Ionic chitosan/silica nanocomposite as efficient adsorbent for organic dyes.

A new adsorbent from chitosan and anionic silica was prepared by ionic interaction followed by sol-gel process. The obtained nanocomposite was characterized by different techniques: FTIR, XRD, SEM/EDX, TGA, and TEM. The results showed that silica precursor interacts with chitosan and deposits as regular spherical nanoparticles. The methylene blue (MB) adsorption by chitosan/silica nanocomposite achieved the adsorption equilibrium within 60 min. The adsorption method is fitted to the pseudo-second-order kinetic model and the Langmuir adsorption model with a maximum adsorption capacity of 847.5 mg/g at slight alkaline solution. Chitosan/silica composite displayed high regeneration capability and recovery of MB up to five cycles without the loss of the adsorption efficiency. The current study showed that as-prepared chitosan/silica nanocomposite is an appropriate material for the adsorption of organic pollutants from wastewater.

Grafted TEMPO-oxidized cellulose nanofiber embedded with modified magnetite for effective adsorption of lead ions.

According to the World Health Organization, nearly a billion people do not have incoming to pure drinking water and much of that water is contaminated with high levels of heavy elements. In this study, adsorption of lead ions has been studied by nanocomposites which prepared through acrylic acid grafting and amino-functionalized magnetized (FM-NPs) TEMPO-oxidized cellulose nanofiber (TEMPO-CNF). The amino-functionalized magnetite was acting as a crosslinked. The crystallinity of TEMPO-CNF was 75 with a 4-10 nm diameter range, while the average particle size of FM-NPs was 30 nm. The adsorption studies illustrated that the elimination efficiency of lead ions was 80% by the prepared nanocomposite that includes a minimum amount of crosslinker (1%), which demonstrated that the magnetic grafted oxidized cellulose nanofiber nanocomposite is a promising green adsorbent material to eliminate heavy metal ions and is additionally easy to get rid of due to its magnetic property. The kinetics and isotherms studied found that the sorption reaction follows a pseudo-second-order model (R2 = 0.997) and Freundlich model (R2 = 0.993), respectively, this indicated that the adsorption of lead ion occurs within the pores and via the functional groups present on the nanocomposite.

Multifunctional cellulose nanocrystal /metal oxide hybrid, photo-degradation, antibacterial and larvicidal activities.

Cellulose nanocrystal (CNC) and ZnO/CuO nanostructure were successfully synthesized by acid hydrolysis and sol-chemical methods, respectively. For the first time, CNC was used as a host polymer for synthesis of CNC/ZnO/CuO through In-situ solution casting technique. Morphological and structural of CNC, ZnO/CuO and hybrid CNC/ZnO/CuO were investigated by TEM, SEM-EDX, FT-IR, XRD and XPS analyses. The analysis revealed that, poly-dispersed, smooth and rod like CNC with an average length of ∼ 85.4 nm, average diameter of ∼13.9 nm and surface charge of 0.01 mmol/gm. As well, irregular shapes as hexagonal, spherical and cluster or star like of ZnO/CuO were formed. EDX and XRD spectra exhibited highly purified CNC/ZnO/CuO and pointed to cellulose II crystallite form with a monoclinic structure. The results demonstrated that, 91.3 % and 99.7 % dye degradation was achieved after 40 min of irradiation due to ZnO/CuO and CNC/ZnO/CuO treatment. Moreover, the inhibition zones formed due to 100 ppm ZnO/CuO were duplicated after integrating CNC (from 7.7:10.3 mm to 14.3:20.3 mm). The hybrid nanostructure exhibit larvicidal activity against Anopheles stephensi better than CNC and ZnO/CuO nanostructures.

Soy protein hydrolysate grafted cellulose nanofibrils with bioactive signals for bone repair and regeneration.

TEMPO oxidized cellulose nanofibers (T-CNF) were prepared from cellulose pulp which is extracted from bagasse. Soy protein hydrolysate (SPH) was grafted on T-CNF via amidation of carboxylic groups. Biomineralization was, then, assessed via calcium phosphates (CaP) precipitation in twice-simulated body fluid until formation of a new bioactive material. Protein was efficiently grafted without alteration of morphology and nanofibrils packing as reported by Fourier Transform infrared analysis /X Ray Diffraction /Scanning and Transmission Electron Microscopy / Atomic Force Microscopy. Highly crystalline calcium phosphate deposits - ca. 22.1% - were detected, with a Ca/P ratio equal to 1.63, in agreement with native bone apatite composition. In vitro response of human Mesenchymal Stem Cells confirmed the biocompatibility. No significant differences in terms of cell adhesion were recognized while a significant increase in cell proliferation was detected until 7 days. The presence of calcium phosphates tends to cover the nanofibrillar pattern, inducing the inhibition of cell proliferation and promoting the ex-novo precipitation of mineral phases. All the results suggest a promising use of these biomaterials in the repair and/or the regeneration of hard tissues such as bone.

Oxidized alginate/gelatin decorated silver nanoparticles as new nanocomposite for dye adsorption.

In the current article di-aldehyde alginate (DAA) crosslinking gelatin (Ge) hydrogel was prepared and investigated for stabilizing silver nanoparticles. DAA/Ge decorated silver nanoparticles hydrogel was characterized by IR, XRD, TGA, SEM and AFM. The outcomes demonstrate that silver nanoparticles with uniform sizes were homogenously distributed through DAA/Ge hydrogel. DAA/Ge decorated silver nanocomposite was examined for the rejection of methylene blue (MB) from aqueous solutions. Comparing with DAA/Ge hydrogel, the nanocomposite has high efficiency for removal of MB. The highest MB removal efficiency was observed at pH 7 and the adsorption process is well described by pseudo-second order and Langmuir adsorption model with adsorption capacity of 625 mg/g. Our results proved that the DAA/Ge/Ag nanocomposite could be used for removal of MB from decontaminated solutions.

Novel method of preparation of tricarboxylic cellulose nanofiber for efficient removal of heavy metal ions from aqueous solution.

2,3,6­Tricarboxy cellulose nanofiber (TPC-CNFs) was prepared by 2,2,6,6-tetramethylpiperidine­1­oxyl (TEMPO) oxidation of dissolving cellulose pulp (selective at C-6) followed by periodate-chlorite oxidation (selective on C-2 and C-3). Characterization of the prepared samples were carried out using, atomic force microscope (AFM), carboxylate content determination, FTIR spectroscopy, X-ray diffraction and light transmittance spectra. Also, the mechanical properties of TEMPO-oxidized of cellulose nanofiber (T-CNFs) and TPC-CNFs with and without polyamide-amine-epichlorohydrin crosslinker (PAE) films were determined which the tensile strength were 8.19, 12.43 and 20.5 MPa and elastic moduli of 1814, 1097 and 1150 MPa respectively. Tricaboxy cellulose nanofiber was developed as a novel adsorbent of heavy metal ions. Removal of heavy metals such as Cu2+, Ca2+ and Pb2+ from aqueous solution was carried out and the adsorption efficiencies were analyzed. On the other hand, the effect of the addition of the crosslinking agent to CNFs and the carboxylate contents of CNFs were investigated.

Development of wheat gluten/nanocellulose/titanium dioxide nanocomposites for active food packaging.

Bionanocomposites were developed by casting/evaporation of wheat gluten (WG), cellulose nanocrystals (CNC), and TiO2 nanoparticles. The effect of addition of different percentages of CNC, and TiO2 on tensile strength (TS), Young's modulus and water sensitivity was studied. A significant improvement in the studied properties is observed when 7.5% CNC and 0.6% TiO2 is added to WG. WG/CNC 7.5%/0.6% TiO2 blend suspension was chosen to coat commercial packaging unbleached kraft paper sheets via 1, 2 and 3 coating layers. A significant enhancement of 56% and 53% in breaking length and burst index, respectively, was achieved for 3 layers coated paper. The antimicrobial activity of the coated papers, against Saccharomyces cervisiae, Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus, was investigated and expressed in terms of reduction % of surviving number (CFU) of the tested organisms. More than 98.5% reduction in CFU was observed against the organisms compared to TiO2-free coated paper.

Carboxymethyl cellulose/silica hybrids as templates for calcium phosphate biomimetic mineralization.

Multiphase hybrid materials were synthesized using carboxymethyl cellulose (CMC) as bioactive polymer, silica gel as matrix assisted networks and calcium phosphate as inorganic mineral phase. These hybrids were investigated with infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Biomimetic crystal growth nucleated from the CMC/silica hybrids was suggested as amorphous calcium phosphate with an evidence that hydroxyapatite, the mineralized component of bone, may be formed at high CMC content. This study provides an efficient approach toward bone-like hybrids with potential bone healing applications.

Plant proteins as binders in cellulosic paper composites.

Plant proteins are used - for the first time - in this work as bulk binders for cellulosic fibers in paper composites. Soy bean protein and wheat gluten were denatured by two methods, namely by: urea+NaOH and by urea+NaOH+acrylamide. Addition of increased amounts of the denatured proteins resulted in a significant increase in all paper strength properties. Soy protein led, in addition, to a remarkable enhancement in opacity. The use of proteins increased kaolin retention in the paper composites, while keeping the paper strength higher than the blank protein-free paper. The results show that plant proteins are favorable than synthetic adhesives; because they are biodegradable and do not cause troubles in paper recycling i.e. they are environmentally friendly.