Activable carboxylic acid functionalized crystalline nanocellulose/PVA- co -PE composite nanofibrous membrane with enhanced adsorption for heavy metal ions

Emerging environmentally friendly bio-based nanocomposites for the efficient removal of dyes and micropollutants from wastewater by adsorption: a comprehensive review

Water scarcity will worsen due to population growth, urbanization, and climate change. Addressing this issue requires developing energy-efficient and cost-effective water purification technologies. One approach is to use biomass to make bio-based materials (BBMs) with valuable attributes. This aligns with the goal of environmental conservation and waste management. Furthermore, the use of biomass is advantageous because it is readily available, economical, and has minimal secondary environmental impact. Biomass materials are ideal for water purification because they are abundant and contain important functional groups like hydroxyl, carboxyl, and amino groups. Functional groups are important for modifying and absorbing contaminants in water. Single-sourced biomass has limitations such as weak mechanical strength, limited adsorption capacity, and chemical instability. Investing in research and development is crucial for the development of efficient methods to produce BBMs and establish suitable water purification application models. This review covers BBM production, modification, functionalization, and their applications in wastewater treatment. These applications include oil-water separation, membrane filtration, micropollutant removal, and organic pollutant elimination. This review explores the production processes and properties of BBMs from biopolymers, highlighting their potential for water treatment applications. Furthermore, this review discusses the future prospects and challenges of developing BBMs for water treatment and usage. Finally, this review highlights the importance of BBMs in solving water purification challenges and encourages innovative solutions in this field.

Recent advances in cellulose-based sustainable materials for wastewater treatment: An overview

Water pollution presents a significant challenge, impacting ecosystems and human health. The necessity for solutions to address water pollution arises from the critical need to preserve and protect the quality of water resources. Effective solutions are crucial to safeguarding ecosystems, human health, and ensuring sustainable access to clean water for current and future generations. Generally, cellulose and its derivatives are considered potential substrates for wastewater treatment. The various cellulose processing methods including acid, alkali, organic & inorganic components treatment, chemical treatment and spinning methods are highlighted. Additionally, we reviewed effective use of the cellulose derivatives (CD), including cellulose nanocrystals (CNCs), cellulose nano-fibrils (CNFs), CNPs, and bacterial nano-cellulose (BNC) on waste water (WW) treatment. The various cellulose processing methods, including spinning, mechanical, chemical, and biological approaches are also highlighted. Additionally, cellulose-based materials, including adsorbents, membranes and hydrogels are critically discussed. The review also highlighted the mechanism of adsorption, kinetics, thermodynamics, and sorption isotherm studies of adsorbents. The review concluded that the cellulose-derived materials are effective substrates for removing heavy metals, dyes, pathogenic microorganisms, and other pollutants from WW. Similarly, cellulose based materials are used for flocculants and water filtration membranes. Cellulose composites are widely used in the separation of oil and water emulsions as well as in removing dyes from wastewater. Cellulose's natural hydrophilicity makes it easier for it to interact with water molecules, making it appropriate for use in water treatment processes. Furthermore, the materials derived from cellulose have wider application in WW treatment due to their inexhaustible sources, low energy consumption, cost-effectiveness, sustainability, and renewable nature.

Recent advances and future perspective on nanocellulose-based materials in diverse water treatment applications

Over the past few years, nanocellulose and its derivatives have drawn attention as promising bio-based materials for water treatment applications due to their high surface area, high strength, and renewable, biocompatible nature. The abundance of hydroxyl functional groups on the surfaces of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) enables a broad range of surface modifications which results in propitious nanocomposites with tunable characteristics. In this context, this review describes the continuously developing applications of nanocellulose-based materials in the areas of adsorption, catalysis, filtration, and flocculation, with a special emphasis on the removal of contaminants such as heavy metals, dyes, and pharmaceutical compounds from diverse water systems. Recent progresses in the diverse forms of application of nanocellulose adsorbents (suspension, hydrogel, aerogel, and membrane) are also highlighted. Finally, challenges and future perspectives on emerging nanocellulose-based materials and their possible industrial applications are presented and discussed.

A Review on Nanocellulose and Superhydrophobic Features for Advanced Water Treatment

Globally, developing countries require access to safe drinking water to support human health and facilitate long-term sustainable development, in which waste management and control are critical tasks. As the most plentiful, renewable biopolymer on earth, cellulose has significant utility in the delivery of potable water for human consumption. Herein, recent developments in the application of nanoscale cellulose and cellulose derivatives for water treatment are reviewed, with reference to the properties and structure of the material. The potential application of nanocellulose as a primary component for water treatment is linked to its high aspect ratio, high surface area, and the high number of hydroxyl groups available for molecular interaction with heavy metals, dyes, oil-water separation, and other chemical impurities. The ability of superhydrophobic nanocellulose-based textiles as functional fabrics is particularly acknowledged as designed structures for advanced water treatment systems. This review covers the adsorption of heavy metals and chemical impurities like dyes, oil-water separation, as well as nanocellulose and nanostructured derivative membranes, and superhydrophobic coatings, suitable for adsorbing chemical and biological pollutants, including microorganisms.

Cellulose Nanopaper: Fabrication, Functionalization, and Applications

Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices, food packaging, biomedical application, and so forth, owing to their various advantages such as good flexibility, tunable light transmittance, high thermal stability, low thermal expansion coefficient, and superior mechanical properties. Herein, recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies. We begin with a brief introduction of the three types of nanocellulose: cellulose nanocrystals, cellulose nanofibrils and bacterial cellulose, recapitulating their differences in preparation and properties. Then, the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared. Furthermore, the advanced applications of cellulose nanopaper including energy storage, electronic devices, water treatment, and high-performance packaging materials were highlighted. Finally, the prospects and ongoing challenges of cellulose nanopaper were summarized.

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 Progress on Nanomaterial-Based Membranes for Water Treatment

Nanomaterials have emerged as the new future generation materials for high-performance water treatment membranes with potential for solving the worldwide water pollution issue. The incorporation of nanomaterials in membranes increases water permeability, mechanical strength, separation efficiency, and reduces fouling of the membrane. Thus, the nanomaterials pave a new pathway for ultra-fast and extremely selective water purification membranes. Membrane enhancements after the inclusion of many nanomaterials, including nanoparticles (NPs), two-dimensional (2-D) layer materials, nanofibers, nanosheets, and other nanocomposite structural materials, are discussed in this review. Furthermore, the applications of these membranes with nanomaterials in water treatment applications, that are vast in number, are highlighted. The goal is to demonstrate the significance of nanomaterials in the membrane industry for water treatment applications. It was found that nanomaterials and nanotechnology offer great potential for the advancement of sustainable water and wastewater treatment.

Advances in nanocellulose-based materials as adsorbents of heavy metals and dyes

In recent years, nanocellulose-based materials have been increasingly applied as a lot of biosorbents for the treatment of water pollutants due to their large specific surface area, easy modification, environmental friendliness, and reproducibility. In this review, surface modification of nanocellulose-based adsorbents with various effective adsorption groups is described, as well as polymer grafting and hybrid composite fabrication. The adsorption mechanisms involved in the adsorption process of pollutants by adsorbents are further analysed and summarized. The regeneration methods of nanocellulose adsorbents with different adsorption mechanisms are also demonstrated. In addition, this paper also briefly describes the forms of nanocellulose-based adsorbents with large-scale application including membranes, gels, flocculants and magnetic composites.

Nanocellulose-Based Materials for Water Treatment: Adsorption, Photocatalytic Degradation, Disinfection, Antifouling, and Nanofiltration

Nanocelluloses are promising bio-nano-materials for use as water treatment materials in environmental protection and remediation. Over the past decades, they have been integrated via novel nanoengineering approaches for water treatment processes. This review aims at giving an overview of nanocellulose requirements concerning emerging nanotechnologies of waster treatments and purification, i.e., adsorption, absorption, flocculation, photocatalytic degradation, disinfection, antifouling, ultrafiltration, nanofiltration, and reverse osmosis. Firstly, the nanocellulose synthesis methods (mechanical, physical, chemical, and biological), unique properties (sizes, geometries, and surface chemistry) were presented and their use for capturing and removal of wastewater pollutants was explained. Secondly, different chemical modification approaches surface functionalization (with functional groups, polymers, and nanoparticles) for enhancing the surface chemistry of the nanocellulose for enabling the effective removal of specific pollutants (suspended particles, microorganisms, hazardous metals ions, organic dyes, drugs, pesticides fertilizers, and oils) were highlighted. Thirdly, new fabrication approaches (solution casting, thermal treatment, electrospinning, 3D printing) that integrated nanocelluloses (spherical nanoparticles, nanowhiskers, nanofibers) to produce water treatment materials (individual composite nanoparticles, hydrogels, aerogels, sponges, membranes, and nanopapers) were covered. Finally, the major challenges and future perspectives concerning the applications of nanocellulose based materials in water treatment and purification were highlighted.

Cross-Linked Nanocellulosic Materials and Their Applications

Nanocelluloses (NCs) have remarkable mechanical properties and contain abundant surface functional groups that can be modified or cross-linked with other materials. They have been widely used as an environment-friendly reinforcing agent in polymer composites. However, for applications that are carried out in humid environments or aqueous suspensions, hydrophilicity of NCs lower their mechanical integrity. Hence, cross-linking techniques have been investigated in recent years for preparing NC-based materials that are dimensionally stable under humid or aqueous environments and have better physicochemical properties. This Minireview examines the quickly growing field of cross-linked NC-based materials, which have many benefits including improved aqueous, structural, mechanical, and thermal stability. In addition, the potential application of cross-linked NC-based materials in adsorption of heavy metal is discussed.

Supported growth of inorganic-organic nanoflowers on 3D hierarchically porous nanofibrous membrane for enhanced enzymatic water treatment

Organic-inorganic nanoflower is a new type of functional material that can effectively immobilize a wide range of enzymes to form flower-like structures for various enzymatic applications with enhanced catalytic performance and stability. In order to avoid the processing inconvenience and flower structure damage caused by the particular form of these hybrid nanoflowers during material fabrication and catalytic application, different substrates have been used to carry out supported growth of hybrid nanoflowers. However, all previously used substrates have only 2-dimensional feature and only incorporate hybrid nanoflowers on surface with limited nanoflower loading. In this study, three-dimensional (3D) hierarchically porous nanofibrous PVA-co-PE membranes (HPNM) are prepared by a simple template method for effectively immobilizing laccase-Cu₂(PO₄)₃•3H₂O hybrid nanoflowers. Compared with dense nanofibre membrane with only small sized pores (<1 micron), the coexistence of both small and large sized (30-80 microns) pores of HPNM could significantly increase the nanoflower density and allow the penetrated growth of hybrid nanoflowers into the inner structure of the membrane. The hybrid nanoflower containing hierarchically porous nanofibrous membranes (HNF-HPNM) show excellent catalytic performance in degrading different types of textile dyes (reactive blue 2, acid blue 25, acid yellow 76 and indigo carmine), with a degradation efficiency of ˜99.5% for indigo carmine. In addition, the HNF-HPNM could be reused at least 14 times for indigo carmine degradation, with a negligible degradation efficiency drop from 99.48% to 98.52%. These results indicate that hierarchically porous nanofibrous membrane can be a promising type of materials for supported hybrid nanoflower growth for practical applications such as waste water treatment, dye degradation and biosensing.

Preparation of PVA/tetra-ZnO composite with framework-supported pore-channel structure and the removal research of lead ions

Polyvinyl alcohol (PVA) filled with different kinds of ZnO whisker was prepared by chemical cross-linking reaction. It was found that the ZnO whiskers dispersed uniformly after being modified by 3-aminopropyltriethoxysilane (APTES). The PVA/tetrapod-shaped ZnO (PVA/tetra-ZnO) composites showed better adsorption performance than other kinds of PVA/ZnO composites. The framework-supported pore-channel structure was beneficial for the transmission and adsorption of heavy metal ions, and the formation of "brush" pore-channel of PVA/tetra-ZnO composites can effectively retain and capture the heavy metal ions. The PVA/tetra-ZnO composites presented well adsorption on Pb(II), Cd(II), and Cr(III) ions than Ni(II) and showed relatively selective removal on Pb(II) and Cr(III) ions. The adsorbed heavy metal ions presented gradient distribution with high content in the out layer and low content in the inner layer. Pb(II) adsorption capacity q_e increased gradually with the increase of initial solution concentration and contact time which tended to be stable at 400 mg/L and 800 min. The maximal adsorption capacity q_m obtained by nonlinear fitting reached to about 116 mg/g which was very close to the experiment data. Adsorption isotherm results indicated the monolayer adsorption process of the Langmuir model and the adsorption kinetics data fitted well to the pseudo-second-order model. The adsorption process was spontaneous and the high temperature was in favor of adsorption. The adsorption mechanism was explored as the combination of coordination and ion exchange. Besides, the PVA/tetra-ZnO composites exhibited better stress stability, thermo stability, and favorable regeneration than neat PVA.

A positively charged tight UF membrane and its properties for removing trace metal cations via electrostatic repulsion mechanism

The development of highly efficient membranes technology using low-pressure driven filtration process, is one of the principal challenges in the wastewater treatment field, especially those aimed at the removal of trace heavy metals. In this work, a novel positively charged tight ultrafiltration (PCTUF) membrane was developed to remove heavy metal cations (Mn²⁺, Co²⁺, Ni²⁺, Zn²⁺ and Cd²⁺) from contaminated waters via electrostatic repulsion mechanism. The PCTUF membrane was fabricated from a new polymer with poly (vinyl chloride co dimethylaminoethyl methacrylate), P (VC-co-DMA) via a nonsolvent induce phase separation (NIPS) process and following facile surface quaternization. The quaternization conditions, the pore structures and chemical properties of the membranes were investigated in detail. The optimally quaternized membrane possessed a positively charged surface and 3.27 nm charged channel with the water permeability of 84 L m^-2 h^-1 bar^-1. The rejections of heavy metal cations surpassed 95% for feed solutions containing 10 ppm heavy metal. Moreover, the influences of feed concentrations and the operating condition with pressure and pH on the membrane performances were also investigated. The results revealed that the prepared PCTUF membrane with its high perm-selectivity performance provides a worthy reference for highly efficient removal of heavy metal cations.

Polymeric Composites with Embedded Nanocrystalline Cellulose for the Removal of Iron(II) from Contaminated Water

The exponential increase in heavy metal usage for industrial applications has led to the limited supply of clean water for human needs. Iron is one of the examples of heavy metals, which is responsible for an unpleasant taste of water and its discoloration, and is also associated with elevated health risks if it persists in drinking water for a prolonged period of time. The adsorption of a soluble form of iron (Fe2+) from water resources is generally accomplished in the presence of natural or synthetic polymers or nanoparticles, followed by their filtration from treated water. The self-assembly of these colloidal carriers into macroarchitectures can help in achieving the facile removal of metal-chelated materials from treated water and hence can reduce the cost and improve the efficiency of the water purification process. In this study, we aim to develop a facile one-pot strategy for the synthesis of polymeric composites with embedded nanocrystalline cellulose (NCC) for the chelation of iron(II) from contaminated water. The synthesis of the polymeric composites with embedded nanoparticles was achieved by the facile coating of ionic monomers on the surface of NCC, followed by their polymerization, crosslinking, and self-assembly in the form of three-dimensional architectures at room temperature. The composites prepared were analyzed for their physiochemical properties, antifouling properties, and for their iron(II)-chelation efficacies in vitro. The results indicate that the embedded-NCC polymeric composites have antifouling properties and exhibit superior iron(II)-chelation properties at both acidic and basic conditions.

Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications

With increasing environmental and ecological concerns due to the use of petroleum-based chemicals and products, the synthesis of fine chemicals and functional materials from natural resources is of great public value. Nanocellulose may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability, and abundance. In this review, we present nanocellulose-based materials from sourcing, synthesis, and surface modification of nanocellulose, to materials formation and applications. Nanocellulose can be sourced from biomass, plants, or bacteria, relying on fairly simple, scalable, and efficient isolation techniques. Mechanical, chemical, and enzymatic treatments, or a combination of these, can be used to extract nanocellulose from natural sources. The properties of nanocellulose are dependent on the source, the isolation technique, and potential subsequent surface transformations. Nanocellulose surface modification techniques are typically used to introduce either charged or hydrophobic moieties, and include amidation, esterification, etherification, silylation, polymerization, urethanization, sulfonation, and phosphorylation. Nanocellulose has excellent strength, high Young's modulus, biocompatibility, and tunable self-assembly, thixotropic, and photonic properties, which are essential for the applications of this material. Nanocellulose participates in the fabrication of a large range of nanomaterials and nanocomposites, including those based on polymers, metals, metal oxides, and carbon. In particular, nanocellulose complements organic-based materials, where it imparts its mechanical properties to the composite. Nanocellulose is a promising material whenever material strength, flexibility, and/or specific nanostructuration are required. Applications include functional paper, optoelectronics, and antibacterial coatings, packaging, mechanically reinforced polymer composites, tissue scaffolds, drug delivery, biosensors, energy storage, catalysis, environmental remediation, and electrochemically controlled separation. Phosphorylated nanocellulose is a particularly interesting material, spanning a surprising set of applications in various dimensions including bone scaffolds, adsorbents, and flame retardants and as a support for the heterogenization of homogeneous catalysts.

Magnetic organic xerogels: efficient adsorbents for the removal of heavy metal ions from aqueous solutions

The synthesis of novel mobile composite adsorbents dedicated to the efficient removal of heavy metal ions from aqueous solutions is presented.