Novel thin‐film nanocomposite membrane with water‐soluble polyhydroxylated fullerene for the separation of Mg 2+ /Li + aqueous solution

Space-Confined Synthesis of Thinner Ether-Functionalized Nanofiltration Membranes with Coffee Ring Structure for Li+/Mg2+ Separation

Positively charged nanofiltration membranes have attracted much attention in the field of lithium extraction from salt lakes due to their excellent ability to separate mono- and multi-valent cations. However, the thicker selective layer and the lower affinity for Li+ result in lower separation efficiency of the membranes. Here, PEI-P membranes with highly efficient Li+/Mg2+ separation performance are prepared by introducing highly lithophilic 4,7,10-Trioxygen-1,13-tridecanediamine (DCA) on the surface of PEI-TMC membranes using a post-modification method. Characterization and experimental results show that the utilization of the DCA-TMC crosslinked structure as a space-confined layer to inhibit the diffusion of the monomer not only increases the positive charge density of the membrane but also reduces its thickness by ≈35% and presents a unique coffee-ring structure, which ensures excellent water permeability and rejection of Mg2+. The ion-dipole interaction of the ether chains with Li+ facilitates Li+ transport and improves the Li+/Mg2+ selectivity (SLi,Mg = 23.3). In a three-stage nanofiltration process for treating simulated salt lake water, the PEI-P membrane can reduce the Mg2+/Li+ ratio of the salt lake by 400-fold and produce Li2CO3 with a purity of more than 99.5%, demonstrating its potential application in lithium extraction from salt lakes.

Membrane modification with carbon nanomaterials for fouling mitigation: A review

This paper provides a comprehensive overview of recent advancements in membrane modification for fouling mitigation in various water treatment processes, employing carbon nanomaterials such as fullerenes, nanodiamonds, carbon quantum dots, carbon nanotubes, and graphene oxide. Currently, using different carbon nanomaterials for polymeric membrane fouling mitigation is at various stages: CNT-modified membranes have been studied for more than ten years and have already been tested in pilot-scale setups; tremendous attention has been paid to utilizing graphene oxide as a modifying agent, while the research on carbon quantum dots' influence on the membrane antifouling properties is in the early stages. Given the intricate nature of fouling as a colloidal phenomenon, the review initially delves into the factors influencing the fouling process and explores strategies to address it. The diverse chemistry and antibacterial properties of carbon nanomaterials make them valuable for mitigating scaling, colloidal, and biofouling. This review covers surface modification of existing membranes using different carbon materials, which can be implemented as a post-treatment procedure during membrane fabrication. Creating mixed-matrix membranes by incorporating carbon nanomaterials into the polymer matrix requires the development of new synthetic procedures. Additionally, it discusses promising strategies to actively suppress fouling through external influences on modified membranes. In the concluding section, the review compares the effectiveness of carbon materials of varying dimensions and identifies key characteristics influencing the antifouling properties of membranes modified with carbon nanomaterials.

Multipass Nanofiltration for Lithium Separation with High Selectivity and Recovery

Nanofiltration (NF) is a promising and sustainable process to extract Li+ from brine lakes with high Mg2+/Li+ mass ratios. However, a trade-off between Li/Mg selectivity and Li recovery exists at the process scale, and the Li/Mg selectivity of commercially and lab-made NF membranes in a single-pass NF process is insufficient to achieve the industrially required Li purity. To overcome this challenge, we propose a multipass NF process with brine recirculation to achieve high selectivity without sacrificing Li recovery. We experimentally demonstrate that Li/Mg selectivity of a three-pass NF process with a commercial NF membrane can exceed 1000, despite the compromised Li recovery as a result of co-existing cations. Our theoretical analysis further predicts that a four-pass NF process with brine recirculation can simultaneously achieve an ultrahigh Li/Mg selectivity of over 4500 and a Li recovery of over 95%. This proposed process could potentially facilitate efficient NF-based solute-solute separations of all kinds and contribute to the development of novel membrane-based separation technologies.

One-Step Construction of the Positively/Negatively Charged Ultrathin Janus Nanofiltration Membrane for the Separation of Li+ and Mg2

To coordinate the trade-off between the separation and permeation of the nanofiltration membrane for the separation of Mg²⁺/Li⁺, we regulated poly(ethyleneimine)/piperazine interface polymerization parameters to construct a positively/negatively charged ultrathin Janus nanofiltration membrane at a free aqueous-organic interface. At the optimized interfacial polymerization parameters, 0.03 wt % of piperazine reacted with trimethylbenzene chloride prior to poly(ethyleneimine), forming a primary polyamide layer with fewer defects or limiting large-scale defects of the polyamide layer. The controlled subsequent reaction of poly(ethyleneimine) and trimethylbenzene chloride results in a Janus nanofiltration membrane, with one side enriched with the carboxyl groups, the other side enriched with the amine groups, and a dense polyamide structure in the middle. Under the optimum conditions, the positive potential of the rear surface of the prepared membrane was 14.57 mV, and the water contact angle reached 71.31°, while the negative potential of the front surface was -25.48 mV, and the water contact angle was 12.93°, confirming a Janus membrane with opposite charges and large hydrophilicity differences in the front and rear surfaces. With a high cross-linking degree, a 40 nm thick polyamide layer is 29.09% more thinner than the traditional polyamide membrane. The ultrathin Janus nanofiltration membrane showed an excellent separation factor (S_Li,Mg of 18.26), stability, and water permeability flux (10.6 L·m^-2·h^-1·bar^-1). The rejections to MgCl₂, CaCl₂, MgSO₄, and Na₂SO₄ are measured above 90% at a nearly constant permeability of 10.6 L·m^-2·h^-1·bar^-1, particularly stable rejections to MgCl₂ and Na₂SO₄.

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 Era of Nanomaterials: A Safe Solution or a Risk for Marine Environmental Pollution?

In recent years, the application of engineered nanomaterials (ENMs) in environmental remediation gained increasing attention. Due to their large surface area and high reactivity, ENMs offer the potential for the efficient removal of pollutants from environmental matrices with better performances compared to conventional techniques. However, their fate and safety upon environmental application, which can be associated with their release into the environment, are largely unknown. It is essential to develop systems that can predict ENM interactions with biological systems, their overall environmental and human health impact. Until now, Life-Cycle Assessment (LCA) tools have been employed to investigate ENMs potential environmental impact, from raw material production, design and to their final disposal. However, LCA studies focused on the environmental impact of the production phase lacking information on their environmental impact deriving from in situ employment. A recently developed eco-design framework aimed to fill this knowledge gap by using ecotoxicological tools that allow the assessment of potential hazards posed by ENMs to natural ecosystems and wildlife. In the present review, we illustrate the development of the eco-design framework and review the application of ecotoxicology as a valuable strategy to develop ecosafe ENMs for environmental remediation. Furthermore, we critically describe the currently available ENMs for marine environment remediation and discuss their pros and cons in safe environmental applications together with the need to balance benefits and risks promoting an environmentally safe nanoremediation (ecosafe) for the future.

Metal ferrite incorporated polysulfone thin-film nanocomposite membranes for wastewater treatment

Effluents from food, fermentation, and sugar industries contain a large quantity of glucose which has to be removed to limit the chemical oxygen demand (COD) of the water discharged. This work proposes novel thin-film nanocomposite (TFN) membranes incorporated with MgFe₂O₄ and ZnFe₂O₄ nanoparticles to address this concern. The nanoparticles synthesized by the sol-gel method was extensively characterized and then incorporated into the active polyamide layer of the thin-film composite polysulfone membranes. The change in membrane morphology, wettability, chemical structure, and mechanical strength with the incorporation of nanoparticles was studied in detail. Membranes with 0.005 wt.% MgFe₂O₄ nanoparticle exhibited highest glucose rejection (96.52 ± 2.35%) at 10 bar, 25 °C, and sufficiently high pure water flux (50.54 ± 1.92 L/m²h). This membrane also displayed 69.1 ± 5.12% salt rejection when challenged with 2000 ppm synthetic NaCl solution.

Engineered Zero-Dimensional Fullerene/Carbon Dots-Polymer Based Nanocomposite Membranes for Wastewater Treatment

With the rapid growth of industrialization, diverse pollutants produced as by-products are emitted to the air-water ecosystem, and toxic contamination of water is one of the most hazardous environmental issues. Various forms of carbon have been used for adsorption, electrochemical, and ion-exchange membrane filtration to separation processes for water treatment. The utilization of carbon materials has gained tremendous attention as they have exceptional properties such as chemical, mechanical, thermal, antibacterial activities, along with reinforcement capability and high thermal stability, that helps to maintain the ecological balance. Recently, engineered nano-carbon incorporated with polymer as a composite membrane has been spotlighted as a new and effective mode for water treatment. In particular, the properties of zero-dimensional (0D) carbon forms (fullerenes and carbon dots) have encouraged researchers to explore them in the field of wastewater treatment through membrane technologies as they are biocompatible, which is the ultimate requirement to ensure the safety of drinking water. Thus, the purpose of this review is to highlight and summarize current advances in the field of water purification/treatment using 0D carbon-polymer-based nanocomposite membranes. Particular emphasis is placed on the development of 0D carbon forms embedded into a variety of polymer membranes and their influence on the improved performance of the resulting membranes. Current challenges and opportunities for future research are discussed.