Green synthesis of iron oxide nanoparticles using Terminalia bellirica and Moringa oleifera fruit and leaf extracts: Antioxidant, antibacterial and thermoacoustic properties

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.

A comprehensive review on Moringa oleifera nanoparticles: importance of polyphenols in nanoparticle synthesis, nanoparticle efficacy and their applications

Moringa oleifera is one of the popular functional foods that has been tremendously exploited for synthesis of a vast majority of metal nanoparticles (NPs). The diverse secondary metabolites present in this plant turn it into a green tool for synthesis of different NPs with various biological activities. In this review, we discussed different types of NPs including silver, gold, titanium oxide, iron oxide, and zinc oxide NPs produced from the extract of different parts of M. oleifera. Different parts of M. oleifera take a role as the reducing, stabilizing, capping agent, and depending on the source of extract, the color of solution changes within NP synthesis. We highlighted the role of polyphenols in the synthesis of NPs among major constituents of M. oleifera extract. The different synthesis methods that could lead to the formation of various sizes and shapes of NPs and play crucial role in biomedical application were critically discussed. We further debated the mechanism of interaction of NPs with various sizes and shapes with the cells, and further their clearance from the body. The application of NPs made from M. oleifera extract as anticancer, antimicrobial, wound healing, and water treatment agent were also discussed. Small NPs show better antimicrobial activity, while they can be easily cleared from the body through the kidney. In contrast, large NPs are taken by the mono nuclear phagocyte system (MPS) cells. In case of shape, the NPs with spherical shape penetrate into the bacteria, and show stronger antibacterial activity compared to the NPs with other shapes. Finally, this review aims to correlate the key characteristics of NPs made from M. oleifera extract, such as size and shape, to their interactions with the cells for designing and engineering them for bio-applications and especially for therapeutic purposes.

Potential applications of green-synthesized iron oxide NPs for environmental remediation

Water pollution is a significant issue worldwide due to an increase in anthropogenic activities. Heavy metals and dyes are among the most problematic contaminants that threaten the environment and negatively impact human health. Iron oxide nanoparticles (IONPs) synthesized using green methods have shown potential in these areas due to their significant adsorption capacity and photocatalytic potential. The size and morphology of biogenic IONPs can be tailored depending upon the concentration of the reducing medium and metal salt precursor. Green-synthesized IONPs have been found to be effective, economical, and environmentally friendly with their large surface area, making them suitable for removing toxic matter from contaminated water. Furthermore, they exhibit antibacterial potential against harmful microorganisms. The study emphasizes the importance of using such environmentally friendly tools to remove heavy metal ions and organic compounds from contaminated water. The underlying mechanism for the adsorption of heavy metal ions, photocatalytic degradation of organic compounds, and antimicrobial action has been explored in detail. The future prospective for the beneficial utilization of biogenic IONPs has also been signified to provide a detailed overview.

Moringa oleifera Use in Maintaining Oral Health and Its Potential Use in Regenerative Dentistry

Phytomedicine refers to the use of naturally derived products to cure and mitigate human conditions. Natural products have the advantages of causing minimum side effects, being biocompatible, available, and economical, with a wide array of biological activities. Reports have described the use of natural products with antimicrobial and anti-inflammatory properties to treat oral conditions and promote wound healing. Moringa oleifera, known as the "drumstick" or "horseradish" tree, is believed to have medicinal properties regarding a range of medical conditions, though there is limited information on its use in oral medicine. This narrative review focuses on the use of Moringa extracts in the management of oral conditions, including oral infections, inflammatory conditions, the remineralization of hard tissues, oral wound healing, and tissue regeneration, drawing from both in vitro and in vivo studies which indicate that the potential of Moringa extracts in supporting dentin-pulp regeneration after caries or trauma is worthy of more careful consideration.

Field emission scanning electron microscopic, X-ray diffraction and ultraviolet spectroscopic analysis of Terminalia bellerica based silver nanoparticles and evaluation of their antioxidant, catalytic and antibacterial activity

In recent years, scientists have come up with ways to make nanoparticles that are inexpensive and good for the environment. Terminalia bellerica-based silver nanoparticles (TBAgNPs) were made in this study using methanol extract from T. bellerica fruits. This method was quick, economical, and good for the environment. The biosynthesized TBAgNPs were used as antioxidants, antibacterial agents, and anti-catalytic agents. Analytical techniques like XRD, FESEM, and UV-Vis were used to find out more about the spherical TBAgNPs that were made. Also, Cefotaxime-resistant bacteria found in hospitals were used to test how well the TBAgNPs killed bacteria. With the Bauer-agar Kirby's gel diffusion and Mueller-Hinton broth methods, the ability of the synthesized TBAgNPs to stop bacterial growth was tested. After the TBAgNPs were studied, it was found that the average size of their crystals was between 10 and 25 nm. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) reducing tests showed that these AgNPs could act as antioxidants, and TBAgNPs (%inhibition = 20.90% to 94.94%) were better antioxidant than ascorbic acid (%inhibition = 13.80% to 86.10%) and extract (%inhibition = 16.90% to 80.50%). The reduction of methylene blue (MB) to leucomethylene blue (LMB) with sodium borohydride (NaBH₄) was used as a model to test the catalytic potential of TBAgNPs. On UV spectroscopic analysis at room temperature, TBAgNPs at different concentrations were able to reduce methylene blue effectively. For Escherichia coli and Klebsiella pneumoniae, the minimum inhibitory concentration (MIC) for TBAgNPs was 0.625 μg/mL and 1.25 μg/mL, respectively. Based on these results, silver nanoparticles made with Terminalia bellerica extract may have much biological importance and could be used in making useful therapeutic applications.

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.

Application of Iron Nanoparticle-Based Materials in the Food Industry

Due to their different properties compared to other materials, nanoparticles of iron and iron oxides are increasingly used in the food industry. Food technologists have especially paid attention to their ease of separation by magnetic fields and biocompatibility. Unfortunately, the consumption of increasing amounts of nanoparticles has raised concerns about their biotoxicity. Hence, knowledge about the applicability of iron nanoparticle-based materials in the food industry is needed not only among scientists, but also among all individuals who are involved in food production. The first part of this article describes typical methods of obtaining iron nanoparticles using chemical synthesis and so-called green chemistry. The second part of this article describes the use of iron nanoparticles and iron nanoparticle-based materials for active packaging, including the ability to eliminate oxygen and antimicrobial activity. Then, the possibilities of using the magnetic properties of iron nano-oxides for enzyme immobilization, food analysis, protein purification and mycotoxin and histamine removal from food are described. Other described applications of materials based on iron nanoparticles are the production of artificial enzymes, process control, food fortification and preserving food in a supercooled state. The third part of the article analyzes the biocompatibility of iron nanoparticles, their impact on the human body and the safety of their use.

Fabrication and response optimization of Moringa oleifera-functionalized nanosorbents for the removal of diesel range organics from contaminated water

The purpose of this research is to synthesize environmentally friendly nanosorbents for the novel adsorption of diesel range organics (DRO) from contaminated water. Central composite design (CCD) analysis of response surface methodology (RSM) was employed in a model fitting of the variables predicting the adsorption efficiency of Moringa oleifera-functionalized zerovalent iron particles (ZINPs) for the removal of DRO. The effects of the reaction parameters on the response were screened using 2⁴ factorial designs to determine the statistically significant independent variables. A quadratic model predicting the DRO adsorption efficiency of ZINPs with an F value of 276.84 (p value < 0.0001) was developed. Diagnostic plots show that the predicted values were in excellent agreement with actual experimental values (R² = 0.99). The maximum percentage removal of DRO of 92.6% was achieved after optimization, using the synthesized ZINPs after 8 h of contact between DRO substrates and ZINPs at pH of 8, the temperature of 25 °C, with an adsorbent dosage of 2 g/L and at composite desirability of 1. Characterization of ZINPs revealed the formation of quasi nanospheres and nanocubes with an average particle diameter of 50.9 ± 9.7, a crystallite size of 15.31 nm, a crystallinity index of 32.47% and a pore width of 75.69-88.59 nm. The adsorption equilibrium data modelling of ZINPs for adsorption of DRO was best described by Langmuir isotherm with the maximum monolayer coverage capacity of 7.194 mg/g. The separation factor [Formula: see text], indicated favourable adsorption. The adsorption kinetic data were consistent with pseudo-second-order kinetics indicating probable chemisorption.

Green Biosynthesis of Silver Nanoparticles from Moringa oleifera Leaves and Its Antimicrobial and Cytotoxicity Activities

The plant occupied the largest area in the biosynthesis of silver nanoparticles, especially the medicinal plants, and it has shown great potential in biotechnology applications. In this study, green synthesis of silver nanoparticles from Moringa oleifera leaves extract and its antifungal and antitumor activities were investigated. The formation of silver nanoparticles was observed after 1 hour of preparation color changing. The ultraviolet and visible spectrum, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques were used to characterize synthesis particles. Ultraviolet and visible spectroscopy showed a silver surface plasmon resonance band at 434 nm. Fourier transform infrared analysis shows the possible interactions between silver and bioactive molecules in Moringa oleifera leaves extracts, which may be responsible for the synthesis and stabilization of silver nanoparticles. X-ray diffraction showed that the particles were a semicubic crystal structure and with a size of 38.495 nm. Scanning electron microscopy imaging shows that the atoms are spherical in shape and the average size is 17 nm. The transmission electron microscopy image demonstrated that AgNPs were spherical and semispherical particles with an average of (50–60) nm. The nanoparticles also showed potent antimicrobial activity against pathogenic bacteria and fungi using the well diffusion method. Candida glabrata found that the concentration of 1000 μg/mL exhibited the highest inhibition. As for bacteria, the concentration of 1000 μg/mL appeared to be the inhibition against Staphylococcus aureus. Moringa oleifera AgNPs inhibited human melanoma cells A375 line significant concentration-dependent cytotoxic effects. The powerful bioactivity of the green synthesized silver nanoparticles from medical plants recommends their biomedical use as antimicrobial as well as cytotoxic agents.

Cefotaxime removal enhancement via bio-nanophotocatalyst α-Fe2O3 using photocatalytic degradation technique and its echo-biomedical applications

The present paper evaluates the photocatalytic degradation (PCD) performance of the biofabricated hematite nanoparticles (α-HNPs) for the degradation approach of the Cefotaxime (Cfm). The optimum pH of the solution to achieve the best PCD was found to be 10.5. The kinetics study for the PCD of the Cfm via α-HNPs has been investigated and the reaction was found to be fellow pseudo-first-order at R² = 0.992. The mass loading impact of α-HNPs was investigated and estimated for the maximum degradation of Cfm 0.4 mg/mL. UV–Vis confirmed that α-HNPs had a direct transition bandgap at 3.78 eV at a maximum absorption wavelength of 362 nm with suspension stability for 7 days. The probable mechanism of the Cfm PCD via α-HNPs and the degradation pathway was conducted. The validation of the suspension stability of the α-HNPs (−68.6 ± 11.8 mV) was determined using the zeta potential investigation test. XRD investigation was conducted after Cfm PCD showing an average crystallite size of 27.0 nm. XRD, TEM, SEM, EDX, and FT-IR analyses have been conducted for the α-HNPs before and after Cfm PCD confirming the high efficiency for the reusability of the current biocatalyst α-HNPs for further use. TEM results of the particle sizes of α-HNPs were found at 19.2 ± 4.4 and 20.6 ± 7.4 nm respectively before and after Cfm PCD. The efficiency of the Cfm PCD was found to be 99.1% after 6 h. High potent as an antibacterial agent of α-HNPs was investigated either α-HNPs alone or after its PCD activity against Cfm. The antibacterial activity revealed high sensitivity, especially toward Gram-positive species indicating its promising ability against pathogenic issues. Interestingly, Cfm@α-HNPs showed superior anti-proliferative activity as tested by MTT assay and were able to induce apoptosis in MCF7 and HepG2 cell lines using the flow cytometry technique at 20.7% and 17% respectively. Also, The IC₅₀ of hydrogen peroxide scavenging was estimated and it was manifested that 635.8 and 665.6 μg/mL of α-HNPs before and after the PCD process of Cfm respectively.

Green synthesis and characterization of iron-oxide nanoparticles using Moringa oleifera: a potential protocol for use in low and middle income countries

Objective

Green synthesized iron(III) oxide (Fe₃O₄) nanoparticles are gaining appeal in targeted drug delivery systems because of their low cost, fast processing and nontoxicity. However, there is no known research work undertaken in the production of green synthesized nano-particles from the Ugandan grown Moringa Oleifera (MO). This study aims at exploring and developing an optimized protocol aimed at producing such nanoparticles from the Ugandan grown Moringa.

Results

While reducing ferric chloride solution with Moringa oleifera leaves, Iron oxide nanoparticles (Fe₃O₄-NPs) were synthesized through an economical and completely green biosynthetic method. The structural properties of these Fe₃O₄-NPs were investigated by Ultra Violet–visible (UV–Vis) spectrophotometry, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). These nanoparticles exhibited UV–visible absorption peaks at 225 nm (nm) for the sixth dilution and 228 nm for the fifth dilution which indicated that the nanoparticles were photosensitive and the SEM study confirmed the spherical nature of these nanoparticles. The total synthesis time was approximately 5 h after drying the moringa leaves, and the average particle size was approximately 16 nm. Such synthesized nanoparticles can potentially be useful for drug delivery, especially in Low and Middle Income Countries (LMICs).

Iron Oxide Nanoparticles-Plant Insignia Synthesis with Favorable Biomedical Activities and Less Toxicity, in the “Era of the-Green”: A Systematic Review

In the era of favoring environment-friendly approaches for pharmaceutical synthesis, “green synthesis” is expanding. Green-based nanomedicine (NM), being less toxic and if having biomedical acceptable activities, thence, the chemical methods of synthesis are to be replaced by plants for reductive synthesis. Iron oxide nanoparticles (IONPs) exhibited remarkable anti-microbial and anti-cancer properties, besides being a drug delivery tool. However, owing to limitations related to the chemical synthetic method, plant-mediated green synthesis has been recognized as a promising alternative synthetic method. This systematic review (SR) is addressing plant-based IONPs green synthesis, characteristics, and toxicity studies as well as their potential biomedical applications. Furthermore, the plant-based green-synthesized IONPs in comparison to nanoparticles (NPs) synthesized via other conventional methods, characteristics, and efficacy or toxicity profiles would be mentioned (if available). Search strategy design utilized electronic databases including Science Direct, PubMed, and Google Scholar search. Selection criteria included recent clinical studies, available in the English language, published till PROSPERO registration. After screening articles obtained by first electronic database search, by title, abstract and applying the PICO criteria, the search results yielded a total of 453 articles. After further full text filtrations only 48 articles were included. In conclusion, the current SR emphasizes the perspective of the IONPs plant-mediated green synthesis advantage(s) when utilized in the biomedical pharmaceutical field, with less toxicity.

Comparative analysis of iron oxide nanoparticles synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum cyminum) to induce resistance in wheat against drought stress

In the present study, iron oxide nanoparticles (Fe3O2-NPs) synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum Cyminum L.) extracts were investigated to reveal their potential to enhance the growth and drought resistance of wheat plants under drought stress. In an In Vitro experiment, four different concentrations for Fe3O2-NPs (0.3 mM, 0.6 mM, 0.9 mM, and 1.2 mM) of ginger and cumin seeds were tested. Among all the concentrations tested, ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) were more effective to enhance wheat germination, biomass, and survival percentage under drought stress and irrigated conditions than the non-treated control plant. In a pot experiment, wheat plants under induced water stress showed marked up-regulation in the biochemical resistance mechanisms when treated with ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) than the non-treated control. Cumin seeds Fe3O2-NPs (1.2 mM) were more effective than ginger Fe3O2-NPs (0.6 mM) in ameliorating adverse effects of drought stress in wheat. Results demonstrated that cumin seeds Fe3O2-NPs (1.2 mM) exhibited a higher increase in chlorophyll a, b and carotenoids (72%, 265% and 96% respectively), proline (127%), superoxide dismutase (115%), peroxidase (43.8%), ascorbate peroxidase (44.6%). This also showed higher reduction in lipid peroxidation, electrolyte leakage and increased soluble sugars and total Fe content in the roots and shoots than non-treated plants under drought. Hence, nano-priming can be considered an effective strategy for sustainable food production in marginal soils.

Biosynthesis of chitosan-coated iron oxide (Fe3O4) hybrid nanocomposites from leaf extracts of Brassica oleracea L. and study on their antibacterial potentials

In this study, we prepared chitosan (CS)-coated iron oxide (Fe₃O₄) nanocomposites (NCs) by employing the aqueous leaf extract of Brassica oleracea L. and evaluated its antimicrobial potential. The characterization of hybrid CS-Fe₃O₄ NCs was performed using Fourier-transform infrared spectroscopy (FTIR) analysis to evaluate the chemical bonding of chitosan to nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) studies revealed the presence of oxidation state elements Fe 2p, O 1s, N 1s, and C 1s, and the zeta potential analysis was found to have well-colloidal stability (+ 76.9 mV) of NCs. Transmission electron microscopy (TEM) analysis determined that CS-Fe₃O₄ NCs were spherical with an average particle size of 27 nm. The X-ray diffractometer (XRD) spectrum ascertained the crystallinity of the hybrid NCs and the vibrating sample magnetometer (VSM) inferred the ferromagnetic behavior of the synthesized NCs. Furthermore, the significant antibacterial efficacy of NPs was demonstrated against foodborne bacterial pathogens, such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and the highest zone of inhibition was observed to be 11.5 mm and 13.5 mm in CS-Fe₃O₄ NCs, respectively. In comparison with Fe₃O₄ NPs, synergistic impacts of CS-Fe₃O₄ NCs displayed great antibacterial potential as exhibited by a clearly enlarged zone. Thus, CS-Fe₃O₄ NCs could be used as efficacious antimicrobial agents in food packaging and food preservation fields.

Environmental Sustainability Evaluation of Iron Oxide Nanoparticles Synthesized via Green Synthesis and the Coprecipitation Method: A Comparative Life Cycle Assessment Study

Green synthesis, based on green chemistry, is replacing the traditional methods, aiming to contribute with an enhanced environmental sustainability, which can be achieved using nontoxic compounds from biological resources, such as natural extracts from plants. In this study, the life cycle assessment (LCA) of iron oxide nanoparticles prepared through the green synthesis and the coprecipitation method is reported by following a cradle-to-gate approach. The LCA allowed quantifying and normalized the environmental impacts produced by the green synthesis (1.0 × 10-9), which used a Cymbopogon citratus (C. citratus) extract and sodium carbonate (Na2CO3). The impacts were also determined for the coprecipitation method (1.4 × 10-8) using the iron(II) salt precursor and sodium hydroxide (NaOH). The contribution of C. citratus extract and Na2CO3 as the precursor and pH-stabilizing agents, respectively, was compared regarding the iron(II) and NaOH compounds. Environmental sustainability was evaluated in human toxicity, ecosystem quality, and resource depletion. The major environmental contribution was found in the marine aquatic ecotoxicity (7.6 × 10-10 and 1.22 × 10-8 for green synthesis and the coprecipitation method) due to the highest values for ethanol (3.5 × 10-10) and electricity (1.4 × 10-8) usage since fossil fuels and wastewater are involved in their production. The C. citratus extract (2.5 × 10-12) presented a better environmental performance, whereas Na2CO3 (4.3 × 10-11) showed a slight increase contribution compared to NaOH (4.1 × 10-11). This is related to their fabrication, involving toxic compounds, land occupation, and excessive water usage. In general, the total environmental impacts are lower for the green synthesis, suggesting the implementation of environmentally friendlier compounds based on natural sources for the production of nanomaterials.

A review of green methods for phyto-fabrication of hematite (α-Fe2O3) nanoparticles and their characterization, properties, and applications

The aim of the current work is the introduction of a quick and simple literature survey about the bio-fabrication of the Alpha Hematite nanoparticles (α-Fe₂O₃) using the plant extracts green method. The survey manifested the utilities of the environmentally friendly biosynthesis methods via extracting different plant species, some of its important physicochemical properties, various instrumental analysis characterization tools, and potential applications.

A plant-mediated synthesis of nanostructured hydroxyapatite for biomedical applications: a review

The engineering of calcium-based phosphate materials at the nanoscale gains several unique properties compared to the bulky state. The effort to scale down, e.g., from bulky state to nanoscale in order to control the morphology and improve structural properties requires the use of varying reagents that can be detrimental to the environment. A typical example of these materials is hydroxyapatite (HAp), one of the well-known calcium phosphate materials, which has a close resemblance to human bone tissue. HAp has valuable applications in catalysis, drug delivery, bone and dental implant formation, and adsorption. Hydroxyapatite-based nanomaterials synthesized through conventional routes make use of reagents that are not environmental friendly and are very costly. Since the current research trends are geared towards producing/synthesizing nanomaterials through an eco-friendly approach, there is the need to consider the techniques and reagents involved in the synthesis of HAp. This review touches on the possible replacement of such synthetic chemical reagents, synthesis routes, and toxic capping agents with plant extracts for synthesizing HAp-based nanomaterials for multi-functional applications. The influence of biomolecules from plants on synthesized HAps and the attainable mechanism during these green approaches are discussed. Viable future modifications of the methods used to obtain extracts from plants are also studied.

Ionic Cross-Linking Fabrication of Chitosan-Based Beads Modified with FeO and TiO2 Nanoparticles: Adsorption Mechanism toward Naphthalene Removal in Seawater from Cartagena Bay Area

Polycyclic aromatic hydrocarbons (PAHs) are complex molecules produced by the thermal decomposition of organic matter in anthropogenic activities. Novel composites with enhanced physicochemical properties aim to overcome limitations such as adsorption capacity, affinity, and stability for PAHs adsorption. Composites based on chitosan are promising due to the good biocompatibility and adsorption properties. This study focuses on the facile preparation of chitosan beads modified with iron oxide (FeO) and titanium dioxide (TiO₂) nanoparticles via ionic cross-linking (Ch-FeO/TiO₂). FeO and TiO₂ were synthesized performing co-precipitation and green chemistry methods, respectively. The characterization evidenced the formation of Ch-FeO/TiO₂ with good crystallinity, excellent thermal stability, and superparamagnetic response, attributed to the presence of FeO and TiO₂ nanoparticles. High thermal stability up to 270 °C was related to the cross-linked chitosan network. The enhanced adsorption mechanism of Ch-FeO/TiO₂ was determined by removing naphthalene from water and seawater samples. The Ch-FeO/TiO₂ showed a higher adsorption capacity of 33.1 mg/g compared to 29.8 mg/g of the unmodified chitosan (un-Ch) beads. This is due to the higher functional surface area of 27.13 m²/g, compared to that of 0.708 m²/g for un-Ch. We found a rapid adsorption rate of 240 min and the maximum adsorption capacity of 149.3 mg/g for Ch-FeO/TiO₂. A large number of actives sites allows for increasing the naphthalene molecules interaction. Adsorption in seawater samples from Cartagena Bay (Colombia) exhibits an outstanding efficiency of up to 90%. These results suggest a promising, cheap, and environmentally friendly composite for remediation of water sources contaminated with complex compounds.