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 µm, 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/m2 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.