Fouling Analysis in One-Stage Ultrafiltration of Precipitation-Treated Bacillus subtilis Fermentation Liquors for Biosurfactant Recovery

Research Progress of Water Treatment Technology Based on Nanofiber Membranes

In the field of water purification, membrane separation technology plays a significant role. Electrospinning has emerged as a primary method to produce nanofiber membranes due to its straightforward, low cost, functional diversity, and process controllability. It is possible to flexibly control the structural characteristics of electrospun nanofiber membranes as well as carry out various membrane material combinations to make full use of their various properties, including high porosity, high selectivity, and microporous permeability to obtain high-performance water treatment membranes. These water separation membranes can satisfy the fast and efficient purification requirements in different water purification applications due to their high filtration efficiency. The current research on water treatment membranes is still focused on creating high-permeability membranes with outstanding selectivity, remarkable antifouling performance, superior physical and chemical performance, and long-term stability. This paper reviewed the preparation methods and properties of electrospun nanofiber membranes for water treatment in various fields, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, and other special applications. Lastly, various antifouling technologies and research progress of water treatment membranes were discussed, and the future development direction of electrospun nanofiber membranes for water treatment was also presented.

State-of-the-Art of Polymer/Fullerene C60 Nanocomposite Membranes for Water Treatment: Conceptions, Structural Diversity and Topographies

To secure existing water resources is one of the imposing challenges to attain sustainability and ecofriendly world. Subsequently, several advanced technologies have been developed for water treatment. The most successful methodology considered so far is the development of water filtration membranes for desalination, ion permeation, and microbes handling. Various types of membranes have been industrialized including nanofiltration, microfiltration, reverse osmosis, and ultrafiltration membranes. Among polymeric nanocomposites, nanocarbon (fullerene, graphene, and carbon nanotubes)-reinforced nanomaterials have gained research attention owing to notable properties/applications. Here, fullerene has gained important stance amid carbonaceous nanofillers due to zero dimensionality, high surface areas, and exceptional physical properties such as optical, electrical, thermal, mechanical, and other characteristics. Accordingly, a very important application of polymer/fullerene C₆₀ nanocomposites has been observed in the membrane sector. This review is basically focused on talented applications of polymer/fullerene nanocomposite membranes in water treatment. The polymer/fullerene nanostructures bring about numerous revolutions in the field of high-performance membranes because of better permeation, water flux, selectivity, and separation performance. The purpose of this pioneering review is to highlight and summarize current advances in the field of water purification/treatment using polymer and fullerene-based nanocomposite membranes. Particular emphasis is placed on the development of fullerene embedded into a variety of polymer membranes (Nafion, polysulfone, polyamide, polystyrene, etc.) and effects on the enhanced properties and performance of the resulting water treatment membranes. Polymer/fullerene nanocomposite membranes have been developed using solution casting, phase inversion, electrospinning, solid phase synthesis, and other facile methods. The structural diversity of polymer/fullerene nanocomposites facilitates membrane separation processes, especially for valuable or toxic metal ions, salts, and microorganisms. Current challenges and opportunities for future research have also been discussed. Future research on these innovative membrane materials may overwhelm design and performance-related challenging factors.

The Application of the Nanofiltration Membrane NF270 for Separation of Fermentation Broths

The potential for nanofiltration (NF) in removing both relatively low molecular weight (MW) organic species and charged solutes from complex media is noteworthy. The main aim of the current work was to improve understanding of the separation mechanisms of fermentation broths components in the NF process. For this purpose, the experimental investigations were performed using the commercial polyamide NF270 membrane. The feed solution was ultrafiltered 1,3-propanediol (1,3-PD) broths. The separation results were analyzed and discussed in light of the detailed characteristics of both the membrane and the broth components. It has been noted that the membrane ensured the complete 1,3-PD permeability and significant rejection of some feed components. A thorough analysis showed that the retention of carboxylic acids was based on both the Donnan effect and sieve mechanism, according to the following order: succinic acid > lactic acid > acetic acid > formic acid. Indeed, acids retention increased with increasing charged acids ions valency, Stokes radius (rS) as well as MW, and decreasing diffusion coefficient (D). In turn, for ions, the following orders retention was determined: SO42− = PO43− > Cl− and Ca2+ > Na+ > NH4+ ~ K+. It indicated that the ions retention increased with increasing ions charge density, hydrated radius (rH), and hydration energy (Eh). It showed that the separation of the ions was based on the Donnan exclusion, sieving effect, and dielectric exclusion.