Experimental Investigation of Cellulose/Silver Nanocomposites Using In Situ Generation Method

Cellulose gel films were prepared by regeneration process using pre-cooled aq.(8 wt% LiOH + 15 wt% urea) mixture as solvent and ethyl alcohol as non solvent. The Terminus cattapa leaf extract diffused wet cellulose films were then dipped in 1–5 mM aq.AgNO₃ solutions to allow in situ generation of silver nanoparticles (AgNPs). Besides the in situ generation, some AgNPs were also formed outside the wet films in the solution. The AgNPs formed outside the films were observed under transmission electron microscope and scanning electron microscope. The nanocomposite films were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis and tensile test. The thermal stability of the composite films was lower than that of the matrix up to a temperature of ~300 °C and afterwards showed a reverse trend. The tensile strength of the nanocomposite films was found to be higher than the matrix but decreased with increasing concentration of aq.AgNO₃. The cellulose/AgNPs composite films showed good antibacterial activity against E. coli (gram positive) and Bacillus sp. (gram negative). Based on the aforementioned properties, the cellulose/AgNPs composite films can be considered for antibacterial packaging and medical applications.     

Green Synthesis of Silver Nanoparticle Capped with <Emphasis Type="Italic">Allium cepa</Emphasis> and Their Catalytic Reduction of Textile Dyes: An Ecofriendly Approach

Today, environment pollution control is a matter of concern, everybody is willing to make a product that should be ecofriendly. Nowadays, water resources are full of untreated waste materials, discharge of hazardous and toxic dyes coming from textile and other chemical industries. These environmental hazards are difficult to remove by commercial water treatment plans, thus we need something that would present an efficient means for removal of these hazards. In this research paper, we have synthesize silver nanoparticle in a green way by using aqueous extract of Allium cepa (onion), and further these silver nanoparticle were tested for the catalytic degradation of various dyes by UV/Visible spectroscopy and silver nanoparticle showed reduction in dyes intensity after a particular period of incubation time. SEM and TEM, Particle size and Zeta potential analysis was done to analyze the surface morphology, particle size range and stability of the silver nanoparticle. Greenly synthesized silver nanoparticle was found to be spherical in shape, having particle size value ranged from 50 to 100 nm with a zeta potential value of ?29 mV. An EDX spectroscopy method was used to confirm the presence of silver nanoparticle in the synthesized material. An X-ray crystallography was done to ensure the crystallinity of the silver nanoparticle. Further an ATR-FTIR was performed to confirm the capping of the silver nanoparticle with the phenolic group of the onion. All these study emphasized that silver nanoparticle capped with onion (AgNPs@Ac) is the excellent catalyst for the reduction of hazardous and toxic dyes as well as they serve best purpose of the eco-friendly approach.     

Mechanical and Thermal Properties of PLLA/PCL Modified Clay Nanocomposites

Poly(l-lactic acid) (PLLA)/poly(caprolactone) (PCL) and two types of organoclay (OMMT) including a fatty amide and ocatdecylamine montmorillonite (FA-MMT and ODA-MMT) were employed to produce polymer nanocomposites by melt blending. Materials were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), elemental analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties were also investigated for these nanocomposites. The nanocomposites showed increasing mechanical properties and thermal stability. XRD results indicated that the materials formed nanocomposites. SEM morphology showed that increasing content of OMMT reduced the domain size of phase separated particles. TEM outcomes have confirmed the intercalated type of nanocomposite. Additionally, a solution casting process has been used to prepare these nanocomposites and characterized to compare these results with the above process.     

Electrospun ZnO Nanoparticles Doped Core–Sheath Nanofibers: Characterization and Antimicrobial Properties

Coaxial electrospinning technique was used to fabricate the core–sheath composite nanofibers of ZnO nanoparticle (Nps) (10%, 20% w/w) doped polymethyl methacrylate (PMMA) (as sheath) and polyvinyl alcohol (PVA) (as core). Fourier transform infrared (FT-IR) spectra were confirmed the weak forces arise between ZnO Nps, PMMA and PVA matrixes. The hexagonal (wurtzite) structure of ZnO Nps with ~?30.8 nm of diameter was confirmed from the X-ray diffraction pattern. The morphology and microstructure of core–sheath composite nanofibers were confirmed from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is clearly seen from the TEM images that the PMMA encapsulate the PVA core. Core–sheath composite nanofibers were assessed against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria through quantitative, disk diffusion and viable cell count methods. It was found that ZnO Nps doped core–sheath nanofibers were effectively inhibit the growth of gram positive bacteria, B. subtilis.     

Effect of Varying Filler Concentration on Zinc Oxide Nanoparticle Embedded Chitosan Films as Potential Food Packaging Material

Prevailing scenario of non-biodegradable food packaging materials worldwide was the motivation for this research. More than half of the packaging materials used today are non-biodegradable and lack one or the other feature that keeps it from being an ideal food packaging material. Based on the current need of food grade packaging materials, the present study illustrates the amelioration of the properties of biodegradable chitosan films with the incorporation of zinc oxide (ZnO) nanoparticles in varying concentration. The ZnO nanoparticles (ZnONPs) used as fillers in the chitosan films were synthesized by supersaturation method. They were characterized using UV–visible spectrophotometry, X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The particles were observed to be around 100–200 nm in size. The chitosan films with varying concentration of ZnONPs were synthesized and characterized using Fourier transform infrared spectroscopy and FE-SEM. The films were studied for their thermal stability, water vapor transmission rate (WVTR) and mechanical properties. The thermal stability, as determined by Thermo Gravimetric Analysis and Differential Scanning Calorimetry increased slightly with increasing percentage of embedded ZnONPs while a substantial decrease in WVTR was observed. Mechanical properties also showed improvements with 77% increment in tensile modulus and 67% increment in tensile strength. The antimicrobial activity of the films was also studied on gram positive bacterium Bacillus subtilis (B. subtilis) and gram negative bacterium Escherichia coli (E. coli) by serial dilution method. A twofold and 1.5-fold increment in the antimicrobial activity was observed for B. subtilis and E. coli, respectively, with increased ZnONPs concentration in the films from 0(w/w) to 2%(w/w). Films thus prepared can prove to be of immense potential in the near future for antimicrobial food packaging applications.     

Recycling of the hyperaccumulator Brassica juncea L.: synthesis of carbon nanotube-Cu/ZnO nanocomposites

The methods of synthesizing carbon nanotube (CNTs)-Cu/ZnO nanocomposites using a Cu hyperaccumulator (Brassica juncea L.) constitute a new insight into the recycling of hyperaccumulators and provide a new route for the further development of green nanostructure syntheses. In this paper, CNTs-Cu/ZnO nanocomposites have been synthesized using B. juncea plants as the sources of C, Cu, and Zn. The synthesized CNTs-Cu/ZnO nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectra (EDS). The synthesized CNTs were characterized further by selected area diffraction (SAD) patterns and Raman spectroscopy. The results demonstrated that the structure of individual CNTs was middle-hollow, with an outer diameter of about 80 nm. The synthesized CNTs were not at all crystalline and there were a few defects in the walls. The outer diameter of CNTs-Cu/ZnO nanocomposites was 110 nm. The diameters of Cu/ZnO nanoparticles were 29.5/32.7 nm, respectively. Cu/ZnO nanoparticles that had grown onto the CNT surface were nonuniform and agglomerated. The Cu/ZnO nanoparticles were pure.     

Preparation and Fundamental Characterization of Cellulose Nanocrystal from Oil Palm Fronds Biomass

The objective of this work was to isolate cellulose nanocrystal (CNC) from oil palm fronds (Elaeis guineensis) and its subsequent characterization. Isolation involves sodium hydroxide/anthraquinone pulping with mechanical refining followed by total chlorine free bleaching (includes oxygen delignification, hydrogen peroxide oxidation and peracetic acid treatment) before acid hydrolysis. Bleaching significantly decreased kappa number and increased α-cellulose percentage of fibers as confirmed by Technical Association of the Pulp and Paper Industry standards. Transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis revealed that acid hydrolysis along with bleaching improved crystallinity index and thermal stability of the extracted nanocrystals. It was observed that CNC maintained its cellulose 1 polymorph despite hydrolysis treatment. Mean diameter as observed by TEM and average fiber aspect ratio of obtained CNC was 7.44 ± 0.17 nm and 16.53 ± 3.52, respectively making it suitable as a reinforcing material for nanocomposite.     

A novel method for the preparation of silver/chitosan-O-methoxy polyethylene glycol core shell nanoparticles

Uniformly sized silver/chitosan-O-methoxy polyethylene glycol (chitosan-O-MPEG) core shell nanoparticles with different degree of substitution were synthesized. Thus, N-phthaloyl chitosan is reacted with polyethylene glycol monomethyl ether iodide in the presence of silver oxide by the following steps. At first, amino groups of chitosan are protected by fourfold excess of phthalic anhydride. Then N-phthaloyl chitosan is reacted with an appropriate amount of monomethyl ether iodide in the presence of silver oxide and lastly N-phthaloyl groups are removed to yield silver/chitosan-O-MPEG core shell nanoparticles. Structure of prepared silver/chitosan-O-MPEG core shell nanoparticles have been characterized by UV/Vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction, and scan electron microscopy (SEM-EDX). Experimental results revealed that the prepared silver core particles had the size 18?±?2?nm. Core shell structure with chitosan-O-MPEG-coating had the size 40?±?2?nm.     

New Poly(aniline-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine)/Kaolinite Microcomposites for Water Decontamination

Copolymers of aniline and o-phenylenediamine/kaolinite composites were synthesized by 5:1 molar ratios of the respective monomers with different percentages of nanoclay via modified in situ chemical co-polymerization. The results were verified by measuring the FT-IR and UV–vis absorption spectra for PANI-o-PDA/kaolinite composites. The thermal behaviour of the copolymer and composites was studied. PANI-o-PDA/kaolinite composites were thermally more stable than pure copolymer. Surface morphology of copolymer composites was recorded at different magnification power by SEM which revealed whitish micrometric beads distributed all over the field with particle size in the range of 0.122–0.233 μm. This work demonstrates that the PANI-o-PDA/kaolinite composites particles can be considered as potential adsorbents for hazardous and toxic metal ions of water from lake El-Manzala, Egypt. All of Cd(II), Cu(II), and Pb(II) posed dangerous health risk to the local population via fish consumption.     

Green Synthesis of Silver Nanoparticles and Study of Their Antimicrobial Properties

One of the major disadvantages of polymers when used in food-contact applications is that they are very susceptible to microbial attack. On the other hand, silver nanoparticles have received increased attention as novel antimicrobial agents. Therefore, the introduction of silver nanoparticles into conventional polymers results in new materials with improved properties. In this investigation, colloidal silver nanoparticles using an environmentally friendly procedure were synthesized. An aqueous solution of AgNO₃ was used as a silver precursor with ‘green’ reducing agents either different types of honey, or β-d-glucose. In the first case, different pH values, as well as the addition of poly(ethylene glycol), PEG were studied, while in the latter, the effect of reduction time in the presence of PEG with various average molecular weights was examined. Properties of the nanoparticles were measured using X-Ray diffraction, UV–Vis and FTIR spectroscopy. Using honey it seems that spherical particles are produced with the smaller average particle size obtained at pH 8.5. Use of honey has the advantage of being a natural product, although its main drawback is that its composition varies and it cannot be predefined to result in reproducible results. Use of β-d-glucose results in stable silver nanoparticles with small average particle size after 24 h reduction. The addition of low molecular weight PEG seems to be beneficial in the production of stable nanoparticles. Finally, the antimicrobial activity of the nanoparticles produced was investigated at different concentrations on both Gram positive and negative bacteria, such as Bacillus cereus, Bacillus subtilis, Escherichia coli and Staphylococcus aureus.     

Synthesis,Characterization and Environmental Applications of a New Bio-Composite Gelatin-Zr(IV) Phosphate

Gelatin-Zr(IV) phosphate composite (GT/ZPC) was synthesized by sol–gel method. Different techniques viz. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray powdered diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterisation of GT/ZPC composite ion exchanger. The ion exchange capacity (IEC) of GT/ZPC was observed to be better (1.04 meq g^?1) than its inorganic counterpart (0.64 meq g^?1). The pH studies revealed the monofunctional nature of GT/ZPC with one inflection point. The distribution studies showed that the GT/ZPC was highly selective for Cd²⁺ as compare to other metal ions. The environmental applicability of ion exchanger has been analysed for binary separations of metal ions using column method. Cd²⁺ was effectively removed from synthetic mixture of metal ions (Zn²⁺, Pb²⁺, Ni²⁺, Co²⁺ and Cu²⁺).     

A Microscopic Study of Paper Decayed by <Emphasis Type="Italic">Trichoderma harzianum</Emphasis> and <Emphasis Type="Italic">Paecilomyces variotii</Emphasis>

The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because the intensity of peaks at 1335 and 1111 cm^?1 significantly decreased due to the fungal decay. Furthermore, the intensity of O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.     

Characterization of Super Paramagnetic Nanoparticles Coated with a Biocompatible Polymer Produced by Dextransucrase from <Emphasis Type="Italic">Weissella cibaria</Emphasis> JAG8

Magnetic nanoparticles (MNPs) synthesised by chemical co-precipitation method was subjected to dextran coating by sonication method. The dextran was enzymatically synthesised by extracellular dextransucrase isolated from Weissella cibaria JAG8. The crystalline nature of MNPs and dextran coated MNPs were confirmed by X-ray diffraction studies with average particle size of 25 nm, which was confirmed further by high resolution transmission electron microscopy. The surface morphology of MNPs and dextran coated MNPs were monitored by scanning electron microscopy studies. The vibrating sample magnetometer investigation displayed the super paramagnetic nature of MNPs and dextran coated MNPs. FT-IR analysis of MNPs and dextran coated MNPs, displayed characteristic band of Fe–O bond at 582 cm^?1. Thermo-gravimetric analysis of MNPs and dextran coated MNPs (1:1) ratio displayed a weight loss of 15 and 18 %, which clearly indicated 3.0 % of dextran was coated on to the MNPs. The elemental composition study by scanning electron microscopy confirmed the association of dextran with MNPs. The in vitro effect of MNPs and dextran coated MNPs was performed on human colon cancer (HT-29) cell lines and the results showed that dextran coated: MNPs (2:1) displayed good biocompatibility results over dextran coated: MNPs (1:1) and un-coated MNPs.     

Active Bio-composite Sodium Alginate/Maltodextrin Packaging Films for Food Containing Azolla pinnata Leaves Extract as Natural Antioxidant

The aim of the current work was to produce sodium alginate (SA) maltodextrins (MD) based functional films incorporated with phenolic extract of Azolla pinnata leaves fern (AF) by solution molding technique. AF with different concentrations (0.8, 1.2 and 1.6% w/w) were integrated inside SA.MD films. The resulted films were characterized to investigate the surface structure by scanning electron microscope (SEM), thermal disposal by (DSC), crystallization by X-ray diffraction (XRD), potential interaction by (FT-IR) and some mechanical properties. The SEM micrographs indicated that the higher concentration (1.6%) of AF extract caused development of wrinkles on the surface of films. And as a result, there were a significant decrease of elongation at break (EB) and tensile strength properties of films to 55.01 and 58.42%, respectively. By continues addition of AF extract to SA.MD films, the film thickness increased from 0.124 to 0.181 mm, the scavenging and antimicrobial properties were enhanced by the attendance of ferulic acid, rutin, thiamine, tamarixetin, astragalin, quercetin, chlorogenic acid and epicatechin inside extracts. Furthermore, the films solubility, swelling degree and water vapor permeability were decreased to 13.08%, 26.41% and 1.662?×?10^??10 g H₂O/m s p.a. The resulted films could be utilized as composite packaging material for different food applications.

     

Extraction and Characterization of Nanocrystalline Cellulose from Doum (<Emphasis Type="Italic">Chamaerops humilis</Emphasis>) Leaves: A Potential Reinforcing Biomaterial

The aim of this investigation was to extract nanocrystalline cellulose (NCC) from Moroccan Doum fibers (Chamaerops humilis) by chemical treatment to examine their potential for use as reinforcement fibers in bionanocomposite applications. The chemical composition, morphological and structural properties of the Doum fibers was determined at different stages of chemical treatment. Morphological (transmission electron microscopy and scanning electron microscopy), structural characterization (X-ray diffraction, Fourier transformed infrared), thermal characterization (thermogravimetric analysis). The suspension electrostatic stabilization (zeta potential) of NCCs was also carried out. The results of these characterization analysis found that average size of the NCC is 220 nm in length and 11 nm in diameter, with high crystallinity index (93 %), a thermal stability comparable to that of untreated Doum fibers (degradation temperature 340 °C), which is reasonably promising for the use of these nanofibers in reinforced-polymer manufacturing, and a good stability in water suspension that it allows their utilization such as reinforcement of the water-soluble polymers to prepare the bio-nanocomposite.     

Selective Lead(II) Adsorption and Flocculation Characteristics of the Grafted Sodium Alginate: A Comparative Study

Synthesis of sodium alginate-g-poly(acrylamide-co-N-methylacrylamide) [S-III], sodium alginate-g-poly(N-methylacrylamide-co-N,N-dimethylacrylamide) [S-II], sodium alginate-g-poly(acrylamide-co-N,N-dimethylacrylamide) [S-I]. Sodium alginate-g-poly(N,N-dimethylacrylamide) [SAG-g-PDMA] and sodium alginate-g-poly(acrylamide) [SAG-g-PAM] were prepared by solution polymerization technique using potassium peroxydisulfate as the initiator at 70?°C in water medium. The graft copolymers were characterized by FTIR and NMR (¹H and ¹³C) spectroscopy, SEM and XRD studies. All the five graft copolymers were used to remove Pb(II) ions from the aqueous solution and also in flocculation studies of kaolin clay (1.0 wt%), silica (1.0 wt%) and iron ore slime (0.25 wt%) suspensions. A comparative studies of all the five graft copolymers were also made in both the two cases. The Pb(II) ion removal capacity of all the graft copolymers follows the order S-III?>?SAG-g-PAM?>?S-II?>?SAG-g-PDMA?>?S-I. But the flocculation performance of the graft copolymers follows the order S-II?>?S-I?>?S-III?>?SAG-g-PDMA?>?SAG-g-PAM. S-III was also used for the competitive metal ion removal with Hg(II), Cd(II), Cu(II) and Zn(II). Pb(II) adsorption of S-III (the best Pb(II) ion adsorber) follows pseudo second order rate equation and Langmuir adsorption isotherm.     

A Study of Physicomechanical and Morphological Properties of Starch/Poly(vinylalcohol) Based Films

Starch/Poly(vinylalcohol) blends in two different ratios (60:40 and 50:50) were prepared with glycerol as a plasticizer. Films were cast by a solution casting method. One set of films were filled with 10 wt% of unmodified bentonite clay and another set of films were crosslinked with epichlorohydrin in an alkaline medium. The prepared film samples were subjected to X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical characterization and scanning electron microscope (SEM). Significant changes in the tensile properties were observed depending on the different chemical constituents of the films. The presence of clay and crosslinking with epichlorohydrin were both found to have considerable effect on the morphology and mechanical property of the films. The SEM investigations, XRD analysis and FTIR studies revealed the interaction between the various chemical components of the films.     

The Influence of Artificial Photodegradation on Properties of Poly(3-hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-3-hydroxyvalerate)(PHBV)/Graphite Nanosheets (GNS) Nanocomposites

The potential use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/graphite nanosheets (GNS) as a biodegradable nanocomposite has been explored. PHBV/GNS nanocomposites films were prepared by solution casting at various concentrations of GNS—0.25, 0.50 and 1.00 wt% GNS. The films were exposed to artificial ultraviolet radiation (UV) during 52 h. The effect of GNS on PHBV photodegradation was investigated and compared to neat PHBV film. The artificial photodegradation induced changes in physical (weight loss), chemical carbonyl index by Fourier transform infrared spectroscopy, thermal degree of crystallinity and melting temperature by differential scanning calorimetry and morphological scanning electron microscopy characteristics. Based on the results obtained from aforementioned analyzes it was verified that GNS inhibits the oxidative degradation of PHBV matrix.     

Environmentally-Friendly Synthesis of Ag Nanoparticles by Fusarium sporotrichioides for the Production of PVA/Bentonite/Ag Composite Nanofibers

Membranes and filters made of nanofibers can have many medicines and water treatment applications. The use of silver nanoparticles (AgNPs) with antibacterial activity in these structures improve their efficiency. However, due to the toxicity of the compounds used in the chemical synthesis of AgNPs, in this study, AgNPs were obtained through a biological process using Fusarium sporotrichioides. AgNPs preparation conditions were optimized, including F. sporotrichioides medium and AgNO₃ concentration. Next, a PVA nanofiber membrane with bentonite and AgNPs (Bio-AgNPs or Chem-AgNPs) was prepared using electrospinning. The optimal conditions for the production of Bio-AgNPs were the culture of F. sporotrichioides in the MGYP culture medium and 12 M of AgNO₃. The Bio-AgNPs particle size and zeta potential were 58 nm and ??16.8 mV, respectively, with antibacterial activity. The PVA/NB/AgNPs nanofibers operation conditions included 7.5% w/w PVA, 3% w/w bentonite, and AgNPs 5% w/w at a voltage of 11 kV, feed rate of 0.5 mL/h, and 15 cm distance between the needle and the collector. The average diameter of the PVA/NB/Bio-AgNPs nanofibers was 230 nm. Also, the presence of silver in the nanofibers was confirmed through EDX and XRD methods. The antibacterial assay of the nanofibers showed that the inhibition zone of PVA/NB/Bio-AgNPs against E. coli and S. aureus was 0.62 and 0.36 mm, which is better than PVA/NB/Chem-AgNPs and comparable with chloramphenicol. The produced membrane is suitable for water treatment, food packaging, and wound dressing because of its good thermal, mechanical, and antibacterial properties.