In the present study, graphene oxide (GO) was incorporated as a nanoadditive into a polyphenylsulfone (PPSU) to develop a PPSU/GO nanocomposite membrane with enhanced antifouling properties. A series of membranes containing different concentrations (0.2, 0.5 and 1.0 wt.%) of GO were fabricated via the phase inversion method, using N-methyl pyrrolidone (NMP) as the solvent, deionized water as the non-solvent, and polyvinylpyrrolidone (PVP) as a pore forming agent. The prepared nanocomposite membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and were also characterized with respect to contact angle, zeta potential and porosity, mean pore radius, tortuosity and molecular weight cut-off (MWCO). Thermogravimetric analysis (TGA) and tensile testing were used to measure thermal and mechanical properties. The membrane performance was evaluated by volumetric flux and rejection of proteins, and antifouling properties. According to the results, the optimum addition of 0.5 wt% GO resulted in a membrane with an increased flux of 171 ± 3 Lm⁻²h⁻¹ with a MWCO of ~40 kDa. In addition, the GO incorporation efficiently inhibited the interaction between proteins and the membrane surface, thereby improving the fouling resistance ability by approximately 58 ± 3%. Also, the resulting membranes showed a significant improvement in mechanical and thermal properties.

The objective of the present work was to investigate the efficacy of indigenously developed polyacrylonitrile (PAN) based ultrafiltration (UF) membrane for chromium ions removal from potable water. The hydrolyzed PAN membranes effectively rejected chromium anions in the feed ranging from 250 ppb to 400 ppm and a rejection of ≥90% was achieved for pH ≥ 7 at low chromate concentration (≤25 ppm) in feed. The rejection mechanism of chromium ions was strongly dependent on Donnan exclusion principle, while size exclusion principle for UF did not play a major role on ions rejection. Feed pH played a vital role in changing porosity of membrane, which influenced the retention behavior of chromate ions. Cross-flow velocity, pressure did not play significant role for ions rejection at low feed concentration. However, at higher feed concentration (≥400 ppm), concentration polarization became important and it reduced the chromate rejection to 32% at low cross flow and high pressure. Donnan steric-partitioning pore and dielectric exclusion model (DSPM-DE) was applied to evaluate the chromate ions transport through PAN UF membrane as a function of flux by using optimized model parameters and the simulated data matched well with experimental results.

A bi-metallic titanium–tantalum carbide MXene, Ti_xTa_(4−x)C₃ is successfully prepared via etching of Al atoms from parent Ti_xTa_(4−x)AlC₃ MAX phase for the first time. X-ray diffractometer and Raman spectroscopic analysis proved the crystalline phase evolution from the MAX phase to the lamellar MXene arrangements. Also, the X-ray photoelectron spectroscopy (XPS) study confirmed that the synthesized MXene is free from Al after hydro fluoric acid (HF) etching process as well as partial oxidation of Ti and Ta. Moreover, the FE-SEM and TEM characterizations demonstrate the exfoliation process tailored by the Ti_xTa_(4−x)C₃ MXene after the Al atoms from its corresponding MAX Ti_xTa_(4−x)AlC₃ phase, promoting its structural delamination with an expanded interlayer d-spacing, which can allow an effective reversible Li-ion storage. The lamellar Ti_xTa_(4−x)C₃ MXene demonstrated a reversible specific discharge capacity of 459 mAhg⁻¹ at an applied C-rate of 0.5 °C with a capacity retention of 97% over 200 cycles. An excellent electrochemical redox performance is attributed to the formation of a stable, promising bi-metallic MXene material, which stores Li-ions on the surface of its layers. Furthermore, the Ti_xTa_(4−x)C₃ MXene anode demonstrate a high rate capability as a result of its good electron and Li-ion transport, suggesting that it is a promising candidate as Li-ion anode material.

We investigate the removal of heavy metal ions from synthetic contaminated water on a laboratory scale using a carboxylated-graphene oxide (GO)-incorporated polyphenylsulfone (PPSU) nanofiltration membrane (the so called PPSU/carboxylated-GO nanocomposite membrane). The prepared membranes were characterized with respect to the rheology of the doping solutions and based on the morphology, topography, and charge density of the membranes. Spectroscopic analysis of the membranes was also performed. The nanofiltration performance was demonstrated by the removal of five heavy metal ions (arsenic, chromium, cadmium, lead, and zinc). The effects of carboxylated-GO on the membrane molecular weight cut-off, hydraulic permeability, and heavy metal ion removal performance were investigated with respect to different factors, including feed concentration from single ions, transmembrane pressure (TMP) with mixed ions, and permeate flux. The addition of carboxylated-GO produced a membrane with enhanced properties that exhibited superior performance. Increasing the feed concentration and TMP did not affect the removal of anions; however, the removal of cations slightly decreased with the resulting membrane. The maximum removal rates of heavy metal ions were >98% and ∼80% for the anions and cations, respectively, and an enhanced volumetric flux of 27 ± 3 L m⁻² h⁻¹ was observed. This result is based on the Donnan exclusion principle, which is attributable to the surface charge of −70 mV and the order of the hydrated metal radii. The prepared PPSU/carboxylated-GO nanocomposite membrane provided impressive heavy metal ion removal and showed an acceptable volumetric flux under the applied parameters; this work demonstrates very economically advantageous conditions for heavy metal ion removal.