ZnO Decorated Electrospun Polylactic Acid Membrane for Organic Dyes Removal From Wastewaters

Abstract

The present work reports the design of a novel nanocomposite adsorbent based on a bio-based PLA electrospun membrane doped with ZnO (28 wt% confirmed by TGA analysis) (ZnO@PLA) for removing different organic dyes (methyl orange [MO], congo red, and acid yellow 17) from wastewater. After characterizing the produced samples, batch tests were conducted to compare the removal capacities of pristine PLA and ZnO@PLA. MO was chosen to assess the effect of temperature (25°C–80°C), contact time (0–24 h), pH (3–9), initial dye concentration (25–200 ppm), salinity (0–100 000 ppm), and adsorbent dosage (0.5–3 g/L). The Langmuir model best fits the adsorption data, providing a q_m = 94.07 mg/g. Thermodynamic calculations demonstrate the spontaneity of the MO removal process and its favorability at low temperatures due to the negative value of enthalpy. Kinetic modeling suggests an excellent fit with the PSO model. Furthermore, the design of experiments (DoEs) method was applied to forecast the removal (%) of MO through a polynomial model by modifying the temperature, pH, and initial MO concentration, confirming that both elevated temperature and higher dye concentrations slightly suppress the adsorption recovery. Finally, an adsorption mechanism was proposed based on interactions of MO with the ZnO-modified electrospun adsorbent.