Search

Chromium (Cr), due to its greater contamination in aquifers and distinct eco-toxic impacts, is of greater environmental concern. This study aimed to synthesize nanocomposites of almond shells biochar (BC) with zerovalent bismuth and/or copper (Bi0/BC, Cu0/BC, and Bi0–Cu0/BC) for the removal of Cr from aqueous solution. The synthesized nanocomposites were investigated using various characterization techniques such as XRD, FTIR spectroscopy, SEM, and EDX. The Cr removal potential by the nanocomposites was explored under different Cr concentrations (25–100 mg/L), adsorbent doses (0.5–2.0 g/L), solution pH (2–8), and contact time (10–160 min). The above-mentioned advanced techniques verified successful formation of Bi0/Cu0 and their composite with BC. The synthesized nanocomposites were highly effective in the removal of Cr. The Bi0–Cu0/BC nano-biocomposites showed higher Cr removal efficiency (92%) compared to Cu0/BC (85%), Bi0/BC (76%), and BC (67%). The prepared nanocomposites led to effective Cr removal at lower Cr concentrations (25 mg/L) and acidic pH (4.0). The Cr solubility changes with pH, resulting in different degrees of Cr removal by Bi0–Cu0/BC, with Cr(VI) being more soluble and easier to adsorb at low pH levels and Cr(III) being less soluble and more difficult to adsorb at high pH levels. The experimental Cr adsorption well fitted with the Freundlich adsorption isotherm model (R2 > 0.99) and pseudo-second-order kinetic model. Among the prepared nanocomposites, the Bi0–Cu0/BC showed greater stability and reusability. It was established that the as-synthesized Bi0–Cu0/BC nano-biocomposite showed excellent adsorption potential for practical Cr removal from contaminated water. [ABSTRACT FROM AUTHOR]

Hexavalent chromium Cr(VI) has emerged as a contaminant of prime concern for the environmentalists because of its improper disposal by tannery, dye, and electroplating industries. Adsorption is the most exploited method for its removal from industrial wastewater because of its high removal efficiency even at low Cr(VI) concentration, minimal sludge, and ease of regeneration. In recent years, several adsorbents of biological origin such as plants, algae, fungi, and bacteria have been explored for Cr(VI) remediation. This review comprehends the recent studies involving usage of biopolymer‐based nano‐composites with respect to its adsorption mechanisms, adsorption capacities, isotherms, and kinetics. The conventional abiotic and biotic techniques for removal of Cr(VI) are also discussed with a comparative insight of their adsorption capacity and removal efficiency. Nano‐biocomposites integrate the functional properties of both nanoparticles and biopolymers, which make them efficient biosorbents. Nano‐biocomposites offer a large surface area, reduced particle loss, minimal particle agglomeration on the surface, and high stability. Common kinetic models among the nano‐biocomposites, and various equilibrium models are also analyzed to understand the mode of adsorption and associated factors. These materials are mostly found to follow monolayer adsorption with ion exchange, electrostatic interaction, and surface complexation as major players in the process. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of CMC/PUA via sustainable approch. • CMC/PUA naobiocomposites is utilize for coatings. • It will serve as environmentally friendly material for protective coatings. • CMC/PUA bionanocomposites characterize by FTIR, SEM and XRD,. An effort has been made to synthesize sustainable polyurethane-amide (PUA) organoclay by incorporating natural materials. Polyol derived from castor oil, toluene diisocyanate (TDI), and cetyl pyridinium chloride (CPC) modified Montmorillonite (Mt) clay have been used in this purpose. The modification of Mt clay with CPC serves a dual purpose by increasing the D -spacing between clay layers and enhancing the compatibility of clay with organic polymers. The investigations included varying the percentage of TDI at three different levels to assess its impact on the physical, mechanical and corrosion resistance characteristics of bio-nanocomposite. The presence of characteristics C H bonds at 2854 cm−1 (sym. −CH 2) and 2928 cm−1 (asym. −CH 2 –) in CMC are absent in Mt, confirming formation of CPC modified Mt clay (CMC). Structural investigations of nanobiocomposites were done by Scanning electron microscopy and X-ray diffraction studies and TGA analysis. The findings suggest that the synthesized bio-nanocomposites could serve as a novel and environmentally friendly material for protective coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

Fossil oil derived materials exhibit non‐degradable properties with a limited availability. To overcome these limitations, a biodegradable starch/poly(ε‐caprolactone) based Coloisite‐20A nanocomposites are developed in this research study. The overall performance of these newly developed nanocomposite materials is deeply investigated. First, the morphological analysis of the nanocomposites is examined using X‐ray diffraction, transmission electron microscopy, and atomic force microscopy. Thereafter, mechanical performance of the nanocomposites is analyzed through tensile and flexural tests. The water‐based contact angle and sorption testing are conducted to confirm the hydrophobic or hydrophilic nature of the nanocomposite. Finally, the degradation behavior of this nanocomposite is estimated by the soil‐burial tests followed by Fourier transform infrared analysis, field emission electron microscopy, and transmission electron microscopy. All the experiments are performed for the control and the test samples. The developed nanocomposites exhibit maximum tensile strength of 6.30 MPa with a water sorption of 6.08% for a 24 h of water immersion tests. On the other hand, the soil‐burial degradation reflects a maximum weight loss of 45.4% after 56 days of degradation period. Hence, moderately hydrophobic, low strength, biodegradable hybrid nanocomposites are developed to counter the use of non‐degradable plastic composites. [ABSTRACT FROM AUTHOR]

The purpose of this investigation is to study the influence of Spruce sawdust (SD) coated by magnesium oxide (MgO) nanoparticles in the removing of methylene blue (MB) from an aqueous solution which is in a batch system. The adsorbent was characterized by FTIR, FE-SEM, BET and XRD analysis. The high adsorption potential of SD-MgO nano-biocomposite was revealed by these findings, therefore, it is usable for dye-containing wastewater treatment. By investigating the impact of particular conditions like MB concentrations, the dose of adsorbent and pH, it became possible to confirm the effectiveness of the process. The OOP (which stands for Optimum Operating Parameters) were evaluated by RSM (which stands for Response Surface Methodology) which is based on BBD (Box-Behnken design) and is used for removing MB dye. The adsorbent dosage is the highest effective degree of the individual factor on MB removal. Maximum removal of MB dye was detected at pH 11 with 3.50 g L-1 adsorbent dosage. The surface area of 0.873 m2 g-1 and mesoporous adsorbent prepared gave good adsorption capacity of 26.657 mg g-1 for MB. Furthermore, in order to predict the empirical variables’ significance, the variances’ analysis (ANOVA) was used. The predicated removal efficiency which is proved to be the potency of the process and its effectiveness was found to be 94.05%. Different equilibrium and kinetic models were utilized to the experimental data. Both Pseudo-second order kinetic model and Freundlich adsorption isotherm showed the better fitness to the experimental data.

In recent years, controlled drug delivery has become an important area of research. Nano-biocomposites can fulfil the necessary requirements of a targeted drug delivery device. This review describes use of polymeric nano-biocomposites in controlled drug delivery devices. Selection of suitable biopolymer and methods of preparation are discussed. [ABSTRACT FROM AUTHOR]

The essence of the present research is based on reinforcement mechanism of hibiscus cannabinus fiber (KF) and graphene nanoplatelets (GNP) on mechanical and thermal properties of hybrid hibiscus cannabinus fiber/polypropylene (PKMG 1–5 phr) nano-biocomposites. TGA results revealed inclusion of KF and GNP enhanced charring and thermal stability of the bio-nanocomposites. DSC analysis revealed improved melting and crystallization temperatures of the materials. Flexural modulus significantly increased on inclusion of 20 wt.% kenaf fiber and 5 phr GNP. XRD studies confirmed KF and GNP induced nucleation of β-crystals of PP which improved toughness and impact properties of the nano-biocomposites especially at 3 phr.

In the present study, cationized high amylose maize starches (CS) with different degrees of substitution (DS) were prepared. The physical properties and microstructures of CS/montmorillonite (Mt and D1821Mt) films were investigated. Morphological analysis showed stronger intercalations of CS with hydrophilic montmorillonite (Mt) than with hydrophobic montmorillonite (D1821Mt). For CS/Mt nanocomposite films, an increasing exfoliation trend was detected with the increase in DS. On the whole, the tensile strength of CS/Mt nanocomposite films decreased while water vapor permeability increased with an increase of DS. The CS/Mt film with the DS of 0.04 showed the highest tensile strength (14.01 MPa) and lowest water vapor permeability (1.80 × 10 −10  g m/m 2  s Pa). Rheological measurements confirmed that the intermolecular forces between CS and Mt decreased with increasing DS. Mt could obviously increase the thermal stability of the films. Overall, CS with lower DS had better compatibility with Mt, which helped improve the properties of CS/Mt nanocomposite films. [ABSTRACT FROM AUTHOR]

The essence of the present research is based on reinforcement mechanism of hibiscus cannabinus fiber (KF) and graphene nanoplatelets (GNP) on mechanical and thermal properties of hybrid hibiscus cannabinus fiber/polypropylene (PKMG 1–5 phr) nano-biocomposites. TGA results revealed inclusion of KF and GNP enhanced charring and thermal stability of the bio-nanocomposites. DSC analysis revealed improved melting and crystallization temperatures of the materials. Flexural modulus significantly increased on inclusion of 20 wt.% kenaf fiber and 5 phr GNP. XRD studies confirmed KF and GNP induced nucleation of β-crystals of PP which improved toughness and impact properties of the nano-biocomposites especially at 3 phr. [ABSTRACT FROM PUBLISHER]

This paper presents leaching behavior of chromium from the stabilized/solidified (S/S) matrixes of tannery sludge. S/S matrixes were formed using cement, and nanoparticles and nano-biocomposites. The chromium in tannery sludge was immobilized by ZVIN (zero-valent iron nanoparticles), MIN (magnetic iron oxide nanoparticles), ZVIN-SB (zero-valent iron nanoparticles/sugarcane bagasse composite) and MIN-SB (magnetic iron oxide nanoparticles/sugarcane bagasse composite). The semi-dynamic leachate tests such as ANS 16.1 and ASTM C 1308 were performed to evaluate the efficacy of S/S matrixes. The parameters such as leaching rate, cumulative fraction leached, effective diffusivity, leachability index and leaching mechanism were calculated for the S/S matrixes containing sludge stabilized by nanoparticles and nano-biocomposites and unstabilized sludge. The leaching rate of chromium from the test specimens showed the effectiveness of nanoparticles and nano-biocomposites. Diffusion studies from the S/S matrixes indicated immobility of chromium. The mean leachability index was found to be higher than 13 for all the test specimens which shows that the S/S matrixes can be effectively utilized for 'controlled applications.' Further, nanoparticles and nano-biocomposites increased compressive strength of the S/S matrixes. XRD, SEM/EDX and FTIR revealed that chromium could be chemically fixed into cement matrixes. [ABSTRACT FROM AUTHOR]

Water quality is deteriorating continuously as increasing levels of toxic inorganic and organic contaminants mostly discharging into the aquatic environment. Removal of such pollutants from the water system is an emerging research area. During the past few years use of biodegradable and biocompatible natural additives has attracted considerable attention to alleviate pollutants from wastewater. The chitosan and its composites emerged as a promising adsorbents due to their low price, abundance, amino, and hydroxyl groups, as well as their potential to remove various toxins from wastewater. However, a few challenges associated with its practical use include lack of selectivity, low mechanical strength, and solubility in acidic medium. Therefore, several approaches for modification have been explored to improve the physicochemical properties of chitosan for wastewater treatment. Chitosan nanocomposites found effective for the removal of metals, pharmaceuticals, pesticides, microplastics from the wastewaters. Nanoparticle doped with chitosan in the form of nano-biocomposites has recently gained much attention and proven a successful tool for water purification. Hence, applying chitosan-based adsorbents with numerous modifications is a cutting-edge approach to eliminating toxic pollutants from aquatic systems with the global aim of making potable water available worldwide. This review presents an overview of distinct materials and methods for developing novel chitosan-based nanocomposites for wastewater treatment. • Chitosan a bio-sorbent play an important role in wastewater treatment. • Nanocomposites reduce wastewater pollutants with wider applications. • Nanocomposites affect the metal sorption properties during wastewater treatment. • Chitosan showed potential adsorption in the removal of toxic chemicals. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were synthesized in a chitosan matrix with varying AgNO3 (1, 3, 5 mM) and chitosan (1, 3%) concentrations via the one-step solution plasma process (SPP). Plasma was discharged for 3 min in the AgNO3 and chitosan solutions using unipolar power at 800 V with a frequency of 30 kHz. Fibrous 3D scaffolds were prepared by lyophilizing the nano-biocomposite solutions, and they were stabilized via cross-linking with UV irradiation. UV-Vis spectroscopy showed strong peaks with maximal absorbance at 415-440 nm, indicating the formation of AgNPs in the chitosan with an increase in peak height as the concentration of the precursor, AgNO3, increased. The chemical association between AgNPs and chitosan was confirmed using Fourier transform infrared spectroscopy (FTIR). The scaffolds had a micro-porous structure with pore diameters in the range of 5.8-157.0 μm, and a transmission electron microscopy (TEM) analysis revealed that spherical shaped AgNPs with diameters in the range of 2.5-27.6 nm were well-dispersed in the biocomposites. The nano-biocomposites had a broad spectrum of antimicrobial activity against various pathogens with minimal inhibition concentrations of 0.68-2.71 and 2.71-10.80 μg mL-1 for bacteria and fungi, respectively. These are the lowest concentrations achieved by nano-biocomposites reported thus far. The SPP was shown to be a facile, effective, and eco-friendly method of synthesizing nano-biocomposites for biomedical applications. [ABSTRACT FROM AUTHOR]

Poly(3hydroxybutyrate- co -4hydroxybutyrate) (P(3HB- co -4HB)) is a polyhydroxyalkanoate (PHA), which is known for its properties and performance leading to a wide range of applications. Compared to more conventional PHAs such as P(3HB) or P(3HB-4HV), P(3HB- co -4HB) is known for its mechanical properties. P(3HB- co -4HB) has the potential to replace some fossil-based thermoplastics in certain fields. However, it is thermally sensitive like most PHAs and this puts limitations on its potential as an important biobased and biodegradable polymer. The present work is based on the study of multiphase systems of P(3HB- co -4HB) elaborated to prepare nano-biocomposites using two nanoclays, montmorillonite (MMT) and sepiolite (Sep). The clays differ in geometries with MMT having sheet structure and Sep having fiber structure. The environment-friendly non-solvent based elaboration of P(3HB- co -4HB) in the presence of nanoclays allows for minimizing thermal degradation while improving the overall mechanical properties and thermal resistance of the final multiphase materials. The degree of improvement in the properties is found to be not only a function of the clay dispersion in the polymer matrix but also on the morphology/shape of the clay particles and interfacial polymer-clay interactions. It has been found that despite the higher aspect ratio of lamellar-type MMT clays, the fiber-like Sep clay has better stiffening properties arising mainly from the better polymer-clay interactions through the silanol groups along the length of the fiber. As a result of this increased “effective” aspect ratio of Sep, the properties of the Sep-based nano-biocomposites are greatly enhanced. The detailed analyses using various techniques (TGA, DSC, TEM, XRD, uniaxial tensile test) allows comparison and analysis of the structure-property relationships between MMT and Sep nano-biocomposites. [ABSTRACT FROM AUTHOR]

Thiol-Michael addition of pentaerythritol tetrakis(3-mercaptopropionate) (PE3MP) to a high oleic sunflower oil derivative containing enone groups (ETG), has been used to prepare vegetable oil derived renewable thermosets in an efficient way and under mild conditions. The same formulation has been used to prepare nano-biocomposites by incorporating into the polymerization mixture, 1 wt%, 5 wt% and 10 wt% of cellulose nanocrystals (CNC) modified with Beycostat A B09® as surfactant. The chosen methodology allows a good dispersion of the nano filler in a low polarity reactive media which still is a challenging approach. The morphological, thermal and mechanical properties of the different nano-biocomposites were evaluated and compared with the pristine thermoset. Morphological analysis shows that good dispersion of the nanofillers is achieved in all formulations. Mechanical properties show an improvement of the Young Modulus for all nanofiller contents, showing a maximum at 5 wt% loading (32 and 78 MPa for the pristine and 5% CNC nano-composite respectively) that has been related with the reinforcement effect of the modified CNC. CNC dispersion also affects positively the surface properties, thus reducing drastically the contact angle values (78.0–16.0° for the pristine and 10% CNC nano-composite respectively). Finally, protein adsorption was measured in order to evaluate potential application of these materials as biosensors and cell growing supports. [ABSTRACT FROM AUTHOR]

The main directions in food packaging research are targeted towards improvements in food quality and food safety. For this purpose, food packaging providing longer product shelf-life, as well as the monitoring of safety and quality based upon international standards, is desirable. New active packaging strategies represent a key area of development in new multifunctional materials where the use of natural additives and/or agricultural wastes is getting increasing interest. The development of new materials, and particularly innovative biopolymer formulations, can help to address these requirements and also with other packaging functions such as: food protection and preservation, marketing and smart communication to consumers. The use of biocomposites for active food packaging is one of the most studied approaches in the last years on materials in contact with food. Applications of these innovative biocomposites could help to provide new food packaging materials with improved mechanical, barrier, antioxidant and antimicrobial properties. From the food industry standpoint, concerns such as the safety and risk associated with these new additives, migration properties and possible human ingestion and regulations need to be considered. The latest innovations in the use of these innovative formulations to obtain biocomposites are reported in this review. Legislative issues related to the use of natural additives and agricultural wastes in food packaging systems are also discussed.

Chitin nano-size fillers, i.e. nanocrystals (CHNC) and nanofibers (CHNF), were incorporated in thermoplastic starch matrix via melt-mixing. The two types of thermoplastic starch-based nano-biocomposites (S/CHNC and S/CHNF) were characterized and compared in terms of morphology, chemical and crystal structure, thermal and mechanical properties, and water resistance. In general, all thermoplastic starch-based nano-biocomposites showed better thermal stability, mechanical properties, and storage modulus than thermoplastic starch matrix without chitin nano-size fillers. This can be linked to the good dispersion of the nano-size fillers in the matrix, resulting from their chemical similarity, and also to the strong nano-size fillers-matrix adhesion by hydrogen bonding interactions. The results showed that the final properties of the nano-biocomposites were dependent of the concentration and type of chitin nano-size filler introduced in the thermoplastic starch matrix. In general, the thermoplastic starch-based nano-biocomposites prepared with chitin nanofibers showed better thermal and mechanical properties and storage modulus than those prepared with chitin nanocrystals. [ABSTRACT FROM AUTHOR]

The terpene compounds, α-pinene and linalool were formulated with silica nanoparticles (SNPs) by a simple immersion method and the antifeedant activity of these formulations was evaluated against two major agricultural pests, the tobacco cutworm ( Spodoptera litura F.) and the castor semilooper ( Achaea janata L.) in laboratory bioassays. The interaction between terpenes and SNPs, shelf-life, suspension stability as well as the bioactivity of the nanoformulations were also studied. Both these terpenes in their pure form are known to deter feeding in several lepidopterous insects. However, formulating these pure terpene compounds with nano silica enhanced their biological activity up to 25 times to S. litura. Fourier transform infrared spectroscopy analysis of these nano botanical formulations indicated the presence of hydrogen bonding between terpenes and the surface of SNPs. Transmission electron microscopy images confirmed the higher aggregation property of the SNPs. Suspension studies validated the improved shelf-life of the nano-biocomposites, while X-ray diffraction (XRD) revealed the amorphous nature of formulations and no crystalline impurities. Adsorption of α-pinene and linalool onto SNPs resulted in an effective formulation that enhanced the antifeedant potential of the individual terpenes against insects while producing longer shelf-life for the terpenes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ternary PLA nano-biocomposites with synthesized cellulose and silver were developed. [•] The functionalization of the CNC surface favoured its dispersion in the PLA matrix. [•] The combination of cellulose and silver particles increased the barrier properties. [•] Overall and specific migration values were well below the limits indicated by EFSA. [•] Nano-biocomposites showed a significant antibacterial activity due to the Ag effect. [ABSTRACT FROM AUTHOR]

Highlights: [•] PLA nano-biocomposites with cellulose and silver were developed for food-packaging. [•] Binary and ternary systems were prepared by solvent casting. [•] The combination of cellulose and silver particles increased the barrier properties. [•] The overall migration level of PLA nano-biocomposites was below the normative limits. [Copyright &y& Elsevier]

This research work focus on the development of jute reinforced biodegradable nano-biocomposite using soy milk as matrix and nanoclay as additive. These composites were characterized for mechanical, dynamic mechanical properties, and moisture sensitivity. X-ray diffraction (XRD) and transmission electron microscopic (TEM) of the nano-biocomposites were accomplished to study the formation of exfoliated structure of nano-biocomposite. Mechanical and dynamic strength obtained for nanoclay-reinforced jute-soy composites are promising and developed composites might prove an alternative for nondegradable plastic-reinforced composite. Developed composites can be utilized in automotive, packaging, cuboids, railway wagon, and furniture industry as a substitute of plastic composites. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to report the impact of the addition of cellulose nanocrystals on the barrier properties and on the migration behaviour of poly(lactic acid), PLA, based nano-biocomposites prepared by the solvent casting method. Their microstructure, crystallinity, barrier and overall migration properties were investigated. Pristine (CNC) and surfactant-modified cellulose nanocrystals (s-CNC) were used, and the effect of the cellulose modification and content in the nano-biocomposites was investigated. The presence of surfactant on the nanocrystal surface favours the dispersion of CNC in the PLA matrix. Electron microscopy analysis shows the good dispersion of s-CNC in the nanoscale with well-defined single crystals indicating that the surfactant allowed a better interaction between the cellulose structures and the PLA matrix. Reductions of 34% in water permeability were obtained for the cast films containing 1wt.% of s-CNC while good oxygen barrier properties were detected for nano-biocomposites with both 1wt.% and 5wt.% of modified and un-modified cellulose nanocrystals, underlining the improvement provided by cellulose on the PLA films. Moreover, the migration level of the studied nano-biocomposites was below the overall migration limits required by the current normative for food packaging materials in both non-polar and polar simulants. [Copyright &y& Elsevier]

The present paper reports the successful development of a straightforward clay organomodification protocol named “Shear Induced Clay Organomodification” process, or SICO. To develop such a fast process, natural montmorillonite has been organomodified with cationic starch surfactant under shearing. According to the obtained results, this process allows the preparation of a preexfoliated montmorillonite, organomodified by cationic starch OMMTCS. Then, the OMMTCS has been dispersed into different plasticized starchbased plastics, varying the polysaccharide botanical source, to obtain nanobiocomposites displaying an exfoliated morphology. To establish the efficiency of this protocol and highlight this nanostructuration, uniaxial tensile tests have been performed on these materials. The mechanical properties have been compared with those obtained with nanobiocomposites elaborated with OMMTCS prepared with the conventional and efficient ExfoliationAdsorption technique. Since comparable properties are obtained, we assume that the SICO process is a powerful technique to easily and quickly organomodify the montmorillonite clay and to obtain exfoliated nanobiocomposites. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aliphatic-aromatic biodegradable random copolyester, poly (butylene sebacate-co-butylene isophthalate) (PBSeI) was synthesized by a two step direct melt polycondensation method. This copolyester was characterized by solubility studies, viscosity measurements, infrared, ¹H-NMR, 13C-NMR and thermal data. However, to be a real alternative to classical synthetic polymers and find applications, the thermal properties of biodegradable polymers have to be improved. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to create polymers with characteristic properties. In the present study, the nano-biocomposites were synthesized by dispersing different weight percentages (1, 3 and 5%) of organo-modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by the solvent intercalation method. Structural characterization and thermal analysis were carried out to better understand, the relationship between the structuring of the nanofillers and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of the OMMT-clay in the polyester networks. The scanning electron microscopy and high resolution transmission electron microscopy analyses showed that there was no phase separation between the two components which confirmed the compatibility of polyester with the organo-modified clay system. The results show that clay incorporation improved the thermal properties of PBSeI due to the exfoliated structure of the nanocomposites formed, and thus may increase the applicability of this biodegradable polymer in different fields. [ABSTRACT FROM AUTHOR]

Abstract: The last decade has seen the development of an alternative chemistry, which intends to reduce the human impact on the environment. The polymers are obviously involved into this tendency and numerous bio-sourced plastics (bioplastics), such as polylactide, plasticized starch, etc., have been elaborated. However, even if a lot of commercial products are now available, their properties (mechanical properties, moisture sensitivity) have to be enhanced to be really competitive with the petroleum-based plastics. One of the most promising answers to overcome these weaknesses is the elaboration of nano-biocomposites, namely the dispersion of nano-sized filler into a biopolymer matrix. This review reports the last developments in nano-biocomposites based on polysaccharides and nanoclays. The main elaboration strategies developed in starch, chitosan, cellulose acetate and pectin based nano-biocomposites elaborated with montmorillonite as the nanofiller are exposed herein. The corresponding dispersion state and properties are discussed. [Copyright &y& Elsevier]

Population growth and industrialization is associated with the elevation of hazardous pollutants, including heavy metals, biomedical wastes, personal-care products, endocrine-disrupters, pharmaceutically active compounds, and colorants in the environment. The scientific focus has been devoted to developing novel adsorbents to mitigate hazardous pollutants by constructing hybrids of different polymers and nano-structured materials for improved workability and physicochemical attributes. Recently, much attention has been devoted to nanomaterials in environmental remediation, owning to their exceptional characteristics including novel electrical/chemical features, quantum size effects, tunable functionalization, high scalability, and surface-area-to-volume ratio. Target-specific designing of nanocomposites impart high functionality. The cost-effective and eco-friendly synthesis of bioadsorbent materials is increasing for the removal of hazardous pollutants. Due to biocompatible, biodegradable, and eco-friendly nature, sodium alginate has been widely reported for the preparation of bioadsorbent materials to remove different inorganic/organic pollutants. In this review, the potentialities of alginate-based nanocomposites have been described for environmental remediation purposes. Different nanomaterials, including silica, metallic oxide, graphene oxide, hybrid inorganic-organic, non-magnetic-magnetic, carbon nanorods, nanotubes, polymeric nanocarriers, and several other materials have been described in combination with alginate biopolymer for environmental remediation. [Display omitted] • Alginate-based nano-adsorbent materials to remediate pollutants are reviewed. • Recalcitrant pollutants present a serious threat to environmental sustainability. • Various nanohybrids-assisted remediation approaches are given for pollutants. [ABSTRACT FROM AUTHOR]

Abstract: In the recent years, bio-based products have raised great interest since sustainable development policies tend to expand with the decreasing reserve of fossil fuel and the growing concern for the environment. Consequently, biopolymers, i.e., biodegradable polymers, have been the topic of many researches. They can be mainly classified as agro-polymers (starch, protein, etc.) and biodegradable polyesters (polyhydroxyalkanoates, poly(lactic acid), etc.). These latter, also called biopolyesters, can be synthesized from fossil resources but main productions are obtained from renewable resources. Unfortunately for certain applications, biopolyesters cannot be fully competitive with conventional thermoplastics since some of their properties are too weak. Therefore, to extend their applications, these biopolymers have been formulated and associated with nano-sized fillers, which could bring a large range of improved properties (stiffness, permeability, crystallinity, thermal stability). The resulting ‘nano-biocomposites’ have been the subject of many recent publications. This review is dedicated to this novel class of materials based on clays, which are nowadays the main nanofillers used in nanocomposites systems. This review highlights the main researches and developments in biopolyester/nanoclay systems during the last decade. [Copyright &y& Elsevier]

Abstract: The aim of this work was to predict the effective elastic properties of starch-based nano-biocomposites. Experiments (materials elaboration, morphological characterization and determination of mechanical properties) were conducted on both the pristine matrix (plasticized starch) and the matrix filled with montmorillonite nanoclay. Aggregated/intercalated and exfoliated nano-biocomposites were produced and mechanically tested under uniaxial tension to understand the effect of montmorillonite morphology/dispersion on the stiffness properties of starch-based nano-biocomposites. Micromechanical models, based on the classical bounds and the Mori–Tanaka approaches, were developed taking into consideration the influence of the clay concentration, the exfoliation ratio, the relative humidity and the storage time (ageing). Predicted results are in a good agreement with our experiments and show that the micromechanical model can be used as an indirect characterization technique to quantify the exfoliation/aggregation degree in the plasticized starch/clay nano-biocomposites. [Copyright &y& Elsevier]

Biodegradable polymers are one of the most promising ways to replace non-degradable polymers. But, to be a real alternative to classical synthetic polymers and find applications, biopolymer (biodegradable polymer) properties have to be enhanced. Nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, are an interesting way to achieve these improvements. Modified and unmodified montmorillonites have been introduced into a biodegradable aromatic copolyester, poly(butylene adipate- co-terephthalate) (PBAT). Structural characterization, thermal and mechanical tests have been carried out to understand better the relations between the nanofillers structuring and the final nano-biocomposite properties. Main results show that clay incorporation and the obtained intercalated structures improve PBAT properties (enhanced thermal stability, increased stiffness) and thus may increase the attractiveness of this biopolymer. [ABSTRACT FROM AUTHOR]

In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and thermal stability of polypropylene (PP) and PP/kenaf fiber biocomposites has been investigated. Different volume contents of HNTs ranging from 1 to 10 vol.% were melt mixed with PP and PP/kenaf fibers. The volume content of kenaf fibers was kept constant at 30%. The morphology of HNTs within the PP matrix has been studied via scanning electron microscopy (SEM). The morphological results revealed that HNT was uniformly dispersed in the PP matrix already at a low concentration of 1 and 2 vol.%. The mechanical properties of the manufactured nanocomposites and hybrid biocomposites such as Young's modulus, tensile strength, elongation at break, flexural modulus, flexural strength, and notched Izod strength have been measured. The results show that Young's modulus and strengths have been improved along with the addition of low content of HNTs. Moreover, the gain of notched Izod impact strength obtained by the addition of short kenaf fibers was maintained in hybrids with low concentrations of HNTs. Finally, the thermogravimetric analysis shows that at 10% and 50% weight loss, the thermal degradation rate of the PP and PP/kenaf biocomposites decreased by the addition of HNTs. [ABSTRACT FROM AUTHOR]

• Halloysite nanotubes (HNTs) improved performances of thermoplastic starch (TPS)-based blends. • HNTs enhanced compatibility between TPS and poly(butylene adipate- co -terephthalate) (PBAT). • HNTs improved mechanical and thermal properties of the TPS/PBAT blend. • Compatibilizing effect of HNTs was more pronounced for the composites with high proportion of TPS. The incorporation of halloysite clay nanotubes (HNTs) into thermoplastic starch/poly(butylene adipate- co -terephthalate) (TPS/PBAT) blends has been investigated with the aim of improving the compatibility and properties of the matrix. TPS/PBAT/HNTs nano-biocomposites with different TPS/PBAT weight fractions and HNTs contents were elaborated using a melt blending process, and their morphology and properties were investigated. The TPS80/PBAT20 and TPS20/PBAT80 blends exhibited dispersed phases of small droplets of PBAT or TPS, respectively, whereas the TPS50/PBAT50 blend presented a more homogeneous structure. Elongation at break of the TPS/PBAT/HNTs biocomposites with 5 wt% of HNTs significantly increased with increasing PBAT proportion, i.e., 6.5 %, 41.3 %, and 351.5 % for the composites based on TPS80/PBAT20, TPS50/PBAT50, and TPS20/PBAT80, respectively. The incorporation of 5 wt% of HNTs improved compatibility and increased Young's modulus of the TPS80/PBAT20, TPS50/PBAT50, and TPS20/PBAT80 blends approx. 350 %, 142 %, and 18 %, respectively. These results demonstrate that HNTs are promising nanofillers to improve properties of TPS-based blends. [ABSTRACT FROM AUTHOR]

The currently observed development of medical science results from the constant search for innovative solutions to improve the health and quality of life of patients. Particular attention is focused on the design of a new generation of materials with a high degree of biocompatibility and tolerance towards the immune system. In addition, apart from biotolerance, it is important to ensure appropriate mechanical and technological properties of materials intended for intra-body applications. Knowledge of the above parameters becomes the basis for considerations related to the possibilities of choosing the appropriate polymer materials. The researchers' interest, as evidenced by the number of available publications, is attracted by nanobiocomposites based on chitosan and carbon nanotubes, which, due to their properties, enable integration with the tissues of the human body. Nanosystems can be used in many areas of medicine. They constitute an excellent base for use as dressing materials, as they exhibit antimicrobial properties. In addition, they can be carriers of drugs and biological macromolecules and can be used in gene therapy, tissue engineering, and construction of biosensors. For this reason, potential application areas of chitosan-carbon nanotube nanocomposites in medical sciences are presented in this publication, considering the characteristics of the system components., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)