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Biofilm and bionanocomposite films were synthesized from polyvinylpyrrolidone (PVP), chitosan (CS), citric acid (CA), and zinc oxide-nanoparticles (ZnO-NPs). Effects of gamma-irradiation dose and ZnO-NPs concentrations; 0, 0.1, 0.3, 0.6, 0.9, 1.2, and 1.5 (wt/wt,)% were studied. Biofilms and bionanocomposite films were characterized by Fourier transform infrared, Raman spectroscopy, transmission electron microscopy, thermal gravimetric analysis, X-rays diffraction, energy dispersive X-ray, and mechanical properties to identify structure of biofilm and bionanocomposite films. Swelling (g/g)% and gelation (g/g)% of biofilms were carried out at diverse compositions of PVP to CS of (1/1), (1/2), and (2/1) (v/v). Swelling (g/g)% results of (1/1), (1/2), and (2/1) (v/v) were 116, 110, and 126, respectively. Values of highest and lowest gelation (g/g)% of (1/2) and (2/1) (v/v) are 98.0 [+ or -] 1.8 and 85.0 [+ or -] 2.6, respectively at 30 kGy. Water vapor transmission rate was studied for films and exposed 3450 [+ or -] 4.1 and 185.8 [+ or -] 1.2 (kg/[m.sup.2]. day) for open bottle and (PVP/CS/PCA)/(ZnO-NPs-1.5), respectively. Values of water solubility (g/g)% were investigated and found 30.21 [+ or -] 1.3 and 15.4 [+ or -] 2.5 for (PVP/CS/PCA)/(ZnO-NPs-0) and (PVP/CS/PCA)/(ZnO-NPs-1.5), accordingly. Bionanocomposite films displayed a broad-spectrum antimicrobial activity against Gram-negative bacteria and Gram-positive bacteria. (PVP/CS/PCA)/(ZnO-NPs-0.1) showed lowest inhibition zone; 4 [+ or -] 0.2, 9 [+ or -] 0.5, 19 [+ or -] 0.1, and 8 [+ or -] 0.3 (mm) compared with (PVP/CS/PCA)/(ZnO-NPs-1.5) of highest inhibition zone; 16 [+ or -] 0.5, 28 [+ or -] 0.2, 33 [+ or -] 0.6, and 18 [+ or -] 0.3 (mm) for Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus, respectively. Antimicrobial activity increased with increasing ZnO-NPs concentrations. Biodegradation of biofilms and bionanocomposite films were examined under soil from 0 to 120 days. Results of weight loss (g/g)% at 120 days of (PVP/CS/PCA)/(ZnO-NPs-0) and (PVP/CS/PCA)/(ZnO-NPs-1.5) are 72 [+ or -] 4.5 and 47.5 [+ or -] 3.8, respectively. Bionanocomposite films were used in food preservation of fresh cherry tomatoes for 30 days and showed goodness. Therefore, these results suggest that the possibility of using bionanocomposite films in food-packaging applications. Highlights * Synthesis of development of (polyvinylpyrrolidone/chitsoan/citric acid)/ (zinc oxide-nanoparticles) bionanocomposite films. * Characterization of bionanocomposite films by different techniques. * Study of biodegradation of bionanocomposite films. * Study of antimicrobial of bionanocomposite films. * Usage of bionanocomposite films in cherry tomatoes preservation for 30 days. KEYWORDS antimicrobial, biodegradability, cherry tomatoes preservation, gamma irradiation, nanocomposites, 1 | INTRODUCTION The headache trouble of nonbiodegradable polymeric wastes has really become a terrible and horrible issue in recent years with catastrophic impacts on environmental. Biodegradable polymers are deemed [...]

Luminescent carbon dots (CDs) are emerging carbon nanomaterials whose tunable and exceptional optoelectronic properties have found applications as alternatives to traditional fluorophores and metal-based catalysts. Further, they can be easily prepared from biomass and using green solvents. Biomass sources of CDs, however, often result in the formation of thousands of products, which are difficult to separate. In this study CDs were synthesized using a urea-choline chloride deep eutectic solvent and shrimp shell-derived chitin as raw materials through a low-temperature solvothermal treatment. This was followed by a facile liquid-liquid extraction with acetone to improve the optical properties and narrow the size distribution of the CDs. The acetone-extracted CDs (ACDs) showed good performance in photocatalytic degradation of the aquatic pollutant, malachite green. They also show good potential in monitoring various toxic water pollutants through the quenching effect of selected pesticides, antibiotics, heavy metals, and anions on the fluorescence of ACDs. Key words: luminescent nitrogen-doped carbon dots, deep eutectic solvent, solvothermal synthesis, bio-based carbon dots, acetone extraction, malachite green decolourization, Introduction Carbon dots (CDs) refer to a class of carbon-based nanomaterials that exhibit exceptional electrical, optical, and mechanical properties in addition to good biocompatibility low cytotoxicity, and solvent dispersibility. (1) [...]

Water pollution has emerged as a formidable issue of utmost concern in the world, and the design of three-dimensional porous, high adsorption performance, and sustainable adsorbent materials is of great significance for wastewater purification. Naturally abundant sodium alginate was used to prepare oxidized sodium alginate (OSA), a biomass macromolecule containing an aldehyde group. A double network interpenetrating structure based on carboxymethyl chitosan (CMS) and OSA was constructed without any small molecule cross-linking agent throughout, and a Schiff base reaction occurred at room temperature to prepare chemically stable CMS@OSA aerogels, which contain a continuous and dense porous structure inside the aerogel. CMS and OSA both contain an anionic reactive group, carboxyl, which makes them both matrix and functional materials, enabling selective adsorption of malachite green (MG) dyes. The prepared aerogel adsorbent showed a high adsorption capacity (302 mg/g) for MG at room temperature. The adsorption mechanism between the aerogel adsorbent and the adsorbent mass was investigated, and the effect of different factors on the adsorption performance was analyzed. The fitting coefficients of both the adsorption kinetic model and the isotherm model reached 0.99. The ingenious preparation method and excellent adsorption performance offer great prospects for chitosan biomass aerogels to play a role in environmental protection and economy. Highlights * An interpenetrating structure based on the Schiff base reaction. * Construction of three-dimensional porous structures. * Pure ecological raw materials without toxic crosslinkers. * High adsorption capacity at 302 mg/g for malachite green. KEYWORDS adsorption, aerogel, chitosan, malachite green, sodium alginate, 1 | INTRODUCTION Water is considered to be the most important natural resource for human survival. A healthy and adequate water supply is the basis for human well-being and an [...]

Exploring new and efficient adsorbents for the purification of water from heavy metals and organic waste to provide clean drinking water is highly demanded. Herein, the synthesis of polymeric materials based on grafting chitosan (Cs) by various acrylic monomers as acrylic acid (AA), 2-acrylamide-2-methyl propane sulfonic acid (AMPS), and acrylamide (Am) namely S1, S2, or S3, respectively, using methylene bisacrylamide (NMBAm) as crosslinker was performed. The formed polymeric compound was characterized by utilizing Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray, and Brunauer-Emmett-Teller. It was determined that S2 possessed a higher specific surface area of 109.133 [m.sup.2]/g, which is higher than S1 (71.2553 [m.sup.2]/g) and S3 (62.8847 [m.sup.2]/g). The as-prepared polymeric compounds were utilized for the removal of copper ions ([Cu.sup.2+]) and methylene blue (MB) from wastewater in the absence and presence of UV light irradiation. The kinetic study and the adsorption isotherms for the removal of [Cu.sup.2+] and MB as organic pollutants using the as-prepared polymeric compound were studied. KEYWORDS copper ions removal, modified chitosan, organic pollutants, photocatalytic, wastewater treatment, 1 | INTRODUCTION The hazardous impact of heavy metal and organic dye on the environment and bioaccumulation, which pose a major threat to both human health and the ecosystem, has [...]

Solar interfacial water evaporation to obtain pure water has attracted extensive attention in recent years. In this work, based on the excellent optical property of [FeS.sub.2] and the cross-linking nanostructure of chitosan (CTS), a [FeS.sub.2]@CTS hydrogel composite film for solar interfacial water evaporation was developed by hydrothermal synthesis and the following composite coating technology. The prepared [FeS.sub.2]@CTS presented high solar absorptivity of 95.27% and fast optical response capability. Under the optimized condition, the evaporation rate of pure water reached 3.34 kg [m.sup.-2] [h.sup.-1] and the photothermal conversion efficiency was 103.06% under one sun irradiation. In five runs, the evaporation rate of the [FeS.sub.2]@CTS was stable, indicating the excellent cycle stability. Also, in the desalination test, the stable evaporation rate of 1.74 kg [m.sup.-2] [h.sup.-1] was obtained in five runs. Due to the simple preparation method, low cost, and outstanding interfacial evaporation property, this [FeS.sub.2]@CTS indicates great potential for the seawater desalination or other photothermal conversion applications. Key words: photothermal conversion, [FeS.sub.2]@CTS, solar interfacial evaporation, desalination, 1. Introduction According to the statistics of the World Health Organization, one-fifth of the world's population is facing the shortage of clean water, and the pollution of existing water sources [...]

Abstract The poly(vinyl alcohol) (PVA), a biodegradable and semiciystalline polymer composed of vinyl monomer -(C[H.sub.2]-CHOH)n- units, combines different advantages such as biodegradability, good mechanical, and adhesive properties, among others. The [...]

In this paper, 2-hydroxyethyl methacrylate (HEMA) was graft copolymerized onto chitosan (CHI) at different ratios using a radical initiator. The grafted hydrogel composites were then characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and thermo-gravimetric analysis (TGA). Swelling behavior of the hydrogels was investigated at different pH and different times. The antimicrobial activity of the chitosan-graft-HEMA (CHIHEMA) against gram-negative bacteria and gram-positive bacteria was studied by the standard agar well diffusion assay method. The CHI-HEMA 1:1 and CHIHEMA 1:2 showed an obvious antimicrobial effect against six test strains. The CHI-HEMA 1:1 and CHI-HEMA 1:2 exhibited a highly significant increase (p < 0.01) in diameter of the inhibition zones compared with the standard antibiotics. Furthermore, CHI-HEMA 1:1 presented the highest antimicrobial activity against all test strains with a significant difference (p < 0.01) compared with CHI-HEMA 1:2. Meanwhile, the decreasing order of the average sensitivity to CHI-HEMA 1:1 and CHI-HEMA 1:2 was observed to be S. marcescens > E. colt > S. aureus subsp. aureus > S. enteritidis > E. faecalis > E. aerogenes. These results indicate potential application of CHI-HEMA 1:1 and CHI-HEMA 1:2 graft hydrogels as a novel and efficient antimicrobial agent in biomedical fields. KEYWORDS antimicrobial activity, chitosan, HEMA, hydrogel, swelling, 1 | INTRODUCTION Chitosan is a natural cationic polymer obtained by deacetylation of chitin, which is one of the most abundant natural polymers. [1] Chitosan, a natural polysaccharide, attracts attention [...]

In this work, Palygorskite (Pal) nanorods, chitosan (CS), and polyethylene glycol (PEG) are used to prepare new composite lubricants in order to improve the lubrication performance of water. The tribological experimental results showed that the composite lubricant composed with 1 wt% Pal, 10 wt% PEG and 2 wt% CS has excellent lubrication performance. The tribological data showed that the friction coefficient reached 0.021, and the composite lubricant lubrication performance was about 4 times higher than that of deionized water. The materials were characterized by scanning electron microscope (SEM), thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which revealed that the composite lubricant contained many oxygen-containing functional groups, and there was no chemical reaction between these functional groups. Instead, a lubricating film that can reduce friction and wear was formed through the hydrogen bond effect between functional groups. In this paper, a general and simple preparation method of new composite lubricant was proposed, which can be wildly used in many fields such as water-based lubrication. KEYWORDS chitosan, composite lubricant, palygorskite, polyethylene glycol, tribological, 1 | INTRODUCTION Polymer is a common matching material for key friction pairs of hydraulic components, pumps and hydraulic turbines. Adding water-based nano lubricant can reduce the wear of friction [...]

Polymer metal nano-composites (PMNC) were synthesized by integrating different weight percentage of chitosan (CS), N,N'-methylenebisacrylamide (MBA) crosslinked poly(aciylic acid-co-hydroxyethyl methacrylate) copolymer and Cu nanoparticles (CuNPs). CuNPs were generated in situ during polymerization by reducing CuS[O.sub.4].5[H.sub.2]O with ascorbic acid. The presence of the CuNPs in the polymer network, functionality, crystallinity, morphology, size distribution of the CuNPs, elemental composition, thermal characteristics, network parameters, pH sensitivity, and strength of the composites was evaluated. The CuNP-loaded PMNC4 composite prepared with 10:1 acrylic acid : hydroxyethyl methacrylate molar ratio, 1 wt% each of initiator and MBA crosslinker and 4 wt% CS showed a photodegradation efficiency of 64% in 5 h for 50 mg/L methyl violet dye in water. The same polymer showed a rejection of 91.45% and a mass transfer coefficient of 4.14 * [10.sup.-5] cm/s for continuous adsorption of 20 mg/L Pb(II) ion in water in a fixed bed of height 22 mm for an inflow rate of 30 ml/min. KEYWORDS chitosan, column adsorption of Pb(II) from water, composite adsorbent, copolymer, CuNP, photocatalytic reduction, 1 | INTRODUCTION Nanometals of Ag, Au, Pd, Pt, Co, Ni, and Cu were reported as very efficient catalyst for reduction of organic pollutants such as synthetic dyes [1,2] and [...]

The presence of microalgae affects water quality and beneficial uses of surface freshwaters. Chitosan with proven potential for harvesting specific microalgae species from their culture medium to produce biofuels and bioproducts also appears promising for efficient removal of mixed microalgae species from surface freshwaters. The main focus of the present study was on removal of mixed microalgae species using chitosan as a coagulant to help improve water quality. Important operational parameters were optimized for economical microalgae removal. The microalgae cells, chlorophyll-a, total nitrogen, and total phosphorous removal efficiency were 82.06%, 89.90%, 69.32%, and 44.01%, respectively, at an optimum chitosan dose of 10 mg/L, pH 8, slow mixing time 7 min, slow mixing rate 30 rpm, and settling time of 15 min. The results show that chitosan coagulation efficiently removed mixed microalgae species from surface freshwater with significant improvement in water quality and recovery of algal biomass for other beneficial applications. Key words: chitosan, microalgae harvesting, flocculation, water quality improvement, microalgal biomass. La presence de microalgues a une incidence sur la qualite de l'eau et les utilisations benefiques des eaux douces de surface. Le chitosane, avec un potentiel confirme en matiere de recolte d'especes precises de microalgues a partir de leur milieu de culture pour la production de biocarburants et de bioproduits, semble egalement prometteur pour l'elimination efficace des especes mixtes de microalgues des eaux douces de surface. L'objectif principal de la presente etude etait d'eliminer les microalgues mixtes en utilisant le chitosane comme coagulant pour ameliorer la qualite de l'eau. Des parametres operationnels importants ont ete optimises pour l'elimination economique des microalgues. L'efficacite d'elimination des cellules de microalgues, de chlorophylle-a, d'azote total et de phosphore total etaient 82.06, 89.90, 69.32 et 44.01 %, respectivement, a une dose optimale de chitosane de 10 mg/L, pH 8, temps de melange lent 7 min, vitesse de melange lente 30 rpm et temps de sedimentation de 15 min. Les resultats ont montre que la coagulation du chitosane a permis d'eliminer efficacement les microalgues mixtes des eaux douces de surface, ce qui a permis d'ameliorer considerablement la qualite de l'eau et de recuperer la biomasse algale pour d'autres applications benefiques. Mots-cles : chitosane, recolte de microalgues, floculation, amelioration de la qualite de l'eau, biomasse de microalgues., 1. Introduction Excessive growth of microalgae, especially cyanobacteria, in surface freshwaters forms unsightly surface scum, causes severe oxygen depletion and fish mortalities upon die-off, releases algal toxins, taste and odour, [...]

Crosslinking behavior of Diglycidyl Ether of Bisphenol A (DGEBA) resins cured by chitosan was isothermally studied by Fourier Transform Infrared (FTIR) Spectroscopy for various molar ratios of chitosan at different temperatures. Results indicated that oxirane undergoes nucleophilic attack by the primary amine groups in chitosan to form crosslinked structure. Epoxy fractional conversion ([alpha]) was calculated by following the change in area of oxirane peak at 914 [cm.sup.-1]. Value of [alpha] and reaction rate (d[alpha]/dt) increased with increase in curing temperature and chitosan concentration. The maximum epoxy fractional conversion of 70% was obtained for 1:4 molar ratio (EpoxyrChitosan) at 200[degrees]C. A four parameter kinetic model with two rate constants was employed to simulate the experimental data. Overall reaction order and activation energy for all compositions were in the range of 2.5-3 and 25-50 kJ [mol.sup.-1], respectively. Results indicated that cure reaction is autocatalytic and does not follow simple nth order cure kinetics. Thermogravimetric analysis (TGA) performed on chitosan cured DGEBA films and compared against neat epoxy and neat chitosan films. Results showed that the degradation of chitosan crosslinked epoxy network occurred in the temperature range of 450-550[degrees]C. POLYM. ENG. SCI., 57:865-874, 2017. [c] 2016 Society of Plastics Engineers, INTRODUCTION Epoxy resins, characterized by presence of one or more oxirane rings in the structure, are one of the versatile thermosetting polymers which has a wide range of applications such [...]

Abstract: A simple and sensitive sensor has been developed for the electrochemical determination of ciprofloxacin (CF). The proposed sensor was designed by chitosan-coated [Fe.sub.3][O.sub.4] magnetic nanoparticle incorporated in the carbon [...]

Polyelectrolyte complex (PEC) of chitosan (CH) and hyaluronic acid (HA) are widely used for skin, cartilage, and bone tissue engineering. However, no reports are seen on their response at high ionic media, like increased [Ca.sup.2+] where they are likely to be exposed in the form of bone constructs and the influence of these ions on modulating the release of incorporated entities such as drugs and growth factors. Here, we prepared freeze dried scaffolds of PEC of CH and HA (CH-HA) and characterized them by FTIR, TGA, SEM, and ESEM. FITC conjugated BSA, designated as FA, was incorporated into the PEC to study the release properties in response to [Ca.sup.2+]. The swellability of CH-HA and the extent of drug release from the matrix, FA loaded CH-HA was studied in deionised water and aqueous Na + and [Ca.sup.2+] solutions. Swelling and drug release were high for the matrix in aqueous [Ca.sup.2+] whereas it was remarkably low in water and Na+. Drug released was found to increase with concentrations of [Ca.sup.2+] (0.02-1.0M) indicating that CH-HA is a promising matrix for [Ca.sup.2+] responsive delivery of agents to accelerate healing of bone cracks, which is known to release high amount of [Ca.sup.2+]., INTRODUCTION Polymeric architectures responsive to local stimuli have enabled extensive applications in areas such as drug delivery, scaffolds for tissue engineering, antibacterial surfaces, and as highly selective sensors. In spite [...]

An effective method was developed to isolate toxic heavy metal ions from the aqueous solution by the magnetic nanopolymers. The magnetic sorbent was prepared with radiation-induced crosslinking polymerization of chitosan (CS), 2-acrylamido-glycolic acid (AMGA), and acrylic acid (AAc), which stabilized by magnetite ([Fe.sub.3][O.sub.4]) as nanoparticles. The formation of magnetic nanoparticles (MNPs) into the hydrogel networks was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and Scanning electron microscopy, which revealed the formation of MNPs throughout the hydrogel networks. The swelling behavior of the hydrogels and magnetic ones was evaluated at different pH values. The adsorption activity for heavy metals such as [Cu.sup.2+] and [Co.sup.2+] by nonmagnetic and magnetic hydrogels, [Fe.sub.3][O.sub.4]/CS/ (AMGA-co-AAc), in terms of adsorption amount was studied. It was revealed that hydrogel networks with magnetic properties can effectively be used in the removal of heavy metal ions pollutants and provide advantageous over conventional ones., INTRODUCTION Due to the scientific and technological progress, toxic metal contamination is a serious problem threatening human health. Removal of toxic heavy metal ions from industrial and mining wastewaters has [...]

Chitosan-stearate complexes (CSC) were prepared by reacting chitosan (CS) with stearic acid. The formation and characteristics of CSC were studied by FTIR spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the complexes were synthesized by the electrostatic interaction between the amino group of CS and the carboxyl group of stearic acid. The crystallinity and thermal stability of complexes decreased with the increasing content of stearic acid adsorbed by CS through electrostatic interaction. The in vitro assays show that the complexes of CS adsorbed more deoxycholic acid salt than CS per se at the same pH than that of chitosan. Moreover, CSCs which were more hydrophobic bound bile salt more effectively. POLYM. ENG. SCI., 54:592-597, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION Chilosan(CS), which is nontoxic and biodegradable (1-3), is a naturally occurring copolymer of glucosamine and N-aeetyl-glucosamine produced by the deacelylation of chitin (4). Because of the unique polycalionic nature, [...]