The good mechanical and chemical stability of textile acrylic fibers waste has promoted its candidacy for fabricating low cost membranes for wastewater treatment. In this work, nanofiltration membranes based on the acrylic fibers waste were successfully prepared using the phase inversion technique. First, membrane solutions with different concentrations (16, 18, 20, and 22%) of acrylic fibers waste (AF) in dimethyl formamide (DMF) were prepared. Evaluation of the membrane performance in terms of water flux and dyes (Congo red and methylene blue) rejection was investigated. Nanofiltration membrane with good water flux and dyes rejection was obtained at 20% polymer concentration. This membrane was modified by adding different ratios (3, 5, and 10 wt%) of polyvinyl pyrrolidone (PVP) to enhance the membrane performance. Characterization of the prepared membrane was explored using attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric analysis, scanning electron microscopy (SEM), contact angle, and swelling properties. The results show that the addition of 5% PVP elevated its performance to a high water flux equal 320 L/m²/h and complete removal of Congo red and 90% rejection of methylene blue at low pressure (3 bar). The molecular weight cutoff of the produced membrane found to be 319.85 Dalton. Moreover, the effect of dye concentration on water flux and dye rejection at different applied pressure was studied. The entire work presented an optimization procedure for obtaining standalone nanofiltration membrane with high performance using low cost waste materials (textile fiber waste).

In this work, new chitosan derivative nanofibers that exhibit antibacterial properties were successfully fabricated. The two CS Schiff base derivatives (CS-APC and CS-2APC) were prepared by incorporating 4-amino antipyrine moiety in two different ratios, followed by a reductive amination to obtain the corresponding derivatives CS-APCR and CS-2APCR. Spectral analyses were used to confirm the chemical structure. The molecular docking evaluation of CS-APC, CS-APCR, and CS was conducted on DNA topoisomerase IV, thymidylate kinase and SARS-CoV-2 main protease (3CL^pro) active sites. CS-APCR showed a well-fitting into the three enzyme active sites with docking score values of − 32.76, − 35.43 and − 30.12 kcal/mol, respectively. The nanocomposites of CS derivatives were obtained by electrospinning the blends of CS-2APC and CS-2APCR with polyvinyl pyrrolidone (PVP) at 20 kV. The morphology of the nanofibers was investigated by scanning electron microscopy (SEM). It was found that fiber diameters were significantly decreased when CS-2APC and CS-2APCR were incorporated into pure PVP to reach 206–296 nm and 146–170 nm, respectively, compared to 224–332 nm for pure PVP. The derivatives of CS and their nanofibers with PVP were found to have antibacterial activities against two strains of Staphylococcus aureus and Escherichia coli. Data revealed that CS-2APC nanofibers showed antibacterial activity to the two strains of E. coli less than CS-2APCR nanofibers.

The use of biodegradable polyesters derived from green sources and their combination with natural abundantly layered aluminosilicate clay, e.g., natural montmorillonite, meets the requirements for the development of new sustainable, disposable, and biodegradable organic dye sorbent materials. In this regard, novel electrospun composite fibers, based on poly β-hydroxybutyrate (PHB) and in situ synthesized poly(vinyl formate) (PVF), loaded with protonated montmorillonite (MMT-H) were prepared via electrospinning in the presence of formic acid, a volatile solvent for polymers and a protonating agent for the pristine MMT-Na. The morphology and structure of electrospun composite fibers were investigated through SEM, TEM, AFM, FT-IR, and XRD analyses. The contact angle (CA) measurements showed increased hydrophilicity of the composite fibers incorporated with MMT-H. The electrospun fibrous mats were evaluated as membranes for removing cationic (methylene blue) and anionic (Congo red) dyes. PHB/MMT 20% and PVF/MMT 30% showed significant performance in dye removal compared with the other matrices. PHB/MMT 20% was the best electrospun mat for adsorbing Congo red. The PVF/MMT 30% fibrous membrane exhibited the optimum activity for the adsorption of methylene blue and Congo red dyes.