreased to 4.0 mg/g in aqueous human serum albumin. The novel composite adsorbent was prepared by the oxidation of a crosslinked β-cyclodextrin and cellulose dialytic membrane. It was found that the composite adsorbent had a higher urea adsorption selectivity and capacity compared with that of the oxidation of a crosslinked β-cyclodextrin adsorbent when urea is in aqueous human serum albumin. Copyright © 1999 John Wiley & Sons, Ltd.

Study of the oxidation of crosslinked β-cyclodextrin polymer and its use in the removal of urea. I

A novel urea sorbent with an aldo structure was obtained by the oxidation of a crosslinked β-cyclodextrin polymer. The highest urea sorption capacity reached ∼ 65.0 mg of urea per gram of sorbent at 37°C and pH 7.0 and the concentration of urea in the buffer solution was 1300 mg/l. The sorption of urea was related to the degree of crosslinking, the aldo content, temperature of sorption, concentration of urea and the pH of the sorption medium. It was found that this kind of sorbent has a higher urea sorption capacity compared to that of oxystarch and oxycellulose.

Complexation of nitrostyrenes with soluble ?-cyclodextrin polymer studied by reversed-phase thin-layer chromatography

Cyclodextrin complexation decreases the apparent lipophilicity of hydrophobic guest molecules. A higher complex stability results in a larger decrease of lipophilicity as determined by reversed-phase thin-layer chromatography. The method was applied to study the complex formation of 33 nitrostyrene derivatives with a water soluble cross linked β-cyclodextrin polymer (weight average molecular weight: 4300). The substituents in thepara position of the benzene ring had a higher impact on the complex stability than those in themeta andortho positions. The substituents on the alkyl side chain influenced the complex stability to the same extent as those on the benzen ring.

Absorption and excretion of tablet disintegrating β-cyclodextrin polymer in rats

Absorption and excretion of a new tablet disintegrating agent, a crosslinked β-cyclodextrin polymer was investigated following per os administration in the rat. The polymer, which is insoluble but swells in water, was prepared from β-cyclodextrin by reacting with [2- 14C]epichlorohydrin in an alkaline medium. Radioactivity of blood, urine, faeces, exhaled carbon dioxide and the gastrointestinal tract was determined by a liquid scintillation method. No radioactivity could be detected in the blood up to 24 h after the administration of the polymer. Radioactivity of urine and exhaled carbon dioxide together did not exceed 0·11% of the total administered radioactivity, 98% of which was found in the large intestine and the faeces. Therefore, it is assumed that β-cyclodextrin polymer could not be absorbed from the gastrointestinal tract.