Characterisation and swelling–deswelling properties of superabsorbent membranes made of PVA and cellulose nanocrystals

Advances in Membrane Separation for Biomaterial Dewatering

Biomaterials often contain large quantities of water (50-98%), and with the current transition to a more biobased economy, drying these materials will become increasingly important. Contrary to the standard, thermodynamically inefficient chemical and thermal drying methods, dewatering by membrane separation will provide a sustainable and efficient alternative. However, biomaterials can easily foul membrane surfaces, which is detrimental to the performance of current membrane separations. Improving the antifouling properties of such membranes is a key challenge. Other recent research has been dedicated to enhancing the permeate flux and selectivity. In this review, we present a comprehensive overview of the design requirements for and recent advances in dewatering of biomaterials using membranes. These recent developments offer a viable solution to the challenges of fouling and suboptimal performances. We focus on two emerging development strategies, which are the use of electric-field-assisted dewatering and surface functionalizations, in particular with hydrogels. Our overview concludes with a critical mention of the remaining challenges and possible research directions within these subfields.

Antimicrobial chitosan-agarose full polysaccharide silver nanocomposite films

The antibacterial and biocompatible films have attracted much attention due to their wide range of applications. Although a lot of work has been done in this area, research in this field is still very active and associated with the continuous development of new materials. In the present study full polysaccharide chitosan-agarose (CS-AG) films were produced by reaction of chitosan with periodate activated agarose, followed by reductive amination. Activated agarose was prepared by periodate oxidation of agarose, and then applied as a crosslinking agent to form a new polymeric network. The structure of periodate activated agarose was studied by nuclear magnetic resonances spectroscopy (¹H NMR) and Fourier-transform infrared spectroscopy (FT-IR). Rheological experiments showed that the viscosity of agarose solution changes rapidly by addition of periodate to the solution. Swelling, deswelling, and gel content of the films were determined at different pH. Chitosan-agarose silver nanocomposite (CS-AG/n-Ag) films were prepared by loading silver ions and subsequent reduction. The CS-AG/n-Ag films were characterized by FT-IR, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM).Transmission electron microscopy (TEM) image showed that the size of silver nanoparticles was about 2-7 nm. The bactericidal capacities (MBC/MIC) of the CS-AG/Ag films for Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) were obtained 2.0, 1.0 and 2.0, respectively. The results demonstrate that the CS-AG/n-Ag films have good antibacterial activity against both the gram-negative and the gram-positive bacteria which make them suitable for food packaging and wound healing applications.

Hydrogel membranes: A review

Hydrogel membranes (HMs) are defined and applied as hydrated porous media constructed of hydrophilic polymers for a broad range of applications. Fascinating physiochemical properties, unique porous architecture, water-swollen features, biocompatibility, and special water content dependent transport phenomena in semi-permeable HMs make them appealing constructs for various applications from wastewater treatment to biomedical fields. Water absorption, mechanical properties, and viscoelastic features of three-dimensional (3D) HM networks evoke the extracellular matrix (ECM). On the other hand, the porous structure with controlled/uniform pore-size distribution, permeability/selectivity features, and structural/chemical tunability of HMs recall membrane separation processes such as desalination, wastewater treatment, and gas separation. Furthermore, supreme physiochemical stability and high ion conductivity make them promising to be utilised in the structure of accumulators such as batteries and supercapacitors. In this review, after summarising the general concepts and production processes for HMs, a comprehensive overview of their applications in medicine, environmental engineering, sensing usage, and energy storage/conservation is well-featured. The present review concludes with existing restrictions, possible potentials, and future directions of HMs.