•Urea was used as both solvent and porogen to prepare cellulose hydrogel.•Porous structure was introduced by urea hydrolysis reaction with acid treatment.•Acid treated cellulose hydrogel has a high ...swelling rate in deionized water.
Fast-swelling, porous cellulose hydrogels (PCHs) were generated via simple acid treatment of cellulose hydrogel prepared in NaOH/urea medium. Structural characteristics of the PCHs were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behavior was assessed by measuring the swelling kinetics in deionized water. Mechanical properties were also examined. The results showed that acid treated PCHs had many more micropores, mesopores and macropores, and PCH-6% displayed a high specific surface area of 33.98 m2/g. However, cellulose hydrogel without acid treatment had a low specific surface area (2.499 m2/g). Mechanical property of hydrogel was found to be slightly deteriorated with the improvement of porous structure. The equilibrium swelling rate of PCHs had drastically improvement after acid treatment. This porous cellulose hydrogel skeleton presents a wide range of possibilities for the further development of fast swelling cellulose-based functional hydrogel.
Astaxanthin is receiving increasing interest as an antioxidant and high value-added secondary metabolite.
Haematococcus pluvialis
is the main source for astaxanthin production, and many studies are ...being conducted to increase the production of astaxanthin. In this study, we linked polyethylenimine (PEI) with chitosan to maintain astaxanthin-inducing ability while securing the recyclability of the inducer. Astaxanthin accumulation in
H. pluvialis
was induced to 86.4 pg cell
−1
with the PEI-chitosan fiber (PCF) treatment prepared by cross-linking of 10 μM PEI and low molecular weight (MW) chitosan via epichlorohydrin. PEI concentration affected the astaxanthin accumulation, whereas the MW of chitosan did not. In addition, the PCF treatment in
H. pluvialis
increased the reactive oxygen species (ROS) content in cells, thereby upregulating the transcription of enzymes involved in astaxanthin biosynthesis. PCF can be reused multiple times with the maintenance of over 90% of the astaxanthin production efficiency. This study offers a reusable PCF stimulation strategy for enhancing natural astaxanthin content, and PCF treatment will easily increase the production scale or reduce production costs by using recyclability that is not available in current methods.
Key points
•
Polyethylenimine-chitosan fiber (PCF) was applied to Haematococcus pluvialis
•
PCF promotes astaxanthin accumulation by enhancing oxidative stress in H. pluvialis
•
PCF can be reused multiple times with maintaining over 90% production efficiency
Mixed hydroxy-aryloxy cyclotriphosphazenes have been synthesized via the interaction of hexachlorocyclotriphosphazene with a mixture of 4-allyl-2-methoxyphenol and diphenylolpropane (molar ratio 3.5 ...: 7.0). Their subsequent epoxidation with epichlorohydrin has afforded phosphazene-containing oligoepoxides with the phosphazene fraction of 50%. Optimal conditions for the synthesis of the composition-uniform phosphazene-containing oligoepoxides bearing one, two, and three epoxide groups in the phosphazene cycle have been elaborated. Such phosphazene-containing oligoepoxides can be cured with the curing agents common for the epoxy resins, to afford self-extinguishing compositions.
Microbial inhibition of carboxymethyl dextran (CMD) magnetic nanoparticles (MNPs) was investigated on two different bacterial cultures, Escherichia coli and Staphylococcus aureus, where inhibition ...properties of CMD-MNPs were confirmed, while uncoated MNPs exhibited no inhibition properties. To such CMD-MNPs, enzyme alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae was immobilized. Later on, CMD-MNPs were functionalized, using an epoxide cross-linker epichlorohydrin (EClH) for another option of ADH immobilization. Residual activities of immobilized ADH onto epoxy functionalized and non-functionalized CMD-MNPs were determined. Effect of cross-linker concentration, temperature of immobilization and enzyme concentration on residual activities of immobilized ADH were determined, as well. With optimal process conditions (4% (v/v) EClH, 4 °C and 0.02 mg/mL of ADH), residual activity of immobilized ADH was 90%. Such immobilized ADH was characterized using FT-IR, SEM and DLS analysis.
In this article, flame‐retardant cotton fabric was prepared by a step‐by‐step dip‐coating method, in which flame retardants were introduced onto the surface of the cotton fabric by hydrogen bonding ...association and surface grafting reaction. First, the epichlorohydrin‐modified aramid nanofibers (AEP) were accumulated onto the surface of cotton fabric (Cot/AEP) through hydrogen bond association. Subsequently, the ionic liquid (IL) was grafted onto the surface of AEP to obtain Cot/AEP/IL. The fire safe performance of cotton fabrics was investigated by the limiting oxygen index test (LOI), vertical flammability test (VFT), and cone calorimeter test (CCT), and so forth. The LOI value of Cot/AEP/IL was as high as 29.5%. The VFT results showed that Cot/AEP/IL was self‐extinguishing rather than ignited, leaving a char length of 111 mm. The CCT results demonstrated that the peak heat release rate and total heat release of Cot/AEP/IL decreased by 42.5% and 58.8% compared with untreated cotton fabrics, respectively. The TG test showed that Cot/AEP/IL had more residues left than untreated cotton under both N2 and air atmospheres. The presence of phosphorus enables the cotton fabric to generate an aromatic phosphor carbonaceous structure during the combustion process. In addition, the tensile strength of cotton fabric was tested. After the introduction of AEP/IL, the average tensile strength value of untreated cotton improved from 129 to 167 N in the warp direction and 125–155 N in the weft direction. In summary, the introduction of AEP/IL improved both the flame‐retardant and mechanical properties of the cotton fabric significantly.
In the preparation of polyammonium resin by polycondensation of equimolar amounts of epichlorohydrin and 1,3-bis(dimethylamino)propanol-2 in aqueous solutions, a nonstandard concentration effect was ...revealed, which manifested itself in a sharp increase in the reduced reaction rate, equilibrium conversion, and achievable molecular weight of the polymer at initial concentrations of reagents close to 2.0 mmol/g (the concentration range of 0.5–3.5 mmol/g was studied). The data obtained can be used in the search for additional economical resources to improve the technical and economic indicators of organic synthesis processes.
In this research an efficient ionic liquid based ferrofluid system was developed for efficient adsorption/preconcentration of cadmium using magnetic mesoporous carbon – chitosan nanohybrid. ...Mesoporous CMK - 3 was synthesized using MCM – 48 as ordered template. Then magnetic CMK was combined with chitosan through reaction with epichlorohydrin. The nanohybrid was characterized with FESEM, TEM, XRD, SEM mapping, FTIR, BET and VSM techniques. Effective parameters on cadmium adsorption was optimized with response surface methodology (RSM) using Box – Behnken design. Solution pH, contact time, adsorbent dosage and ionic strength were four studied variables on cadmium adsorption. Results showed that all studied variables are significant on cadmium adsorption. Isotherm study was performed at optimum conditions (pH=8, time 3min, adsorbent dosage 13mg and ionic strength of 0.15%) based four isotherm models and results showed that cadmium adsorption followed the order of Redlich–Peterson>Freundlich>Langmuir>Dubinin–Radushkevich with maximum adsorption capacity of 251.9mgg−1. Results for kinetic study confirmed that pseudo second order model can better describe cadmium adsorption. Regeneration of the sorbent was performed with HNO3 solution (1.0molL−1). Finally developed adsorption process was employed for cadmium preconcentration from real samples.
•Magnetite CMK – 3 crosslinked chitosan nanohybride was synthesized.•The nanohybride was used for fast cadmium adsorption/preconcentration.•Variables were optimized with response surface methodology and Box – Behnken design.•Isotherm and kineric studies were performed based on four models.
A study investigated the presence of epihalohydrins in organic synthesis. Data indicate that epihalohydrins are commonly used in medicinal chemistry and have applications in polymer and resin ...synthesis as well.
Nowadays, the observed trend in road materials technology covers the study of environmentally-friendly modifiers. Therefore, the possibility of modifying bitumen with chitosan and its mixtures with ...epichlorohydrin was evaluated. The studies were carried out for four different percentages of biopolymer (1.0%, 2.5%, 4.0% and 5.5%) and two percentages (1% and 2%) of crosslinking agents and included the assessment of their influence on the basic binder properties, surface free energy parameters and chemical structure. The results indicate that the appropriately selected quantitative chitosan/epichlorohydrin ratio leads to their crosslinking inside the bitumen causing a softening effect. The study also shows the possible benefits of using biopolymer-modified binders in the production of asphalt mixtures by the enhancement of surface-free energy parameters and reduction of the dynamic viscosity. Chitosan is an environmentally-friendly biodegradable biopolymer, and its chemical crosslinking has a positive effect on the properties of modified bitumen.
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.
PDF
