Desalination Characteristics of Cellulose Acetate FO Membrane Incorporated with ZIF-8 Nanoparticles

Cellulose acetate, a source from discarded cigarette butts for the development of mixed matrix loose nanofiltration membranes for selective separation

This study presents an environmentally friendly method for extracting cellulose acetate (CA) from discarded cigarette filters, which is then utilized in the fabrication of cellulose-based membranes designed for high flux and rejection rates. CA membranes are likeable to separate dyes and ions, but their separation efficiency is exposed when the contaminant concentration is very low. So, we have integrated graphene oxide (GO) and carboxylated titanium dioxide (COOH-TiO2) in CA to develop mixed matrix membranes (MMMs) and studied them against dyes and most used salts. The CA has been extracted from these butts and added GO and COOH-TiO2 nanoparticles to develop MMMs. The present work administers the effective separation of five dyes (methyl orange, methyl violet, methylene blue, cresol red, and malachite green) and salts (NaCl and Na2SO4) along with the high efficiency of water flux by prepared CA membranes. The prepared membranes rejected up to 94.94 % methyl violet, 91.28 % methyl orange, 88.28 % methylene blue, 89.91 % cresol red, and 91.70 % malachite green dye. Along with the dyes, the membranes showed ∼40.40 % and ∼ 42.97 % rejection of NaCl and Na2SO4 salts, respectively. Additionally, these membranes have tensile strength up to 1.54 MPa. Various characterization techniques were performed on all prepared CA membranes to comprehend their behaviour. The antibacterial activity of MMMs was investigated using the Muller-Hinton-Disk diffusion method against the gram-positive bacterium Staphylococcus aureus (S. aureus) and the gram-negative bacterium Escherichia coli (E. coli). We believe the present work is an approach to utilizing waste materials into valuable products for environmental care.

UiO-66-NH2 nanocomposites incorporated cellulose acetate for forward osmosis membranes of high desalination performance

In this paper, the hydrophilic UiO-66-NH2 nanomaterial was synthesized by the solvent-thermal method and characterized. Then, UiO-66-NH2 was introduced into the casting membrane solution of cellulose acetate (CA) forward osmosis (FO) membrane, and CA/UiO-66-NH2 forward osmosis membrane was prepared by the phase inversion method. The optimum preparation conditions of CA/UiO-66-NH2 mixed matrix membranes were determined as follows: the content of UiO-66-NH2 was 0.4 wt%, the coagulation bath temperature was 35°C, the mixing temperature was 50°C and the heat treatment temperature was 50°C. FTIR, SEM, water contact angle and AFM were carried out on CA/UiO-66-NH2 forward osmosis membrane prepared under the best preparation conditions. Compared to the CA forward osmosis membrane, the permeability and selectivity of the CA/UiO-66-NH2 membrane were improved. The water flux and reverse salt flux of the CA/UiO-66-NH2 forward osmosis membrane reached 52.32 L/(m2·h) and 2.43 g/(m2·h), respectively. The permeability selectivity of CA membranes and CA/UiO-66-NH2 membranes did not change much during 180 min, indicating that the two membranes had good long-term stability. This study shows a potential advantage of UiO-66-NH2 as additives for improvement in the desalination performance of forward osmosis membranes.

Advances in Application of Cellulose-MOF Composites in Aquatic Environmental Treatment: Remediation and Regeneration

Metal organic frameworks (MOFs) have gained remarkable interest in water treatment due to their fascinating characteristics, such as tunable functionality, large specific surface area, customizable pore size and porosity, and good chemical and thermal stability. However, MOF particles tend to easily agglomerate in nanoscale, thus decreasing their activity and processing convenience. It is necessary to shape MOF nanocrystals into maneuverable structures. The in situ growth or ex situ incorporation of MOFs into inexpensive and abundant cellulose-family materials can be effective strategies for the stabilization of these MOF species, and therefore can make available a range of enhanced properties that expand the industrial application possibilities of cellulose and MOFs. This paper provides a review of studies on recent advances in the application of multi-dimensional MOF-cellulose composites (e.g., aerogels, membranes, and bulk materials) in wastewater remediation (e.g., metals, dyes, drugs, antibiotics, pesticides, and oils) and water regeneration by adsorption, photo- or chemocatalysis, and membrane separation strategies. The advantages brought about by combining MOFs and cellulose are described, and the performance of MOF-cellulose is described and compared to its counterparts. The mechanisms of relative MOF-cellulose materials in processing aquatic pollutants are included. Existing challenges and perspectives for future research are proposed.

Marine Collagen-Based Antibacterial Film Reinforced with Graphene and Iron Oxide Nanoparticles

It has become more widely available to use biopolymer-based films as alternatives to conventional plastic-based films due to their non-toxic properties, flexibility, and affordability. However, they are limited in application due to deficiencies in their properties. The marine collagen was the specimen for the present study. Thus, the main objective was to reinforce marine collagen-based films with 1.0% (w/w of the dry polymer weight) of iron oxide nanoparticles (IO-NPs), graphene oxide nanoparticles (GO-NPs), or a combination of both oxides (GO-NPs/IO-NPs) as antibacterial and antioxidant additives to overcome some of the limitations of the film. In this way, the nanoparticles were incorporated into the film-forming solution (2% w/v in acetic acid, 0.05 M) and processed by casting. Thereafter, the films were dried and analyzed for their physicochemical, mechanical, microstructural, and functional properties. The results show that the effective combination of GO-NPs/IO-NPs enhanced the physicochemical properties by increasing the water contact angle (WCA) of the films from 77.2 to 84.4° and their transparency (T) from 0.5 to 5.2. Furthermore, these nanoparticles added antioxidant and antibacterial value to the films, with free radical inhibition of up to 95.8% and 23.8 mm of bacteria growth inhibition (diameter). As a result, both types of nanoparticles are proposed as suitable additives to be incorporated into films and enhance their different properties.

Biopolymer-Based Films Reinforced with Green Synthesized Zinc Oxide Nanoparticles

Nowadays, biopolymer-based films are being developed as an alternative to conventional plastic-based films, mainly because they are non-toxic, flexible, inexpensive, and widely available. However, they are restricted in their applications due to several deficiencies in their properties. Accordingly, the reinforcement of these materials with nanoparticles/nanofillers could overcome some of their shortcomings, especially those processed by green methods. Green synthesized zinc oxide nanoparticles (ZnO-NPs) are highly suggested to overcome these deficiencies. Therefore, the main aim of this work was to develop different biopolymer-based films from cellulose acetate (CA), chitosan (CH), and gelatin (GE) reinforced with ZnO-NPs prepared by casting, and to assess their different properties. The results show the improvements produced by the incorporation of ZnO-NPs (1% w/w) into the CA, CH, and GE systems. Thus, the water contact angles (WCAs) increased by about 12, 13, and 14%, while the water vapor permeability (WVP) decreased by about 14, 6, and 29%, the water solubility (WS) decreased by about 23, 6, and 5%, and the transparency (T) increased by about 19, 31, and 20% in the CA, CH, and GE systems, respectively. Furthermore, the mechanical properties were enhanced by increasing the ultimate tensile strength (UTS) (by about 39, 13, and 26%, respectively) and Young's modulus (E) (by about 70, 34, and 63%, respectively), thereby decreasing the elongation at the break (ε_max) (by about 56, 23, and 49%, respectively) and the toughness (by about 50, 4, and 30%, respectively). Lastly, the antioxidant properties were enhanced by 34, 49, and 39%, respectively.

Biopolymer-Based Films Reinforced with FexOy-Nanoparticles

Nowadays, natural polymer-based films are considered potentially environmentally friendly alternatives to conventional plastic films, due to many advantageous properties, including their easy processability, high flexibility, non-toxicity, low cost, high availability, and environmental safety. However, they are limited in their application by a number of shortcomings, including their high water solubility and vapor permeability as well as their poor opacity and low mechanical resistance. Thus, nanoparticles, such as green Fe_xO_y-NPs, can be used to overcome the drawbacks associated with these materials. Therefore, the aim of this study was to develop three different polymer-based films (gelatin-based, cellulose acetate-based and chitosan-based films) containing green synthesized Fe_xO_y-NPs (1.0% w/w of the initial polymer weight) as an additive to improve film properties. This was accomplished by preparing the different films using the casting method and examining their physicochemical, mechanical, microstructural, and functional characteristics. The results show that the incorporation of Fe_xO_y-NPs into the different films significantly enhanced their physicochemical, mechanical, and morphological properties as well as their antioxidant characteristics. Consequently, it was possible to produce suitable natural polymer-based films with potential applications across a wide range of industries, including functional packaging for food, antioxidants, and antimicrobial additives for pharmaceutical and biomedical materials as well as pesticides for agriculture.

Progress and Prospects of Nanocellulose-Based Membranes for Desalination and Water Treatment

Membrane-based desalination has proved to be the best solution for solving the water shortage issues globally. Membranes are extremely beneficial in the effective recovery of clean water from contaminated water sources, however, the durability as well as the separation efficiency of the membranes are restricted by the type of membrane materials/additives used in the preparation processes. Nanocellulose is one of the most promising green materials for nanocomposite preparation due to its biodegradability, renewability, abundance, easy modification, and exceptional mechanical properties. This nanocellulose has been used in membrane development for desalination application in the recent past. The study discusses the application of membranes based on different nanocellulose forms such as cellulose nanocrystals, cellulose nanofibrils, and bacterial nanocellulose for water desalination applications such as nanofiltration, reverse osmosis, pervaporation, forward osmosis, and membrane distillation. From the analysis of studies, it was confirmed that the nanocellulose-based membranes are effective in the desalination application. The chemical modification of nanocellulose can definitely improve the surface affinity as well as the reactivity of membranes for the efficient separation of specific contaminants/ions.