Poly(caprolactone) (PCL) is one of biodegradable and biocompatible polymers, which have received significant attention because they are environmentally friendly and are extensively used in biomedical applications. Electrospinning was a straightforward method to produce nanofibers from polymer solutions in a wide submicron range around 100 nm. However, no clear standard had been established for judging whether a solvent of high solubility for a polymer would produce a solution good for electrospinning. Considering the above-mentioned cause, we explored the effect of solvent on fibrous morphology, FT–IR spectra and 1H NMR spectra, viscosity and shearing strength, differential scanning calorimetry (DSC) of PCL electrospun nonwoven membranes in this article. When NMP and AC were used as the solvent for PCL electrospinning, all of them were composed of smooth and nanosized fibers with similar fiber surface morphologies. Meanwhile, when DCM and CF were used as solvent, there were lots of holes in fibers due to high evaporation. The electrospinnability was good when CA was chosen as solvent due to its lowest viscosity.
In this work, PAN fibers web was fabricated by Electrospinning, and then was pre-oxidated. Effect of the temperature on the structure and property of pre-oxidation web was discussed. The results showed that better level of pre-oxidation nanofibers web can be obtained when the pre-oxidation temperature is 250 °C. At this temperature, Infrared Spectroscopy showed that cyclization and dehydrogenation reaction have occurred and DSC curves showed that cyclization was basically complete, as well as moisture content can be appropriately controlled. Moreover, the preoxidated web with better breaking strength, elongation at break, and the initial modulus could be obtained.
Authors:Qin Li, Yunhai Liu, Xiaohong Cao, Cui Pang, Youqun Wang, Zhibin Zhang, Yating Liu and Ming Hua
The biomass pummelo peel was chosen as a biosorbent for removal of uranium(VI) from aqueous solution. The feasibility of adsorption
of U(VI) by Pummelo peel was studied with batch adsorption experiments. The effects of contact time, biosorbent dosage and
pH on adsorption capacity were investigated in detail. The pummelo peel exhibited the highest U(VI) sorption capacity 270.71 mg/g
at an initial pH of 5.5, concentration of 50 μg/mL, temperature 303 K and contacting time 7 h. The adsorption process of U(VI)
was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it followed both
the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. The thermodynamic parameters values calculated clearly
indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that the
pummelo peel has potential application in the removal of the uranium(VI) from the radioactive waste water.