Use of pineapple peel extract as a mediator in the green synthesis of magnesium oxide nanoparticles.

Description

1 / 14 “USE OF ANANANAS COMOSUS PEEL EXTRACT AS A MEDIATOR IN THE GREEN SYNTHESIS OF MAGNESIUM OXIDE NANOPARTICLES” FIELD OF THE INVENTION

[01] This application is applied in the field of agriculture, livestock, forestry, fishing and aquaculture: agriculture, livestock and related services (agronomy) and, more specifically, refers to a process for synthesizing input for the fertilizer industry using sustainable waste as mediating agents. BACKGROUND

[02] The explosive population growth in the last decade has increased the pressure on the agricultural sector to increase crop productivity, especially in developing countries, where nutrient deficiency in the soil causes significant economic losses and impairs the nutritional quality of crops for humans and animals (Boserup, 1988; Gollin, 2010; Maja; Ayano, 2021). In this scenario, soil fertilization becomes essential for restoring its fertility and increasing production.

[03] Plants require a wide range of minerals for their growth, development, and fruit production, which play vital roles in metabolic and cellular processes (Evans; Sorger, 1966). However, intensive agricultural practices lead to the depletion of soil nutrients, making their replenishment imperative to ensure healthy crop growth (Li et al., 2022; Shah; Wu, 2019). In this scenario, fertilizer application is a widely used solution, providing essential macronutrients such as magnesium (Mg), which promotes the recovery of soil fertility and sustainable agricultural production (Gram et al., 2020; Pandit et al., 2022; Quan et al., 2021; Xu et al., 2012). Petition 870240109461, dated 12 / 23 / 2024, page 8 / 34 2 / 14

[04] Magnesium oxide (MgO) stands out as a source of magnesium, an essential component of chlorophyll and fundamental for photosynthesis, in addition to activating enzymes that participate in energy metabolism and protein synthesis (Ahmed et al., 2023; Chen et al., 2018; Faizan et al., 2022). The application of MgO to the soil increases photosynthetic efficiency, improves nutrient absorption, and increases agricultural productivity. Furthermore, MgO acts as an acidity corrector, favoring root development and nutrient absorption. The introduction of nanostructured MgO, produced by green synthesis, offers even more advantages, such as greater efficiency in magnesium release and less environmental impact, being promising in the development of nanofertilizers (Abinaya et al., 2021; Ahmed et al., 2021).

[05] Green synthesis of nanomaterials emerges as a sustainable alternative to traditional chemical and physical synthesis methods, using natural components as reducing and stabilizing agents, minimizing environmental impacts and risks to human health. MgO synthesized by green routes has gained attention due to its versatile properties, with promising applications in areas such as medicine, industry and agriculture (Abinaya et al., 2021; Silva et al., 2022; Verma et al., 2020).

[06] An innovative example of this approach is the synthesis of MgO using agricultural waste, such as pineapple peel, which is widely available in Brazil (Agyapong et al., 2023; Ahmed et al., 2021; Jeevanandam; Chan; Danquah, 2017). Pineapples generate a large amount of waste, such as peels, leaves, and crowns, which are often disposed of improperly, contributing to environmental pollution and the release of greenhouse gases (Sarangi et al., 2023; Upadhyay; Lama; Tawata, 2013). The reuse of pineapple peel, rich in bioactive compounds such as cellulose, hemicellulose, and lignin, presents great potential, Petition 870240109461, dated 12 / 23 / 2024, page 9 / 34 3 / 14 inclusive for the synthesis of nanomaterials. Thus, its use in the green synthesis of MgO represents a sustainable solution that mitigates environmental impacts and takes advantage of agricultural waste (Bardiya et al., 1996; Rani & Nand, 2004).

[07] The state of the art provides a few examples of the use of Ananas comosus peel extract as a mediator in the green synthesis of MgO nanoparticles.

[08] Document CN108424124, for example, describes a magnesium oxide-based crucible reinforced with in situ synthesized magnesium oxide that allows sintering at low temperature and exhibits excellent chemical stability and thermal shock resistance. The preparation method includes steps such as mixing nanoalumina sol, rheological agent and magnesium oxide ceramic powder with titanium dioxide, followed by sintering at high temperatures and vacuum impregnation with alumina sol.

[09] Document CN108707027 describes an ecological fertilizer based on lotus root, composed of raw materials such as organic fertilizer, ammonium chloride, fishbone powder, potassium and magnesium sulfate, among others, with the addition of a slow-release synergist and micronutrients. The objective is to optimize plant nutrition and improve fertilization efficiency.

[010] Document CN110183262, in turn, describes a specific foliar fertilizer to prevent cracking in the carpodium and fruits of Ananas comosus. The fertilizer contains potassium, calcium, magnesium, and boron, in proportions that increase the mechanical resistance of the plant's cell walls. Its application occurs between the period of slow growth and the appearance of the red coloration of the fruits, reducing the cracking rate to as little as 1%.

[011] Document CN117142900 aims to develop an organic fertilizer from green tangerine peel, combined with inorganic nutrients, for Petition 870240109461, dated 12 / 23 / 2024, page 10 / 34 4 / 14 meet the specific nutritional needs of macadamia trees in different growth stages, improving soil and productivity.

[012] In document CN118064154, the method for preparing an agent for soil remediation is described, and the agent is characterized by being composed of magnesium oxide nano biochar, the magnesium oxide nano biochar comprising activated carbon prepared from palm husks and magnesium oxide nano based on azadirachtin extract. The magnesium oxide nano biochar is obtained by adding magnesium oxide nano based on azadirachtin extract to activated carbon prepared from palm husks. The synthesis process is environmentally friendly and pollution-free, and the cost is low. Meanwhile, the method has a very good removal rate of cadmium and dibutyl phthalate in polluted soil.

[013] Finally, in document CN118287043, the biochar-loaded superfine magnesium oxide nanomaterial, as well as a method for its preparation and application, is described. The method comprises the following steps: immersing cellulose biomass in a magnesium salt solution to obtain a solid matter; mixing and stirring the solid matter and an alkaline solution to obtain a stirred matter, and washing and drying the stirred matter to obtain a precursor; and pyrolysis of the precursor in an inert atmosphere to obtain the carbon-loaded superfine magnesium oxide nanomaterial. According to the invention, cellulose biomass is used as raw material, magnesium oxide nano is loaded onto the biochar, and a material with a large amount of surface-loaded superfine magnesium oxide nano is obtained using different types of magnesium salts, a precipitation process, an oxygen-limited environment, and a large number of pores in the biochar.The material has a high adsorption capacity and is beneficial for the effective treatment of wastewater. Petition 870240109461, dated 12 / 23 / 2024, page 11 / 34 5 / 14

[014] It is clear that the state of the art does not yet explore the subject matter of the present application, although some documents use pineapple peel and others target magnesium oxide, none of them uses the procedures described and the application of the present application. SUMMARY OF THE INVENTION

[015] The objective of this application can be outlined in two main aspects: (1) mitigating the waste generated by the disposal of pineapple peel, promoting the valorization of this material as a sustainable resource; and (2) reducing the dependence on magnesium oxide (MgO) in agricultural practices by obtaining an innovative nanofertilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[016] Figure 1 shows an illustrative diagram of the complete synthesis steps according to the present application.

[017] Figure 2 illustrates a detailed green synthesis process of magnesium oxide nanoparticles.

[018] Figure 3 shows an illustration of results obtained through the characterizations of MgO-Np.

[019] Figure 4 shows a representation of the initial samples of different concentrations of the Pérola pineapple peel extract solution.

[020] Figure 5 corresponds to: a) Transmission microscopy of MgO; b) X-ray diffraction of MgO.

[021] Figure 6 corresponds to energy dispersive spectroscopy results for magnesium oxide.

[022] Figure 7 corresponds to: a) Germination data of carrot seeds; b) dry mass of carrot seeds; c) length of beet seeds. Petition 870240109461, dated 12 / 23 / 2024, page 12 / 34 6 / 14

[023] Figure 8 illustrates: a) Germination of beet seeds with water, MgO nanoparticles (MgO-Np), and a commercial non-nano oxide; b) germination of carrot seeds with water, MgO nanoparticles (MgO-Np), and a commercial non-nano oxide. DETAILED DESCRIPTION OF THE INVENTION

[024] The peel of the Pérola variety pineapple, which would be discarded after consumption, is initially crushed in a knife mill and then washed three times with distilled water. After washing, the peels are dried in an oven at 60 °C for 5 h, weighed and prepared for extraction of the extract.

[025] A total of 100 g of dried bark is mixed in 1 l of distilled water (1:10 ratio), followed by stirring and heating on a hot plate for 30 min at 60 °C. Subsequently, it is filtered and 150 mL of the extracted solution is removed and combined with 50 mL of a 0.75 molar magnesium chloride hexahydrate solution (3:1 ratio). The pH of the solution is adjusted with the help of NaOH (5 mL), where it goes from pH 3.5 to pH 10, resulting in the formation of a precipitate.

[026] Next, the solution is transferred to a hydrothermal reactor (Figure 1), and kept under agitation at 500 rpm at 100 °C for 3 h. After this period, the solution is centrifuged three times for 15 min, with the addition of distilled water between centrifugations for washing and removal of the supernatant, using a speed of 4000 rpm.

[027] At the end of the process, the sedimented material is dried in a crucible in an oven for 24 h, then calcined at 600 °C for 2 h in a muffle furnace. After calcination, the sample is macerated with a pestle and the necessary characterizations of the material are carried out.

[028] The scheme presented in Figure 2 illustrates a green synthesis process of magnesium oxide (MgO) nanoparticles, structured in Petition 870240109461, dated 12 / 23 / 2024, page 13 / 34 7 / 14 four main stages. Initially, an aqueous extract is produced from pineapple peel, an agro-industrial residue rich in bioactive compounds such as tannins, proteins, carotenoids, gallic acid, and bromelain, essential for the process. This extract, obtained by hot water extraction, solubilizes the bioactive compounds that will act as stabilizing and reducing agents in the subsequent stage. During the stabilization and reduction reaction, these compounds promote the formation and stabilization of nanoparticles, preventing their agglomeration and favoring their stability in solution. Tannins form complexes with magnesium ions (Mg2+), while proteins, biosurfactants, and carotenoids contribute to reduction and stabilization.

[029] In the synthesis step, the reaction mixture containing the extract and MgO precursors is subjected to heating and agitation, crucial parameters for determining the size and morphology of the nanoparticles. After the reaction, the product is purified by centrifugation, obtaining nanoparticles with high surface area and reactivity. These characteristics make nanometric MgO promising for applications in agribusiness, including efficient fertilization and disease control due to its antimicrobial properties. Thus, the process represents a sustainable alternative by utilizing agro-industrial waste and minimizing the use of chemicals, standing out as an innovative approach for agriculture. Further studies, however, are needed to validate its efficacy and safety on a large scale.

[030] Characterizations were performed such as: XRD (X-ray diffraction) to determine the crystalline structure and phase of the materials, providing information on the atomic organization of the compound; FTIR (Fourier Transform Infrared Spectroscopy) to identify functional groups and chemical bonds present in the material, analyzing the interaction of infrared radiation with the Petition 870240109461, dated 12 / 23 / 2024, page 14 / 34 8 / 14 molecules; FEG-SEM (Field Emission Scanning Electron Microscopy) to obtain high-resolution images of the material's surface, allowing for morphological and topographic analysis; TEM (Transmission Electron Microscopy) to examine the internal structure and microstructure of the material at the atomic level, offering detailed information on the arrangement of atoms; EDS (Energy Dispersive Spectroscopy) to analyze the elemental composition of the material, identifying the elements present and their proportions; DLS (Dynamic Light Diffraction Spectroscopy) to measure the size distribution of particles in suspension, helping to understand the homogeneity and stability of the dispersion; Zeta potential to evaluate the stability of colloidal particles in suspension, indicating the tendency for aggregation or dispersion based on the electrical charge of the particles;TGA (Thermogravimetric Analysis) is used to evaluate the thermal stability of the material, quantifying mass loss as a function of temperature and identifying decomposition processes, as shown in Figure 3.

[031] Initially, concentration tests were performed with solutions of extract from the peel of Pérola pineapple (acquired from local commerce), a common variety in Brazil. The concentrations tested were 25 g / L, 50 g / L, and 100 g / L, keeping the precursor solution of MgCl2^6H2O constant at 0.75 M and 50 °C. After 3 h of synthesis in a hydrothermal reactor, the samples were centrifuged, dried in an oven for 24 h, and then calcined at 600 °C for 2 h. The resulting samples were analyzed by XRD to verify the crystalline structure and phase of the materials, all being characterized as periclase (MgO), according to the JCPDS 780439 standard. However, each sample presented different crystallite sizes, as illustrated in Figure 4.

[032] The observed trend was consistent with the literature, where higher extract concentrations tend to reduce crystallite size (Fan et al., 2023; Petition 870240109461, dated 12 / 23 / 2024, page 15 / 34 9 / 14 (Otsuka; Kondo; Suzuki, 2024; Spanhel; Anderson, 1991). Thus, the concentration of 100 g / L, which provided the highest yield, was used in subsequent syntheses to test different temperatures (100 °C, 75 °C, and 50 °C) and precursor concentrations (0.25 M, 0.50 M, and 0.75 M). The best yield (44%) was obtained with the synthesis at 100 °C and 0.75 M, and the sample was then characterized and applied. In electron microscopy and X-ray diffraction analyses (Figure 5), it was observed that the material is monocrystalline, with crystals (33.7 nm) of equivalent size to the particles (34.1 nm), which confirms the structural uniformity of the product, indicating the formation of magnesium oxide nanoparticles.

[033] In addition, the sample was characterized by Energy Dispersive Spectroscopy (EDS) in order to determine the elemental composition of the material, identifying the elements present and their respective proportions. According to the results obtained, the analysis indicated that the sample is composed entirely of the expected elements (Magnesium and Oxygen), as illustrated in Figure 6.

[034] Evident peaks in the spectrum at 0.5 keV correspond to oxygen electronic transitions and at 1.25 keV to magnesium transitions, while the peak between 2.1 keV - 2.5 keV is attributed to carbon electronic transitions present in the conductive tape used for fixing and electrical contact of the sample in the stub (Rempel et al., 2020; Selvam et al., 2011).

[035] The synthesized MgO-Np (nanoparticle) was tested on two vegetable crops (beetroot and carrot) at concentrations of 0 mg / L (T0), 25 mg / L (T1), 50 mg / L (T2), 100 mg / L (T3) and 200 mg / L (T4), where the MgO nanoparticles showed statistically satisfactory results in germination, growth and dry mass (Figure 7). Petition 870240109461, dated 12 / 23 / 2024, page 16 / 34 10 / 14

[036] The synthesis of magnesium oxide nanoparticles (MgO-NPs) mediated by the extract of Pérola pineapple peel showed promising results. This sustainable process not only reuses organic waste, but also represents an efficient and green alternative to increase agricultural productivity. In the tests carried out, the ideal concentration of MgO-NPs was identified as 50 mg / L, and this formulation was compared with commercial magnesium oxide. The results obtained indicated a significant superiority of MgO-NPs in the performance of parameters such as germination, leaf size and plant dry mass, surpassing the products currently available on the market, as shown in Figure 8.

[037] This novel method stands out for its integration of sustainability and efficiency, promoting the circular economy by using an abundant agricultural waste product as raw material for the production of high value-added nanomaterials. The reduction in the use of toxic chemical reagents further reinforces the environmentally responsible nature of the approach.

[038] Although the present application has been described with respect to a preferred embodiment, it should be understood that many variations, modifications, equivalent structural elements, combinations, sub-combinations and other applications of the present invention may be made and do not depart from the scope of protection of the present application. BIBLIOGRAPHIC REFERENCES

[039] ABINAYA, S. et al. Green synthesis of magnesium oxide nanoparticles and its applications: A review. Sustainable Chemistry and Pharmacy, vol. 19, p. 100368, apr. 2021. Petition 870240109461, dated 12 / 23 / 2024, page 17 / 34 11 / 14

[040] AGYAPONG, P. O. et al. Synthesis of magnesium oxide from waste magnesium-rich Cucurbita pepo (pumpkin) seeds. Sustainable Environment, v. 9, n. 1,31 dez. 2023.

[041] AHMED, N. et al. The power of magnesium: unlocking the potential for increased yield, quality, and stress tolerance of horticultural crops. Frontiers in Plant Science, v. 14, 24 out. 2023.

[042] AHMED, T. et al. Green magnesium oxide nanoparticles-based modulation of cellular oxidative repair mechanisms to reduce arsenic uptake and translocation in rice (Oryza sativa L.) plants. Environmental Pollution, v. 288, p. 117785, nov. 2021.

[043] BARDIYA, N.; SOMAYAJI, D.; KHANNA, S. Biomethanation of banana peel and pineapple waste. Bioresource Technology, v. 58, n. 1, p. 73-76, out. 1996.

[044] BOSERUP, E. Population Growth as a Stimulant to Agricultural Development. Em: [s.l: s.n.]. p. 61-75.

[045] CHEN, Z. C. et al. Functional dissection and transport mechanism of magnesium in plants. Seminars in Cell & Developmental Biology, v. 74, p. 142-152, fev. 2018.

[046] EVANS, H. J.; SORGER, G. J. Role of Mineral Elements with Emphasis on the Univalent Cations. Annual Review of Plant Physiology, v. 17, n. 1, p. 47-76, jun. 1966.

[047] FAIZAN, M. et al. Magnesium Oxide Nanoparticles (MgO-NPs) Alleviate Arsenic Toxicity in Soybean by Modulating Photosynthetic Function, Nutrient Uptake and Antioxidant Potential. Metals, v. 12, n. 12, p. 2030, 26 nov. 2022.

[048] FAN, Y. et al. Optical and Antibacterial Properties of Chiral ArginineStabilized ZnO Nanoparticles. Langmuir, v. 39, n. 11, p. 4161-4169, 21 mar. 2023. Petição 870240109461, de 23 / 12 / 2024, pág. 18 / 34 12 / 14

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[050] GRAM, G. et al. Combining organic and mineral fertilizers as a climatesmart integrated soil fertility management practice in sub-Saharan Africa: A metaanalysis. PLOS ONE, v. 15, n. 9, p. e0239552, 24 set. 2020.

[051] JEEVANANDAM, J.; CHAN, Y. S.; DANQUAH, M. K. Biosynthesis and characterization of MgO nanoparticles from plant extracts via induced molecular nucleation. New Journal of Chemistry, v. 41, n. 7, p. 2800-2814, 2017.

[052] LI, L. et al. Enhanced Agriculture Insurance with Climate Forecast. Sustainability, v. 14, n. 17, p. 10617, 25 ago. 2022.

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[054] OTSUKA, Y.; KONDO, H.; SUZUKI, K. Facile Synthesis of Novel ShortChain Ligand-Capped Colloidal Metal Oxide Nanoparticles for Printed Flexible Devices. ACS Applied Materials & Interfaces, v. 16, n. 28, p. 36567-36576, 17 jul. 2024.

[055] PANDIT, N. R. et al. Optimum Rate and Deep Placement of Nitrogen Fertilizer Improves Nitrogen Use Efficiency and Tomato Yield in Nepal. Soil Systems, v. 6, n. 3, p. 72, 17 set. 2022.

[056] QUAN, Z. et al. Fates and Use Efficiency of Nitrogen Fertilizer in Maize Cropping Systems and Their Responses to Technologies and Management Practices: A Global Analysis on Field 15 N Tracer Studies. Earth’s Future, v. 9, n. 5, 5 maio 2021.

[057] RANI, D. S.; NAND, K. Ensilage of pineapple processing waste for methane generation. Waste Management, v. 24, n. 5, p. 523-528, jan. 2004. Petição 870240109461, de 23 / 12 / 2024, pág. 19 / 34 13 / 14

[058] REMPEL, S. et al. Toxicity effects of magnesium oxide nanoparticles: a brief report. Matéria (Rio de Janeiro), v. 25, n. 4, 2020.

[059] SARANGI, P. K. et al. Recent Progress and Future Perspectives for Zero Agriculture Waste Technologies: Pineapple Waste as a Case Study. Sustainability, v. 15, n. 4, p. 3575, 15 fev. 2023.

[060] SELVAM, N. C. S. et al. Comparative study of microwave and conventional methods for the preparation and optical properties of novel MgO-micro and nano-structures. Journal of Alloys and Compounds, v. 509, n. 41, p. 9809-9815, out. 2011.

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Claims

1 / 1 CLAIMS 1. Use of extract from the peel of Ananas comosus characterized by its role as a mediator in the green synthesis of magnesium oxide nanoparticles.

2. Green synthesis of magnesium oxide nanoparticles characterized by comprising the following steps: - Raw material preparation, comprising grinding the peel of Ananas comosus in a knife mill and then washing these ground peels three times with distilled water and in which, after washing, the peels are dried in an oven at 60 °C for 5 h, weighed and prepared for extraction; - Extraction, comprising mixing the dried peel from the previous step in distilled water, followed by stirring and heating on a hot plate for 30 min at 60 °C and in which, subsequently, the mixture is filtered and a portion of the extracted solution is removed and combined with a 0.75 molar magnesium chloride hexahydrate solution (3:1 ratio); - pH adjustment, in which the pH of the solution is adjusted with the aid of NaOH, and where pH 3.5 is raised to pH 10, resulting in the formation of a precipitate;- Reaction, in which the pH-adjusted solution is transferred to a hydrothermal reactor and kept under agitation at 500 rpm at 100 °C for 3 h, after which the solution is centrifuged three times for 15 min, with the addition of distilled water between centrifugations for washing and removal of the supernatant, using a speed of 4000 rpm; and - Drying, in which the sedimented material is dried in a crucible in an oven for 24 h, subsequently calcined at 600 °C for 2 h in a muffle furnace, and after calcination, the sample is macerated with a pestle. Petition 870240109461, dated 12 / 23 / 2024, page 22 / 34;

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