Electrospun chitosan-based nanobres for removal of phenols from drinking water

Chitosan-based nanofibres were synthesized using a fibre electrospinning technique and tested for the removal of 3-methyl- 4-nitrophenol from aqueous solutions. The downside of chitosan-based materials is swelling. In this study, it was found that the addition of polyisoprene not only improved the electrospinning ability of chitosan but also reduced the swelling of the nanofibres by 50%. the adsorption studies of 3-methyl-4-nitrophenol on the chitosan-based nanobres were conducted in a batch process. e nanobres were found to remove up to 90% of 3-methyl-4-nitrophenol with an adsorption reduction capacity of 12% at each cycle of reusability test. The reduction capacity was associated with the chemical interaction of the adsorbate and the adsorbent. this indicated that the nanofibres can effectively remove 3-methyl-4-nitrophenol from water for at least 3 cycles. the adsorption efficiency improved as the degree of cross-linking was reduced and the adsorption mechanism followed the Freundlich isotherm suggesting that the adsorption of 3-methyl-4-nitrophenol occurred in different layers on the surface of the nanofibres. e degree of crosslinking of the electrospun nanobres with glutaraldehyde was found to affect the adsorption capacity. Nanofibres with different degrees of crosslinking were used to study the effect of pH, adsorbent dose, and initial concentration.Keywords: 3-methyl-4-nitrophenol, adsorption, chitosan nanofibres, the degree of cross-linking, removal efficienc

Removal of Fe and Mn from polluted water sources in Lesotho using modified clays

This paper reports the use of unfunctionalized and phenylalanine functionalized clays as an alternative cost effective, environmental friendly and efficient sorbent for the removal of Mn and Fe from polluted drinking water sources in Lesotho. The Mn and Fe metals were adsorbed on two different clays (clay Aa black clay and clay Ba yellow clay) collected from Ha-Teko in Maseru (clay A) and Phoqoane in Mafeteng district (clay B). Comprehensive batch test studies were performed to assess the effect of pH, stirring time and initial concentration of Mn and Fe. The adsorption of the metals was greater at higher pH and equilibrium was reached at pH 8 after 30 min of stirring. The phenylalanine functionalized clays displayed improved adsorption efficiency of up 100% (Fe adsorption using clay A in 30 min) while the unfunctionalized clays gave relatively low adsorption of up to 70% (Fe and Mn adsorption using clay A). The clays, which are present in abundance in Lesotho, can be effectively used for the removal of Fe and Mn from drinking water sources

Environmentally benign chitosan-based nanofibres for potential use in water treatment

Chitosan (CS)-based nanocomposite materials are highly prone to swelling when in contact with water. It is therefore essential to modify them to enhance their resistance to swelling, in order to be applicable in water treatment. In this study, the CS-based nanofibres were prepared using the electrospinning technique. The nanofibres were prepared from a polymer blend of CS, and other polymers (polyacrylamide (PAA) and polyethylene glycol (PEG)) added in small optimized quantities to enhance the ability to electrospun CS. Elastic polyisoprene (PIP) and functionalized multi-walled carbon nanotubes (f-MWCNTs) were incorporated in the electrospinnable solution blend of CS, PAA and PEG to reduce the swelling behaviour of the CS-based nanofibres and to improve their mechanical strength and thermal properties. PIP did not only improve the morphology of the resulting nanofibres but also reduced their swelling behaviour by twofold. The addition of f-MWCNTs was found to improve the tensile strength of the nanofibres by twofold, relative to nanofibres with no f-MWCNTs. The thermal degradation of the nanofibres was improved by a magnitude of 50 degrees C. Antibacterial silver (Ag) and iron (Fe) nanoparticles (NPs) were embedded on the nanofibres for their possible use in disinfection processes. These NPs have demonstrated a potential to kill bacteria in water and, therefore, the prepared nanofibres can be used in disinfection water treatment processes with reduced swelling capacity

Electrospun chitosan-based nanofibres for removal of phenols from drinking water

Chitosan-based nanofibres were synthesized using a fibre electrospinning technique and tested for the removal of 3-methyl-4-nitrophenol from aqueous solutions. The downside of chitosan-based materials is swelling. In this study, it was found that the addition of polyisoprene not only improved the electrospinning ability of chitosan but also reduced the swelling of the nanofibres by 50%. The adsorption studies of 3-methyl-4-nitrophenol on the chitosan-based nanofibres were conducted in a batch process. The nanofibres were found to remove up to 90% of 3-methyl-4-nitrophenol with an adsorption reduction capacity of 12% at each cycle of reusability test. The reduction capacity was associated with the chemical interaction of the adsorbate and the adsorbent. This indicated that the nanofibres can effectively remove 3-methyl-4-nitrophenol from water for at least 3 cycles. The adsorption efficiency improved as the degree of cross-linking was reduced and the adsorption mechanism followed the Freundlich isotherm suggesting that the adsorption of 3-methyl-4-nitrophenol occurred in different layers on the surface of the nanofibres. The degree of crosslinking of the electrospun nanofibres with glutaraldehyde was found to affect the adsorption capacity. Nanofibres with different degrees of crosslinking were used to study the effect of pH, adsorbent dose, and initial concentration

Thermally and mechanically stable β-cyclodextrin/cellulose acetate nanofibers synthesized using an environmentally benign procedure

Electrospun cyclodextrin (CD)-based nanofibers with capabilities to remove pollutants from water have been synthesized and characterized. The high-quality nanofibers presented here were synthesized in two simple steps that involved in-situ electrospinning of the nanofibers and all nanocomponents, followed by the reduction of silver (Ag+) and iron (Fe3+) ions to nanoparticles using an environmentally benign process that involved irradiation of the electrospun fibers using a tailor-made UV-equipped furnace at low temperatures. In the previously reported study it was observed that Ag and Fe nanoparticles effectively removed a range of different strains of Gram-negative and Gram-positive bacteria from water. As such, this study focused on improving the thermal and mechanical properties of the nanofibers prepared from polymer blends of beta-CDs with cellulose acetate (CA) and small additions (2wt%) of functionalized multiwalled carbon nanotubes (f-MWCNTs). The electrospinning parameters were varied to determine the optimum conditions for preparation of uniform non-beaded nanofibers. Bead-free and uniform nanofibers were obtained at a polymer concentration of 32% at the ratio of 1:1 -CDs:CA, syringe injection flow rate of 0.7mLh(-1), 15cm between the tip of the spinneret and the collector, and a voltage of 16 kV. The addition of f-MWCNTs was found to improve the tensile strength of the nanofibers by twofold, relative to nanofibers with no f-MWCNTs. The thermal degradation of the nanofibers was improved by a magnitude of 50 degrees C. The study has shown that adding small amounts of f-MWCNTs improved the thermal stability and mechanical strength of the CD/CA nanofibers significantly