Green synthesis of Fe nanoparticles using eucalyptus leaf extracts for treatment of eutrophic wastewater

Plant biomass-based nanoparticles for remediation of contaminants from water ecosystems: Recent trends, challenges, and future perspectives

Green nanomaterials can mitigate ecological concerns by minimizing the impact of toxic contaminants on human and environmental health. Biosynthesis seems to be drawing unequivocal attention as the traditional methods of producing nanoparticles through chemical and physical routes are not sustainable. In order to utilize plant biomass, the current review outlines a sustainable method for producing non-toxic plant biomass-based nanoparticles and discusses their applications as well as recent trends involved in the remediation of contaminants, like organic/inorganic pollutants, pharmaceuticals, and radioactive pollutants from aquatic ecosystems. Plant biomass-based nanoparticles have been synthesized using various vegetal components, such as leaves, roots, flowers, stems, seeds, tuber, and bark, for applications in water purification. Phyto-mediated green nanoparticles are effectively utilized to treat contaminated water and reduce harmful substances. Effectiveness of adsorption has also been studied using variable parameters, e.g., pH, initial contaminant concentration, contact time, adsorbent dose, and temperature. Removal of environmental contaminants through reduction, photocatalytic degradation, and surface adsorption mechanisms, such as physical adsorption, precipitation, complexation, and ion exchange, primarily due to varying pH solutions and complex functional groups. In the case of organic pollutants, most of the contaminants have been treated by catalytic reduction and photodegradation involving the formation of NaBH4, H2O2, or both. Whereas electrostatic interaction, metal complexation, H-bonding, π- π associations, and chelation along with reduction have played a major role in the adsorption of heavy metals, pharmaceuticals, radioactive, and other inorganic pollutants. This review also highlights several challenges, like particle size, toxicity, stability, functional groups, cost of nanoparticle production, nanomaterial dynamics, and biological interactions, along with renewability and recycling of nanoparticles. Lastly, this review concluded that plant-biomass-based nanoparticles provide a sustainable, eco-friendly remediation method, utilizing the unique properties of nanomaterials and minimizing chemical synthesis risks.

Biochar-enhanced bioremediation of eutrophic waters impacted by algal blooms

The permanent problem of formation of algal blooms in water polluted with nitrogen and phosphorus is one of the formidable environmental problems. Biochar has the potential to solve the issues related to eutrophication due to its special structure and ability to absorb the nutrients. Biochar's exceptional nutrient absorption capacity allows it to absorb excess nutrients, causing the algae to use fewer nutrients. This review deals with effective performance of biochar in reducing the effects caused by algal blooms and improving the environmental conditions. Besides, an analysis of the issues involved addresses the origins and consequences of nitrogen and phosphorus pollution, and the formation of algal blooms is also reviewed. It then delves deeply into biochar, explaining its properties, production methods, and their uses in environmental contexts. The review emphasizes that biochar can be effective in dealing with many challenges associated with environments affected by algal blooms, specifically focusing on the positive effects of biochar and algae to examine their roles in controlling algae growth. Finally, the review emphasizes new achievements and innovative ideas to foster sustainable aquatic ecosystems. The discussions emphasize the central role of biochar in managing nutrient-rich waters and algal blooms.

Anticancer efficacy of magnetite nanoparticles synthesized using aqueous extract of brown seaweed Rosenvingea intricata, South Andaman, India

Cancer is a global issue and hence various efforts are being made. Iron oxide is considered a significant biochemical agent in the biomedical arena for cancer treatment. Marine macroalgae-mediated iron oxides especially, magnetite (Fe3O4) nanoparticles (NPs) are a prospective alternative to diagnose and treat cancer owing to their fluorescent and magnetic properties. We intend to appraise the usability of the aqueous extract of Rosenvingea intricata (R. intricata) in Fe3O4 NPs synthesis and to study their cytotoxic effects against human hepatocarcinoma (Hep3B) and pancreatic (PANC1) cancer cells. In the present study, R. intricata were collected from the coastal region of South Andaman, India. Aqueous extracts of R. intricata were utilized to synthesize Fe3O4 NPs via the co-precipitation method. Phycosynthesized Fe3O4 NPs exhibited wide peak at 400-600 nm from ultraviolet-visible diffused reflectance spectroscopic analysis which validated the formation of NPs. Band edge emission peak at 660 nm in fluorescent spectra confirmed the quantum confinement in Fe3O4 NPs. Fourier transform infrared spectroscopy confirmed the role of R. intricata as a capping and reducing agent with functional groups such as O-H, C-H, C=O, N=O, C=C, C-O, C-N, and C-S arising from amino acids, polysaccharides, aliphatic hydrocarbons, esters, amides, lignins, alkanes, aliphatic amines, and sulfates. Physicochemical properties such as crystallite size (14.36 nm), hydrodynamic size (84.6 nm), irregular morphology, elemental composition, particle size (125 nm), crystallinity, and saturation magnetization (0.90007 emu/g) were obtained from x-ray diffractometer, dynamic light scattering, scanning electron microscopy, energy dispersive x-ray spectrometer, high-resolution transmission electron microscopy, selected area electron diffraction and vibrating sample magnetometer techniques, respectively. The cell viability showed dose-dependent cytotoxic effects and enhanced the apoptosis against Hep3B and PANC1 cancer cells. R. intricata extract capped Fe3O4 NPs could be the most appropriate and effective nanomaterial for cancer treatment and management.

Green synthesis of Fe and Zn-NPs, phytochemistry and pharmacological evaluation of Phlomis cashmeriana Royle ex Benth

This investigation portrays the phytochemical screening, green synthesis, characterization of Fe and Zn nanoparticles, their antibacterial, anti-inflammation, cytotoxicity, and anti-thrombolytic activities. Four dissimilar solvents such as, n-hexane, chloroform, ethyl acetate and n-butanol were used to prepare the extracts of Phlomis cashmeriana Royle ex Benth. This is valued medicinal plant (Family Lamiaceae), native to mountains of Afghanistan and Kashmir. In the GC-MS study of its extract, the identified phytoconstituents have different nature such as terpenoids, alcohol and esters. The synthesized nanoparticles were characterized by SEM, UV, XRD, and FT-IR. The phytochemical analysis showed that the plant contains TPC (total phenolic content) 297.51 mg GAE/g and TFC (total flavonoid content) 467.24 mg CE/g. The cytotoxicity values have shown that the chloroform, n-butanol and aqueous extracts were more toxic than other extracts. The anti-inflammatory potential of n-butanol and aqueous extracts was found higher than all other extracts. Chloroform and n-hexane extracts have low MIC values against both E. coli and S. aureus bacterial strains. Chloroform and aqueous extracts have great anti-thrombolytic potential than all other extracts. Overall, this study successfully synthesized the nanoparticles and provides evidence that P. cashmeriana have promising bioactive compounds that could serve as potential source in the drug formulation.

Green low-cost synthesis of zero-valent iron nanoparticles from Palm Petiole Extract for Cr(VI) removal from water

One of the hottest research topics over the last decades was the valorization or/and recycling of agro-industrial wastes into different valuable liquid or solid products, which is considered a sustainable and low-cost approach. In this study, we developed zero-valent iron nanoparticles from Palm Petiole Extract (P-NZVI) using a green and straightforward approach. The as-synthesized P-NZVI was used to adsorb Cr(VI) in water. The physico-chemical characterizations of P-NZVI, including the particle size, crystalline structure, surface area, morphology, and functional groups, were investigated via several techniques such as UV-vis spectroscopy, SEM, TEM, XRD, FTIR, AFM, DLS, pHZPC measurement, and BET analysis. The adsorption performance of P-NZVI was studied under different operational parameters, including pollutant concentration, pH, temperature, and adsorbent mass. The adsorption rate was found to be 89.3% within 40 min, corresponding to the adsorption capacity of 44.47 mg/g under the following conditions: initial Cr(VI) concentration of 40 mg/L, pH 5, and a P-NZVI dosage of 1 g/L. It was found that the adsorption pattern follows the Langmuir and the pseudo-second-order kinetic models, indicating a combination of monolayer adsorption and chemisorption mechanisms. The thermodynamic study shows that the adsorption process is endothermic and spontaneous. The reusability of P-NZVI was carried out four times, showing a slight decrease from 89.3 to 87%. These findings highlight that P-NZVI's could be an effective green adsorbent for removing Cr(VI) or other types of toxic pollutants from water.

Comparative Effect of Antioxidant and Antibacterial Potential of Zinc Oxide Nanoparticles from Aqueous Extract of Nepeta nepetella through Different Precursor Concentrations

Antibiotic resistance is a global health crisis caused by the overuse and misuse of antibiotics. Accordingly, bacteria have developed mechanisms to resist antibiotics. This crisis endangers public health systems and medical procedures, underscoring the urgent need for novel antimicrobial agents. This study focuses on the green synthesis of ZnO nanoparticles (NPs) using aqueous extracts from Nepeta nepetella subps. amethystine leaves and stems, employing different zinc sulfate concentrations (0.5, 1, and 2 M). NP characterization included transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), along with Fourier transform infrared spectroscopy (FTIR) analysis. This study aimed to assess the efficacy of ZnO NPs, prepared at varying concentrations of zinc sulfate, for their capacity to inhibit both Gram-positive and Gram-negative bacteria, as well as their antioxidant potential using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. SEM and TEM results showed predominantly spherical NPs. The smallest size (18.5 ± 1.3 nm for leaves and 18.1 ± 1.3 nm for stems) occurred with the 0.5 M precursor concentration. These NPs also exhibited remarkable antibacterial activity against both Gram-positive and Gram-negative bacteria at 10 µg/mL, as well as the highest antioxidant activity, with an IC50 (the concentration of NPs that scavenge 50% of the initial DPPH radicals) of 62 ± 0.8 (µg/mL) for the leaves and 35 ± 0.6 (µg/mL) for the stems. NPs and precursor concentrations were modeled to assess their impact on bacteria using a 2D polynomial equation. Response surface plots identified optimal concentration conditions for antibacterial effectiveness against each species, promising in combating antibiotic resistance.

Supercapacitors and triboelectric nanogenerators based on electrodes of greener iron nanoparticles/carbon nanotubes composites

The development of supporting materials based on carbon nanotubes (CNTs) impregnated with iron nanoparticles via a sustainable and green synthesis employing plant extract of Punica granatum L. leaves was carried out for the iron nanoparticle modification and the following impregnation into the carbon nanotubes composites (CNT-Fe) that were also coated with polypyrrole (CNT-Fe + PPy) for use as electrode for supercapacitor and triboelectric nanogenerators. The electrochemical characterization of the materials by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) assays revealed that the CNT-Fe + PPy gave rise to better performance due to the association of double-layer capacitance behavior of carbon derivative in association with the pseudocapacitance contribution of PPy resulting in an areal capacitance value 202 mF/ cm2 for the overall composite. In terms of the application of electrodes in triboelectric nanogenerators, the best performance for the composite of CNT-Fe + PPy was 60 V for output voltage and power density of 6 μW/cm2. The integrated system showed that the supercapacitors can be charged directly by the nanogenerator from 0 to 42 mV in 300 s. The successful green synthesis of iron nanoparticles on CNT and further PPy coating provides a feasible method for the design and synthesis of high-performance SCs and TENGs electrode materials. This work provides a systematic approach that moves the research front forward by generating data that underpins further research in self-powered electronic devices.

A novel approach for the green synthesis of iron nanoparticles using marigold extract, black liquor, and nanocellulose: Effect on marigold growth parameters

This study aimed to investigate a novel method for the green synthesis of iron nanoparticles (FeNPs) using marigold extract (Calendula officinalis L), kraft pulping black liquor, and nanocellulose. Then, the efficacy of FeNPs as a direct nanofertilizer on the growth parameters of marigold was investigated. Characterization techniques including FESEM, EDX, VSM, and FTIR were used to confirm the successful synthesis of FeNPs. The characterization results confirmed the formation and presence of FeNPs in the 20-100 nm range. FeNPs synthesized with nanocellulose notably enhanced marigold growth parameters compared to other materials. However, all nanoparticle variants, including those from marigold extract and black liquor, improved germination, plant height, root length, and plant dry weight compared to the control. Moreover, treatments exhibited higher available iron and total plant iron levels than the control. Thus, employing 10 mg FeNPs (prepared with 5.0 % nanocellulose) appears optimal for enhancing marigold growth and yield.

Agro-Waste Sweet Pepper Extract-Magnetic Iron Oxide Nanoparticles for Antioxidant Enrichment and Sustainable Nanopackaging

This study synthesizes magnetic iron oxide nanoparticles from agro-waste sweet pepper extract, exploring their potential as antioxidant additives and in food preservation. Iron (III) chloride hexahydrate is the precursor, with sweet pepper extract as both a reducing and capping agent at pH 7.5. Characterization techniques, including microscopy and spectroscopy, analyze the sweet pepper extract-magnetic iron oxide nanoparticles. Antioxidant capacities against 2,2-diphenyl-1-picrylhydrazyl are assessed, incorporating nanoparticles into banana-based bioplastic for grape preservation. Microscopy reveals cubic and quasi-spherical structures, and spectroscopy confirms functional groups, including Fe-O bonds. X-ray diffraction identifies cubic and monoclinic magnetite with a monoclinic hematite presence. Sweet pepper extract exhibits 100% inhibitory activity in 20 min, while sweet pepper extract-magnetic iron oxide nanoparticles show an IC50 of 128.1 µg/mL. Furthermore, these nanoparticles, stabilized with banana-based bioplastic, effectively preserve grapes, resulting in a 27.4% lower weight loss rate after 144 h compared to the control group (34.6%). This pioneering study encourages institutional research into the natural antioxidant properties of agro-waste sweet pepper combined with magnetic iron and other metal oxide nanoparticles, offering sustainable solutions for nanopackaging and food preservation. Current research focuses on refining experimental parameters and investigating diverse applications for sweet pepper extract-magnetic iron oxide nanoparticles in varied contexts.

Efficient removal of tetracycline in water using modified eggplant straw biochar supported green nanoscale zerovalent iron: synthesis, removal performance, and mechanism

A novel NaOH modified eggplant straw biochar supported green nanoscale zerovalent iron (P-nZVI/ESBC) composite was synthesized and its removal performance and reaction mechanism for tetracycline (TC) in water were investigated. Multiple characterizations showed that the prepared P-nZVI/ESBC composite contained oxygen-containing functional groups (hydroxyl, carbonyl, and carboxyl groups) and Fe species (nZVI and its oxides). The dosage of composite, temperature, and solution pH significantly affected the removal capacity of the P-nZVI/ESBC composite for TC. The Avrami fraction-order kinetic model and Sips adsorption isotherm model can fit well the removal process of TC by the P-nZVI/ESBC composite, indicating that the adsorption behavior of TC involved multiple adsorption mechanisms and chemical adsorption might occur. The maximum adsorption capacity of the P-nZVI/ESBC composite for TC was 304.62 mg g-1. The adsorption and reductive degradation were the dominant mechanisms of TC removal by the P-nZVI/ESBC composite. This work offers abundant information on the application of eggplant straw to manufacture biochar-based composites for the efficient removal of antibiotic contaminants from aquatic environments.

Accelerated Cr (VI) removal by a three-dimensional electro-Fenton system using green iron nanoparticles

Green-synthesized iron nanoparticles (GAP-FeNP) were used as particle electrodes in a three-dimensional electro-Fenton (3DEF) process to accelerate the removal of hexavalent chromium [Cr (VI)]. Removal was evaluated by varying the pH (3.0, 6.0, and 9.0) and initial Cr (VI) concentrations (10, 30, and 50 mg/L) at 5 and 25 min. These results demonstrated that GAP-FeNP/3DEF treatment achieved more than 94% Cr (VI) removal under all tested conditions. Furthermore, it was observed that Cr (VI) removal exceeded 98% under pH 9.0 in all experimental parameters tested. The results of the response surface methodology (RSM) determined two optimal conditions: the first, characterized by a pH of 3.0, Cr (VI) concentration at 50 mg/L, and 25 min, yielded a Cr (VI) removal of 99.7%. The second optimal condition emerged at pH 9.0, with Cr (VI) concentrations of 10 mg/L and 5 min, achieving a Cr (VI) removal of 99.5%. This study highlights the potential of the GAP-FeNP to synergistically accelerate Cr (VI) removal by the 3DEF process, allowing faster elimination and expansion of the alkaline (pH 9.0) applicability. PRACTITIONER POINTS: The required time for >99% of Cr (VI) removal by the GAP-FeNP/3DEF process was shortened from 25 to 5 min. EF process with GAP-FeNP reduces the time necessary for Cr (VI) removal, which is 67% faster than conventional methods. EF process using GAP-FeNP removed >94% of Cr (VI) after 25 min for all initial Cr (VI) concentrations and pH treatments. Cr (VI) removal by the GAP-FeNP/3DEF process was >98% at a pH of 9.0, widening the solution pH applicability.

Green synthesis of iron nanoparticles: Sources and multifarious biotechnological applications

Green synthesis of iron nanoparticles is a highly fascinating research area and has gained importance due to reliable, sustainable and ecofriendly protocol for synthesizing nanoparticles, along with the easy availability of plant materials and their pharmacological significance. As an alternate to physical and chemical synthesis, the biological materials, like microorganisms and plants are considered to be less costly and environment-friendly. Iron nanoparticles with diverse morphology and size have been synthesized using biological extracts. Microbial (bacteria, fungi, algae etc.) and plant extracts have been employed in green synthesis of iron nanoparticles due to the presence of various metabolites and biomolecules. Physical and biochemical properties of biologically synthesized iron nanoparticles are superior to that are synthesized using physical and chemical agents. Iron nanoparticles have magnetic property with thermal and electrical conductivity. Iron nanoparticles below a certain size (generally 10-20 nm), can exhibit a unique form of magnetism called superparamagnetism. They are non-toxic and highly dispersible with targeted delivery, which are suitable for efficient drug delivery to the target. Green synthesized iron nanoparticles have been explored for multifarious biotechnological applications. These iron nanoparticles exhibited antimicrobial and anticancerous properties. Iron nanoparticles adversely affect the cell viability, division and metabolic activity. Iron nanoparticles have been used in the purification and immobilization of various enzymes/proteins. Iron nanoparticles have shown potential in bioremediation of various organic and inorganic pollutants. This review describes various biological sources used in the green synthesis of iron nanoparticles and their potential applications in biotechnology, diagnostics and mitigation of environmental pollutants.

Outstanding adsorption capacity of iron oxide synthesized with extract of açaí berry residue: kinetic, isotherm, and thermodynamic study for dye removal

Contamination of water by toxic dyes is a serious environmental problem. Adsorbents prepared by an environmentally safe route have stood out for application in pollutant removal. Herein, iron oxide-based nanomaterial composed of Fe(III)-OOH and Fe(II/III) bound to proanthocyanidins, with particles in the order of 20 nm, was prepared by green synthesis assisted by extract of açaí (Euterpe oleracea Mart.) berry seeds from an agro-industrial residue. The nanomaterial was applied in the adsorption of cationic dyes. Screening tests were carried out for methylene blue (MB), resulting in an outstanding maximum adsorption capacity of 531.8 mg g-1 at 343 K, pH 10, 180 min. The kinetics followed a pseudo-second-order model and the isotherm of Fritz-Schülnder provided the best fit. Thermodynamic data show an endothermic process with entropy increase, typical of chemisorption. The proposed mechanism is based on the multilayer formation over a heterogeneous adsorbent surface, with chemical and electrostatic interactions of MB with the iron oxide nanoparticles and with the proanthocyanidins. The high adsorption efficiency was attributed to the network formed by the polymeric proanthocyanidins that entangled and protected the iron oxide nanoparticles, which allowed the reuse of the nanomaterial for seven cycles without loss of adsorption efficiency.

Efficient heterogeneous Fenton-like degradation of methylene blue using green synthesized yeast supported iron nanoparticles

To reduce the consumption of oxidant and catalyst in Fenton-like reaction and to realize the reuse of catalyst, yeast supported iron nanoparticles (nZVI@SCM) was synthesized by tobacco leaf extract and applied in the heterogeneous Fenton-like degradation of aqueous methylene blue (MB) at ambient conditions. The performance of the composite was exploited in terms of catalytic activity and factors influencing MB degradation. The surface changes of nZVI@SCM before and after reaction were characterized by XPS, SEM, FT-IR and XRD. Iron leaching, primary reactive oxidizing species, and the storage stability and reusability of catalyst were also investigated. Typically, 99.7% removal of 50 mg/L MB, with a TOC removal of 97.2%, could be achieved within 10 h by 0.1 g/L nZVI@SCM coupled with 1.0 mM H2O2. The MB degradation is in good agreement with the pseudo-first-order model, and hydroxyl radicals in the bulk solution is the main reactive oxidizing species responsible for MB degradation. Based on the identified intermediates by liquid chromatography/mass spectrometry, the possible MB degradation mechanism in the nZVI@SCM/H2O2 system is discussed. The developed high-performance nZVI@SCM catalyst strategy can provide a new route in enhancing the Fenton-like degradation of organic contaminants with less consumption of catalyst and oxidant.

Effect of green Fe2O3 nanoparticles in controlling Fusarium fruit rot disease of loquat in Pakistan

The subtropical fruit known as the loquat is prized for both its flavour and its health benefits. The perishable nature of loquat makes it vulnerable to several biotic and abiotic stressors. During the previous growing season (March-April 2021), loquat in Islamabad showed signs of fruit rot. Loquat fruits bearing fruit rot symptoms were collected, and the pathogen that was causing the disease isolated and identified using its morphology, microscopic visualisation, and rRNA sequence. The pathogen that was isolated was identified as Fusarium oxysporum. Green synthesized metallic iron oxide nanoparticles (Fe2O3 NPs) were employed to treat fruit rot disease. Iron oxide nanoparticles were synthesized using a leaf extract of the Calotropis procera. Characterization of NPs was performed by different modern techniques. Fourier transform infrared spectroscopy (FTIR) determined the existence of stabilizing and reducing compounds like phenol, carbonyl compounds, and nitro compounds, on the surface of Fe2O3 NPs. X-ray diffraction (XRD) explained the crystalline nature and average size (~49 nm) of Fe2O3 NPs. Energy dispersive X-ray (EDX) exhibited Fe and O peaks, and scanning electron microscopy (SEM) confirmed the smaller size and spherical shape of Fe2O3 NPs. Following both in vitro and in vivo approaches, the antifungal potential of Fe2O3 NPs was determined, at different concentrations. The results of both in vitro and in vivo analyses depicted that the maximum fungal growth inhibition was observed at concentration of 1.0 mg/mL of Fe2O3 NPs. Successful mycelial growth inhibition and significantly reduced disease incidence suggest the future application of Fe2O3 NPs as bio fungicides to control fruit rot disease of loquat.

Convenient green synthesis of Cu/Fe nanoparticles using pomegranate peel extracts and their performance for tetrabromobisphenol A removal

In this work, pomegranate peel extracts were used as the green reducing agent to synthesize Cu/Fe nanoparticles (P-Cu/Fe nanoparticles) and removed tetrabromobisphenol A (TBBPA) in aqueous solution. P-Cu/Fe nanoparticles were amorphous and irregularly spherical. The surfaces of nanoparticles contained Fe0, Fe3+ oxides (hydroxides), and Cu0. The bioactive molecules from pomegranate peel were extremely important for the synthesis of nanoparticles. P-Cu/Fe nanoparticles had excellent removal performance for TBBPA, and 98.6% of TBBPA (5 mg L-1) was removed within 60 min. The removal reaction of TBBPA by P-Cu/Fe nanoparticles was well-fitted with the pseudo-first-order kinetic model. The Cu loading was critical for TBBPA removal with an optimum value of 1.0 wt%. A weakly acidic condition (pH 5) was more favorable for the removal of TBBPA. The removal efficiency of TBBPA increased with the rise of temperature and decreased with increasing initial TBBPA concentration. The activation energy (Ea) was 54.09 kJ mol-1, indicating that the removal of TBBPA by P-Cu/Fe nanoparticles was mainly surface-controlled. Reductive degradation was the main mechanism of TBBPA removal by P-Cu/Fe nanoparticles. In conclusion, green synthesized P-Cu/Fe nanoparticles using pomegranate peel waste show great potential for the remediation of TBBPA in aqueous solution.

Light-Driven Catalytic Activity of Green-Synthesized SnO2/WO3-x Hetero-nanostructures

This work reports an environmentally friendly and economically feasible green synthesis of monometallic oxides (SnO₂ and WO₃) and their corresponding mixed metal oxide (SnO₂/WO_3-x) nanostructures from the aqueous Psidium guajava leaf extract for light-driven catalytic degradation of a major industrial contaminant, methylene blue (MB). P. guajava is a rich source of polyphenols that acts as a bio-reductant as well as a capping agent in the synthesis of nanostructures. The chemical composition and redox behavior of the green extract were investigated by liquid chromatography-mass spectrometry and cyclic voltammetry, respectively. Results acquired by X-ray diffraction and Fourier transform infrared spectroscopy confirm the successful formation of crystalline monometallic oxides (SnO₂ and WO₃) and bimetallic SnO₂/WO_3-x hetero-nanostructures capped with polyphenols. The structural and morphological aspects of the synthesized nanostructures were analyzed by transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. Photocatalytic activity of the synthesized monometallic and hetero-nanostructures was investigated for the degradation of MB dye under UV light irradiation. Results indicate a higher photocatalytic degradation efficiency for mixed metal oxide nanostructures (93.5%) as compared to pristine monometallic oxides SnO₂ (35.7%) and WO₃ (74.5%). The hetero-metal oxide nanostructures prove to be better photocatalysts with reusability up to 3 cycles without any loss in degradation efficiency or stability. The enhanced photocatalytic efficiency is attributed to a synergistic effect in the hetero-nanostructures, efficient charge transportation, extended light absorption, and increased adsorption of dye due to the enlarged specific surface area.

Green synthesis and characterization of iron oxide nanoparticles for the removal of heavy metals (Cd2+ and Ni2+) from aqueous solutions with Antimicrobial Investigation

Clove and green Coffee (g-Coffee) extracts were used to synthesize green iron oxide nanoparticles, which were then used to sorb Cd²⁺ and Ni²⁺ ions out of an aqueous solution. Investigations with x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and desorption (BET), Zeta potential, and scanning electron microscopy were performed to know and understand more about the chemical structure and surface morphology of the produced iron oxide nanoparticles. The characterization revealed that the main component of iron nanoparticles was magnetite when the Clove extract was used as a reducing agent for Fe³⁺, but both magnetite and hematite were included when the g-Coffee extract was used. Sorption capacity for metal ions was studied as a function of sorbent dosage, metal ion concentration, and sorption period. The maximum Cd²⁺ adsorption capacity was 78 and 74 mg/g, while that of Ni²⁺ was 64.8 and 80 mg/g for iron nanoparticles prepared using Clove and g-Coffee, respectively. Different isotherm and kinetic adsorption models were used to fit experimental adsorption data. Adsorption of Cd²⁺ and Ni²⁺ on the iron oxide surface was found to be heterogeneous, and the mechanism of chemisorption is involved in the stage of determining the rate. The correlation coefficient R² and error functions like RMSE, MES and MAE were used to evaluate the best fit models to the experimental adsorption data. The adsorption mechanism was explored using FTIR analysis. Antimicrobial study showed broad spectrum antibacterial activity of the tested nanomaterials against both Gram positive (S. aureus) (25923) and Gram negative (E. coli) (25913) bacteria with increased activity against Gram positive bacteria than Gram negative one and more activity for Green iron oxide nanoparticles prepared from Clove than g-Coffee one.

Exploring the multipotentiality of plant extracts for the green synthesis of iron nanoparticles: A study of adsorption capacity and dye degradation efficiency

The goal of the project was to create environmentally friendly and economically viable materials for thoroughly purifying contaminated water. An affordable, phytogenic, and multifunctional plant-based nanomaterial was prepared in this context. The work demonstrates an effective green synthesis method for producing iron nanoparticles (FeNPs) using six different plant extracts as a reducing agent. The characterization of green synthesized catalysts was concluded via Spectroscopy (tauc plot), XRD, FE-SEM, and FT-IR. The produced nanomaterial, which had an X-ray diffractogram (XRD) peak at 43.33⁰ and a size range of 1.82-63.63 nm, functioned as a highly effective nano-photocatalyst for the degradation of cationic dye. Due to the presence of a lower overall secondary metabolites quota, Ocimum sanctum plant extract reduced iron precursor produced the highest yield of dried NPs, followed by Azadirachta indica, Prosopis cineraria, Syzygium cumini, Citrus limon, and Salvadora oleoides. Further, the synthesized catalyst was tested for its effectiveness against gentian violet dye degradation. Ocimum sanctum plant extract reduced iron precursor produced the highest yield of dried NPs, followed by Azadirachta indica, Prosopis cineraria, Syzygium cumini, Citrus limon, and Salvadora oleoides, in that order. The dye removal efficiency of nanoparticles was 51% (Azadirachta indica), 83% (Ocimum sanctum), 59% (Syzygium cumini), 40% (Salvadora oleoides), 59% (Prosopis cineraria), and 63% (Citrus limon) after 12 h of visible light irradiation. The key factor in the process of deterioration is •O^2-. As a result, the nanoparticles can be used in antibacterial and photocatalytic processes. The reduced band gap was responsible for the increased photocatalytic quantity. The maximum adsorption capacity at the time of equilibrium was obtained in order as Ocimum sanctum > Citrus limon > Prosopis cineraria > Syzygium cumini > Azadirachta indica > Salvadora oleoides. The simplicity of production, low cost, magnetic property, and high adsorption capacity will increase the efficacy of the water treatment method. This article reports on the creation of unique iron nanoparticles and their use in the purification of water.

Green Synthesis of Iron Oxide (Hematite) Nanoparticles and Their Influence on Sorghum bicolor Growth under Drought Stress

Drought is a major abiotic stress that confronts plant growth and productivity, thus compromising food security. Plants use physiological and biochemical mechanisms to cope with drought stress, but at the expense of growth. Green-synthesized nanoparticles (NPs) have gained great attention in agriculture due to their environmental friendliness and affordability while serving as potential biofertilizers. This study investigates the role of hematite (αFe₂O₃) NPs, synthesized from Aspalathus linearis (rooibos), to improve Sorghum bicolor growth under drought stress. About 18 nm, spherical, and highly agglomerated hematite (αFe₂O₃) NPs were obtained. Sorghum seeds were primed with 5, 10, and 15 mg/L αFe₂O₃ NPs, and, after seven days of germination, the seedlings were transferred into potting soil, cultivated for fourteen days, and were subsequently water deprived (WD) for a further seven days. A reduction in plant height (78%), fresh (FW; 35%) and dry (DW; 36%) weights, and chlorophyll (chl) content ((total chl (81%), chla (135%), and chlb (1827%)) was observed in WD plants, and this correlated with low nutrients (Mg, Si, P, and K) and alteration in the anatomic structure (epidermis and vascular bundle tissues). Oxidative damage was observed as deep blue (O₂^●-) and brown (H₂O₂) spots on the leaves of WD plants, in addition to a 25% and 40% increase in oxidative stress markers (H₂O₂ and MDA) and osmolytes (proline and total soluble sugars), respectively. Seed priming with 10 mg/L αFe₂O₃ NPs improved plant height (70%), FW (56%), DW (34%), total Chl (104%), chla (160%) and chlb (1936%), anatomic structure, and nutrient distribution. Priming with 10 mg/L αFe₂O₃ NPs also protected sorghum plants from drought-induced oxidative damage by reducing ROS formation and osmolytes accumulation and prevented biomolecule degradation. The study concludes that green synthesized hematite NPs positively influenced sorghum growth and prevented oxidative damage of biomolecules by improving nutrient uptake and osmoregulation under drought stress.

Effect of Calcination Temperature and Time on the Synthesis of Iron Oxide Nanoparticles: Green vs. Chemical Method

Nowadays, antioxidants and antibacterial activity play an increasingly vital role in biosystems due to the biochemical and biological reactions that involve free radicals and pathogen growth, which occur in many systems. For this purpose, continuous efforts are being made to minimize these reactions, including the use of nanomaterials as antioxidants and bactericidal agents. Despite such advances, iron oxide nanoparticles still lack knowledge regarding their antioxidant and bactericidal capacities. This includes the investigation of biochemical reactions and their effects on nanoparticle functionality. In green synthesis, active phytochemicals give nanoparticles their maximum functional capacity and should not be destroyed during synthesis. Therefore, research is required to establish a correlation between the synthesis process and the nanoparticle properties. In this sense, the main objective of this work was to evaluate the most influential process stage: calcination. Thus, different calcination temperatures (200, 300, and 500 °C) and times (2, 4, and 5 h) were studied in the synthesis of iron oxide nanoparticles using either Phoenix dactylifera L. (PDL) extract (green method) or sodium hydroxide (chemical method) as the reducing agent. The results show that calcination temperatures and times had a significant influence on the degradation of the active substance (polyphenols) and the final structure of iron oxide nanoparticles. It was found that, at low calcination temperatures and times, the nanoparticles exhibited small sizes, fewer polycrystalline structures, and better antioxidant activities. In conclusion, this work highlights the importance of green synthesis of iron oxide nanoparticles due to their excellent antioxidant and antimicrobial activities.

Synthesis of phytoextract-mediated Ag-doped graphitic carbon nitride (Ag@GCN) for photocatalytic degradation of dyes

The present work focuses on the green synthesis of Ag-doped graphitic carbon nitride (Ag@GCN) for photocatalytic activities, which can contribute to a more sustainable environment. The leaf extract of the Ocimum tenuiflorum (Tulsi) plant was used to prepare the silver nanoparticles, as the plant extract serves as a stabilizing and capping agent in producing silver nanoparticles. Both Ag nanoparticles and urea-derived GCN were synthesized by thermal polymerization. The Ag-doped GCN nanocomposites were synthesized using various millimolar concentrations of Ag nanoparticles (NPs) with a fixed amount of GCN. The green nanocomposites (NCs) were synthesized by calcinating leaf extract at about 550 °C. They were then characterized for surface morphology by SEM coupled with energy-dispersive X-ray spectroscopy (EDX), and elemental composition by XRD, Fourier-dispersive infrared spectroscopy (FTIR), and transmission electron microscope (TEM). Thermal stability and estimation of the Ag content in GCN were done through thermogravimetric analysis. The prepared series of nanocomposites (Ag-doped GCN 0.5 mM, 1.0 mM, 1.5 mM, 2.0 mM) were used to study the photocatalytic degradation efficiency of rose bengal (RB) and xylenol orange (XO) dyes. The degradation efficiency of dyes gets enhanced due to the doping of Ag nanoparticles into GCN. The efficiency increased from 54 to 76% and 15 to 36% in the case of RB and XO dyes, respectively. The apparent rate constant value increased up to 2.5 times in the case of the Ag-doped GCN (1.5 mM) nanocomposite in comparison to GCN. The result obtained from the study confirmed that Ag-doped GCN (1.5 mM) could act as a potential photocatalyst for wastewater remediation applications.

Sustainable Synthesis of Iron-Zinc Nanocomposites by Azadirachta indica Leaves Extract for RSM-Optimized Sono-Adsorptive Removal of Crystal Violet Dye

Environmental pollution has exacerbated the availability of clean water to mankind. In this study, Azadirachta indica leaf extract was used for sustainable synthesis of Fe-Zn nanocomposites (IZNC). The instrumental techniques of Fourier transformed infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were used to determine the structural and chemical composition. The overall surface was mildly acidic in nature, as the pH_PZC was observed to be 6.00. The ultrasonicated adsorption experiments were designed by central composite design (CCD). The best responses, which proposed a contaminants removal of 80.39%, were assessed using the response surface methodology (RSM). By repeating experimental runs at the expected optimum operating parameters (OOP), the method was experimentally affirmed with the %mean error and %RSD₉ being 2.695% and 1.648%, respectively. The interaction of CV dye and the nanocomposite showed tremendous adsorption efficiency towards crystal violet (CV) dye, as revealed by isotherm studies. Fitting kinetics and isotherm models were affirmed by root mean square error (RMSE), χ2, and a Pearson regression coefficient. Thermodynamic studies proved spontaneity of the CV dye adsorption over the nanocomposites. The values for ΔG^o, ΔH^o, and ΔS^o were observed to be -1.089 kJ/mol, 28.59 kJ/mol, and -3.546 kJ/mol, respectively. Recovery of CV dye was carried out in a variety of media, including NaOH, NaCl, and CH₃COOH. The maximum CV recovery was achieved in an acidic media. The robustness of adsorption was affirmed by the interference of various matrix ions, including KCl, LiCl, NaCl, and MgCl₂, which did not significantly affect the adsorption process. The maximum adsorption capacity was obtained at a low concentration of LiCl. The results show that a green synthesis approach for nanocomposite synthesis might be an effective and economical way to remove organic contaminants from wastewater. Moreover, it is also effective for effluent treatment plants (ETP) for waste management purposes, in which it may be coupled with chlorine as a disinfectant to purify water that can be used for domestic and irrigation purposes.

Synthesize palladium nanoparticles from the macroalgae Sargassum fusiforme: An eco-friendly tool in the fight against Plasmodium falciparum?

Although numerous drugs are practiced to control malaria and its vectors, more recently, eco-friendly control tools have been proposed to battle its etiologic agents. Thus, using green bionanotechnology approaches, we aimed to synthesize palladium nanoparticles (Pd NPs) from the macroalgae Sargassum fusiforme (Sf), its potential antiparasitic activity against P. falciparum, as well as its possible cytotoxicity, in HeLa cells. After the biosynthesis of the PdSf NPs, their characterization was carried out by UV-Vis, FESEM, and EDX analyses, and their hydrodynamic size, zeta potential, and surface area were determined. Furthermore, the functional groups of the PdSf NPs were analyzed by FT-IR and GC-MS. While PdSf NPs had an IC50 of 7.68 μg/mL (Chloroquine (CQ)-s) and 16.42 μg/mL, S. fusiforme extract had an IC50 of 14.38 μg/mL (CQ-s) and 35.27 μg/mL (CQ-r). With an IC50 value of 94.49 μg/mL, PdSf NPs exhibited the least toxic effect on the HeLa cells. The Lipinski rule of five and ADMET prediction were used to assess the in silico models of caffeine acid hexoside and quercetin 7-O-hexoside for the presence of drug-like properties. Pathogenic proteins, primarily responsible for motility, binding, and disease-causing, were the target of the structurally based docking studies between plant-derived compounds and pathogenic proteins. Thus, our study pioneered promising results that support the potential antiplasmodial activity of eco-friendly synthesized PdSf NPs using S. fusiforme extract against P. falciparum, opening perspectives for further exploration into the use of these NPs in malaria therapy.

Nano-decolorization of methylene blue by Phyllanthus reticulatus iron nanoparticles: an eco-friendly synthesis and its antimicrobial, phytotoxicity study

The present study was investigated to synthesis the iron nanoparticles (FeNPs) using the leaf extract of Phyllanthus reticulatus. The phytosynthesized FeNPs exhibited UV-visible absorption peaks at 229 nm and its crystalline nature was confirmed through XRD. FT-IR analysis revealed the presence of various functional groups which are responsible for the bioreduction of FeNPs. The SEM results showed that FeNPs were aggregated, irregular sphere shaped with rough surfaces and EDX spectrum recorded densely occupied iron nanoparticles region. The particle size range of the synthesized iron nanoparticles was 185.6 nm. The FeNPs showed potential methylene blue decolourisation activity which was visually observed by gradual colour change in the dye solution from deep blue to colorless. The control exhibited no change in coloration during exposure to sunlight and the iron nanoparticles completely disintegrated the methylene blue within 10 s in 10 mg/L methylene blue (98%), whereas the color change was decreased when the concentration of the dye increased. In addition, the phyto-synthesized FeNPs exhibited extensive antibacterial and antifungal activity against the selected pathogens. Phytotoxicity assay confirms the potential of biosynthesized iron nanoparticles as a fertilizer for the growth of green gram seeds. Thus the present study leads to development of cost-effective green synthesis, reduction of toxic chemicals and its extensive applications in the biological sciences.

Green Synthesis of FexOy Nanoparticles with Potential Antioxidant Properties

Iron oxide nanoparticles (FexOy-NPs) are currently being applied in numerous high-tech sectors, such as in chemical sectors for catalysis and in the medical sector for drug delivery systems and antimicrobial purposes, due to their specific, unique and magnetic properties. Nevertheless, their synthesis is under continuous investigation, as physicochemical methods are considered expensive and require toxic solvents. Thus, green nanotechnology has shown considerable promise in the eco-biogenesis of nanoparticles. In the current study, FexOy-NPs were synthesized by two different methods: via green synthesis through the use of polyphenols, which were extracted from Phoenix dactylifera L.; and via chemical synthesis, in which the reducing agent was a chemical (NaOH), and iron chloride was used as a precursor. Thus, polyphenol extraction and its ability to produce nanoparticles were evaluated based on the drying temperature used during the Phoenix dactylifera L. recollection, as well as the extraction solvent used. The results highlight the potential of polyphenols present in Phoenix dactylifera L. for the sustainable manufacture of FexOy-NPs. Finally, green and chemical syntheses were compared on the basis of physicochemical characteristics and functional properties.

Soil Fungi as Biomediator in Silver Nanoparticles Formation and Antimicrobial Efficacy

Introduction and Objectives

Biogenic agents in nanoparticles fabrication are gaining great interest due to their lower possible negative environmental impacts. The present study aimed to isolate fungal strains from deserts in Saudi Arabia and assess their ability in silver nanoparticles (AgNPs) fabrication and evaluate their antibacterial effect.

Methods

Soil fungi were identified using 18s rDNA, and their ability in NPs fabrication was assessed as extracellular synthesis, then UV-vis spectroscopy, dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy, and transmission electron microscopy were used for AgNPs characterization. The antibacterial activity of fungal-based NPs was assessed against one Gram-positive methicillin-resistant S. aureus (MRSA) and three Gram-negative bacteria (E. coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae). Ultrastructural changes caused by fungal-based NPs on K. pneumoniae were investigated using TEM along with SDS-PAGE for protein profile patterns.

Results

The three fungal isolates were identified as Phoma sp. (MN995524), Chaetomium globosum (MN995493), and Chaetomium sp. (MN995550), and their filtrate reduced Ag ions into spherical P-AgNPs, G-AgNPs, and C-AgNPs, respectively. DLS data showed an average size between 12.26 and 70.24 nm, where EDX spectrums represent Ag at 3.0 keV peak. G-AgNPs displayed strong antibacterial activities against Klebsiella pneumoniae, and the ultrastructural changes caused by NPs were noted. Additionally, SDS-PAGE analysis of treated K. pneumoniae revealed fewer bands compared to control, which could be related to protein degradation.

Conclusion

Present findings have consequently developed an eco-friendly approach in NPs formation by environmentally isolated fungal strains to yield NPs as antibacterial agents.

Biosynthesis of Iron Oxide Nanoparticles: Physico-Chemical Characterization and Their In Vitro Cytotoxicity on Healthy and Tumorigenic Cell Lines

Iron oxide nanoparticles were synthesized starting from two aqueous extracts based on Artemisia absinthium L. leaf and stems, employing a simplest, eco-friendliness and low toxicity method—green synthesis. The nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), X-ray fluorescence analysis (XRF), thermal analysis (TG/DSC), and scanning electron microscopy (SEM). Lack of magnetic properties and the reddish-brown color of all the samples confirms the presence of hematite as majority phase. The FTIR bands located at 435 cm⁻¹ and 590 cm⁻¹, are assigned to Fe-O stretching vibration from hematite, confirming the formation of α-Fe₂O₃ nanoparticles (NPs). The in vitro screening of the samples revealed that the healthy cell line (HaCaT) presents a good viability (above 80%) after exposure to iron oxide NPs and lack of apoptotic features, while the tumorigenic cell lines manifested a higher sensitivity, especially the melanoma cells (A375) when exposed to concentration of 500 µg/mL iron oxide NPs for 72 h. Moreover, A375 cells elicited significant apoptotic markers under these parameters (concentration of 500 µg/mL iron oxide NPs for a contact time of 72 h).

Colloidal carriers of almond gum/gelatin coacervates for rosemary essential oil: Characterization and in-vitro cytotoxicity

The potential of almond gum and gelatin complex coacervates as a colloidal carrier for rosemary essential oil (REO) was investigated along with in-vitro gastrointestinal release and cytotoxicity. The optimum formulation (1 gelatin:2 almond gum and 7% (w/w) REO) was selected based on encapsulation efficiency (43.6%) and encapsulation yield (99.3%). The particle size was 6.9 µm with a high negative zeta-potential (-37.3 mV). FTIR and XRD data revealed that REO was properly loaded within carriers and there were interactions between gelatin and almond gum. Thermal stability of REO was enhanced after complex coacervation according to TGA. REO released slowly from carriers under simulated gastrointestinal fluid. Cytotoxicity of pure REO and REO-loaded complexes was evaluated on 4 T1 cell lines. Encapsulation of REO caused a reduction in toxicity. Overall, coacervates of gelatin-almond gum could be a promising carrier to enhance the application of bioactives in the food and drug industry with low toxicity.

Safer plant-based nanoparticles for combating antibiotic resistance in bacteria: A comprehensive review on its potential applications, recent advances, and future perspective

BACKGROUND

Antibiotic resistance is one of the current threats to human health, forcing the use of drugs that are more noxious, costlier, and with low efficiency. There are several causes behind antibiotic resistance, including over-prescription of antibiotics in both humans and livestock. In this scenario, researchers are shifting to new alternatives to fight back this concerning situation.

SCOPE AND APPROACH

Nanoparticles have emerged as new tools that can be used to combat deadly bacterial infections directly or indirectly to overcome antibiotic resistance. Although nanoparticles are being used in the pharmaceutical industry, there is a constant concern about their toxicity toward human health because of the involvement of well-known toxic chemicals (i.e., sodium/potassium borohydride) making their use very risky for eukaryotic cells.

KEY FINDINGS AND CONCLUSIONS

Multiple nanoparticle-based approaches to counter bacterial infections, providing crucial insight into the design of elements that play critical roles in the creation of antimicrobial nanotherapeutic drugs, are currently underway. In this context, plant-based nanoparticles will be less toxic than many other forms, which constitute promising candidates to avoid widespread damage to the microbiome associated with current practices. This article aims to review the actual knowledge on plant-based nanoparticle products for antibiotic resistance and the possible replacement of antibiotics to treat multidrug-resistant bacterial infections.

Plant-Derived Iron Nanoparticles for Removal of Heavy Metals

Nanoparticle synthesis has seen exponential development recently as its characteristics of high surface area, high rate of adsorption, and easy, cost-effective synthesis have been exploited for the purpose of ground water purification via the removal of organic and inorganic compounds, along with the removal of heavy metals and microbes. The synthesis of Zero-Valent Iron Nanoparticles (ZVI NPs) by green methods has proved to be environmentally friendly in many ways as it employs the use of naturally occurring plant extracts. These nanoparticles have large surface areas and efficiently remove heavy metals. The reducing potential of these ZVI NPs is mostly −0.44 V, thus allowing them to reduce heavy metal compounds such as cadmium, lead, zinc, copper, and arsenic present in wastewater. Irradiated nanoparticles have also exhibited antimicrobial resistance and adsorption. It is also observed that nanoparticles show a higher rate of efficacy at a lower pH. The adsorbent, which is ZVI NPs in this case, when present in large doses reduces heavy metal compounds rapidly and effectively.

Synchronous Efficient Reduction of Cr (VI) and Removal of Total Chromium by Corn Extract / Fe (III) System

In this study, a cost-effective and environmentally friendly composite system for the remediation of Cr (VI)-polluted groundwater was developed. The system of simultaneous reduction of Cr (VI) and precipitation of Cr (III) was innovatively constructed, using corncob extract as electron donor and Fe (III) as strengthening reagent. In the process of the total chromium removal, the addition of alkaline substances was not required, when pH ≤ 4 it showed an optimal reduction of Cr (VI). In addition, the removal rate of total chromium reached 88% within 120 min. To understand the mechanism of this system, we characterized the corn extract and particulate matter before and after the reaction. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry suggested that alcohols, phenols, and aldehydes provided the electrons that were required to reduce Cr (VI). As an electron shuttle, Fe (III) improved the efficiency of electron transfer, and Fe (II) and nano-zerovalent iron (nZVI) particles were formed during this process. X-ray diffraction and transmission electron microscopy analyses showed that FeOCl was formed under the action of the plant extract and adsorbed Cr (III), thus reducing total chromium. Both nZVI and FeOCl were covered with a layer of paste cap, which maintained the stability of their physical and chemical properties. The regulation of pH during the repair process was not required, and the cost of the process was significantly reduced. Therefore, this technology provides a new strategy for the in situ remediation of Cr (VI) pollution in groundwater.

Hexavalent chromium removal from aqueous solutions using biogenic iron nanoparticles: Kinetics and equilibrium study

Green mediated biosynthesis of iron oxide nanoparticles utilising Rosa indica flower petal extracts (RIFP-FeONPs) was used in this investigation. The RIFP-FeONPs were evaluated by the UV-Visible Spectroscopy, FTIR, SEM, EDX, XRD, Zeta potentials, and DLS, and been engaged than for the elimination of Cr (VI) from the contaminated environments. At 269 nm, the RIFP-FeONPs surface plasmon vibration bands were observed, which attributed to the Fe³⁺. XRD patterns of RIFP-FeONPs depicted the intense diffraction peak of face-centered cubic (fcc) iron at a 2θ value of 45.33° from the (311) lattice plane indisputably revealed that the particles are constituted of pure iron. The fabricated nanomaterials are spherical and polydisperse with a diameter of 70-120 nm, and various agglomeration clusters are attributable to intermolecular interaction. Zeta potential measurement and particle size distribution of RIFP-FeONPs showed a mean average size of 115.5 ± 29 nm and a polydispersity index (PDI) of 0.420. The study aims to analyse the appropriateness of RIFP-FeONPs for removing hexavalent chromium from the aqueous environment and the application of adsorption isotherm and statistical models in the experiment. The sorption of Cr (VI) on RIFP-FeONPs was observed to fit well with the isothermal models (R² = 0.98). The linear correlation between processing parameters and time demonstrated that the adsorption efficiency of Cr (VI) well correlated with the pseudo-first order kinetic model and isothermal adsorption with the Langmuir and Freundlich isothermal models, so that the RIFP-FeONPs could be a prospective nanosorbent for hexavalent chromium removal from industrial waste.

Green synthesis of Fe0 nanoparticles using Eucalyptus grandis leaf extract: Characterization and application for dye degradation by a (Photo)Fenton-like process

Zero-valent iron nanoparticles (EGnZVI) were synthesized using Eucalyptus grandis (EG) leaf extract as a reducing/stabilizing agent. The studied materials (EG leaves, extract and EGnZVI) were characterized using the XRD, FTIR, Raman spectroscopy, SEM, TEM/EDS techniques. The results indicate that several organic compounds, including phenolics, present in the EG leaves were successfully extracted and incorporated into the structure of the material, possibly promoting the capping and stabilization of the formed zero-valent iron particles. The EGnZVI presented low crystallinity, varied size (50-500 nm), approximately spherical shape, and formed aggregates. The EGnZVI were utilized in the removal of the Direct Red 80 (DR80), an azo dye. The effects of the temperature (15-35 °C), initial DR80 concentration (10-250 mg L-1), initial pH (2.5-8.5), the doses of H2O2 (0.5-5 mmol L-1) and EGnZVI (0.2-10 mg L-1), and the incidence of UV-light were evaluated. The EGnZVI did not present reactivity towards the DR80 in the absence of H2O2. However, in the presence of H2O2, the EGnZVI was highly efficient at removing the DR80 at slightly acidic pH0 values (4 and 5.5). Under these pH0 conditions, the EGnZVI/Fenton process proved to be more effective than the classic homogenous Fenton. Finally, in the presence of the UV-light, the process was highly efficient throughout the studied pH0 interval, with increased removal rates. Therefore, the nZVI/Fenton process, using the synthesized material, presents itself as a promising alternative for the degradation of organic pollutants, and the incidence of UV light can considerably improve its efficiency.

Green Synthesis of Superparamagnetic Iron Oxide Nanoparticles with Eucalyptus globulus Extract and Their Application in the Removal of Heavy Metals from Agricultural Soil

The green synthesis of metal oxide nanoparticles is presented as an excellent sustainable alternative for achieving nanostructures, with potential applications. This research provides important information regarding the influence of the type of solvent used in extracting organic reducing agents from E. globulus on the FeO NPs green synthesis protocol. A broad approach to characterization is presented, where UV-vis spectrophotometry suggests the presence of this type of nanoparticulate material. Likewise, the reduction mechanism was evaluated by FT-IR and the magnetic properties were evaluated by PPSM. In addition, characterizations were linked via elemental analysis (EDX), crystallographic characterization (XRD), electron microscopy (SEM/STEM), and Z potential to evaluate colloidal stability. The results show the influence of the type of solvent used for the extraction of organic reducing agents from E. globulus, and the effect on the synthesis of FeO NPs. In addition, the nanostructure material obtained showed excellent efficiency in the remediation of agricultural soil, eliminating metals such as Cr-VI, Cd, and, to a lesser extent, Pb.

Removal of organochlorine pesticides using zerovalent iron supported on biochar nanocomposite from Nephelium lappaceum (Rambutan) fruit peel waste

Unique zerovalent iron (Fe⁰) supported on biochar nanocomposite (Fe⁰-B_RtP) was synthesized from Nephelium lappaceum (Rambutan) fruit peel waste and were applied for the simultaneous removal of 6 selected organochlorine pesticides (OCPs) from aqueous medium. During facile synthesis of Fe⁰-B_RtP, Rambutan peel extract was used as the green reducing mediator to reduce Fe²⁺ to zerovalent iron (Fe⁰), instead of toxic sodium borohydride which were used for chemical synthesis. For comparison, chemically synthesized Fe⁰-B_Che nanocomposite was also prepared in this work. Characterization study confirmed the successful synthesis and dispersion of Fe⁰ nanoparticles on biochar surface. Batch experiments revealed that Fe⁰-B_RtP and Fe⁰-B_Che nanocomposites combine the advantage of adsorption and dechlorination of OCPs in aqueous medium and up to 96-99% and 83-91% removal was obtained within 120 and 150 min, respectively at initial pH 4. Nevertheless, the reactivity of Fe⁰-B_Che nanocomposite decreased 2 folds after being aged in air for one month, whilst Fe⁰-B_RtP almost remained the same. Adsorption isotherm of OCPs were fitted well to Langmuir isotherm and then to Freundlich isotherm. The experimental kinetic data were fitted first to pseudo-second-order adsorption kinetic model and then to pseudo-first-order reduction kinetic model. The adsorption mechanism involves π-π electron-donor-acceptor interaction and adsorption is facilitated by the hydrophobic sorption and pore filling. After being reused five times, the removal efficiency of regenerated Fe⁰-B_Che and Fe⁰-B_RtP was 5-13% and 89-92%, respectively. The application of this Fe⁰-B_RtP nanocomposite could represent a green and low-cost potential material for adsorption and subsequent reduction of OCPs in aquatic system.

A systematic review on iron-based nanoparticle-mediated clean-up of textile dyes: challenges and prospects of scale-up technologies

The projected increase of the global textile industry to USD1002.84 billion in 2027 indicates a simultaneous increase in water pollution due to textile dye-rich voluminous effluents highlighting the requirement of source clean-up. This review analyzes the colossal amount of literature on lab-scale nanoremediation technologies involving iron-based nanoparticles and the mechanistic aspects. However, not many studies are in place with regard to execution because there are several bottlenecks in the scale-up of the technology. This review attempts to identify the limitations of scale-up by focusing on each step of nanoremediation from synthesis of iron-based nanoparticles to their applications. The most prominent appears to be the low economic viability of physico-chemical synthesis of nanoparticles, lack of appropriate toxicity studies of iron-based nanoparticles, and dearth of studies on field applications. It is recommended that above studies should be made not only on lab scale but also on field samples preferably utilizing microbial products based green synthesized iron-based nanoparticles and conducting toxicity studies. Besides, immobilization of the nanoparticles on renewable material greatly enhances the sustainability and economic value of the process. Furthermore, since the chemical composition of dye-rich effluents varies among industries, effluent specific optimization of process parameters and kinetics thereof is also a major prerequisite for scale-up. The value of this review lies in the fact that it brings, for the first time, a comprehensive and critical systematization of various aspects needing attention in order to scale-up such effective nanoremediation processes.

Water Purification through a Novel Electrospun Carbon Nanofiber Membrane

Here, we report water purification through novel polyvinyl alcohol (PVA)-based carbon nanofibers synthesized through the electrospinning technique. In our novel approach, we mix PVA and tetraethyl orthosilicate (TEOS) with green tea solutions with different concentrations to synthesize carbon-based nanofibers (CNFs) and further calcine at 280 °C for carbonization. The scanning electron microscopy (SEM) results show the diameter of the nanofibers to be ∼500 nm, which decreases by about 50% after carbonization, making them more suitable candidates for the filtration process. Next, using these carbon nanofibers, we prepare filters for water purification. The synthesized CNF filters show excellent performance and successful removal of contaminants from the water by analyzing the CNF-based filters before and after the filtration of water through SEM and energy-dispersive X-ray (EDX) spectroscopy. Our SEM and EDX results indicate the presence of various nanoparticles consisting of different elements such as Mg, Na, Ti, S, Si, and Fe on the filters, after the filtration of water. Additionally, the SEM results show that PVA and TEOS concentrations play an important role in the formation, uniformity, homogeneity, and particularly in the reduction of the nanofiber diameter.