Chitosan (Mw; Medium molecular weight) and poly(vinyl alcohol) (Mw ~ 145000), were purchased from Sigma-Aldrich and Merck, respectively, were used for preparation of the electrospinning dope. Acetic Acid, hydrochloric acid, sodium hydroxide and glutaraldehyde were supplied from Merck. Double-distillated water was used for all preparation and washing stages. Direct red 80 was used as a model dye. The properties of DR80 are shown in Table 1.
2.2 Preparation of electrospun membrane
A spinning solution containing 6% polymer was prepared by dissolving PVA/chitosan ratio of 80/20 in 50% acetic acid solution by a stirrer rotating at 200 rpm for 24 h at room temperature. The spinning dope was extruded by means of a syringe pump from a syringe needle at a flow rate of 0.3 mL/h and collected on a rotating drum which was placed 15 cm away from the needle tip and with an aluminum foil wrapped on its surface. The rotational speed of the drum was 250 rpm. A high voltage of 25 kV was applied between the needle and the…show more content… The nanofiber mat specimens were placed in a batch containing 200 mL solution of DR80. The initial pH value of each solution was adjusted to the desired value using 0.1 mol/L HCl and NaOH. Dye concentration in solution was measured by a single beam UV-vis spectrophotometer (CECIL2021) at the maximum wavelength of DR80 (528 nm). The effect of initial dye concentration (20, 35 and 50 mg/L) on dye removal was investigated at pH = 2.1 and adsorbent dosage = 0.02 g for 90 min. The dye removal of electrospun mat (0.02 g) at various pH values (2.1, 5 and 8) was investigated by containing 200 mL DR80 solution with an initial concentration 20 mg/L. The effect of adsorbent dosage was studied by varying nanofiber weight within the range of 0.01–0.02 g at pH = 2.1 and initial concentration = 20 mg/L. The dye removal percentage was evaluated as a function of time according to Eq.