Green Nanomaterials Research Articles

Green and Sustainable Nanomaterials for Energy Applications and Corrosion Inhibition

Green and Sustainable Nanomaterials for Energy Applications and Corrosion Inhibition

How Science Can Contribute to the Remedial Conservation of Cultural Heritage

Colloid science is contributing solutions to counteract the degradation of artifacts, favoring their transfer to future generations. Advanced materials such as nanoparticles, coatings, gels and microemulsions have been assessed in conservation, spanning from archeological sites to modern and contemporary art. We give an overview of the fundamental milestones and latest innovations in conservation science, targeting solutions and tools for remedial conservation based on green nanomaterials and hybrid systems. Future perspectives and outstanding challenges in this exciting field are then outlined.

A Review on Green Synthesis, Characterization and Anticancer Application of Metallic Nanoparticles.

Cancer is one of the leading causes of death worldwide and also the main obstacle of accelerating anticipation. It is globally recognized as overwhelmingly challenging in terms of clinical management. Cancer is taken into account because a prime lethal disease affects different organs of the body. Even with the rapid improvements in the medical sciences, there are no proper medicines to treat specific kinds of cancer. One of the fundamental issues within the malignant growth treatment is the side effect because of conventional treatment systems. Nanotechnology might be an extremely encouraging field for the therapeutic and drug areas; thus, it assumes a crucial part in improving humankind's satisfaction. In the infield of nanotechnology, a plant-mediated fusion of metal nanoparticles has been developed as a substitute to defeat the limitations of traditional synthesis approaches similar to physical and synthetic strategies. These tunable properties of nanomaterials make them progressed apparatuses in the biomedical platform particularly for the improvement of new diagnostics and focused on therapeutics for malignancy.This review incorporates the characterization of nanoparticles with size and shape and features critical uses of biosynthesized green nanomaterials in cancer theranostics.

Photoautotrophs-Bacteria Co-Cultures: Advances, Challenges and Applications.

Photosynthetic microorganisms are among the fundamental living organisms exploited for millennia in many industrial applications, including the food chain, thanks to their adaptable behavior and intrinsic proprieties. The great multipotency of these photoautotroph microorganisms has been described through their attitude to become biofarm for the production of value-added compounds to develop functional foods and personalized drugs. Furthermore, such biological systems demonstrated their potential for green energy production (e.g., biofuel and green nanomaterials). In particular, the exploitation of photoautotrophs represents a concrete biorefinery system toward sustainability, currently a highly sought-after concept at the industrial level and for the environmental protection. However, technical and economic issues have been highlighted in the literature, and in particular, challenges and limitations have been identified. In this context, a new perspective has been recently considered to offer solutions and advances for the biomanufacturing of photosynthetic materials: the co-culture of photoautotrophs and bacteria. The rational of this review is to describe the recently released information regarding this microbial consortium, analyzing the critical issues, the strengths and the next challenges to be faced for the intentions attainment.

Modification of Nitrogen Doped Carbon Quantum Dots Emissive States Using Plasma-Induced Non-Equilibrium Electrochemistry

Highly luminescent nanomaterials with ambient stability, environmental friendliness, low-cost and abundance are in demand for various applications in biological sensing, imaging and optoelectronics [1-6]. Many of the photoluminescent nanomaterials are semiconductors and usually contain toxic elements, heavy and expensive metals which have limited their applications. Carbon nanoparticles are a promising alternative to semiconductor nanocrystals as next generation green nanomaterials due to excellent biocompatibility, low cytotoxicity and solution processability which results in ease of production and incorporation in devices [7]. In the current work, nitrogen doped carbon quantum dots (N-CQDs) are synthesized by plasma-induced non-equilibrium electrochemistry utilizing a direct-current atmospheric pressure microplasma. The direct current microplasmas used in this work serve as a reliable and highly reproducible synthesis method for tuning the optical properties of carbon-based quantum dots. The outcome of precursors and discharge current affecting the surface chemistry and optical properties are studied using various characterization techniques, which have contributed to determine the mechanisms leading to QD formation from the plasma-induced reactions at the interface. The synthesized N-CQDs are crystalline with graphitic core doped with nitrogen and functionalized surface. The luminescence which originates from the combined effect of core and surface states can be finely controlled by changing synthesis conditions. These N-CQDs have potential to be used as an active material in next-generation solar cells or even as down-converters for high energy photons to be absorbed by a lower bandgap transporter [8]. The particularly high photoluminescence quantum yield (33% to 68%) can be exploited for optoelectronic applications.

Green Approach to Develop Bee Pollen-Loaded Alginate Based Nanofibrous Mat.

Green electrospun materials are gaining popularity in the quest for a more sustainable environment for human life. Bee pollen (BP) is a valuable apitherapeutic product and has many beneficial features such as antioxidant and antibacterial properties. Alginate is a natural and low-cost polymer. Both natural materials show good compatibility with human tissues for biomedical applications and have no toxic effect on the environment. In this study, bee pollen-loaded sodium alginate and polyvinyl alcohol (SA/PVA) nanofibrous mats were fabricated by the electrospinning technique. The green electrospun nanofibrous mats were analyzed by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and differential scanning calorimeter (DSC). According to the findings of the study, the toxin-free electrospinning method is suitable for producing green nanomaterial. Because of the useful properties of the bee pollen and the favorable biocompatibility of the alginate fibers, the bee pollen-loaded SA/PVA electrospun mats have the potential for use in a variety of biomedical applications.

Green Biosynthesis of CdS NPs and CdS/Fe3O4 NCs by Hawthorn Plant Extract for Photodegradation of Methyl Orange Dye and Antibacterial Applications

In the present study, green nanomaterials were synthesized using hawthorn plant extract as a natural stabilizer, reducing and capping agent. Biosynthesized CdS nanoparticles (NPs) and the coupled CdS/Fe3O4 nanocomposites (NCs) have been verified by various techniques such as XRD, SEM, EDS, TEM, FTIR and Uv–Vis. The average size about 24.2 nm was estimated for the composite crystals of SEM images and XRD (by the Scherrer and Williamson-Hall methods). The EDS results showed a mole ratio of 1:1 for the CdS NPs and 1:2 for CdS/Fe3O4 nanocomposite. Photocatalytic activity studies have shown that green synthesized CdS/Fe3O4 NCs (dosage: 0.1 g/L) have high photocatalytic activity toward photodegradation of methyl orange (MO) 1.2 × 10–5 M in aqueous solution under UV irradiation. Impacts of reaction conditions such as solution pH of rage (3–10) and contact time for about 105 min on the photodegradation rate of MO dye by CdS/Fe3O4 NCs photocatalysts have been investigated. Photocatalytic experimental results showed that the highest photodegradation rates occurred in a basic solutions at pH 10. Adsorption kinetics followed the pseudo-first-order kinetics model for photodegradation of MO. The adsorption kinetics results showed that degradation rate was increased toward increase of pH of 3 to 10 with apparent rate constant (0.090, 0.107, 0.187 and 0.268 min−1), respectively. In addition, the antibacterial effect of CdS/Fe3O4 NCs against pathogenic bacteria was tested, which revealed that nanocomposites had moderate antibacterial activity against both gram-positive (Enterobacter aeruginosa) and gram-negative (E. coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) at different concentrations of CdS/Fe3O4 NCs (0.001 to 0.025 g/ml).

Recent Trends in Development of Nanomaterials Based Green Analytical Methods for Environmental Remediation

Background: In recent years, the occurrence and fate of environmental pollutants has been recognized as one of the emerging issues in environmental chemistry. A survey documented a wide variety of these pollutants, which are often detected in our environment and these are a major cause of shortened life spans and global warming. These pollutants include toxic metal, pesticides, fertilizers, drugs, and dyes released into the soil and major water bodies. The presence of these contaminants causes major disturbance in the balance of the eco-system. To tackle these issues, many technological improvements are made to detect minute contaminations. The latest issue being answered by scientists is the use of green nanomaterials as sensors which are economical, instant and give much better results at low concentrations and can be used for the field measurements resulting in no dangerous by-product that could lead to more environmental contamination. Nanomaterials are known for their wide bandgap, enhanced physical, and optical properties with the option of tuneability as per need, by optimizing certain parameters. They are proved to be a good choice for analytical/ optical sensors with high sensitivity. Objective: This review holds information about multiple methods that use green nanomaterials for the analytical assessment of environmental pollutants. UV-Vis spectrophotometry and electrochemical analysis using green and reproducible nanomaterials are the major focus of this review article. To date, there are a number of spectrophotometric and electrochemical methods available that have been used for the detection of environmental pollutants such as toxic metals, pesticides, and dyes. Conclusion: The use of nanomaterials can drastically change the detection limits due to having a large surface area, strong catalytic properties, and tunable possibility. With the use of nanomaterials, lower than the marked limit of detection and limit of quantification were seen when compared with previously reported work. The used nanomaterials could be washed, dried, and reused, which makes the methods more proficient, cost-effective, and environmentally friendly.

Recent Advances in Environmental Analysis Towards Green Nanomaterials

Background: The protection of the ecology is an important task to control and restore the quality of environmental media through the reduction or prevention of the pollutants. Due to the growing awareness of safety, health and environmental issues, the use of non-toxic, clean and ecofriendly methods in the synthesis of nanoparticles has emerged out of necessity. Methods: In this article, the following concepts were considered: strategies of green chemistry, green chemistry metrics, waste management, green nanotechnology/nanoscience and characterization. Furthermore, the tables that include the covered topics were also presented in the manuscript. Results: The green synthesis of nanomaterials is a safe, energy-efficient and fast method which reduces the use of solvents, reagents, and preservatives that are hazardous to environment and human health. Conclusion: The fabrication of nanomaterials with green methods is a clean, safe, nontoxic and environmentally- friendly application which is necessary especially in large-scale operations.

A comprehensive review on carbon nano-tube synthesis using chemical vapor deposition

The current article reviews on Chemical Vapor Deposition (CVD) methodology to synthesize Carbon Nanotubes (CNTs). CVD is considered the most popular CNT synthesis methodology, which facilitates the utilization of carbonaceous precursor sources, catalysts supplemented with optimized processing conditions. It is considered as comparatively simpler and much more economical synthesis methodology with higher control, purity, and reproducibility of CNT dimensions. The growth mechanisms and process flow are discussed. By adding green nanomaterials, we can make this process more efficient and environment friendly which can be used as a sustainable solution.

Editorial

Nanomaterials and nanotechnologies have conquered almost all domains of science and technology. However, the environmental and health impacts associated with the synthesis of nanoparticles, and the use of nanoproducts and technologies have been a serious concern. Thus, the emerging trend is to adopt green approaches wherein clean, non-toxic, and eco-friendly reagents and procedures are employed for the synthesis of nanoparticles. Proper linkage of nanotechnology with green chemistry could pave the way for an environmentally sustainable society, which is an ongoing challenge. Abundant literature is available on the green nanomaterials and nanotechnologies, and a brief review of the application of green nanomaterials and technologies for energy applications is presented in this article. There is a wide scope for extensive research in this domain for the effective utilization of green nanomaterials towards realizing efficient and sustainable energy technologies for the future.

Sustainability consolidation via employment of biomimetic ecomaterials with an accentuated photo-catalytic potential: emerging progressions

Abstract Environmental pollution produced due to direct and untreated release of toxic organic pollutants such as dyes from the textile industries is not only effect the human life but also contaminates the ecosystem through different transferal modes. Green nanomaterials synthesized by using biological reducing agents offer sustainable, economically viable, facile, rapid and eco-friendly approach with photocatalytic degradation efficiencies >90% for organic dyes over the other traditional technologies. Current review has for the first time comprehensively abridged the suitability of green nanoparticles over chemogenic nanoparticles, the remediative role of these biogenic nanoparticles with major emphasis on the recent progressions in the photocatalysis of different toxic dyes and pollutants. Unlike physicochemically processed nanoparticles, biogenic nanoparticles has profound contribution to the sustainable development goals due to their cleaner and economical synthesis in addition to their detoxifying role. Meticulous review of the publications are strongly suggestive of the adoptability of biogenic nanoparticles at an implementation scale for their auspicious remediative role in addition to facile fabrication, natural reducing agents based synthetic mode, toxicity free and sustainable nature. However, the studies are also indicative of the need for utilization of biogenic synthesis at practical scale to derive maximum sustainability and ecological benefits.

Hydrogen peroxide assisted synthesis of sulfur quantum dots for the detection of chromium (VI) and ascorbic acid.

Sulfur quantum dots (SQDs), heavy-metal-free quantum dots, are regarded as the next generation promising green nanomaterials compared with traditional heavy-metal-based quantum dots. However, there have been few reports on the synthesis and application of SQDs for analytical detection. Herein, an H2O2-assisted top-down method is used to synthesize SQDs. The as-obtained SQDs have good water dispersion, stability, photoluminescence (PL) properties and achieving a quantum yield (QY) to 11%. After adding Cr (VI) in SQDs, the fluorescence intensity decreases base on inner filter effect (IFE). Moreover, Cr (VI) can be reduced to Cr(III) when ascorbic acid (AA) is introduced into the SQDs - Cr (VI) system, accompanying the recovery of the fluorescence intensity. The fluorescence sensor displays high sensitivity and quickly response toward Cr (VI) and AA in a range of 10-120μmol L-1 and 20-500μmol L-1 with a detection limit of 0.36μmol L-1 and 1.21μmol L-1, respectively. In addition, the fluorescence sensor has been applied for the determination of Cr (VI) and AA in real samples.

A review on design, material selection, mechanism, and modelling of permeable reactive barrier for community-scale groundwater treatment

Over the last thirty years, several techniques of groundwater (GW) remediation based on the principles of physical (air sparging), biological (bioventing), and chemical (e.g., ion exchange) processes have proven to be effective; however, only a handful of them could successfully be implemented at a community or regional scale due to issues like longevity, a requirement of significant investment and operation cost, skilled labours, and others. Therefore, considering the scope of Permeable Reactive Barriers (PRBs) to be implemented on a regional scale and its capability to be a significant replacement for several existing GW treatment methods, this review was prepared with the following objectives: (i) to compare the PRB method with the conventional methods of groundwater treatment along with the possibility and problems associated with the PRB installation in pilot-scale; (ii) to enlist all the probable sets of adsorbents (reactive materials) that can be used for different types of organic and inorganic contaminants; (iii) to understand the key mechanisms of degradation/removal of contaminants involved in PRB design; and (iv) to put forward the future research perspectives of this domain. Review augments that PRBs certainly has a low maintenance cost and a longer life span of ̃30 years that requires very ordinary skills. PRBs promise to be effective in developing countries like India, Bangladesh, and Sri Lanka for the removal of geogenic contaminants like arsenic and fluoride given the appropriate aquifer depth and hydrogeological settings like hydraulic gradient and transmissivity. Furthermore, reactive fillers required in PRBs are readily available, have longer expected life, and operate with no surrounding disturbances. With the advent of several green nanomaterials based adsorbents, PRB’s performance can achieve another height, but it needs the experiences from several pilot and larger scale projects. Indeed PRBs are the need of the hour, but a more programming-based investigation would be expected for its superior comprehension.

Green synthesis and evaluation of n-type ZnO nanoparticles doped with plant extract for use as alternative antibacterials

Emergence of resistance to antibiotics in bacterial pathogens and prevalence of residual effects of drugs pose serious challenges to public health worldwide. Diminishing efficacy of antibiotics calls for an expedited development of alternative antimicrobials. In this regard, zinc oxide (ZnO) nanoparticles (NPs) signify a latent and versatile inorganic nanostructure that possesses enhanced antimicrobial effects. In the present study, green synthesis of n-type ZnO-NPs was undertaken, which was then doped with various concentrations of extracts from ginger and garlic roots. The synthesized product was applied in low and high dosage to evaluate its antimicrobial efficacy against pathogenic E. coli. The results were compared to those obtained from chemically synthesized ZnO. Characterization of NPs was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–Vis), field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HR-TEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence (PL) emission. Strong absorption at 362 nm was observed for green synthesized NPs. HR-TEM exhibited interlayer spacing of 0.317, 0.312 and 0.308 nm, which is consistent with XRD results. Significant inhibition zones of 2.95–4.00 mm were observed for ZnO-NPs doped with ginger extract at an optimized concentration of 6 ml: 1. Similarly, garlic-doped NPs exhibited 1.85 and 2.75 mm inhibition zones at low and high dosage, respectively. The photodegradation study of synthesized products was undertaken using methylene blue (MB) dye under visible light source, where ZnO exhibited nearly complete decolourization of MB dye following a pseudo-first-order kinetics. The present study exemplifies an eco-friendly green nanomaterials synthesis technique using natural products (i.e., garlic and ginger), which can be expanded to include other green synthesized metal oxide NPs.

Current State of Applications of Nanocellulose in Flexible Energy and Electronic Devices.

Novel and unique applications of nanocellulose are largely driven by the functional attributes governed by its structural and physicochemical features including excellent mechanical properties and biocompatibility. In recent years, thousands of groundbreaking works have helped in the development of targeted functional nanocellulose for conductive, optical, luminescent materials, and other applications. The growing demand for sustainable and renewable materials has led to the rapid development of greener methods for the design and fabrication of high-performance green nanomaterials with multiple features, and consequently new challenges and opportunities. The present review article discusses historical developments, various fabrication and functionalization methods, the current stage, and the prospects of flexible energy and hybrid electronics based on nanocellulose.

Bioprospecting a native silver-resistant Bacillus safensis strain for green synthesis and subsequent antibacterial and anticancer activities of silver nanoparticles

Green nanomaterials have gained much attention due to their potential use as therapeutic agents. The present study investigated the production of silver nanoparticles (AgNPs) from a silver-resistant Bacillus safensis TEN12 strain, which was isolated from metal contaminated soil and taxonomically identified through 16S rRNA gene sequencing. The formation of AgNPs in bacterial culture was confirmed by using UV–vis spectroscopy with an absorption peak at 426.18 nm. Fourier transform infrared (FTIR) spectroscopy confirmed the involvement of capping proteins and alcohols for stabilization of AgNPs. Moreover, X-ray diffraction analysis (XRD), scanning and transmission electron microscopy (SEM and TEM) confirmed the crystalline nature and spherical shape of AgNPs with particle size ranging from 22.77 to 45.98 nm. The energy dispersive X-ray spectroscopy (EDX) revealed that 93.54% silver content is present in the nano-powder. AgNPs showed maximum antibacterial activity (20.35 mm and 19.69 mm inhibition zones) at 20 µg mL−1 concentration against Staphylococcus aureus and Escherichia coli, respectively and significantly reduced the pathogen density in broth culture. Furthermore, AgNPs demonstrated significant anticancer effects in the human liver cancer cell line (HepG2) in MTT assay, whereas, no cytotoxic effects were demonstrated by AgNPs on normal cell line (HEK293). The present study suggests that the biogenic AgNPs may substitute chemically synthesized drugs with wider applications as antibacterial and anticancer agents.

Low-cost microwave reactor for green synthesis of nanomaterials

Introduction: This contribution is about a low-cost microwave reactor for green synthesis of nanomaterials. The paper reflects research results achieved at the NanoFab group of the Universidad Militar Nueva Granada, within the line of nanophotonics, sensors and nanotechnology. Investigations and analyses were carried out during 2019. Problem: Conventional synthesis processes usually affect the environment and human health, due to contaminant reagents and generation of by-products. Objective: The aim of this research is the modification of a microwave oven that assists in the green synthesis of nanomaterials with potential applications in homeland security. Methodology: In this investigation, the modification of a domestic microwave was carried out. The implemented reactor features a heat exchange unit to reduce volatile elements, and a digital magnetic stirrer for local homogenization. Synthesis begins with a trisodium-citrate solution, continuously stirred at 37 °C. Next, the precursor is mixed with silver-nitrate for 2 minutes. Then, the mixture was treated for 20 minutes in the microwave reactor. Finally, the nanoparticles are recovered. Results: The homemade microwave reactor is suitable for producing nanoparticles. Particularly, the 20-minute microwave exposure time for the reactants results in a nanoparticle size between 80-90 nm. To probe reaction parameters, impedance spectroscopy analysis is performed. Results revealed that the resistance of the medium of silver nanoparticles is 2.5 ohms, while for sodium citrate and nitrate it is 8.8 and 11.8 ohms, respectively. Conclusion: It is demonstrated that the modified microwave reactor is suitable for nanomaterial production. Lower amounts of solvent are required during nanoparticle synthesis. Microwave synthesis allows for green nanomaterials production with a minor impact on the environment. Limitation: Homogeneous heating of reactants in a stationary microwave cavity is limited to waveguide design; in this case, to a multimodal-microwave waveguide. Originality: Low-cost reactor for nanomaterial production and greener synthesis.

The Influence of Reduced Graphene Oxide Nanoparticles (rGO NPs) on The Microstructure of Metakaolin Geopolymer

Reduced graphene oxide nanoparticles (rGO NPs) is one of the advanced green nano-materials with valuable properties that offer promising novel applications particularly when it is combine with other materials. The main objective of this study was to investigate the influence of rGO addition on the microstructure character of metakaolin based geopolymer. Graphene oxide nanoparticles (GO NPs) was synthesized from graphite by using modified Hummer’s method and rGO NPs was produced from GO through thermal calcination at 160°C for 4 hours in an autoclave. Geopolymer paste was produced through alkali activation method of metakaolin and cured at temperature 70°C for 2 hours. rGO NPs was dispersed into geopolymer paste with various concentrations, 0, 3, 6 and 9% relative to the mass of metakaolin. The crystal structure and morphology of rGO NPS and geopolymer-rGO NPs composites were investigated by means of x-ray diffraction (XRD), Fourier Transform Infrared (FTIR), scanning electron microscopy (SEM) and The results indicated that rGO NPs as two-dimensional material were successfully produced and characterized. The addition of rGO NPs was found to form strong bond with geopolymer species and hence improve the microstructure character of geopolymer.

Plasma Induced Non-Equilibrium Electrochemistry for Synthesis of Nitrogen Doped Carbon Quantum Dots Applied to Third-Generation Solar Cells

Highly luminescent nanomaterials with ambient stability, environmental friendliness, low-cost and abundance are in demand for various applications in biological sensing, imaging and optoelectronics [1-6]. Many of the photoluminescent nanomaterials are semiconductors and usually contain toxic elements, heavy and expensive metals which have limited their applications. Carbon nanoparticles are a promising alternative to semiconductor nanocrystals as next generation green nanomaterials due to excellent biocompatibility, low cytotoxicity and solution processability which results in ease of production and incorporation in devices [7]. In the current work, nitrogen doped carbon quantum dots (N-CQDs) are synthesized by one-step atmospheric pressure microplasma process. The direct current microplasmas used in this work serve as a reliable and highly reproducible synthesis method for tuning the optical properties of carbon-based quantum dots in colloid form which result as being highly stable and environmentally-friendly. The outcome of precursors and discharge current affecting the particle morphology and optical properties are studied using various characterization techniques, which have contributed to determine the mechanisms leading to QD formation from the plasma-induced reactions at the interface. The synthesized N-CQDs are crystalline with graphitic core doped with nitrogen and functionalized surface. The particle size and luminescence can be finely controlled to give either excitation dependent or fixed wavelength emission in the visible region. The synthesis conditions can be easily controlled by changing the precursors or the discharge current of the plasma to give rise to required particle size and absorbance in the ultraviolet-visible region. These N-CQDs have potential to be used as an active material in next-generation solar cells or even as down-converters for high energy photons to be absorbed by a lower bandgap transporter [8]. The possible synthesis mechanisms have been analysed and potential chemical pathways leading to the formation of the QDs are described. The particularly high photoluminescence quantum yield (33% to 68%) can be exploited for applications.