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 e...

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

In the face of water shortages, the world seeks to explore all available options in reducing the over exploitation of limited freshwater resources. One of the surest available water resources is wastewater. As the population grows, industrial, agricultural, and domestic activities increase accordingly in order to cater for the voluminous needs of man. These activities produce large volumes of wastewater from which water can be reclaimed to serve many purposes. Over the years, conventional wastewater treatment processes have succeeded to some extent in treating effluents for discharge purposes. However, improvements in wastewater treatment processes are necessary in order to make treated wastewater re-usable for industrial, agricultural, and domestic purposes. Membrane technology has emerged as a favorite choice for reclaiming water from different wastewater streams for re-use. This review looks at the trending membrane technologies in wastewater treatment, their advantages and disadvantages. It also discusses membrane fouling, membrane cleaning, and membrane modules. Finally, recommendations for future research pertaining to the application of membrane technology in wastewater treatment are made.

Membrane Technologies in Wastewater Treatment: A Review.

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. 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 (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

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Nanocellulose: From Fundamentals to Advanced Applications

The electrospinning process was used successfully to fabricate nanofibers of poly(ethylene oxide) (PEO) in which multiwalled carbon nanotubes (MWCNT) are embedded. Initial dispersion of MWCNTs in water was achieved using amphiphiles, either as small molecules (sodium dodecyl sulfate, SDS) or as a high molecular weight, highly branched polymer (Gum Arabic). These dispersions provided separation of the MWCNTs and their individual incorporation into the PEO nanofibers by subsequent electrospinning. The focus of this work is on the development of axial orientations in these multicomponent nanofibers. A theoretical model is presented for the behavior of rodlike particles representing CNTs in electrospinning. Initially the rods are randomly oriented, but due to the sinklike flow in a wedge they are gradually oriented mainly along the stream lines, so that straight CNTs are almost oriented upon entering the electrospun jet. The degrees of orientation of polymer, surfactant, and MWCNT were studied using X-ray dif...

Carbon Nanotubes Embedded in Oriented Polymer Nanofibers by Electrospinning

Commercial application of cellulose nano-composites - A review.

On the basis of nanocellulose obtained by acidic swelling and ultrasonication, rodlike nanocellulose/polyaniline nanocomposites with a core–shell structure have been prepared via in situ polymerization. Compared to pure polyaniline, the nanocomposites show superior film-forming properties, and the prepared nanocomposite films demonstrate excellent electrochemical and electrochromic properties in electrolyte solution. Nanocomposite films, especially the one prepared with 40% polyaniline coated nanocomposite, exhibited faster response time (1.5 s for bleaching and 1.0 s for coloring), higher optical contrast (62.9%), higher coloration efficiency (206.2 cm2/C), and more remarkable switching stability (over 500 cycles). These novel nanocellulose-based nanorod network films are promising novel electrochromic materials with excellent properties.

Preparation, Characterization, and Electrochromic Properties of Nanocellulose-Based Polyaniline Nanocomposite Films

Poly(vinylidene fluoride) (PVDF)-based piezoelectric materials are promising candidates for sensors, transducers, and actuators, due to several distinctive characteristics such as good flexibility, easy processability, and high mechanical resistance. In the present work, PVDF-based nanocomposites loaded with BaTiO3 nanoparticles (NPs) of various weight fractions were prepared by the electrospinning technique and used for the fabrication of a flexible piezoelectric pressure tactile sensor (PPTS). The addition (5, 10, and 20 wt %) of piezoelectric BaTiO3 NPs improves the piezoelectric performance, especially the β phase crystals of PVDF/BaTiO3 (10 wt %) nanocomposites that can reach 91.0%. In addition, the mechanical strength of PVDF/BaTiO3 nanocomposites is up to 26.7 MPa, which is an increase of 66% compared to neat PVDF. It should be emphasized that the elongation at break continuously increases from 71% to 153% with increasing BaTiO3 NPs. More importantly, the PPTS (piezoelectric pressure tactile sensor) with the combination of electrospun PVDF/BaTiO3 nanocomposite membranes and polydimethylsiloxane (PDMS) displays excellent flexibility and linear response to external mechanical force. The flexible PPTS devices capable of detecting different music sounds have potential uses in wide fields, such as voice recognition, speech therapy, and ultrasound imaging.

Flexible Piezoelectric Pressure Tactile Sensor Based on Electrospun BaTiO3/Poly(vinylidene fluoride) Nanocomposite Membrane.

A hierarchically structured three-dimensional network nanofibrous composite membrane was prepared through in situ growing uniform polyaniline nanofibers on the surfaces of poly(ethylene-co-glycidyl methacrylate) (PE-co-GMA) nanofibers. And the nanocomposite membrane was fabricated into a super sensitive sensor of ammonia gas in ambient temperature. Morphological analysis of the nanocomposite membranes revealed uniform small nanofibers of PANI rooted on the surface of PE-co-GMA large nanofibers and a three-dimensional porous nanocomposite structure formed. Because of the ultrahigh surface areas and three-dimensional porous architecture, the prepared sensor demonstrated high sensitivity in the parts per billion range and quick response with good reproducibility to ammonia gas.

High sensitivity ammonia sensor using a hierarchical polyaniline/poly(ethylene-co-glycidyl methacrylate) nanofibrous composite membrane.

A novel flexible zinc oxide/poly(vinylidene fluoride) (ZnO/PVDF) nanocomposite was prepared by electrospinning for fabricating a piezoelectric nanogenerator (PNG). The ZnO nanoparticles (NPs) and nanorods (NRs) were used as nanofillers of piezoelectric PVDF to prepare fibrous nanocomposite membranes. It has been found that the addition of piezoelectric ZnO NPs and NRs can improve the overall performance of the PNGs fabricated with the electrospun membranes. A large electrical throughput (open circuit voltage ∼85 V and short circuit current ∼2.2 μA) from the ZnO NR/PVDF fiber membrane-based PNG (ZR-PNG) indicates that ZnO NRs are effective functional fillers for PVDF. The high aspect ratio and flexibility characteristics of ZnO NRs were found to be highly beneficial for improving the piezoelectric properties of the nanocomposites. ZnO NRs act as nucleating agents of β-phase PVDF, and ZnO NRs can also produce piezoelectric charges when they deform with the composite fibrous membrane. It has been concluded t...

Sheng Chen

Papers

Preparation, Characterization, and Electrochromic Properties of Nanocellulose-Based Polyaniline Nanocomposite Films

Flexible Piezoelectric Pressure Tactile Sensor Based on Electrospun BaTiO3/Poly(vinylidene fluoride) Nanocomposite Membrane.

High sensitivity ammonia sensor using a hierarchical polyaniline/poly(ethylene-co-glycidyl methacrylate) nanofibrous composite membrane.

High Performance Piezoelectric Nanogenerators Based on Electrospun ZnO Nanorods/Poly(vinylidene fluoride) Composite Membranes

An integrated coagulation-ultrafiltration-nanofiltration process for internal reuse of shale gas flowback and produced water