A critical review on the biosynthesis, properties, applications and future outlook of green MnO2 nanoparticles.

MnO2 nanoparticles have played a vital role in biomedical, catalysis, electrochemical and energy storage fields, but requiring toxic chemicals in the fabrication intercepts their applications. There is an increasing demand for biosynthesis of MnO2 nanoparticles using green sources such as plant species in accordance with the purposes of environmental mitigation and production cost reduction. Here, we review recent advancements on the use of natural compounds such as polyphenols, reducing sugars, quercetins, etc. Extracted directly from low-cost and available plants for biogenic synthesis of MnO2 nanoparticles. Role of these phytochemicals and formation mechanism of bio-medicated MnO2 nanoparticles are shed light on. MnO2 nanoparticles own small particle size, high crystallinity, diverse morphology, high surface area and stability. Thanks to higher biocompatibility, bio-mediated synthesized MnO2 nanoparticles exhibited better antibacterial, antifungal, and anticancer activity than chemically synthesized ones. In terms of wastewater treatment and energy storage, they also served as efficient adsorbents and catalyst. Moreover, several aspects of limitation and future outlook of bio-mediated MnO2 nanoparticles in the fields are analyzed. It is expected that the present work not only expands systematic understandings of synthesis methods, properties and applications MnO2 nanoparticles but also pave the way for the nanotechnology revolution in combination with green chemistry and sustainable development.

Green synthesis of ZnFe2O4@ZnO nanocomposites using Chrysanthemum spp. floral waste for photocatalytic dye degradation.

The occurrence of textile dyeing wastewater discharged into the environment has been recently increasing, resulting in harmful effects on living organisms and human health. The use of green nanoparticles for water decontamination has received much attention. Floral waste can be extracted with the release of natural compounds, which act as reducing and stabilizing agents during the biosynthesis of nanoparticles. Herein, we report the utilization of Chrysanthemum spp. floral waste extract to synthesize green ZnFe2O4@ZnO (ZFOZx) nanocomposites for the photocatalytic degradation of Congo red under solar light irradiation. The various molar ratio of ZnFe2O4 (0-50%) was incorporated into ZnO nanoparticles. The surface area of green ZFOZx nanocomposites was found to increase (7.41-42.66 m2 g-1) while their band gap energy decreased from 1.98 eV to 1.92 eV. Moreover, the results exhibited the highest Congo red dye degradation efficiency of 94.85% at a concentration of 5.0 mg L-1, and a catalyst dosage of 0.33 g L-1. The •O2- reactive species played a vital role in the photocatalytic degradation of Congo red dye. Green ZFOZ3 nanocomposites had good recyclability with at least three cycles, and an excellent stability. The germination results showed that wastewater treated by ZFOZ3 was safe enough for bean seed germination. We expect that this work contributes significantly to developing novel green bio-based nanomaterials for environmental remediation as well as reducing the harm caused by flower wastes.

Facile synthesis of CoFe2O4@MIL-53(Al) nanocomposite for fast dye removal: Adsorption models, optimization and recyclability.

The global occurrence of textile dyes pollution has recently emerged, posing a serious threat to ecological systems. To abate dye contamination, we here developed a novel magnetic porous CoFe2O4@MIL-53(Al) nanocomposite by incorporating magnetic CoFe2O4 nanoparticles with MIL-53(Al) metal-organic framework. This nanocomposite possessed a surface area of 197.144 m2 g-1 and a pore volume of 0.413 cm3 g-1. The effect of contact time (5-120 min), concentration (5-50 mg L-1), dosage (0.1-1.0 g L-1), and pH (2-10) on Congo red adsorption was clarified. CoFe2O4@MIL-53(Al) could remove 95.85% of Cong red dye from water with an accelerated kinetic rate of 0.6544 min-1 within 10 min. The kinetic and isotherm models showed the predominance of Bangham and Temkin. According to Langmuir, the maximum uptake capacities of CoFe2O4@MIL-53(Al), CoFe2O4, and MIL-53(Al) adsorbents were 43.768, 17.982, and 15.295 mg g-1, respectively. CoFe2O4@MIL-53(Al) was selected to optimize Cong red treatment using Box-Behnken experimental design. The outcomes showed that CoFe2O4@MIL-53(Al) achieved the highest experimental uptake capacity of 35.919 mg g-1 at concentration (29.966 mg L-1), time (14.926 min), and dosage (0.486 g L-1). CoFe2O4@MIL-53(Al) could treat dye mixture (methylene blue, methyl orange, Congo red, malachite green, and crystal violet) with an outstanding removal efficiency of 81.24% for 30 min, and could be reused up to five cycles. Therefore, novel recyclable and stable CoFe2O4@MIL-53(Al) is recommended to integrate well with real dye treatments systems.

Formation, antimicrobial activity, and biomedical performance of plant-based nanoparticles: a review.

Because many engineered nanoparticles are toxic, there is a need for methods to fabricate safe nanoparticles such as plant-based nanoparticles. Indeed, plant extracts contain flavonoids, amino acids, proteins, polysaccharides, enzymes, polyphenols, steroids, and reducing sugars that facilitate the reduction, formation, and stabilization of nanoparticles. Moreover, synthesizing nanoparticles from plant extracts is fast, safe, and cost-effective because it does not consume much energy, and non-toxic derivatives are generated. These nanoparticles have diverse and unique properties of interest for applications in many fields. Here, we review the synthesis of metal/metal oxide nanoparticles with plant extracts. These nanoparticles display antibacterial, antifungal, anticancer, and antioxidant properties. Plant-based nanoparticles are also useful for medical diagnosis and drug delivery.

Occurrence, toxicity and adsorptive removal of the chloramphenicol antibiotic in water: a review.

Chloramphenicol is a broad-spectrum bacterial antibiotic used against conjunctivitis, meningitis, plague, cholera, and typhoid fever. As a consequence, chloramphenicol ends up polluting the aquatic environment, wastewater treatment plants, and hospital wastewaters, thus disrupting ecosystems and inducing microbial resistance. Here, we review the occurrence, toxicity, and removal of chloramphenicol with emphasis on adsorption techniques. We present the adsorption performance of adsorbents such as biochar, activated carbon, porous carbon, metal-organic framework, composites, zeolites, minerals, molecularly imprinted polymers, and multi-walled carbon nanotubes. The effect of dose, pH, temperature, initial concentration, and contact time is discussed. Adsorption is controlled by π-π interactions, donor-acceptor interactions, hydrogen bonding, and electrostatic interactions. We also discuss isotherms, kinetics, thermodynamic data, selection of eluents, desorption efficiency, and regeneration of adsorbents. Porous carbon-based adsorbents exhibit excellent adsorption capacities of 500-1240 mg g-1. Most adsorbents can be reused over at least four cycles.

Recent advances and challenges of the green ZnO-based composites biosynthesized using plant extracts for water treatment.

Recently, there has been a notable rise in the prevalence of persistent pollutants in the environment, posing a significant hazard due to their toxicity and enduring nature. Conventional wastewater treatment methods employed in treatment plants rarely address these persistent pollutants adequately. Meanwhile, the concept of green synthesis has garnered considerable attention, owing to its environmentally friendly approach that utilizes fewer toxic chemicals and solvents. The utilization of materials derived from sustainable sources presents a promising avenue for solving pressing environmental concerns. Among the various sources of biological agents, plants stand out for their accessibility, eco-friendliness, and rich reserves of phytochemicals suitable for material synthesis. The plant extract-mediated synthesis of zinc oxide nanoparticles (ZnONPs) has emerged as a promising solution for applications in wastewater treatment. Thorough investigations into the factors influencing the properties of these green ZnONPs are essential to establish a detailed and reliable synthesis process. Major weaknesses inherent in ZnONPs can be addressed by changing the optical, magnetic, and interface properties through doping with various semiconductor materials. Consequently, research efforts to mitigate water pollution are being driven by both the future prospects and limitations of ZnO-based composites. This review underscores the recent advancements of plant extract-mediated ZnONP composites for water treatment.

Recent advances in the biosynthesis of ZnO nanoparticles using floral waste extract for water treatment, agriculture and biomedical engineering.

Flowers are often discarded after cultural and religious events, making it worthwhile to explore the utilization of this floral waste for material production. Floral extracts contain a diverse array of phytochemicals such as polyphenols, flavonoids, and reducing sugars, which play a significant role in the formation and influencing the properties of zinc oxide (ZnO) nanoparticles. In this review, we delve into the importance of floral extract, methodology, mechanism, and influencing factors in the production of ZnO nanoparticles. Additionally, the role of green ZnO nanoparticles as an adsorbent and photocatalyst for water treatment is discussed. These floral extract-mediated ZnO nanoparticles exhibit advantages in agricultural and biomedical applications, including promoting seed germination and demonstrating antibacterial, anticancer, and antifungal properties. Cost analysis reveals that while various expenses are associated with ZnO production, scaling up processes can help reduce these costs. This review underscores the potential of floral waste extract for the synthesis of green ZnO nanoparticles, thereby contributing to waste-to-wealth strategies and adhering to green chemistry principles.

Synthesis strategies, regeneration, cost analysis, challenges and future prospects of bacterial cellulose-based aerogels for water treatment: A review.

Clean water is an integral part of industries, agricultural activities and human life, but water contamination by toxic dyes, heavy metals, and oil spills is increasingly serious in the world. Aerogels with unique properties such as highly porous and extremely low density, tunable surface modification, excellent reusability, and thermal stability can contribute to addressing these issues. Thanks to high purity, biocompatibility and biodegradability, bacterial cellulose can be an ideal precursor source to produce aerogels. Here, we review the modification, regeneration, and applications of bacterial cellulose-based aerogels for water treatment. The modification of bacterial cellulose-based aerogels undergoes coating of hydrophobic agents, carbonization, and incorporation with other materials, e.g., ZIF-67, graphene oxide, nanoparticles, polyaniline. We emphasized features of modified aerogels on porosity, hydrophobicity, density, surface chemistry, and regeneration. Although major limits are relevant to the use of toxic coating agents, difficulty in bacterial culture, and production cost, the bacterial cellulose aerogels can obtain high performance for water treatment, particularly, catastrophic oil spills.

Recent progress and challenges of MOF-based nanocomposites in bioimaging, biosensing and biocarriers for drug delivery.

Metal-organic frameworks (MOFs), a burgeoning class of coordination polymers, have garnered significant attention due to their outstanding structure, porosity, and stability. They have been extensively studied in catalysis, energy storage, water harvesting, selective gas separation, and electrochemical applications. Recent advancements in post-synthetic strategies, surface functionality, and biocompatibility have expanded the application scope of MOFs, particularly in various biomedical fields. Herein, we review MOF-based nanomaterials bioimaging nanoplatforms in magnetic resonance imaging, computed tomography, and fluorescence imaging. MOFs serve as the foundation for biosensors, demonstrating efficiency in sensing H2O2, tumor biomarkers, microRNA, and living cancer cells. MOF-based carriers are well designed in drug delivery systems and anticancer treatment therapies. Additionally, we examine the challenges and prospects of MOFs in surface modification, release of metal ions, and interaction with intracellular components, as well as their toxicity and long-term effects.

Green synthesis of ZnFe2O4 nanoparticles using plant extracts and their applications: A review.

Magnetic nanoparticles, particularly ZnFe2O4 are of enormous significance in biomedical and water treatment fields. However, chemical synthesis of ZnFe2O4 nanoparticles endures some major limitations, e.g., the use of toxic substances, unsafe procedure, and cost-ineffectiveness. Biological methods are more preferable approaches since they take advantages of biomolecules available in plant extract serving as reducing, capping, and stabilizing agents. Herein, we review plant-mediated synthesis and properties of ZnFe2O4 nanoparticles for multiple applications in catalytic and adsorption performance, biomedical, catalyst, and others. Effect of several factors such as Zn2+/Fe3+/extract ratio, and calcination temperature on morphology, surface chemistry, particle size, magnetism and bandgap energy of obtained ZnFe2O4 nanoparticles was discussed. The photocatalytic activity and adsorption for removal of toxic dyes, antibiotics, and pesticides were also evaluated. Main results of antibacterial, antifungal and anticancer activities for biomedical applications were summarized and compared. Several limitations and prospects of green ZnFe2O4 as an alternative to traditional luminescent powders have been proposed.

A critical review on the bio-mediated green synthesis and multiple applications of magnesium oxide nanoparticles.

Nowadays, advancements in nanotechnology have efficiently solved many global problems, such as environmental pollution, climate change, and infectious diseases. Nano-scaled materials have played a central role in this evolution. Chemical synthesis of nanomaterials, however, required hazardous chemicals, unsafe, eco-unfriendly, and cost-ineffective, calling for green synthesis methods. Here, we review the green synthesis of MgO nanoparticles and their applications in biochemical, environmental remediation, catalysis, and energy production. Green MgO nanoparticles can be safely produced using biomolecules extracted from plants, fungus, bacteria, algae, and lichens. They exhibited fascinating and unique properties in morphology, surface area, particle size, and stabilization. Green MgO nanoparticles served as excellent antimicrobial agents, adsorbents, colorimetric sensors, and had enormous potential in biomedical therapies against cancers, oxidants, diseases, and the sensing detection of dopamine. In addition, green MgO nanoparticles are of great interests in plant pathogens, phytoremediation, plant cell and organ culture, and seed germination in the agricultural sector. This review also highlighted recent advances in using green MgO nanoparticles as nanocatalysts, nano-fertilizers, and nano-pesticides. Thanks to many emerging applications, green MgO nanoparticles can become a promising platform for future studies.

A comparative study on the malachite green dye adsorption of chemically synthesized and green MgFe2O4 nanoparticles using gerbera floral waste extract.

The situation of discharging a large amount of dyes from the textile industries has caused many adverse effects on human health and the ecosystems. Emerging bio-nanomaterials represent a new trend in efficient dye removal in aqueous media. Herein, we mention that MgFe2O4 bioprepared using gerbera extract has been successfully used to adsorb malachite green (MG) in water. A comparison was made to determine the dye removal efficiency between biogenic MgFe2O4 (MFOB) and chemical MgFe2O4 (MFOC). The spherical MFOB material exhibited a large surface area of 85.0 m2 g-1 and high crystallinity. The obtained outcomes showed that the highest adsorption capacity of MG dye was 584.49 mg g-1 at a MFOB dose of 0.05 g L-1 and MG concentration of 10 mg L-1. Higher correlation coefficients in the Langmuir isotherm suggested monolayer adsorption of MG. The Box-Behnken design and response surface method were established to optimize MG removal percentage under the conditions, i.e., initial MG concentration (10-30 mg L-1), adsorbent dose (0.02-0.08 g L-1), and pH of dye solution (6-8). MFOB had good reusability with high removal efficiencies after three continuous cycles. Post reuse, this adsorbent still showed excellent stability through the verification of their structural properties in comparison with fresh MFOB, showing potential for practical applications.

Simultaneous optimization of production yield and sulfadiazine adsorption of MgFe2O4 loaded on prickly pear biochars using Box-Behnken design.

A major challenge that humans facing is the uncontrolled discharge of antibiotic-containing wastewater into the environment, accompanying with huge threats to human community. The utilization of cost-effective biomass-based adsorbents is considered a potential solution for the treatment of antibiotic wastewater. This study aims to optimize the synthesis of MgFe2O4 nanoparticles loaded on prickly pear biochar (PPB) with outstanding sulfadiazine adsorbability using response surface methodology. Thirteen materials (MgFe2O4-PPB) produced based on Box-Behnken design were tested to evaluate the impact of the main factors on the material preparation process, including ratio of MgFe2O4:PPB precursors, calcination temperature and calcination time. Under optimized conditions, i.e., MgFe2O4:PPB ratio 0.5, temperature 600 °C and time 1 h, the production yield of 46.5% and sulfadiazine removal percentage of 85.4% were obtained. Characterization of optimized MgFe2O4-PPB indicated the good porosity and functionality suitable for the adsorption of sulfadiazine. Elovich model showed the best description of kinetic process. Temkin model was considered to be an accurate description of the isotherm adsorption. Proposed mechanism for antibiotic adsorption onto MgFe2O4-PPB was described. We clarify cost-benefit analysis to asses the importance of MgFe2O4-PPB as well as the economic and environmental impacts of biochar-based composites.

Boosting the catalytic activity of nanostructured ZnFe2O4 spinels incorporating with Cu2+ for photo-Fenton degradation under visible light.

Methylene blue (MB) is hazardous in natural water because this dye causes serious diseases that endangers public health and ecosystems. Photocatalytic degradation is a prominent technique for achieving the effective elimination of dye pollutants from wastewater and contribute vitally to ecology and environmental safety. Herein, Cu2+-substituted ZnFe2O4 nanomaterials (CuxZn1-xFe2O4; x = 0, 0.1, 0.2, 0.3, 0.4, 0.6) were synthesized, characterized, and applied for the photocatalytic degradation of MB dye beneath visible light with the assistance of hydrogen peroxide (H2O2). The feature of the photo-catalysts was determined by XRD, EDX, FTIR, DRS, BET, SEM, and TEM techniques. Incorporation of Cu2+ ions changed the crystalline phase, particle size, morphology, and surface area. The photocatalysis condition was optimized with the following major factors, the amout of doping Cu2+ ions, H2O2 concentration, adsorbent dosage, and MB concentration. As a result, the photocatalytic MB degradation efficiency by Cu0.6Zn0.4Fe2O4 catalyst was 99.83% within 90 min under LED light (λ ≥ 420 nm), which was around 4 folds higher than that of pure ZnFe2O4. The photo-Fenton kinetics were in accordance with the pseudo-first-order kinetic model (R2 = 0.981), giving the highes rate constant of 0.034 min-1. It can be, therefore, concluded that Cu2+ substitution considerably boosted the photocatalytic activity of CuxZn1-xFe2O4 ZnFe2O4, suggesting a bright prospect of Cu0.6Zn0.4Fe2O4 as a photo-catalyst in the dyes wastewater treatment.

Recent advances on botanical biosynthesis of nanoparticles for catalytic, water treatment and agricultural applications: A review.

Green synthesis of nanoparticles using plant extracts minimizes the usage of toxic chemicals or energy. Here, we concentrate on the green synthesis of nanoparticles using natural compounds from plant extracts and their applications in catalysis, water treatment and agriculture. Polyphenols, flavonoid, rutin, quercetin, myricetin, kaempferol, coumarin, and gallic acid in the plant extracts engage in the reduction and stabilization of green nanoparticles. Ten types of nanoparticles involving Ag, Au, Cu, Pt, CuO, ZnO, MgO, TiO2, Fe3O4, and ZrO2 with emphasis on their formation mechanism are illuminated. We find that green nanoparticles serve as excellent, and recyclable catalysts for reduction of nitrophenols and synthesis of organic compounds with high yields of 83-100% and at least 5 recycles. Many emerging pollutants such as synthetic dyes, antibiotics, heavy metal and oils are effectively mitigated (90-100%) using green nanoparticles. In agriculture, green nanoparticles efficiently immobilize toxic compounds in soil. They are also sufficient nanopesticides to kill harmful larvae, and nanoinsecticides against dangerous vectors of pathogens. As potential nanofertilizers and nanoagrochemicals, green nanoparticles will open a revolution in green agriculture for sustainable development.