Starch/MWCNT-vitamin C nanocomposites: Electrical, thermal properties and their utilization for removal of methyl orange

Starch/carbon nanofibers bionanocomposites via melt mixing: Effect of dispersion and compatibility on conductivity and mechanical properties

Biodegradable polymers with conductivity and mechanical properties are required in several applications where it is necessary to substitute conductive synthetic plastics due to the high waste produced. In this study, bionanocomposites (BNCs) have been compounded by thermoplastification of rice starch via melt mixing with carbon nanofibers (NPs) and modified NPs (NPs [M]) using plasma of acrylic acid. Spectroscopy analysis, X-ray diffraction, and morphology were studied to elucidate the effect of dispersion and compatibility on the conductivity and mechanical properties. The incorporation of NPs promoted esterification reactions with starch during the melt mixing process, giving rise to changes in its crystal structure. NPs [M] showed better dispersion and compatibility because the plasma prevents reagglomeration and generates a stronger affinity. BNCs showed significative flexibility with remarked % elongation at break from 5.64 % to 248.60 %, and thermal conductivity increased from 0.10 to 0.58 W/m K, with NPs [M] at 5 %. In contrast, the electrical conductivity remained in the same magnitude order (10-4 S/cm). The better compatibility between starch-NPs [M] hinders electronic transport but increases the propagation of phonons to promote thermal conductivity. BNCs fabricated in this study by a dry and scalable process could be of interest in some application areas (intelligent food packing, electronics, textiles, etc.).

Progresses in lignin, cellulose, starch, chitosan, chitin, alginate, and gum/carbon nanotube (nano)composites for environmental applications: A review

Water sources are becoming increasingly scarce, and they are contaminated by industrial, residential, and agricultural waste-derived organic and inorganic contaminants. These contaminants may pollute the air, water, and soil in addition to invading the ecosystem. Because carbon nanotubes (CNTs) can undergo surface modification, they can combine with other substances to create nanocomposites (NCs), including biopolymers, metal nanoparticles, proteins, and metal oxides. Furthermore, biopolymers are significant classes of organic materials that are widely used for various applications. They have drawn attention due to their benefits such as environmental friendliness, availability, biocompatibility, safety, etc. As a result, the synthesis of a composite made of CNT and biopolymers can be very effective for a variety of applications, especially those involving the environment. In this review, we reported environmental applications (including removal of dyes, nitro compounds, hazardous materialsو toxic ions, etc.) of composites made of CNT and biopolymers such as lignin, cellulose, starch, chitosan, chitin, alginate, and gum. Also, the effect of different factors such as the medium pH, the pollutant concentration, temperature, and contact time on the adsorption capacity (AC) and the catalytic activity of the composite in the reduction or degradation of various pollutants has been systematically explained.

Thermoplastic starch nanocomposites: sources, production and applications - a review

The development of materials based on thermoplastic starch (TPS) is an excellent alternative to replace or reduce the use of petroleum-derived polymers. The abundance, renewable origin, biodegradability, biocompatibility, and low cost of starch are among the advantages related to the application of TPS compared to other thermoplastic biopolymers. However, through the literature review, it was possible to observe the need to improve some properties, to allow TPS to replace commonly used polyolefins. The studies reviewed achieved these modifications were achieved by using plasticizers, adjusting processing conditions, and incorporating fillers. In this sense, the addition of nanofillers proved to be the main modification strategy due to the large number of available nanofillers and the low charge concentration required for such improvement. The improvement can be seen in thermal, mechanical, electrical, optical, magnetic, antimicrobial, barrier, biocompatibility, cytotoxicity, solubility, and swelling properties. These modification strategies, the reviewed studies described the development of a wide range of materials. These are products with great potential for targeting different applications. Thus, this review addresses a wide range of essential aspects in developing of this type of nanocomposite. Covering from starch sources, processing routes, characterization methods, the properties of the obtained nanocomposites, to the various applications. Therefore, this review will provide an overview for everyone interested in working with TPS nanocomposites. Through a comprehensive review of the subject, which in most studies is done in a way directed to a specific area of study.

A Comprehensive Review on the Emerging Roles of Nanofillers and Plasticizers towards Sustainable Starch-Based Bioplastic Fabrication

Petroleum-based plastics are associated with environmental pollution problems owing to their non-biodegradable and toxic properties. In this context, renewable and biodegradable bioplastics possess great potential to replace petroleum-based plastics in mitigating these environmental issues. Fabrication of bioplastic films involves a delicate mixture of the film-forming agent, plasticizer and suitable solvent. The role of the plasticizer is to improve film flexibility, whereas the filler serves as a reinforcement medium. In recent years, much research attention has been shifted toward devising diverse methods for enhancing the performance of bioplastics, particularly in the utilization of environmentally benign nanoparticles to displace the conventional hazardous chemicals. Along this line, this paper presents the emergence of nanofillers and plasticizers utilized in bioplastic fabrication with a focus on starch-based bioplastics. This review paper not only highlights the influencing factors that affect the optical, mechanical and barrier properties of bioplastics, but also revolves around the proposed mechanism of starch-based bioplastic formation, which has rarely been reviewed in the current literature. To complete the review, prospects and challenges in bioplastic fabrication are also highlighted in order to align with the concept of the circular bioplastic economy and the United Nations’ Sustainable Development Goals.

Recent Developments in the Removal of Dyes from Water by Starch-Based Adsorbents

Starch-based adsorbents have demonstrated excellent potential for the removal of various noxious dyes from wastewater. This review critically evaluates the recent progress in applications of starch-based adsorbents for the removal of dyes from water. The synthesis methods of starch-based composites and their effects on physicochemical characteristics of produced adsorbents are discussed. The removal of various dyes by starch-based adsorbents are described in detail, with emphasis on the effect of key parameters, adsorption mechanism and their reusability potential. The key challenges related to the synthesis and applications of starch-based adsorbents in water purification are highlighted. Based on the research gaps, recommendations for future research are made. The evaluation of starch-based adsorbents would contribute to the development of sustainable water treatment options in near future.

Enhancing the dispersibility of multiwalled carbon nanotubes within starch-based films by the use of ionic surfactants

The incorporation of carbon-based nanomaterials into biopolymer matrix, to provide mechanical reinforcement and to obtain electrically conductive bionanocomposites, requires the homogeneous dispersion of the fillers. Herein, it is investigated the influence of surfactant structures on the dispersibility of multiwalled carbon nanotubes (MWNT) within starch matrix. Three different ionic surfactants, sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB) and sodium cholate (SC), are employed to disperse the MWNT. Films with MWNT-SC show better dispersibility and an increase of about 75% of tensile strength and 60% of Young's modulus compared with films using MWNT-SDS and MWNT-CTAB. Nevertheless, MWNT functionalized with CTAB impart the highest values of antioxidant activity (scavenging activity around 30% in 1.5 h) and electrical conductivity (σ =14.75 S/m) to starch matrix. The properties of starch-based films can be tailored according to the physical adsorption of each surfactant on MWNT surface and/or the interfacial interaction of the surfactant with starch chains.

The mechanisms and environmental implications of engineered nanoparticles dispersion

Dispersion of engineered nanoparticles (ENPs) has drawn special research attentions because the environmental behavior, risks, and applications of ENPs are greatly dependent on their dispersing status. This review summarizes the latest research progress of dispersion mechanisms, environmental applications in contaminants adsorption, and toxicity of ENPs dispersed in liquid and in solid matrix (3D-ENPs). Dispersion mechanisms of ENPs, including steric hindrance, electrostatic repulsion and "micelle wrapping" are well understood in single dispersing agent, however, the prediction of ENPs dispersion in real environments is not straightforward because of the diversity of structures, components, and properties of natural organic molecule mixtures. The adsorption characteristics, depending on the exposed surface areas in liquid, are significantly different between dispersed and aggregated ENPs. Comparing with the aggregated ENPs, the toxicity of dispersed ENPs is generally enhanced due to the increased uptake, released metal ions, carried contaminants, and induced ROS. 3D-ENPs not only inherit the excellent adsorption performance of ENPs dispersed in liquid, but also are beneficial to the separation and recycle from aqueous solutions due to their 3D rigid structures. However, the adsorption mechanisms as affected by environmental conditions are still unclear. Additionally, the potential risks of 3D-ENPs should be paid more attentions, with an emphasis on free radicals and stability of 3D structure.

Design and identification of poly(vinyl chloride)/layered double hydroxide@MnO2 nanocomposite films and evaluation of the methyl orange uptake: linear and non-linear isotherm and kinetic adsorption models

In this work, an adsorbent based on poly(vinyl chloride) (PVC) for the removal of methyl orange (MO) dye is proposed.

Application of ultrasonic irradiation as a benign method for production of glycerol plasticized-starch/ascorbic acid functionalized MWCNTs nanocomposites: Investigation of methylene blue adsorption and electrical properties

A solution mixing and ultrasonic dispersion method as a green, the fast, inexpensive and effective technique was utilized to prepare glycerol plasticized-starch (GPS)/ascorbic acid (AA)-MWCNTs nanocomposites (NCs) via the introduction of various amounts of AA-MWCNTs (3, 6 and 9wt%) as filler into GPS matrix. The GPS was synthesized by addition of glycerol (50%) as a plasticizer to starch which enhances its flexibility. Characterization of the obtained GPS/AA-MWCNTs NCs was accomplished by different techniques. The optimum filler content for the generation of fine electrical conductivity and good mechanical properties was found to be about 3wt%. The distribution of AA-MWCNTs at the low content (3wt%) in the GPS matrix was better due to the strong linkage between nanofiller and GPS in GPS/AA-MWCNTs NC. The results of adsorption studies showed that the fabricated NC can be a good adsorbent for removal of methylene blue (MB) dye from aqueous solutions.