Nanofiber technology: current status and emerging developments

Starch, cellulose, pectin, gum, alginate, chitin and chitosan derived (nano)materials for sustainable water treatment: A review

The rapid increase in toxic dye wastewater generated from various industries remains a severe public health issue and prime environmental protection concern, posing a major challenge to existing conventional water treatment systems. Consequently, various physicochemical and biological treatment processes have been studied, which exhibit varying removal abilities depending on their experimental constraints. Among them, adsorption is considered to be the most efficient due to its high removal efficiency, easy operation, cost-effectiveness, and recyclability of the adsorbents. Considering this, the present review article focused on presenting a comprehensive summary of the various types of adsorbents such as commercial activated carbon, metal oxide-based, carbon-based, metal–organic framework, and polymer-based adsorbents used in dye remediation of contaminated water. The effects of several critical factors such as initial dye concentration, solution pH, temperature, and adsorbent dose on the dye adsorption performance are also described. In addition, the adsorption mechanisms responsible for dye removal are explained based on electrostatic attraction, ion exchange, surface complexation, and π–π interactions. Finally, critiques, future perspectives, and a summary of the present article are given. Various adsorbents such as carbon-based materials, metal oxides, bio-adsorbents, and polymer-based materials, have been shown to be efficient for the removal of dye pollutants from wastewater. Thus, it is anticipated that dye removal by adsorption can provide a feasible solution for the treatment of dye-laden water.

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Recent advances on the removal of dyes from wastewater using various adsorbents: A critical review

This paper demonstrates a layer-by-layer self-assembled polyaniline (PANI)/graphene oxide (GO) film on quartz crystal microbalance (QCM) for humidity sensing. The morphological and compositional properties of PANI/GO composite films were examined by means of SEM, XRD and FT-IR. The humidity sensing properties of the PANI/GO nanocomposite-based QCM sensor were investigated by exposing to a broad range of 0–97%RH. The experimental results showed that the presented PANI/GO nanocomposite sensor has a high sensitivity, a good repeatability and fast response/recovery characteristics, which surpasses the previous reported counterparts. Moreover, the underlying humidity sensing mechanism of the PANI/GO-based QCM sensor was discussed by using Langmuir adsorption model. This work highlights the unique advantage of layer-by-layer self-assembled route for QCM sensor fabrication.

Facile fabrication of high-performance QCM humidity sensor based on layer-by-layer self-assembled polyaniline/graphene oxide nanocomposite film

As a phenolic acid, tannic acid can be classified into a polyphenolic group. It has been widely studied in the biomedical field of science because it presents unique antiviral as well as antibacterial properties. Tannic acid has been reported to present the activity against Influeneza A virus, Papilloma viruses, noroviruses, Herpes simplex virus type 1 and 2, and human immunodeficiency virus (HIV) as well as activity against both Gram-positive and Gram-negative bacteria as Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Yersinia enterocolitica, Listeria innocua. Nowadays, compounds of natural origin constitute fundaments of material science, and the trend is called “from nature to nature”. Although biopolymers have found a broad range of applications in biomedical sciences, they do not present anti-microbial activity, and their physicochemical properties are rather poor. Biopolymers, however, may be modified with organic and inorganic additives which enhance their properties. Tannic acid, like phenolic acid, is classified into a polyphenolic group and can be isolated from natural sources, e.g., a pure compound or a component of a plant extract. Numerous studies have been carried out over the application of tannic acid as an additive to biopolymer materials due to its unique properties. On the one hand, it shows antimicrobial and antiviral activity, while on the other hand, it reveals promising biological properties, i.e., enhances the cell proliferation, tissue regeneration and wound healing processes. Tannic acid is added to different biopolymers, collagen and polysaccharides as chitosan, agarose and starch. Its activity has been proven by the determination of physicochemical properties, as well as the performance of in vitro and in vivo studies. This systematics review is a summary of current studies on tannic acid properties. It presents tannic acid as an excellent natural compound which can be used to eliminate pathogenic factors as well as a revision of current studies on tannic acid composed with biopolymers and active properties of the resulting complexes.

https://www.mdpi.com/1996-1944/13/14/3224/pdf

Tannic Acid with Antiviral and Antibacterial Activity as A Promising Component of Biomaterials—A Minireview

Adsorption of methylene blue onto chitosan–montmorillonite/polyaniline nanocomposite

In situ polymerization of aniline using ammonium peroxydisulphate (APS) as an oxidizing agent in the presence of chitosan (Cs) was used to synthesize Cs/polyaniline (PANI) nanofibers. The structure and morphology of the Cs/PANI nanofibers powder were characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV–visible spectroscopy and scanning electron microscope (SEM). The surface of the Cs/PANI seems like interconnected nanofibers with diameters of approximately 50 nm. A film of the Cs/PANI nanofibers was built onto a quartz crystal microbalance (QCM) electrode by drop casting and this film was used to develop a sensor to measure the concentration of volatile organic vapors such as amines and alcohols in air. The frequency shifts (Δ f ) of the QCM, due to the vapor adsorption onto the Cs/PANI nanofibers film, were measured and related to the vapors’ concentrations. Linear relationships existed between the Δ f (Hz) and the analytes’ concentrations. The sensor showed a good sensitivity, reproducibility and reversibility. The influence of different temperatures on the vapor adsorption onto the Cs/PANI nanofibers film was studied. The kinetics of diffusion of the gases and the diffusion coefficients ( D ), were discussed.

Chitosan/polyaniline nanofibers coating on the quartz crystal microbalance electrode for gas sensing

pH-responsive and antibacterial properties of self-assembled multilayer films based on chitosan and tannic acid

Chitosan/polyaniline hybrid for the removal of cationic and anionic dyes from aqueous solutions

A simple route was employed for the fabrication of a polyaniline (PANI)–chitosan (CS)–magnetite (Fe3O4) nanocomposite (PANI–CS–Fe3O4) via the in situ polymerization of aniline in the presence of CS using anhydrous iron(III) chloride as an oxidizing agent. The magnetic character of the nanocomposite results from the presence of iron oxide nanoparticles, which were formed as side products during the synthesis of the PANI–CS nanocomposite. The synthesized PANI–CS–Fe3O4 nanocomposite was fully characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The reduction of silver nitrate by the synthesized nanocomposite enables the anchoring of silver (Ag) nanoparticles onto its surface. The catalytic properties of the Ag-decorated nanocomposite (Ag@PANI–CS–Fe3O4) toward the reduction of 4-nitrophenol was investigated using sodium borohydride as a reducing agent.

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Islam M. Minisy

Papers

Adsorption of methylene blue onto chitosan–montmorillonite/polyaniline nanocomposite

Chitosan/polyaniline nanofibers coating on the quartz crystal microbalance electrode for gas sensing

pH-responsive and antibacterial properties of self-assembled multilayer films based on chitosan and tannic acid

Chitosan/polyaniline hybrid for the removal of cationic and anionic dyes from aqueous solutions

Synthesis of silver-anchored polyaniline–chitosan magnetic nanocomposite: a smart system for catalysis