Green synthesis, characterization, and application of metal oxide nanoparticles for mercury removal from aqueous solution

Synergistic effects of Fe3O4-NPs and Enterobacter cloacae in alleviating mercury stress in wheat (Triticum aestivum L.): Insights into morpho-physio-biochemicals attributes

In the current industrial scenario, mercury (Hg) as a metal is of great importance but poses a major threat to the ecosystem because of its toxicity, but fewer studies have been conducted on its effects and alleviation strategies by using nanoparticles (NPs) and plant growth promoting rhizobacteria (PGPR). Taking into consideration the positive effects of iron oxide (Fe3O4)⎯NPs and Enterobacter cloacae rhizobacteria in reducing Hg toxicity in plants, the present study was conducted. A pot experiment was conducted over 60 days using wheat (Triticum aestivum L.) to investigate the effects of varying Hg levels (0, 50 and 100 mg kg⎯1) combined with different concentrations of Fe3O4-NPs (25 and 50 mg L-1) and E. cloacae (10 and 20 ppm) on various morpho-physio-biochemical responses. The research outcomes indicated that elevated levels of Hg stress in the soil significantly (P < 0.05) decreased plant growth and biomass, photosynthetic pigments, nutrients uptake and gas exchange attributes. However, Hg stress also induced oxidative stress in the plants by increasing malondialdehyde (MDA) and hydrogen peroxide (H2O2), which also induced increased compounds of various enzymatic and non-enzymatic antioxidants and also the gene expression and sugar content. Furthermore, a significant (P < 0.05) increase in proline metabolism, the ascorbate-glutathione (AsA-GSH) cycle were observed. Although, the application of Fe3O4-NPs and E. cloacae showed a significant (P < 0.05) increase in plant growth and biomass, nutrients uptake, gas exchange characteristics, enzymatic and non-enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of Fe3O4-NPs and E. cloacae enhanced cellular fractionation and decreased the proline metabolism and AsA-GSH cycle in T. aestivum seedlings. Research findings, therefore, suggest that the application of Fe3O4-NPs and E. cloacae can ameliorate Hg toxicity in T. aestivum seedlings, resulting in improved plant growth and composition under metal stress, as depicted by balanced antioxidant defense mechanism.

Enhanced photocatalytic degradation of malachite green and trypan blue using 3-aminopropyl triethoxysilane (APTES) functionalized iron oxide nanocomposite

Biochar-capped iron oxide nanoparticle functionalized with 3-aminopropyl triethoxysilane (APTES) was synthesized and used as photocatalysts for the degradation of malachite green (MG) and trypan blue (TPB) dyes. Powder X-ray diffraction patterns confirmed the crystalline cubic spinel structure of Fe3O4. HRTEM image shows nanocomposites with an average particle size of 22.4 nm, interplanar spacings of 0.297 nm and 0.245 nm, which correspond to the (220) and (222) planes of Fe3O4. SAED patterns indicate that Fe3O4@BC/APTES nanocomposite is polycrystalline. The energy bandgap of the biochar-capped iron oxide nanoparticles was reduced from 3.47 to 2.85 eV after functionalization with APTES. Photocatalytic degradation potential of the nanocomposite was evaluated with malachite green (MG) and trypan blue (TPB) dyes using the response surface methodology based on the Box-Behnken design (RSM-BDD). The optimal degradation efficiency from RSM-BBD for MG was 99.94% with a catalyst dosage of 7.5 mg, dye concentration of 50 ppm, and pH of 9 for 105 min. The optimum parameters for TPB were found to be a concentration of 30 ppm, a catalyst dosage of 12 mg, a pH of 5, and 85.77% of degradation after 90 min. Reusability studies show that the nanocomposite can be reused five times without significant reduction in the photocatalytic degradation efficiency.

Advancement in nanomaterials for environmental pollutants remediation: a systematic review on bibliometrics analysis, material types, synthesis pathways, and related mechanisms

Environmental pollution is a major issue that requires effective solutions. Nanomaterials (NMs) have emerged as promising candidates for pollution remediation due to their unique properties. This review paper provides a systematic analysis of the potential of NMs for environmental pollution remediation compared to conventional techniques. It elaborates on several aspects, including conventional and advanced techniques for removing pollutants, classification of NMs (organic, inorganic, and composite base). The efficiency of NMs in remediation of pollutants depends on their dispersion and retention, with each type of NM having different advantages and disadvantages. Various synthesis pathways for NMs, including traditional synthesis (chemical and physical) and biological synthesis pathways, mechanisms of reaction for pollutants removal using NMs, such as adsorption, filtration, disinfection, photocatalysis, and oxidation, also are evaluated. Additionally, this review presents suggestions for future investigation strategies to improve the efficacy of NMs in environmental remediation. The research so far provides strong evidence that NMs could effectively remove contaminants and may be valuable assets for various industrial purposes. However, further research and development are necessary to fully realize this potential, such as exploring new synthesis pathways and improving the dispersion and retention of NMs in the environment. Furthermore, there is a need to compare the efficacy of different types of NMs for remediating specific pollutants. Overall, this review highlights the immense potential of NMs for mitigating environmental pollutants and calls for more research in this direction.

Iron Oxide Nanoparticles: Green Synthesis and Their Antimicrobial Activity

The rise of antimicrobial resistance caused by inappropriate use of these agents in various settings has become a global health threat. Nanotechnology offers the potential for the synthesis of nanoparticles (NPs) with antimicrobial activity, such as iron oxide nanoparticles (IONPs). The use of IONPs is a promising way to overcome antimicrobial resistance or pathogenicity because of their ability to interact with several biological molecules and to inhibit microbial growth. In this review, we outline the pivotal findings over the past decade concerning methods for the green synthesis of IONPs using bacteria, fungi, plants, and organic waste. Subsequently, we delve into the primary challenges encountered in green synthesis utilizing diverse organisms and organic materials. Furthermore, we compile the most common methods employed for the characterization of these IONPs. To conclude, we highlight the applications of these IONPs as promising antibacterial, antifungal, antiparasitic, and antiviral agents.

Magnetic biopolymers' nanocomposites from chitosan, lignin and phycosynthesized iron nanoparticles to remediate water from polluting oil

Targeting the remediation of oil pollution in water, the construction of super magnetic adsorbent nanocomposites (NCs) was achieved using the nanoparticles of chitosan (Cht), lignin (Lg) and phycosynthesized iron nanoparticles (Fe MNPs) using Gelidium amansii extract. The syntheses and conjugations of nanomaterials were authenticated via infrared spectral analysis and the structural physiognomies of them were appraised via electron microscopy and zeta analysis. The Lg NPs, Cht NPs, Fe MNPs and their composites (Lg/Cht MNCs) had mean particles' sizes of 42.3, 76.4, 14.2 and 108.3 nm, and were charged with - 32.7, + 41.2, + 28.4 and +37.5 mV, respectively. The magnetometer revealed the high magnetic properties of both Fe MNPs and Lg/Cht MNCs; the maximum swelling of Lg/Cht NPs (46.3 %), and Lg/Cht MNPs (33.8 %) was detected after 175 min. The diesel oil adsorption experiments with Lg/Cht MNPs, using batch adsorption practices, revealed the powerful potentiality of magnetic NCs to remove oil pollution in water; the maximum adsorption capacity (qt) was achieved with the conditions of pH = 7.5, adsorption period = 90 min and adsorbent dose = 200 mg/L. The magnetic Lg/Cht MNCs exhibited excellent recovery/reusability attributes for five adsorption cycles; the qt differences were negligible after the entire oil-adsorption cycles, with oil removal of >90 %. The innovative fabricated Lg/Cht MNCs could provide an effectual, sustainable and eco-friendly approach for the removal of pollutant oil in water resources.