Ion-imprinted aminoguanidine-chitosan for selective recognition of lanthanum (III) from wastewater.

Developing a sorbent for the removal of La3+ ions from wastewater offers significant environmental and economic advantages. This study employed an ion-imprinting process to integrate La3+ ions into a newly developed derivative of aminoguanidine-chitosan (AGCS), synthesized via an innovative method. The process initiated with the modification of chitosan by attaching cyanoacetyl groups through amide bonds, yielding cyanoacetyl chitosan (CAC). This derivative underwent further modification with aminoguanidine to produce the chelating AGCS biopolymer. The binding of La3+ ions to AGCS occurred through imprinting and cross-linking with epichlorohydrin (ECH), followed by the extraction of La3+, resulting in the La3+ ion-imprinted sorbent (La-AGCS). Structural confirmation of these chitosan derivatives was established through elemental analysis, FTIR, and NMR. SEM analysis revealed that La-AGCS exhibited a more porous structure compared to the smoother non-imprinted polymer (NIP). La-AGCS demonstrated superior La3+ capture capability, with a maximum capacity of 286 ± 1 mg/g. The adsorption process, fitting the Langmuir and pseudo-second-order models, indicated a primary chemisorption mechanism. Moreover, La-AGCS displayed excellent selectivity for La3+, exhibiting selectivity coefficients ranging from 4 to 13 against other metals. This study underscores a strategic approach in designing advanced materials tailored for La3+ removal, capitalizing on specific chelator properties and ion-imprinting technology.

Enhancing trimethoprim pollutant removal from wastewater using magnetic metal-organic framework encapsulated with poly (itaconic acid)-grafted crosslinked chitosan composite sponge: Optimization through Box-Behnken design and thermodynamics of adsorption parameters.

Trimethoprim (TMP), an antibiotic contaminant, can be effectively removed from water by using the innovative magnetic metal-organic framework (MOF) composite sponge Fe3O4@Rh-MOF@PIC, which is shown in this study. The composite is made up of magnetite (Fe3O4) nanoparticles and a rhodium MOF embedded in a poly(itaconic acid) grafted chitosan matrix. The structure and characteristics of the synthesized material were confirmed by thorough characterization employing SEM, FTIR, XPS, XRD, and BET techniques. Notably, the composite shows a high magnetic saturation of 64 emu g-1, which makes magnetic separation easier, according to vibrating sample magnetometry. Moreover, BET analysis revealed that the Fe3O4@Rh-MOF@PIC sponge had an incredibly high surface area of 1236.48 m2/g. Its outstanding efficacy was confirmed by batch adsorption tests, which produced a maximum adsorption capacity of 391.9 mg/g for the elimination of TMP. Due to its high porosity, magnetic characteristics, and superior trimethoprim uptake, this magnetic MOF composite sponge is a promising adsorbent for effective removal of antibiotics from contaminated water sources. An adsorption energy of 24.5 kJ/mol was found by batch investigations on the Fe3O4@Rh-MOF@PIC composite sponge for trimethoprim (TMP) adsorption. The fact that this value was up 8 kJ/mol suggests that the main mechanism controlling TMP absorption onto the sponge adsorbent is chemisorption. Chemisorption requires creating strong chemical interactions between adsorbate and adsorbent surface groups, unlike weaker physisorption. The magnetic composite sponge exhibited strong removal capabilities and high adsorption capacities for the antibiotic pollutant. The Fe3O4@Rh-MOF@PIC composite sponge also showed magnetism, which allowed for easy magnetic separation after adsorption. Over the course of 6 cycles, it showed outstanding reusability, and XRD confirmed that its composition was stable. The high surface area MOF's pore filling, hydrogen bonding, π-π stacking, and electrostatic interactions were the main trimethoprim adsorption mechanisms. This magnetic composite is feasible and effective for removing antibiotics from water because of its separability, reusability, and synergistic adsorption mechanisms via electrostatics, H-bonding, and π-interactions. The adsorption results were optimized using Box Behnken-design (BBD).

Design of ion-imprinted cellulose-based microspheres for selective recovery of uranyl ions.

Herein, cellulose was selected as the raw material for the production of sorbent microspheres for the selective separation of uranyl (UO22+) ions by ion-imprinting technique due to their low cost, biodegradability, and renewability. To begin, an amidoxime cellulosic derivative (AOCE) is synthesized by a Michael addition followed by an amidoximation reaction, both of which are homogeneous reactions. In the end, microspheres of ion-imprinted U-AOCE sorbent were made by mixing the developed AOCE derivative with UO22+, crosslinking the UO22+ polymer complex with glyoxal, and eluting the coordinated ions with H+/EDTA. U-AOCE smartly recognized the target ions for fitting the cavities generated during the UO22+-imprinting process, resulting in a much greater adsorption capacity of 382 ± 1 mg/g and enhanced adsorption selectivity for UO22+. A pseudo-second-order model fit the data well in terms of kinetics, while the Langmuir model adequately explained the isotherms, indicating chemisorption and adsorption via UO22+ chelation. The coordination between UO22+ and both the -NH2 and -OH groups of the amidoxime units is the primary adsorption process, as shown by NMR, XPS, and FTIR studies. For UO22+ biosorption from aqueous effluents, the results of this study deliver new guidance for the design of biosorbents with high removal capability and excellent selectivity.

Synthesis of nanostructured silica particles for controlled release of ascorbic acid: Microstructure features and in vitro scratch wound assay.

To date, the long term stability of ascorbic acid (AA) under physiological conditions represents a major issue for wound healing and tissue regeneration applications. In this study, ascorbyl phosphate (AP) was loaded into silica nanoparticles (SiNPs) through a simple one step procedure, in which spherical shaped porous SiNPs were obtained via hydrolysis/condensation of tetraethylorthosilicate (TEOS) in the presence of bicarbonate salt and ammonia. The as-prepared SiNPs were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier Transformer Infrared Spectrophotometer (FTIR). Incorporation of bicarbonate salt resulted in the formation of spherical SiNPs with an average diameter of 460 ± 89 nm, while further increase of bicarbonate salt led to the formation of silica sheet-like structures. The AP-loaded SiNPs exhibited high loading efficiency from 92.3- 81.5%, according to AP content and sustained release over 3 days. According to cell viability assay, the obtained AP-enriched SiNPS showed no toxicity and supportive effect to the proliferation of human skin fibroblast cells (HSF) at a concentration less than 200 µg mL-1 . Moreover, it was observed that the wound closure percentage (%) after 24 h was also shown to increase to 74.1 ± 3.1% for 20AP-loaded SiNPs compared to control samples (50.1 ± 1.8%). The obtained results clearly demonstrated that the developed SiNPs formulation exhibits optimal microstructure features to maintain a sustained release of ascorbic acid AA at wound bed for the healing of skin tissue, including acute and chronic wounds.

Selective removal of uranyl ions using ion-imprinted amino-phenolic functionalized chitosan.

The recovery of uranium from aqueous effluents is very important for both the environment and the future of nuclear power. However, issues of sluggish rates and poor selectivity persist in achieving high-efficiency uranium extraction. In this study, uranyl (UO22+) ions were imprinted on an amino-phenolic chitosan derivative using an ion-imprinting method. First, 3-hydroxy-4-nitrobenzoic acid (HNB) units were joined to chitosan via amide bonding, followed by reducing the -NO2 residues into -NH2. The amino-phenolic chitosan polymer ligand (APCS) was coordinated with UO22+ ions, then cross-linked with epichlorohydrin (ECH), and finally the UO22+ ions were taken away. When compared to non-imprinted sorbent, the resulting UO22+ imprinted sorbent material (U-APCS) recognized the target ions preferentially, allowing for much higher adsorption capacities (qm = 309 ± 1 mg/g) and improved adsorption selectivity for UO22+. The FTIR and XPS analyses supported the pseudo-second-order model's suggestion that chemisorption or coordination is the primary adsorption mechanism by fitting the data well in terms of kinetics. Also, the Langmuir model adequately explained the isotherms, suggesting UO22+ adsorption in the form of monolayers. The pHZPC value was estimated at around 5.7; thus, the optimum uptake pH was achieved between pHs 5 and 6. The thermodynamic properties support the endothermic and spontaneous nature of UO22+ adsorption.

Production of biologically active non-woven textiles from recycled polyethylene terephthalate.

Recently, various studies have focused on the development of multifunctional non-woven polyethylene terephthalate (PT; polyester) textiles. Herein, we introduce multifunctional non-woven polyester fabrics by pad dry curing silver nitrate (AgNO3 ) and aniline monomer into plasma-pretreated non-woven PT textile. This creates a nanocomposite layer of silver nanoparticles (AgNPs) and polyaniline (PANi) on the fabric surface. In order to prepare a non-woven fibrous mat, we applied the melt-spinning technique on previously shredded recycled PT plastic waste. On the surface of the cloth, PANi was synthesized by REDOX polymerization of aniline. Due to the oxidative polymerization, the silver ions (Ag+ ) were converted to Ag0 NPs. PANi acted as a conductor while AgNPs inhibited the growth of microorganisms. Microwave-assisted curing with trimethoxyhexadecylsilane (TMHDS) gave PT textiles with superhydrophobic properties. The morphological studies were performed using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The stiffness and breathability of finished non-woven PT textile materials were analyzed to establish their comfort levels. Both of Escherichia coli and Staphylococcus aureus were used to test the efficacy of the AgNPs-treated textiles as antimicrobial materials. Moreover, the processed polyester textiles showed excellent electrical conductivity and great ultraviolet-ray blocking.

Preparation of chromium (III) ion-imprinted polymer based on azo dye functionalized chitosan.

The main aim of this work is the preparation of azo dye modified chitosan that was subsequently used in the ion-imprinting of Cr(III) ions to finally obtain ion-selective sorbent able to selectively combine with Cr(III) ions from water when coexisting with other similar metal ions. The azo dye derived from resorcinol and p-aminobenzoic acid was prepared and then linked to the chitosan amino groups by amide linkages utilizing EDC/NHS coupling agent. A polymeric complex of the azo dye chitosan derivative AZCS and Cr(III) ions was then prepared and treated with glyoxal solution, which cross-link the main chitosan chains in form of micro-spherical beads in presence of the coordinated Cr(III) ions that were later expelled out of the texture of the beads using acidified EDTA eluent solution while preserving the spatial and geometrical shape of the resulting Cr(III) ions chelating sites.

Amidoxime modified chitosan based ion-imprinted polymer for selective removal of uranyl ions.

Ion-imprinting strategy was utilized in the development of UO2(II) imprinted amidoxime modified chitosan sorbent (U-AOCS) that can selectively remove UO2(II) from water. First, cyanoactic acid was linked to the chitosan -NH2 groups and then the inserted -CN groups were converted into amidoxime moieties, which chelate the UO2(II) ions and then the polymer chains were cross-linked by glyoxal. The UO2(II) ions have been then eluted leaving their matching recognition sites. The prepared U-AOCS along with the control NIP displayed maximum capacities toward the UO2(II) ions around 332 and 186 mg/g, respectively, and the isotherms were interpreted better by the Langmuir model in both adsorbents. Moreover, the selective uptake of the uranyl ions in multi-ionic aqueous solutions containing the tetravalent Th(IV) ions, trivalent Al(III), Eu(III), and Fe(III) ions, beside the divalent Pb(II), Co(II), Ni(II), Cu(II) ions confirmed the successful creation of a considerable UO2(II) ions selectivity in the U-AOCS construction. In addition, the U-AOCS adsorbent displayed economic feasibility by maintaining around 95 % of its initial efficiency after the regeneration and reuse for 5 adsorption/desorption cycles.

Chiral separation of (±)-methamphetamine racemate using molecularly imprinted sulfonic acid functionalized resin.

In the present study, a sulfonic acid functionalized enantio-selective resinous material was developed for effective chiral separation of (±)-methamphetamine racemate. R-methamphetamine-sulfonamide phenolic derivative was first prepared and fully characterized utilizing instrumental and spectroscopic techniques, then the sulfonamide was implemented in an acid catalyzed condensation copolymerization with phenol and formaldehyde. The resulted resinous material was then exposed to successive alkaline and acidic treatments in order to remove the R-methamphetamine enantiomer out of the resin matrix and obtaining the molecularly imprinted enantio-selective material, which was also investigated by scanning electron microscope, FTIR and XPS spectroscopy. The maximum selective extraction of the R-methamphetamine enantiomer was achieved at pH 7. The adsorption isotherms indicated an adsorption capacity of 233 ±â€¯1 mg/g and followed the well-known Langmuir model. Also, the enantio-separation experiment of the racemic mixture was performed by column technique and both the supernatant loading and the eluant recovery solutions indicated an enantiomeric excess of 80% and 67% related to S- and R-methamphetamine, respectively.

Synthesis and characterization of photo-crosslinkable 4-styryl-pyridine modified alginate.

In this article photo-crosslinkablestyryl-pyridine modified alginate (ASP-Alg) was prepared and entirely investigated utilizing different instrumental techniques such as Elemental analysis, Fourier transform infrared (FTIR),(13)C and (1)H nuclear magnetic resonance (NMR), ultraviolet-visible light (UV-vis), X-ray diffraction (XRD) spectra and scanning electron microscope (SEM). Upon irradiation in the UV region, the casted ASP-Alg membranes were cross-linked through the [2π+2π] cycloaddition reaction of the inserted photo-active styryl pyridine moieties. Both cross-linking density and kinetics were monitored by examining the UV-vis light spectra of the irradiated membrane at predetermined time intervals and the obtained results were found to fit with the second order mathematical kinetic model, revealing the performance of the cross-linking via bimolecular [2π+2π] cycloaddition reaction. Also, the swelling behaviors along with biodegradability were also studied, and the results indicated the decrease of the swelling ratio and degradation rate by increasing the cross-linking density. Moreover, the mechanical properties were also examined under both wet and dry conditions.

Synthesis and characterization of ion-imprinted resin for selective removal of UO2 (II) ions from aqueous medium.

In this work, uranyl ion-imprinted resin based on 2-(((4-hydroxyphenyl)amino)methyl)phenol was synthesized by condensation polymerization of its uranyl complex in presence of resorcinol and formaldehyde cross-linkers. Numerous instrumental techniques including elemental analysis, Fourier transform infrared spectroscopy, ultraviolet, (1) H along with (13) C nuclear magnetic resonance spectroscopy have been employed for complete characterization of the synthesized ligand and its uranyl complex. Additionally, the obtained ion-imprinted and non-imprinted resins were investigated using scanning electron microscope and Fourier transform infrared spectroscopy. The effects of various essential parameters such as pH, temperature and contact time on removal of uranyl ions have been examined, and the results indicated that the obtained resin exhibited the optimum activity at pH 5. Furthermore, the adsorption process was spontaneous at all studied temperatures and followed the second-order kinetics model. Also, Langmuir adsorption isotherm exhibited the best fit with the experimental results with maximum adsorption capacity 139.3 mg/g. Moreover, the selectivity studies revealed that the ion-imprinted resin exhibited an obvious affinity toward the uranyl ions in presence of other metal ions compared with the non-imprinted resin.