Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives.

The unique biological and physicochemical characteristics of biogenic (green-synthesized) nanomaterials (NMs) have attracted significant interest in different fields, with applications in the agrochemical, food, medication delivery, cosmetics, cellular imaging, and biomedical industries. To synthesize biogenic nanomaterials, green synthesis techniques use microorganisms, plant extracts, or proteins as bio-capping and bio-reducing agents and their role as bio-nanofactories for material synthesis at the nanoscale size. Green chemistry is environmentally benign, biocompatible, nontoxic, and economically effective. By taking into account the findings from recent investigations, we shed light on the most recent developments in the green synthesis of nanomaterials using different types of microbes and plants. Additionally, we cover different applications of green-synthesized nanomaterials in the food and textile industries, water treatment, and biomedical applications. Furthermore, we discuss the future perspectives of the green synthesis of nanomaterials to advance their production and applications.

High-Surface-Area-Activated Carbon Derived from Mango Peels and Seeds Wastes via Microwave-Induced ZnCl2 Activation for Adsorption of Methylene Blue Dye Molecules: Statistical Optimization and Mechanism.

In this study, Mango (Mangifera indica) seeds (MS) and peels (MP) seeds mixed fruit wastes were employed as a renewable precursor to synthesize high-surface-area-activated carbon (MSMPAC) by using microwave-induced ZnCl2 activation. Thus, the applicability of MSMPAC was evaluated towards the removal of cationic dye (methylene blue, MB) from an aqueous environment. The key adsorption factors, namely A: MSMPAC dose (0.02-0.1 g), B: pH (4-10), and C: time (5-15 min), were inspected using the desirability function of the Box-Behnken design (BBD). Thus, the adsorption isotherm data were found to correspond well with the Langmuir model with a maximum adsorption capacity of (232.8 mg/g). Moreover, the adsorption kinetics were consistent with both pseudo-first-order and pseudo-second-order models. The spontaneous and endothermic nature of MB adsorption on the MSMPAC surface could be inferred from the negative ∆G° values and positive value of ∆H°, respectively. Various mechanisms namely electrostatic forces, pore filling, π-π stacking, and H-bonding govern MB adsorption by the MSMPAC. This study demonstrates the utility of MS and MP as renewable precursors to produce high-surface area MSMPAC with a potential application towards the removal of cationic organic dyes such as MB.

In Situ Nitrogen Functionalization of 2D-Ti3C2Tx-MXenes for High-Performance Zn-Ion Supercapacitor.

Zinc (Zn) ion supercapacitors (ZISCs) have attracted considerable attention as a viable energy storage technology because they are cost-effective, safe, and environmentally friendly. However, cathode materials with suitable properties are rare and need to be explored. In this regard, metal carbides (MXenes) are a good choice for capacitive energy storage, but they exhibit low capacitance. The energy storage performance of MXenes can be bossed using functionalization with heteroatom doping, e.g., nitrogen (N), to simultaneously modify ZISCs' fundamental characteristics and electrochemical properties. Herein, we present an in-situ N-functionalization of Ti3C2Tx-MXene via a hydrothermal reaction with urea (denoted as N-Ti3C2Tx-MXene). N-functionalization into Ti3C2Tx-MXene raised Ti3C2Tx-MXene's interlayer spacing and boosted the Zn-ion storage in 1 M ZnSO4 electrolyte. The N-Ti3C2Tx-MXene electrode delivered an excellent specific capacitance of 582.96 F/g at 1 A/g and retained an outstanding cycle stability of 94.62% after 5000 cycles at 10 A/g, which is 1.8 times higher than pristine Ti3C2Tx-MXene at identical conditions. Moreover, the N-Ti3C2Tx-MXene//Zn device demonstrated a maximum capacitance of 153.55 F/g at 1 A/g, retained 92% of its initial value after 5000 cycles, and its Coulombic efficiency was ~100%. This strategy considerably reduced Ti3C2Tx-MXene nanosheet restacking and aggregation and enhanced electrochemical performance. Further, this research elucidated N-Ti3C2Tx-MXene's charge-storage process and offered a fresh approach to the rational design of novel electrode materials for ZISCs.

A New MBH Adduct as an Efficient Ligand in the Synthesis of Metallodrugs: Characterization, Geometrical Optimization, XRD, Biological Activities, and Molecular Docking Studies.

This article reports the synthesis, characterization, geometrical optimization, and biological studies of new MBH-based organometallic compounds of medicinal significance. The ligand (MNHA) was prepared via the Morita-Baylis-Hillman (MBH) synthetic route, from aromatic aldehyde containing multiple functional groups. Metal complexes were prepared in an alkaline medium and under other suitable reaction conditions. Spectral and elemental analyses were used to identify the structural and molecular formulas of each compound. Optimized geometry was determined through density functional theory (DFT) B3LYP and 6-311++ G (d,p) basis set for the MBH adduct, whereas structures of novel complexes were optimized with the semi-empirical PM6 method. Powder XRD analysis furnished the crystal class of complexes, with Co3+, Cr3+, and Mn2+ being cubic, while Ni2+ was hexagonal, and Cu2+ was orthorhombic. Moreover, the ligand, along with Ni2+ and Co3+ complexes, showed profound antibacterial action against S. aureus, E. coli, B. pumilis, and S. typhi. Additionally, all of the complexes were shown to persist in the positive antioxidant potential of the ligand. Contrarily, not a single metal complex conserved the antifungal potentials of the ligand.

Deep eutectic solvent synthesis of iron vanadate-decorated sulfur-doped carbon nanofiber nanocomposite: electrochemical sensing tool for doxorubicin.

Detection of anticancer drug (doxorubicin) using an electrochemical sensor is developed based on a transition metal vanadate's related carbon composite material. With an environmentally friendly process, we have synthesized a metal oxide composite of iron vanadate nanoparticle assembled with sulfur-doped carbon nanofiber (FeV/SCNF). The FeV/SCNF composite was characterized using XRD, TEM, FESEM with elemental mapping, XPS and EDS. In contrast to other electrodes reported in the literature, a much-improved electrochemical efficiency is shown by FeV/SCNF composite modified electrodes. Amperometric technique has been employed at 0.25 V (vs. Ag/AgCl) for the sensitive detection of DOX within a wide range of 20 nM-542.5 µM and it possesses enhanced selectivity in presence of common interferents. The modified electrochemical sensors show high sensitivity of 46.041 µA µM-1 cm-2. The newly developed sensor could be used for the determination of doxorubicin in both blood serum and drug formulations with acceptable results, suggesting its feasibility for real-time applications.

Magnetic Nitrogen-Doped Porous Carbon Nanocomposite for Pb(II) Adsorption from Aqueous Solution.

We report in the present study the in situ formation of magnetic nanoparticles (Fe3O4 or Fe) within porous N-doped carbon (Fe3O4/N@C) via simple impregnation, polymerization, and calcination sequentially. The synthesized nanocomposite structural properties were investigated using different techniques showing its good construction. The formed nanocomposite showed a saturation magnetization (Ms) of 23.0 emu g-1 due to the implanted magnetic nanoparticles and high surface area from the porous N-doped carbon. The nanocomposite was formed as graphite-type layers. The well-synthesized nanocomposite showed a high adsorption affinity toward Pb2+ toxic ions. The nanosorbent showed a maximum adsorption capacity of 250.0 mg/g toward the Pb2+ metallic ions at pH of 5.5, initial Pb2+ concentration of 180.0 mg/L, and room temperature. Due to its superparamagnetic characteristics, an external magnet was used for the fast separation of the nanocomposite. This enabled the study of the nanocomposite reusability toward Pb2+ ions, showing good chemical stability even after six cycles. Subsequently, Fe3O4/N@C nanocomposite was shown to have excellent efficiency for the removal of toxic Pb2+ ions from water.

Degradation of dye through mechano-catalysis using BaBi4Ti4O15 catalyst.

Ferroelectric BaBi4Ti4O15 was prepared using solid-state calcination at 950 °C for four hours. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy were utilized to understand its microstructure and other structural aspects. Particle size was around < 1.5 µm. This oxide is able to demonstrate piezocatalysis and tribocatalysis as reflected in its dye degradation performance. This oxide showed piezocatalytic activity around 40% in 2 h and tribocatalytic activity around 90% in 12 h. The rate constant for the piezocatalytic reaction is 0.003 min-1 and for tribocatalytic reaction is 0.169 h-1. The rotation speed also affected the tribocatalytic activity of the oxide. Oxide showed 25%, 90%, and 94% tribocatalytic activity at 300, 500, and 700 rpm respectively. This material has demonstrated notable performance of catalysis under different types of mechanical energy sources and under different mechanisms.

Modulation of dielectric and antibacterial properties of Zn0.5Mn0.5O nanoparticles by post growth annealing method.

In this manuscript, we have investigated the dielectric and antibacterial potential of hydrothermally synthesized ZnMnO nanoparticles. The synthesized nanoparticles were annealed at various temperatures ranging from 450 to 650 °C with a step of 50 °C to modulate the structural, vibrational, dielectric, and antibacterial properties. XRD data confirmed the hexagonal structure of the synthesized samples and crystalline size was decreased to 4.8 nm at annealing temperature 600 °C. The lattice structure was further verified by Raman spectroscopy measurements, which strongly verified the XRD data due the presence of ZnMnO vibrational modes. The dielectric measurements revealed that the dielectric constant and los tangent were found to be increased with the increase annealing temperature and decreased with frequency, while a.c conductivity has an increasing trend with both parameters (temperature and frequency). The plot of real and complex parts of impedance against frequency demonstrated that both parameters decrease with the increased in frequency. But when we analyzed the behavior of the real part of impedance against the annealing temperature, a degradation in real part behavior is observed. The antibacterial activity of ZnMnO nanoparticles was determined by using the disc diffusion method against E. coli bacteria, which was grown on a Petri dish at room temperature for 24 h. This observation revealed that the samples annealed at 450 °C and 550 °C show remarkable antibacterial sensitivity as compared to other samples. It is concluded that crystalline size of 20 nm is found to be optimal value for good anti-baterial behavior.

Investigate the suitability of g-C3N4 nanosheets ornamented with BiOI nanoflowers for photocatalytic dye degradation and PEC water splitting.

The two-step thermal polymerization and solvothermal approach is used to construct nano heterostructures of FCN and BiOI (bismuth oxeye iodide), both of which are Nobel metal-free materials. This work reports the effect nano-heterostructure on the micro-structural, light absorption capability, PEC properties and pollutant degradation efficiency of the synthesised heterostructures. The addition to that formation of FCN/BiOI nano-heterostructure enhances the solar light absorption. The FCN/BiOI nano heterostructure shows 10 times higher photocurrent density than the BCN nanostructure and 3.8 time higher that FCN. The FCN/BiOI has a high induced photo-current density (20.17 mA/cm2) and H2 evolution rate (3762 µmol h-1 cm-2) under solar light illumination (λ ≥ 420 nm) in comparison with the other. Furthermore, the photocatalytic performance of this material for the breakdown of methyl red dyes was much greater. Under solar light irradiation, the azo dyes were degraded in 90 min. The FCN/BiOI nano-heterostructure has a higher dye degradation efficiency of 97.91%. The rapid transport of photo-induced electrons in the FCN/BiOI nanocomposite is responsible for the improvement in PEC and PC performances. These impressive findings suggest that this nanocomposite might be used to facilitate the PEC water splitting and the PC degradation of MR in the presence of light. The current research provides insight on how to best tailor composition and structure for efficient FCN photo-electrocatalysis water splitting and Methyl red dye degradation.

Alumina supported copper oxide nanoparticles (CuO/Al2O3) as high-performance electrocatalysts for hydrazine oxidation reaction.

Direct hydrazine liquid fuel cell (DHFC) is perceived as effectual energy generating mean owing to high conversion efficiency and energy density. However, the development of well-designed, cost effective and high performance electrocatalysts is the paramount to establish DHFCs as efficient energy generating technology. Herein, gamma alumina supported copper oxide nanocatalysts (CuO/Al2O3) are synthesized via impregnation method and investigated for their electrocatalytic potential towards hydrazine oxidation reaction. CuO with different weight percentages i.e., 4%, 8%, 12%, 16% and 20% are impregnated on gamma alumina support. X-ray diffraction analysis revealed the cubic crystal structure and nanosized particles of the prepared metal oxides. Transmission electron microscopy also referred to the cubic morphology and nanoparticle formation. Electrochemical oxidation potential of the CuO/Al2O3 nanoparticles is explored via cyclic voltammetry as the analytical tool. Optimization of conditions and electrocatalytic studies shown that 16% CuO/Al2O3 presented the best electronic properties towards N2H2 oxidation reaction. BET analysis ascertained the high surface area (131.2546 m2 g1) and large pore diameter (0.279605 cm³ g-1) for 16% CuO/Al2O3. Nanoparticle formation, high porosity and enlarged surface area of the proposed catalysts resulted in significant oxidation current output (600 µA), high current density (8.2 mA cm-2) and low charge transfer resistance (3.7 kΩ). Electrooxidation of hydrazine on such an affordable and novel electrocatalyst opens a gateway to further explore the metal oxide impregnated alumina materials for different electrochemical applications.

Photocatalytic degradation and electrochemical energy storage properties of CuO/SnO2 nanocomposites via the wet-chemical method.

Integrating semiconducting functional materials is a way to enlarge the photoexcitation, energy range, and charge separation, greatly elongating the photocatalytic efficiency to enhance the chemical and physical properties of the materials. This work depicts and investigates the impact of cuprous oxide (CuO) and tin dioxide (SnO2)-based catalysts with various CuO concentrations on photocatalytic and supercapacitor applications. Moreover, three distinct composites were made with varied ratios of CuO (5, 10, and 15% wt. Are designated as AT-1, AT-2, and AT-3) with SnO2 to get an optimized performance. The photocatalytic properties indicate that the CuO/SnO2 nanocomposite outperformed its bulk equivalents in photocatalysis using Methyl blue (MB) dye in a photoreactor. The results were monitored using a UV-visible spectrometer. The AT-1 ratio nanocomposite displayed 96% photocatalytic degradation compared to pure SnO2 and CuO. CV analysis reveals a pseudocapacitive charge storage mechanism from 0.0 to 0.7 V in a potential window in an aqueous medium. The capacitive performance was also investigated for all electrodes, and we observed that a high capacitance of 260/155 F/g at 1/10 A/g was attained for the AT-1 electrode compared to others, specifying good rate performance.

Green Synthesis of Fe-Cu Bimetallic Supported on Alginate-Limestone Nanocomposite for the Removal of Drugs from Contaminated Water.

In this study Fe-Cu supported on Alginate-limestone (Fe-Cu/Alg-LS) was prepared. The increase in surface area was the main motivation for the synthesis of ternary composites. Scanning electronic microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to examine the surface morphology, particle size, percentage of crystallinity, and elemental content of the resultant composite. Fe-Cu/Alg-LS was used as an adsorbent for the removal of drugs such as ciprofloxacin (CIP) and levofloxacin (LEV)from contaminated medium. The adsorption parameters were computed using kinetic and isotherm models. The maximum removal efficiency of CIP (20 ppm) and LEV (10 ppm) was found to be 97.3% and 100%, respectively. The optimal conditions were pH 6 and 7 for CIP and LEV, optimum contact time 45, 40 min for CIP and LEV, and temperature of 303 K. The pseudo-second-order model, which confirmed the chemisorption properties of the process, was the most appropriate kinetic model among the ones used, and the Langmuir model, which was the most appropriate isotherm model. Moreover, the parameters of thermodynamics were also assessed. The results imply that the synthesized nanocomposites can be used to remove hazard materials from aqueous solutions.

Functional bioinspired nanocomposites for anticancer activity with generation of reactive oxygen species.

Cancer is a debilitating and deadly disease caused by the uncontrolled growth of aberrant cell populations. This disease cannot always be controlled with traditional therapies and medicines. Different medicines are being used for this purpose, however these medicines have their side effects and are harmful to healthy cells. A better way to cure cancer disease is by limiting the agglomeration of cancer cells, minimizing their growth and their population by destroying these harmful cells. This could be achieved by controlling the function of mitochondria and DNA in cancer cells with the use of biocompatible materials with tuneable physical properties. Accordingly, research is ongoing as to the use of nanomaterials and nanotechnology in medicine. Zinc oxide semiconductor nanoparticles have displayed good anticancer behaviour. They have unique properties such as biocompatibility, good stability, and are environmentally friendly. Owing to these characteristics, they are focused on biological applications such as drug delivery and cancer therapy. In the present research work, zinc oxide, titanium dioxide nanoparticles and titanium oxide-zinc oxide nanocomposites were successfully trailed for anti-cancer activity. Pure zinc oxide nanoparticles (ZnO NPs), titanium dioxide nanoparticles (TiO2 NPs) and their nanocomposites (TiO2+ZnO NPs) were prepared by the co-precipitation technique. The structural properties were investigated by X-ray diffraction, which confirmed the Wurtzite structure of pure ZnO NPs. The morphology of the NPs was checked by scanning electron microscopy. For incident light having a higher energy band gap of nanomaterials, the electrons are excited to the conduction band and these electrons generate reactive oxygen species (ROS). The efficacy of these nanomaterials was checked by exposing the NPs to the human liver cancer cell HepG2. The MTT assay describes anticancer activity via cell viability. The cell viability of composites was observed to be greater than pure ZnO NPs. Their results showed that the structure of ZnO NPs remains the same with composites of TiO2 NPs, but the band gap of the composite was intermediate for individual samples. It also showed that the anticancer activity of composites was also less than pure ZnO NPs which is due to the reduction of ROS generation. This is observed that nanocomposites of ZnO and TiO2 could be effective in the development of a treatment of human liver cancer cells.

Binder-free cupric-ion containing zinc sulfide nanoplates-like structure for flexible energy storage devices.

Researchers have been enthusiastic about developing high-performance electrode materials based on metal chalcogenides for energy storage applications. Herein, we developed cupric ion-containing zinc sulfide (ZnS:Cu) nanoplates by using a solvothermal approach. The as-synthesized ZnS:Cu nanoplates electrode was characterized and analyzed by using XRD, SEM, TEM, EDS, and XPS. The binder-free flexible ZnS:Cu nanoplates exhibited excellent specific capacitance of 545 F g-1 at a current density of 1 A g-1. The CV and GCD measurements revealed that the specific capacitance was mainly attributed to the Faradaic redox mechanism. Further, the binder-free flexible ZnS:Cu nanoplates electrode retained 87.4% along with excellent Coulombic efficiency (99%) after 5000 cycles. The binder-free flexible ZnS:Cu nanoplates exhibited excellent conductivity, specific capacitance, and stability which are beneficial in energy storage systems. These findings will also open new horizons amongst material scientists toward the new direction of electrode development.

Effect of TiO2 Nanoparticles on Capillary-Driven Flow in Water Nanofilters Based on Chitosan Cellulose and Polyvinylidene Fluoride Nanocomposites: A Theoretical Study.

In this study, a novel concept of nanofiltration process of drinking water based on capillary-driven nanofiltration is demonstrated using a bio-based nanocomposites' nanofilter as free power: a green and sustainable solution. Based on Lifshitz and Young-Laplace theories, we show that the chitosan (CS), cellulose acetate (CLA), and Polyvinylidene fluoride (PVDF) polymer matrixes demonstrate hydrophobic behavior, which leads to the draining of water from nanopores when negative capillary pressure is applied and consequently prevents the capillary-driven nanofiltration process. By incorporating 10%, 20%, and 30% volume fraction of titanium dioxide (TiO2) nanoparticles (NPs) to the polymers' matrixes, we demonstrate a wetting conversion from hydrophobic to hydrophilic behavior of these polymer nanocomposites. Subsequently, the threshold volume fraction of the TiO2 NPs for the conversion from draining (hydrophobic) to filling (hydrophilic) by capillary pressure were found to be equal to 5.1%, 10.9%, and 13.9%, respectively, for CS/TiO2, CLA/TiO2, and PVDF/TiO2 nanocomposites. Then, we demonstrated the negligible effect of the gravity force on capillary rise as well as the capillary-driven flow for nanoscale pore size. For nanofilters with the same effective nanopore radius, porosity, pore shape factor, and tortuosity, results from the modified Lucas-Washburn model show that the capillary rise as well as the capillary-driven water volume increase with increased volume fraction of the TiO2 NPs for all nanocomposite nanofilter. Interestingly, the capillary-driven water volume was in range (5.26-6.39) L/h·m2 with 30% volume fraction of TiO2 NPs, which support our idea for capillary-driven nanofiltration as zero energy consumption nano-filtration process. Correspondingly, the biodegradable CS/TiO2 and CLA/TiO2 nanocomposites nanofilter demonstrate capillary-driven water volume higher, ~1.5 and ~1.2 times, respectively, more than the synthetic PVDF/TiO2 nanocomposite.

Comparative Evaluation of the Capacity of Commercial and Autochthonous Saccharomyces cerevisiae Strains to Remove Ochratoxin A from Natural and Synthetic Grape Juices.

In this paper, we assessed the ability of two strains of Saccharomyces cerevisiae, in viable and dead forms, to remove ochratoxin A (OTA) from an artificially contaminated synthetic grape juice medium (SGM) (10 µg OTA/L) and a naturally contaminated grape juice (6.64 µg OTA/L). The first strain, named Levulin FB, is a commercial yeast used in making wine. The second, named SC5, is an autochthonous strain isolated from table grapes. OTA concentrations in juices before and after their contact with yeast cells were assessed. A significant decrease in OTA level (p < 0.05) in the SGM medium and in the natural grape juice was observed after 1 h of adding yeast cells (20 g/L) in viable and heat-treated forms. It was inferred that the dead forms of the two strains were more able to eliminate OTA than their viable forms in both media. This study demonstrates the potential application of an autochthonous yeast for the natural decontamination of grape juice from fungal toxins.

Investigation on Crystal-Structure, Thermal and Electrical Properties of PVDF Nanocomposites with Cobalt Oxide and Functionalized Multi-Wall-Carbon-Nanotubes.

Nanocomposites of polyvinylidene fluoride (PVDF) with dimensional (1D) cobalt oxide (Co3O4) and f-MWCNTs were prepared successfully by the solution casting method. The impact of 1D Co3O4 filler and 1D Co3O4/f-MWCNTs co-fillers on the structural, thermal, and electrical behavior of PVDF were studied. The crystal structural properties of pure PVDF and its nanocomposite films were studied by XRD, which revealed a significant enhancement of ß-phase PVDF in the resulting nanocomposite films. The increase in ß-phase was further revealed by the FTIR spectroscopic analysis of the samples. TG, DTA, and DSC analyses confirmed an increase in thermal stability of PVDF with the addition of nano-fillers as well as their increasing wt.%. From impedance spectroscopic studies, it was found that the DC conductivity of PVDF increases insignificantly initially (up to 0.1 wt.% of nano-fillers addition), but a significant improvement in DC conductivity was found at higher concentrations of the nano-fillers. Furthermore, it was observed that the DC conductivity decreases with frequency. The increase in DC conductivity corresponded to the strong interactions of nano-fillers with PVDF polymer chains.

Synthesis and Characterization of a Minophosphonate Containing Chitosan Polymer Derivatives: Investigations of Cytotoxic Activity and in Silico Study of SARS-CoV-19.

Chitosan is broadly used as a biological material since of its excellent biological activities. This work describes investigations of chitosan interaction with SARS-CoV-2, which is occupied by human respiratory epithelial cells through communication with the human angiotension-converting enzyme II (ACE2). The ß-chitosan derivatives are synthesized and characterized by FT-IR, nuclear magnetic resonance (1H and 13C NMR), mass spectrometry, X-ray diffraction, TGA, DSC, and elemental analysis. The ß-chitosan derivatives were screened for cytotoxic activity against the HepG2 and MCF-7 (breast) cancer cell lines. Compound 1h (GI50 0.02 µM) is moderately active against the HepG2 cancer cell line, and Compound 1c is highly active (GI50 0.01 µM) against the MCF-7 cancer cell line. In addition, chitosan derivatives (1a-1j) docking against the SARS coronavirus are found by in-silico docking analysis. The findings show that compound 1c exhibits notable inhibition ability compared with other compounds, with a binding energy value of -7.9 kcal/mol. Based on the molecular docking results, the chitosan analog is proposed to be an alternative antiviral agent for SARS-CoV2.

Design and synthesis of amine grafted graphene oxide encapsulated chitosan hybrid beads for defluoridation of water.

The promising adsorbent like graphene oxide (GO), chitosan (CS) and amine functionalized graphene oxide (AGO) decorated chitosan (CS) namely AGO@CS composite beads was efficiently prepared for defluoridation studies. The prepared AGO@CS composite beads possess enriched defluoridation capacity (DC) of 4650 mgF- kg-1. Batch method was used to optimize the maximum DC of AGO@CS composite beads. The physicochemical properties of AGO@CS composite beads were explored by numerous instrumental techniques viz., FTIR, Raman, XPS, SEM and TGA investigation. The experimental values of AGO@CS composite beads for fluoride removal at various temperature conditions were assessed with adsorption isotherms, kinetic and thermodynamic studies. The possible defluoridation mechanism of AGO@CS beads was mostly proposed that electrostatic attraction. The reusability and field investigation results of AGO@CS beads shows they are regenerable and applicable at field circumstances.

Synthesis, Characterization and Application of Polypyrrole Functionalized Nanocellulose for the Removal of Cr(VI) from Aqueous Solution.

Heavy metals are toxic substances that pose a real danger to humans and organisms, even at low concentration. Therefore, there is an urgent need to remove heavy metals. Herein, the nanocellulose (NC) was synthesized by the hydrolysis of cellulose using sulfuric acid, and then functionalized using polypyrrole (ppy) through a polymerization reaction to produce polypyrrole/nanocellulose (ppy/NC) nanocomposite. The synthesized nanocomposite was characterized using familiar techniques including XRD, FT-IR, SEM, TEM, and TGA. The obtained results showed a well-constructed nanocomposite with excellent thermal stability in the nano-sized scale. The adsorption experiments showed that the ppy/NC nanocomposite was able to adsorb hexavalent chromium (Cr(VI)). The optimum pH for the removal of the heavy metal was pH 2. The interfering ions showed minor effect on the adsorption of Cr(VI) resulted from the competition between ions for the adsorption sites. The adsorption kinetics were studied using pseudo 1st order and pseudo 2nd order models indicating that the pseudo second order model showed the best fit to the experimental data, signifying that the adsorption process is controlled by the chemisorption mechanism. Additionally, the nanocomposite showed a maximum adsorption capacity of 560 mg/g according to Langmuir isotherm. The study of the removal mechanism showed that Cr(VI) ions were removed via the reduction of high toxic Cr(VI) to lower toxic Cr(III) and the electrostatic attraction between protonated ppy and Cr(VI). Interestingly, the ppy/NC nanocomposite was reused for Cr(VI) uptake up to six cycles showing excellent regeneration results. Subsequently, Cr(VI) ions can be effectively removed from aqueous solution using the synthesized nanocomposite as reusable and cost-effective adsorbent.