Cellulose reinforced electrospun chitosan nanofibers bio-based composite sorbent for water treatment applications

Electrospun chitosan-polyethylene oxide/TEMPO-oxidized cellulose (CS-PEO/TOC) bio-based composite was fabricated for the first time for water treatment applications. This new concept allows cellulose and chitosan to be combined in a simpler and efficient way, avoiding the use of harmful solvents, compared to previously published related work. The Sandwich-like material is composed of a porous oxidized cellulosic fibers central core (TOC handsheet) and a thin layer of electrospun CS-PEO nanofibers on both sides of the core. Average diameters for CS-PEO and TOC were 159.3 +/- 33.7 nm and 21.7 +/- 5.1 mu m, respectively. Fourier Transform Infrared Spectroscopy (FTIR) was carried out on the bio-based composite. Results suggest that no covalent bonds are involved but rather electrostatic interactions occur which allows bonding of the electrospun nanofiber layers on TOC core and no delamination. CS-PEO electrospinning time was varied to study the effect of nanofiber's coating weight on strength, permeability and adsorption capacity of the bio-based material. Mechanical properties of the composite were improved over the electrospun nanofiber mat. The CS-PEO provides greater elasticity (strain%) and the TOC provides a higher tensile strength to the material. However, tensile index was reduced by 48% with electrospinning time, while burst index was almost constant. The best conditions were achieved for 2 h electrospinning time. Under these conditions, a high permeable material (290.13 L/m(2) hbar) was developed. The adsorption capacity for Cu (II) ions reached up to 27% with only 12 mg of chitosan onto the CS-PEO/TOC (12.42 mg/g). The data fit better to the pseudo-second order model, suggesting chemisorption as the main mechanism involved for copper adsorption. This study opens-up potential opportunities for the development of a robust material for wastewater applications at an industrial scale. Graphic abstract

Automated summary

A bio-based composite material for water treatment applications was fabricated for the first time, combining chitosan-polyethylene oxide and TEMPO-oxidized cellulose. Fourier Transform Infrared Spectroscopy was used to analyze the structure of the material, and varied electrospinning times revealed that the optimal condition was 2 hours.