Epichlorohydrin Research Articles

Synthesis and characterization of castor oil-based polyols with fluorine-containing pendant groups

A novel castor oil-based polyols with fluorine-containing pendant groups (CO-FPOL) has been synthesized through ring-opening polymerization from castor oil (CO), propylene oxide (PO) and self-made 3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-octyloxymethyl)-Oxirane (TDFOMO). The TDFOMO was synthesized from 3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluoro-1-octanol (TDFOL) and Epichlorohydrin (ECH). Then, the CO-FPOLs further reacted with a 4,4′-diphenylmethane diisocyanate (MDI) to prepare a one-component fluorinated polyurethane coating (CO-FPUP). Strikingly, the fluorine content of CO-FPOL can be easily controlled, the thermal stability of CO-FPOL and CO-FPUP increased with the increasing of fluorine content. It was all found that with the fluorine content of CO-FPOL increasing from 0% to 17.72%, the static water contact angle of CO-FPUPs increased from 90° to 106°, and the static oil contact angle of CO-FPUPs increased from 20° to 54°. The XPS survey spectra revealed that the fluorine in the cured polyurethane would migrate to the surface easier due to the fluorinated pendant groups which moving easier between molecular chains. All the above results suggest that the introduction of fluorinated pendant groups in polyether polyol has great improvements in the thermal stability and the hydrophobic and oleophobic properties of polymer materials.

Efficient Removal of Heavy Metals from Aqueous Solution Using Licorice Residue-Based Hydrogel Adsorbent.

The removal of heavy metals through adsorption represents a highly promising method. This study focuses on the utilization of an abundant cellulose-rich solid waste, licorice residue (LR), as a natural material for hydrogel synthesis. To this end, LR-EPI hydrogels, namely, LR-EPI-5, LR-EPI-6 and LR-EPI-8, were developed by crosslinking LR with epichlorohydrin (EPI), specifically targeting the removal of Pb, Cu, and Cr from aqueous solutions. Thorough characterizations employing Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy confirmed the successful crosslinking of LR-EPIs by EPI, resulting in the formation of porous and loosely structured hydrogels. Batch studies demonstrated the high efficacy of LR-EPI hydrogels in removing the three heavy metal ions from aqueous solutions. Notably, LR-EPI-8 exhibited the highest adsorption capacity, with maximum capacities of 591.8 mg/g, 458.3 mg/g, and 121.4 mg/g for Pb2+, Cr3+, and Cu2+, respectively. The adsorption processes for Pb2+ and Cu2+ were well described by pseudo-second-order kinetics and the Langmuir model. The adsorption mechanism of LR-EPI-8 onto heavy metal ions was found to involve a combination of ion-exchange and electrostatic interactions, as inferred from the results obtained through X-ray photoelectron spectroscopy and FTIR. This research establishes LR-EPI-8 as a promising adsorbent for the effective removal of heavy metal ions from aqueous solutions, offering an eco-friendly approach for heavy metal removal and providing an environmentally sustainable method for the reutilization of Chinese herb residues. It contributes to the goal of "from waste, treats waste" while also addressing the broader need for heavy metal remediation.

Synthesis and application of an unprecedented bioadsorbent for removing arsenic from aqueous systems

A quaternary ammonium anion exchanger (SBTEA) was prepared from sugarcane bagasse (SB) employing an improved two-step synthesis method by chemical modification with epichlorohydrin (EPI) and triethylamine (TEA) using N,N-dimethylformamide as a solvent without catalyst. Two multivariate optimizations were utilized to determine optimum conditions for SBTEA synthesis using Doehlert experimental designs. The optimum synthesis conditions were: VEPI = 12.8 mLgSB−1; VTEA = 22.0 mLgSB−1; and T1 (etherification step) = T2 (amination step) = 100 °C. The chlorine and nitrogen contents of the SBTEA produced under these conditions with a 21-fold increase in the synthesis scale (SBTEA-LS) were 4.2 ± 0.1% and 1.485 ± 0.007%, respectively. The 13C Multi-CP SS NMR revealed that 1.7 quaternary ammonium groups were introduced for 10 cellobiose units. SBTEA-LS was used to remove As(V) from contaminated groundwater samples with high removal efficiency (95 ± 4%), even with strong competitors such as SO42−. The interactions involved in the adsorption were investigated through macroscopic and microscopic measurements, which suggested that the adsorption of As(V) on SBTEA-LS occurred mainly by ion exchange. Desorption experiments proved that SBTEA-LS could be efficiently regenerated (Edes > 90%) using an HNO3 solution, reducing operating costs and favoring technology upscaling.

Cellulose nanofibers (CNF) supported (Salen)Cr(III) composite as an efficient heterogeneous catalyst for CO2 cycloaddition

For the simultaneous attainment of the utilization of renewable biomass resources and the mitigation of greenhouse effects, it is very promising to develop a green, recyclable, and highly efficient heterogeneous catalyst for the synthesis of cyclic carbonates by CO2 cycloaddition reaction with epoxides. Herein, novel cellulose nanofibers (CNF) supported (Salen)Cr(Ⅲ) complex was effectively synthesized for the aforementioned reaction. The cellulose nanofibers (CNF) were firstly modified with (3-aminopropyl) triethoxysilane (APTES), and then its Schiff base with salicylaldehyde was synthesized, which further subjected to coordination treatment with chromium chloride to form a novel heterogeneous catalyst, labelled as CNF-(Salen)Cr(Ⅲ). The catalytic performance of the catalysts shown that CNF-(Salen)Cr(Ⅲ) and co-catalyst TBAB can synergistically catalyze the cycloaddition of CO2 with epichlorohydrin (ECH) at mild reaction conditions, and the yield of chloropropene carbonate (CPC) reached up to 97.8% with high selectivity. The CNF-(Salen)Cr(Ⅲ) complex maintained high catalytic activity after six cycles of repeated runs and has acceptable catalytic effect on other series of epoxies. Based on density functional theory (DFT) calculations, a reaction mechanism including adsorption activation of epoxides, epoxides ring opening, CO2 insertion, and the formation of cyclic carbonate, was proposed for the CNF-(Salen)Cr(Ⅲ) complex catalyzed cycloaddition of CO2 with epoxides.

A strong, hydrostable lignocellulose-based film based on dual cross-linking networks

Green and sustainable biomass materials based on wood processing residues show considerable application potential as substitutes to petroleum-based plastics. However, due to the chemical and structural characteristics of cellulose fibers resulting in their natural hydrophilicity, it is difficult for a single cross-linking network to impart multiple excellent properties to bio-based materials. Here, with wood lignification enhancement inspiration, a high-performance bio-based plastics based on 2,2,6,6-tetramethylpiperidine-1-oxy-oxidized lignocellulose (TOLC) is successfully fabricated by a dual-crosslinking strategy of sodium lignosulfonate (LS) and epichlorohydrin (ECH) modification, and their characterizations were done in terms of SEM, FTIR, XPS, XRD, TG, contact angle and tensile properties. The physical sacrificial bonding between TOLC and LS, in conjunction with the covalent cross-linking network among the TOLC-LS matrix and ECH, contributed to the exceptional tensile strength (383.43 ± 1.57 MPa) and elastic modulus (15.20 ± 0.66 GPa) of the prepared TOLC-LS/ECH film. Furthermore, the maximum weight loss peak of TOLC-LS/ECH III film is observed at 348 °C, higher than TOLC film, which shows exceptional thermal stability. After immersing in water for 24 h, the water absorption rate of TOLC-LS/ECH III film is only 59.72 % of TOLC film, exhibiting increased water resistance. Remarkably, the resulted bio-mass plastics show superior biodegradability with a weight loss of 33.67 % after 30 days in outdoor conditions, while the tensile strength remained 81 % of the original after 6 months in appropriate indoor environments, showing excellent mechanical stability. Compared with most sustainable bio-based plastics, the obtained film shows combination of low production cost, high mechanical properties, and glorious thermal stability, which can effectively expand its application potential in mulch, daily packaging, and so on. This strategy will pave the way for developing sustainable bio-based plastics with low cost, high-performance, and outstanding processing.

Ultrathin ultrastrong transparent films made from regenerated cellulose and epichlorohydrin

Thin films used in electronic devices are often petroleum-based, non-biodegradable, and non-renewable polymers. Herein, ultrathin ultrastrong regenerated cellulose films were made with a facile method by applying a solution of mildly carboxylated nanocellulose and various amounts of epichlorohydrin (ECH) as a crosslinker. The morphology and physiochemical properties of films were measured using FE-SEM, TEM, FTIR, NMR, UV–Vis, XRD, DLS, and TGA. Carboxylated cellulose with a charge content of 1.5 mmol/g was prepared to make alkaline dopes containing nanocrystalline cellulose (CNC). Then, ECH (0–50%) was added and the dope was blade cast, dried in an oven, regenerated in an acid bath, washed, and air dried to make uniform films approximately 1 μm thick. The tensile stress and elastic modulus of the films were measured and found to be 100–300 MPa and 5–12.7 GPa, respectively. Higher amounts of ECH led to stronger films. All films were over 96% transparent, insoluble in water, and absorbed 24–28% moisture. TGA analysis showed ultrathin films were thermally resistant up to 250 °C and were stable and unchanged over a month at 105 °C showing excellent thermal aging resistance. Overall, films with 5–10% ECH are extremely strong, which makes them promising bioresource-based candidates for flexible electronic applications.

Characterization of Cross-Linking in Guar Gum Hydrogels via the Analysis of Thermal Decomposition Behavior and Water Uptake Kinetics

This study aimed to explore a test method for evaluating the effective cross-linking density of hydrogels. A guar gum–epichlorohydrin hydrogel (GEH) was prepared using guar gum (GG) as the raw material and epichlorohydrin (ECH) as the cross-linking agent. The thermal and mechanical properties, equilibrium swelling rate (ESR), water uptake (WU), and mass cross-linking degree of the hydrogels were assessed. Furthermore, the diffusion behavior of water molecules in the freeze-dried GEH was investigated. The experimental results showed the significance of the initial decomposition temperature (Ti) and final decomposition temperature (Tf) of the freeze-dried GEHs in determining the effective cross-linking density. The water uptake kinetics of the freeze-dried GEH was consistent with the linear fitting of the pseudo-second-order kinetic model and nonlinear fitting of the Fickian diffusion model, suggesting that chemisorption dominated the water absorption process in the GEH. Therefore, the effective cross-linking density of the hydrogels could be determined from the thermodynamic analysis and the diffusive behavior of water molecules in the gels. The thermal stability and water diffusion kinetics of the hydrogels were closely linked to the effective cross-linking density and pendant modification.

Dimension and shape controllable ZIFs for highly-efficient chemical fixation of CO2 without solvent and co-catalyst

The cycloaddition of CO2 with epoxides is an important strategy to reach the goal of carbon neutral, at the same time high-value-added products can be obtained. The integration of Lewis acidic and alkaline sites makes ZIFs potential catalysts for the CO2 cycloaddition. Herein, through simply adjusting the water proportion in the synthesis solvent, a series of ZIF materials were prepared and applied in the CO2 cycloaddition. The transitional ZIF-(80)-Co combines the advantages of two-dimensional and three-dimensional ZIFs, namely the two-dimensional morphology, well-developed porous structures, higher CO2 adsorption capacity, and rich acidic/alkaline sites. The outstanding microstructures and surface properties of ZIF-(80)-Co contribute to its superior catalytic performance for the CO2 cycloaddition, and an epichlorohydrin (ECH) conversion of 96.9 % and a cyclic carbonate selectivity of 98 % are achieved without solvent and co-catalyst. Importantly, the cycloaddition of CO2 with ECH over ZIF-(80)-Co is faster than most of the reported ZIFs in literature. Furthermore, ZIF-(80)-Co also exhibits excellent catalytic performance in the CO2 cycloaddition with epoxy butane, allyl glycidyl ether, cyclohexene oxide and styrene oxide.

Eco-friendly cellulose-based hydrogels derived from wastepapers as a controlled-release fertilizer

In this study, an eco-friendly controlled release fertilizer cellulose-based hydrogel was prepared from cellulose fibers derived from wastepaper, epichlorohydrin (ECH) as a crosslinker and carboxy methyl cellulose (CMC) as a gelling agent. A maximum swelling capacity of 2000% was achieved for cellulose hydrogel with optimum composition. The soil moisture contents in the presence of optimized cellulose hydrogels were determined using the digital moisture meter. Maximum soil moisture of 36.5% was obtained in topsoil, followed by 30.1% in wet clayey soil and 23.4% in sandy soil after 7 days. Urea as a model fertilizer was loaded onto the cellulose hydrogels to control the release of fertilizer. The maximum loading capacity of urea in cellulose hydrogel is 0.51 g/g. The urea-controlled release profiles of the cellulose hydrogel in distilled water and various types of soils were investigated. The formulation of cellulose hydrogels was observed to facilitate the gradual release of urea, with about 74.71% release in topsoil, 73.37% release in wet clayey soil and 71.84% release in sandy soil within 42 days when compared to the free urea which was about 97.32%, 95.09% and 98.47% release in topsoil, wet clayey soils and sandy soils, respectively within 7 days. The result of this study shows that the urea-loaded cellulose hydrogel could be a promising controlled-release fertilizer.Graphical

Trimesic acid-functionalized chitosan: A novel and efficient multifunctional organocatalyst for green synthesis of polyhydroquinolines and acridinediones under mild conditions

Trimesic acid-functionalized chitosan (Cs/ECH-TMA) material was prepared through a simple procedure by using inexpensive and commercially available chitosan (Cs), epichlorohydrin (ECH) linker and trimesic acid (TMA). The obtained bio-based Cs/ECH-TMA material was characterized using energy-dispersive X-ray (EDX) and Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The Cs/ECH-TMA material was successfully used, as a multifunctional heterogeneous and sustainable catalyst, for efficient and expeditious synthesis of medicinally important polyhydroquinoline (PHQ) and polyhydroacridinedione (PHA) scaffolds through the Hantzsch condensation in a one-pot reaction. Indeed, the heterogeneous Cs/ECH-TMA material can be considered as a synergistic multifunctional organocatalyst due to the presence of a large number of acidic active sites in its structure as well as hydrophilicity. Both PHQs and PHAs were synthesized in the presence of biodegradable heterogeneous Cs/ECH-TMA catalytic system from their corresponding substrates in EtOH under reflux conditions and high to quantitative yields. The Cs/ECH-TMA catalyst is recyclable and can be reused at least four times without significant loss of its catalytic activity.

Developing thiosemicarbazide-modified/ion-imprinted chitosan for selective cadmium ion biosorption

To ensure environmental and industrial sustainability, cadmium ions (Cd(II)) must be extracted from effluents. However, high-efficiency Cd(II) extraction remains elusive due to issues with slow rates and low selectivity. An ion-imprinting method was used in this study to imprint Cd(II) onto a thiosemicarbazide-chitosan derivative (TCCS) synthesized via an unconventional synthetic route. Following the amide bond formation between cyanoacetyl units and chitosan, thiosemicarbazide was used to modify the –CN residues to obtain the desired TCCS derivative. After that, the Cd(II) ions were coordinated with the TCCS before being cross-linked with epichlorohydrin (ECH) and eluted by a H+/EDTA solution, leaving rigid coordination cavities. The developed Cd-TCCS was able to preferentially identify Cd(II) when compared to non-imprinted sorbent, resulting in significantly higher adsorption capabilities (qm = 305 ± 1 mg/g) and enhanced adsorption selectivity. Also, the pseudo-second-order kinetics model was a good fit for the data, indicating that adsorption is mainly mediated by chemisorption or coordination mechanisms, which were confirmed by the FTIR and XPS investigations. This study expands our understanding of the factors that influences the biosorption of Cd(II) from aqueous media and gives a direction for the development of novel biosorbents with high capacity and excellent selectivity.

Synthesis and properties of double epoxy groups double quaternary ammonium salts

Double epoxy group double quaternary ammonium salts (DEpDQAS) were synthesized by epichlorohydrin (ECH) reacting with N,N,N'N'-tetramethylethylenediamine (TMEDA) and N,N,N'N'-tetramethyl-1,6-hexanediamine (TMHDA), respectively. The results of orthogonal experiments showed that temperature and time were the key factors influencing on epoxy value and quaternarization ratio respectively. The optimal condition for higher epoxy value was the reaction temperature at 15 °C and methanol as solvent. The reaction kinetic process was determined by conductivity, which showed that the reaction had a short induction period and appeared discontinuity in progress that the reaction rate of the first stage was almost constant, while the reaction rate of the second stage decreased gradually. The product was characterized by infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). The results of surface tension testing showed that DEpDQAS-6 with longer spacer chain had better surface activity and lowered the solution surface tension to 26 mN·m−1 at 25 °C and CMC 0.27 mol·L−1. The thermodynamic parameters of micellization were obtained basing on charged pseudo-phase model. The studies of cytotoxicity in vitro and antibacterial activity showed that DEpDQAS was biocompatible and its antibacterial activity was more effective against Escherichia coli than against Staphylococcus aureus.

The effect of the interaction between Cu single atoms and Pt nanoparticles on the selective hydrogenation of epichlorohydrin to chloro-propanol

The catalytic epichlorohydrin (ECH) hydrogenation to chloro-propanol is of great industrial importance due to the extensive application of chloro-propanol as an intermediate for pharmaceutics, fine chemicals, and polymers. The challenge of this catalytic reaction lies in that dechlorination can hardly be inhibited in the selective hydrogenation of the epoxy group because the bond energy of the C-Cl bond is very close to that of the CO bond. Herein, we demonstrated that the selectivity of chloro-propanol could be improved from 82.2 % to 94.6 % by incorporating a small amount of Cu single atoms into Pt/C catalysts to inhibit dechlorination. More interestingly, the ring-opening site of the epoxy group can be also engineered by the incorporation of Cu single atoms, as evidenced by the significant increase in the selectivity of 3-chloro-1-propanol from 0.2 % to 14.5 %. Comprehensive characterizations and density functional theory (DFT) calculations were carried out to understand the interplay of Cu single atoms and Pt nanoparticles as well as its effect on the catalytic performance. The insights gained in this study will benefit the development of catalysts, especially the bimetallic catalysts for the selective hydrogenation of halogeno-aliphatic compounds.

Fully biobased composite made with epoxidized‐lignin, reinforced with bamboo fibers

AbstractIn this study, we entirely replaced petroleum‐based bisphenol A (BPA) with unmodified kraft softwood lignin in epoxy resin formulation. Epoxidized lignin was prepared by reacting lignin with biobased epichlorohydrin (ECH) made from glycerol, and the formation of epoxide rings was confirmed by measuring the epoxy content of the epoxidized lignin using titration and Fourier‐transform infrared spectroscopy (FTIR). A fully biobased epoxy resin was then prepared by mixing the epoxidized lignin with a biobased curing agent derived from chew nutshell (from Cardolite Co.). Pre‐impregnated composite sheets were fabricated by impregnating unidirectional bamboo fibers with the developed water‐dispersion epoxy resin. The properties of the biobased composite samples were measured using a dynamic mechanical analyzer (DMA), scanning electron microscope (SEM), and a universal testing machine. The flexural strength of the lignin‐based epoxy composite was found to be 36% lower (14 MPa) compared to commercial epoxy (22 MPa). However, when bamboo fibers were added to the lignin‐based biocomposite (containing 25 wt.%), a higher flexural strength (116 MPa) was observed, representing an increase of 11% compared to the biocomposite made with EPON and bamboo fiber (104 MPa). Similarly, the addition of bamboo fibers to the lignin epoxy resulted in an increase in the flexural modulus by 1255% (from 0.42 to 5.69 GPa), while the flexural modulus of commercial epoxy was increased by only 736% (from 0.58 to 4.85 GPa). This was attributed to the higher compatibility of bamboo fiber with lignin, which is known to act as a natural glue in plants.

Simultaneous Activation of Carbon Dioxide and Epoxides to Produce Cyclic Carbonates by Cross‐linked Epoxy Resin Organocatalysts

AbstractThe development of efficient bifunctional organocatalysts for the catalytic conversion of CO2under mild conditions remains particularly challenging. Inspired by the synergistic mechanism of intramolecular Lewis acid‐base active sites, we report a series of bifunctional cross‐linked epoxy resin organocatalysts containing multiple active sites for the cycloaddition reaction of dilute CO2with epoxides. These catalysts exhibit high reactivity and product selectivity (10 examples, >99 %) for the cycloaddition reactions of a variety of epoxides and CO2, and surprisingly, epichlorohydrin (ECH), can be converted under ambient temperature and pressure (25 °C, 1.0 bar) without co‐catalysts.1H NMR,13C NMR,19F NMR and in situ IR studies suggest that the simultaneous and efficient activation of CO2and epoxides is responsible for the improved catalytic activity. Upon an insightful investigation of the catalytic mechanism, this protocol will contribute to the development of efficient and environmentally friendly metal‐free catalysts.

Synthesis of New (1-alkylamino-4-phenyldithio-2-bntanol amine) andderivatives.

Anew series of(1-alkylamino-4-phenyldithio-2-bntanol amine) and derivatives,containing two functional groups (pheny ring and NCS2) here been prepared from a reaction by 3steps :- 1-In the first step the preparation of n-phenyl dithio carbamate (A) and derivatives from a reaction between Aniline and carbon disulfide in basic medium. 2-Then , preparation N-3-chloro-2-hydroxy propyl amine tt 3 )) and derivativel from reaction between N-3-chloro-2-hydroxy propylamine and epichloro hydrine in methanolic a queous.3-In three step :-preparation 1-Alkyi amino -4-phenyl dithio-2-butanol amine ( I-IV) from reaction between A,B,and derivatives in absolute methanol The aim:-preparation of new series of propanol amine derivative, these have effect onblood pressure ' and heart rate

LTA zeolite membranes on thin-walled capillary tubes for the high-throughput dehydration of industrially important ternary water/isopropanol/epichlorohydrin mixtures

Among the various zeolite membranes, hydrophilic Linde Type A (LTA) zeolite membranes (LTA membranes) are highly desirable for the dehydration of organic solvents. In particular, both high flux and separation factors for H2O can be achieved with such membranes. Therefore, in this study, we fabricated LTA membranes on thin-walled capillary tubes and compared the dehydration performance with those of LTA membranes prepared on conventional tubular supports. We found that neither LTA membrane contained noticeable defects using fluorescence confocal optical microscopy analysis. Accordingly, both membranes effectively dehydrated an azeotropic ternary mixture of H2O/isopropanol (IPA)/epichlorohydrin (ECH), an industrially important mixture. Specifically, the capillary-supported LTA membrane showed better dehydration performance than that on the conventional tubular support, mainly because of the relatively thinner support thickness (ca. 0.35 mm vs. 2 mm of the conventional tubular support). The corresponding H2O flux was ca. 8.02 ± 0.94 kg·m−2·h−1 for the azeotropic ternary mixture (20 wt% H2O/30 wt% IPA/50 wt% ECH) at 70 °C (vs. 4.26 ± 0.39 kg·m−2·h−1 through the LTA membrane on the conventional tube). Further, the H2O/IPA and H2O/ECH separation factors exceeded approximately 10,000. Finally, a comparison with the literature data revealed that the capillary-supported LTA membrane had higher H2O flux and selectivity for H2O/IPA mixtures than other LTA membranes prepared on conventional discs/sheets/tubes.

Fabrication of 3D Hierarchically Porous Chitosan Monoliths by Thermally Induced Phase Separation of Chemically Modified Chitin

Chitosan (CS), an amino-polysaccharide, has applications in various areas such as drug delivery, biotechnology, food technology, and numerous industrial applications. Monoliths have been developed continuously for several decades, and today, they hold an impressively strong position in highly efficient separation, ion exchange, catalysis, and chromatography. In our previous study, a hierarchical chitin (CT) monolith was fabricated using chemically modified CT through the thermally induced phase separation (TIPS) method. This report generated a template-free approach to prepare highly effective, stable, and reusable hierarchically porous CS monoliths by deacetylation of CT monoliths. The acquired CS monoliths exhibited a high surface area at 144.1 m2 g–1 owing to the presence of hierarchical macro- and mesopores. The monoliths demonstrated efficient removal of metal ions from an aqueous solution in a flow system (adsorption capacity at 92.1 mg g–1). To gain durability of CS monoliths in acidic and basic environments, epichlorohydrin (ECH) was used as a cross-linking agent. The cross-linked monoliths also exhibited excellent performance in the adsorption of Cu(II) ions from the solution (64.4 mg g–1) and good reusability in multiple adsorption–desorption cycles without losing significant performance (with 90.7 ± 6.1% adsorption efficiency and 88.5 ± 7.2% desorption efficiency). The fabricated CS monolith can be modified and applied to various fields such as protein separation, catalysis, and drug delivery.

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.

Cross-linking of Gelatin with Epichlorohydrin in a Sodium-Acetate-Trihydrate/Urea Deep Eutectic Solvent System

To improve the cross-linking efficiency of gelatin molecules, sodium acetate trihydrate/urea deep eutectic solvent with 30% water (SAT/U-DES30W, based on DES weight) was proposed as the solvent of gelatin in this paper. The system could overcome the gelation effect of gelatin at low temperature and expose more active groups of gelatin molecules, resulting in better cross-linking effect. Firstly, the optimal reaction concentration of epichlorohydrin (ECH) was determined by boiling water solubility of cross-linking products, and the cross-linking efficiency of gelatin under two systems was judged together with the Glass transition temperature method. Secondly, the water resistance of the cross-linked product was investigated by swelling capacity and water contact angle. The water absorption rate of GEW and GEDES decreased from 4614% to 1500% and 929% at 12 h, respectively, and the water contact angle also obviously decreased, indicating that the cross-linking efficiency of gelatin under DES system was higher. Finally, the cross-linking mechanism of gelatin and ECH were discussed and it was found the thermal stability of GEDES was significantly improved, which would provide a theoretical basis for gelatin-based materials.