Potential of chitosan/nanocellulose based composite membrane for the removal of heavy metal (chromium ion)

Chitosan-blended membranes for heavy metal removal from aqueous systems: A review of synthesis, separation mechanism, and performance

The environmental pollution caused by heavy metal ions has become a serious global environmental issue. Heavy metal contaminants released from industrial effluents, agricultural runoff, and human activities, can enter into water resources. The toxicity of these heavy metal ions even at trace concentrations presents a substantial hazard to both aquatic systems and human well-being. The membrane separation processes have become more promising sustainable techniques for the separation of metal ions from the effluent. The research efforts have been concentrated on improving the synthesis of membranes and membrane materials to facilitate the sustainable separation of heavy metals. The application of chitosan in the fabrication of membranes is getting more attention. Chitosan, a natural polysaccharide derived from chitin, is abundant in nature and has active hydroxyl and amino groups suitable for the separation of heavy metal ions. It exhibits excellent chelating tendency, biocompatibility, and biodegradability. The functionalization of chitosan to improve its mechanical strength, chemical stability, and antifouling properties has become an ongoing area of research. This review examines the synthesis and efficient applications of chitosan blended membranes. The review concludes by outlining the current challenges and proposing future research prospects to enhance the applicability of chitosan-blended membranes in environmental remediation.

Sustainable Lignin-Reinforced Chitosan Membranes for Efficient Cr(VI) Water Remediation

The pollution of aquatic environments is a growing problem linked to population growth and intense anthropogenic activities. Because of their potential impact on human health and the environment, special attention is paid to contaminants of emerging concern, namely heavy metals. Thus, this work proposes the use of naturally derived materials capable of adsorbing chromium (VI) (Cr(VI)), a contaminant known for its potential toxicity and carcinogenic effects, providing a sustainable alternative for water remediation. For this purpose, membranes based on chitosan (CS) and chitosan/Kraft lignin (CS/KL) with different percentages of lignin (0.01 and 0.05 g) were developed using the solvent casting technique. The introduction of lignin imparts mechanical strength and reduces swelling in pristine chitosan. The CS and CS/0.01 KL membranes performed excellently, removing Cr(VI) at an initial 5 mg/L concentration. After 5 h of contact time, they showed about 100% removal. The adsorption process was analyzed using the pseudo-first-order model, and the interaction between the polymer matrix and the contaminant was attributed to electrostatic interactions. Therefore, CS and CS/KL membranes could be low-cost and efficient adsorbents for heavy metals in wastewater treatment applications.

Removal of propranolol by membranes fabricated with nanocellulose/proanthocyanidin/modified tannic acid: The influence of chemical and morphologic features and mechanism study

Polymer-based membranes containing nanocellulose and natural macromolecules have potential to treat water, however few works have associated the changes in chemical and morphological membrane's features with their performance as adsorbent. Herein, a new green composite based on nanocellulose (NC) and alkylated tannic acid (ATA) and cross-linked with proanthocyanidin was produced and incorporated into polyacrylonitrile (PAN) membranes to eliminate propranolol (PRO) from water. Characterizations revealed that the increasing of NC-ATA content reduced the pore size of the membrane's upper surface and made the finger like structure of the sublayer disappear, due to the formation of hydrophilic domains of NC/ATA which speeds up the external solidification step. The presence of NC-ATA reduced the hydrophilicity, from a water contact angle of 3.65° to 16.51°, the membrane roughness, from 223.5 to 52.0 nm, and the zeta potential from -25.35 to -55.20 mV, improving its features to be a suitable adsorbent of organic molecules. The membranes proved to be excellent green adsorbent, tridimensional, and easy to remove after use, and qmax for PRO was 303 mg·g-1. The adsorption mechanism indicates that H-bonds, ion exchange, and π-π play important role in adsorption. NC-ATA@PAN kept high removal efficiencies after four cycles, evidencing the potential for water purification.

Effect of biocomposite production factors on the development of an eco-friendly chitosan/alginate-based adsorbent with enhanced copper removal efficiency

Nowadays, wastewater treatment is a critical concern, particularly regarding the removal of heavy metals through adsorption methods. Extensive research has been conducted on obtaining high-yield and environmentally friendly adsorbents. Natural polymer adsorbents especially have shown promise in ion and organic molecule adsorption. To enhance the practical applicability of adsorbents, the combination of biopolymers to form biocomposites is a promising alternative. In this study, adsorbents based on a 1:1 wt./wt. of chitosan (CS) and alginate (SA) were prepared. The influence of the regeneration route and drying conditions on the copper adsorption capacity was investigated, along with reaction parameters such as contact time, adsorbent particle size, and pH. The highest adsorption capacity was observed in the composite material obtained through a one-pot regeneration process and freeze-dried. The CSAR3L sample exhibited a remarkable adsorption capacity of 288 mg Cu(II)/g after 360 min at 25 °C. The synergistic effect between the CS and SA precursors was confirmed by analyzing the individual precursors and their mechanical mixture. The initial adsorption rates at pH 6 followed the order: CSAR3-L > Bk-CSR3L > Bk-SAR3L + Bk-CSR3L > Bk-SAR3L. The physicochemical and morphological properties of the materials were studied by FTIR, XRD, DLS, XPS, optical microscopy, EDS-SEM, elemental chemical analysis, and TGA-DTG. The utilization of different drying methods resulted in the formation of calcium carbonate crystalline phases in the as-prepared materials, thus creating substantial adsorption active sites. After the adsorption process, hydroxylated copper sulfate phases and a significant decrease in calcium concentration were observed, indicating that an ion exchange adsorption mechanism occurred. The analysis of adsorption kinetics and the shape of the adsorption isotherms, in agreement with the characterization results, suggested the presence of multiple active sites and the formation of a chemisorption monolayer.

Nanocellulose-Based Nanocomposites for Sustainable Applications: A Review

Nanocellulose has emerged in recent years as one of the most notable green materials available due to its numerous appealing factors, including its non-toxic nature, biodegradability, high aspect ratio, superior mechanical capabilities, remarkable optical properties, anisotropic shape, high mechanical strength, excellent biocompatibility and tailorable surface chemistry. It is proving to be a promising material in a range of applications pertinent to the material engineering to biomedical applications. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations. This review presents an overview of general concepts in nanocellulose-based nanocomposites for sustainable applications. Beginning with a brief introduction of cellulose, nanocellulose sources, structural characteristics and the extraction process for those new to the area, we go on to more in-depth content. Following that, the research on techniques used to modify the surface properties of nanocellulose by functionalizing surface hydroxyl groups to impart desirable hydrophilic-hydrophobic balance, as well as their characteristics and functionalization strategies, were explained. The usage of nanocellulose in nanocomposites in versatile fields, as well as novel and foreseen markets of nanocellulose products, are also discussed. Finally, the difficulties, challenges and prospects of materials based on nanocellulose are then discussed in the last section for readers searching for future high-end eco-friendly functional materials.

Nanocellulose for Sustainable Water Purification

Nanocelluloses (NC) are nature-based sustainable biomaterials, which not only possess cellulosic properties but also have the important hallmarks of nanomaterials, such as large surface area, versatile reactive sites or functionalities, and scaffolding stability to host inorganic nanoparticles. This class of nanomaterials offers new opportunities for a broad spectrum of applications for clean water production that were once thought impractical. This Review covers substantial discussions based on evaluative judgments of the recent literature and technical advancements in the fields of coagulation/flocculation, adsorption, photocatalysis, and membrane filtration for water decontamination through proper understanding of fundamental knowledge of NC, such as purity, crystallinity, surface chemistry and charge, suspension rheology, morphology, mechanical properties, and film stability. To supplement these, discussions on low-cost and scalable NC extraction, new characterizations including solution small-angle X-ray scattering evaluation, and structure-property relationships of NC are also reviewed. Identifying knowledge gaps and drawing perspectives could generate guidance to overcome uncertainties associated with the adaptation of NC-enabled water purification technologies. Furthermore, the topics of simultaneous removal of multipollutants disposal and proper handling of post/spent NC are discussed. We believe NC-enabled remediation nanomaterials can be integrated into a broad range of water treatments, greatly improving the cost-effectiveness and sustainability of water purification.

Recent Development and Environmental Applications of Nanocellulose-Based Membranes

Extensive research and development in the production of nanocellulose production, a green, bio-based, and renewable biomaterial has paved the way for the development of advanced functional materials for a multitude of applications. From a membrane technology perspective, the exceptional mechanical strength, high crystallinity, tunable surface chemistry, and anti-fouling behavior of nanocellulose, manifested from its structural and nanodimensional properties are particularly attractive. Thus, an opportunity has emerged to exploit these features to develop nanocellulose-based membranes for environmental applications. This review provides insights into the prospect of nanocellulose as a matrix or as an additive to enhance membrane performance in water filtration, environmental remediation, and the development of pollutant sensors and energy devices, focusing on the most recent progress from 2017 to 2022. A brief overview of the strategies to tailor the nanocellulose surface chemistry for the effective removal of specific pollutants and nanocellulose-based membrane fabrication approaches are also presented. The major challenges and future directions associated with the environmental applications of nanocellulose-based membranes are put into perspective, with primary emphasis on advanced multifunctional membranes.

Nanocellulose from Agricultural Wastes: Products and Applications—A Review

The isolation of nanocellulose from different agricultural residues is becoming an important research field due to its versatile applications. This work collects different production processes, including conditioning steps, pretreatments, bleaching processes and finally purification for the production of nanocellulose in its main types of morphologies: cellulose nanofiber (CNF) and cellulose nanocrystal (CNC). This review highlights the importance of agricultural wastes in the production of nanocellulose in order to reduce environmental impact, use of fossil resources, guarantee sustainable economic growth and close the circle of resource use. Finally, the possible applications of the nanocellulose obtained as a new source of raw material in various industrial fields are discussed.

Essential oils loaded-chitosan nanocapsules incorporation in biodegradable starch films: A strategy to improve fruits shelf life

Thermoplastic starch (TPS) films filled with chitosan nanocapsules (CN) containing essential oils (EO) were prepared aiming active packaging. Two different EOs were studied: Ho wood (H) and Cinnamon (C). Besides, different capsules concentrations were investigated (1, 3, and 5 wt%), and the films were evaluated by chemical structure, thermal stability, crystallinity, water vapor permeability, antimicrobial assays, and potential application for strawberry packaging. The TPS/CN-Ho wood films showed a strong interaction between chitosan-starch, mainly for 3 and 5 wt%, confirmed by XRD. The FT-Raman spectra of TPS/CN-Cinnamon film indicated that Cinnamon EO quickly migrated to starch films, probably due to the new crystal structure, named C-type, affecting the film's water permeability. The addition of 1 and 3 wt% CN loaded with Ho wood or Cinnamon EO to the films decreased the water permeability. 3 wt% CN was the optimum concentration to inhibit the Escherichia coli or Bacillus subtillis growth on the films, confirming their biological activity. The films' preservation properties were evaluated using strawberries, and films with 1 or 3 wt% loaded-CN could extend the strawberries' shelf life without fungi contamination. The developed TPS films can be used as active food packaging or other films for biomedical or pharmaceutical applications.