Carbon Nanodots-Embedded Pullulan Nanofibers for Sulfathiazole Removal from Wastewater Streams

Abstract

Carbon nanodots (CNDs)-embedded pullulan (PUL) nanofibers were developed and successfully applied for sulfathiazole (STZ) removal from wastewater streams for the first time. The CNDs were incorporated into PUL at 0.0%, 1.0%, 2.0%, and 3.0% (w/w) to produce M1, M2, M3, and M4 nanofibers (PUL-NFs), respectively. The produced PUL-NFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) and applied for STZ removal from aqueous solutions through pH, kinetics, and equilibrium batch sorption trials. A pH range of 4.0–6.0 was observed to be optimal for maximum STZ removal. Pseudo-second order, intraparticle diffusion, and Elovich models were suitably fitted to kinetics adsorption data (R2 = 0.82–0.99), whereas Dubinin–Radushkevich, Freundlich, and Langmuir isotherms were fitted to equilibrium adsorption data (R2 = 0.88–0.99). STZ adsorption capacity of PUL-NFs improved as the amount of embedded CNDs increased. Maximum STZ adsorption capacities of the synthesized PUL-NFs were in the order of: M4 > M3 > M2 > M1 (133.68, 124.27, 93.09, and 35.04 mg g−1, respectively). Lewis acid–base reaction and π-π electron donor–acceptor interactions were the key STZ removal mechanisms under an acidic environment, whereas H-bonding and diffusion were key under a basic environment. Therefore, CNDs-embedded PUL-NFs could be employed as an environmentally friendly, efficient, and non-toxic adsorbent to remove STZ from wastewater streams.

Preparation and Characterization of Electrospun Poly(lactic acid)/Poly(ethylene glycol)–b–poly(propylene glycol)–b–poly(ethylene glycol)/Silicon Dioxide Nanofibrous Adsorbents for Selective Copper (II) Ions Removal from Wastewater

“…The effect of pH on the adsorption efficiency of PLA-based nanofibrous adsorbents is discussed in this section. The pH level of the metal ions solution is crucial in regulating the amount of ions that are adsorbed onto the adsorbent material [ 50 ]. For checking the effect of pH, 10 ppm Cu 2+ solutions were added with suitable amounts of HCl to adjust the pH from 4 to 6.…”

Recent Progress, Challenges, and Opportunities of Membrane Distillation for Heavy Metals Removal

“…Electrospinning has gained a lot of attention because of its versatility in spinning a wide range of polymeric fibers and its ability to consistently produce fibers in the submicron range, which is difficult to achieve using standard mechanical fiber-spinning technology techniques. [142][143][144] Electrospun fibers have effectively been employed in various sectors, including seawater desalination, heavy metals removal, wastewater treatment, nanocatalysis, biomedical, optical electronics, and environmental engineering. [145][146][147] This process has been used in the textile industry for over 60 years to manufacture nonwoven fiber textiles.…”