Antibacterial PES/Vancomycin ultrafiltration membranes with enhanced water flux and low BSA rejection

Polyethersulfone (PES) blended with glycopeptide Vancomycin was fabricated via phase inversion method. The fabricated membranes were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), contact angle (CA) and optical profilometry. The PES/Vancomycin membranes showed a notable increase in hydrophilicity, porosity, pore size, antibacterial activity and water flux in comparison with pristine membranes. The changes are due to the hydrophilic nature of Vancomycin molecules and ability to form hydrogen bond quickly. The surface hydrophilicity of PES/Vancomycin membranes decreased up to 48° with increase in surface roughness (R_a), that is, 0.347 μm, thus increasing the water flux of PES/Vancomycin membranes up to 340 L/m². h. The bovine serum albumin (BSA) rejection decreases, that is, pristine 70.9% to PES/Vancomycin 26% and BSA flux increases at constant ionic strength (0.1) and above the isoelectric point (IEP) of the BSA. Under these conditions, electrostatic interactions are expected to be minimum between protein and the membrane surfaces.     

Current challenges in hydrate-based desalination: Kinetic and thermodynamic perspective

Water scarcity is becoming a severe problem worldwide due to inadequate freshwater resources and swift population growth. Seawater desalination is one of the vital approaches to meet the demand for freshwater. However, energy and associated costs with conventional seawater desalination techniques are incentivizing non-conventional water desalination processes. Water desalination using gas hydrates formation is one of the emerging non-conventional processes. In this perspective article, recent advances in hydrate-based seawater desalination (HBSD) have been critically analyzed to outline a future path towards a clean and efficient hydrate-based desalination process. It provides a detailed comparison of various processes developed over decades, and measured desalination efficiencies with their process details. Moreover, the current challenges, limitations, and future perspectives of hydrate-based desalination are also discussed. The study also recapitulates the thermodynamics and kinetics aspects of the hydrate-based desalination process. In addition, various factors controlling the desalination efficiencies, such as control of the separation of hydrate crystals, salt deposition on hydrate particles, and hydrate morphology, were thoroughly investigated with their proposed process designs. The kinetics of hydrate formation is also assessed, with the possibility of a zero-induction regime and its consequent impact on hydrate morphology. The current capabilities of the thermodynamics models (Gibbs energy minimization + electrolyte equation of state) were discussed using various commercially available software. Additionally, the role of hydrate promotors is also discussed, which can reduce the higher cost associated with the hydrate-based desalination process.