João Otávio Donizette Malafatti's research while affiliated with Empresa de Pesquisa Agropecuária de Minas Gerais and other places

Publications (25)

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Agriculture's importance in human lives and the economy has directed studies to improve crop production. An essential challenge for improving fertilizer efficacy is reducing losses due to leaching and increasing the nutrients supplies. In this context, biodegradable sachets stand out as internal packaging instead of direct insertion into the polyme...
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Cobalt oxide (Co3O4 ) nanoparticles were successfully prepared by sol–gel and hydrothermal methods for antibacterial and photocatalytic applications with the addition of 1%, 4% nickel (Ni), and reduced graphene oxide (rGO). The structural and morphological properties of the nanoparticles were obtained by XRD, TEM and FESEM techniques. Cobalt oxide...
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Fresh fruits and vegetables are essential sources of nutrients and bioactive compounds with a beneficial effect on human health. However, these products are highly perishable and have a short post-harvest life with significant losses worldwide. New advanced technologies, such as nanotechnology, have been used to help reduce post-harvest losses of f...
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Strategies for developing new adsorbents are necessary for more efficient processes to remove contaminants from wastewater. Thus, it is essential to adjust the synthesis parameters of the adsorbent nanomaterial to control the surface area and morphology and, therefore, enhance the adsorption performance. Herein, α-Ni(OH)2 nanosheets were synthesize...
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This study aimed to prepare nanostructured ZnO films deposited on FTO substrate by microwave-hydrothermal method. The effects of synthesis time and post-synthesis heat treatment were assessed. ZnO films exhibited a wurtzite structure and a band gap in the range of 3.2 to 3.4 eV. Microwave time influenced film morphology, which varied from lamellar...
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Photocatalysts supported in magnetic nanocomposites for application in environmental remediation processes have been evaluated for removing contaminants due to easy recovery and low toxicity to the ecosystem. In this work, copper oxide (CuO) nanoparticles with photocatalytic properties were decorated on magnetic support constituted by hydroxyapatit...
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Increasing global warming due to NOx, CO2, and CH4, is significantly harming ecosystems and life worldwide. One promising methodology is converting pollutants into valuable chemicals via photocatalytic processes (by reusable photocatalysts). In this context, the present work aimed to produce a Nb2O5 photocatalyst nanofiber system by electrospinning...
Preprint
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The increase in global warming due to NOx, CO2, and CH4 harmfully different ecosystems and significantly prejudice world life. A promising methodology in this sense is the pollutant conversion into valuable chemicals from photocatalytic processes by reusable photocatalyst. In this way, the present work aimed to produce a Nb2O5 photocatalyst nanofib...
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Drug nanocarriers have been continuously improved to promote satisfactory release control. In this sense, luminescent materials have become an alternative option in clinical trials due to their ability to monitor drug delivery. Among the nanocarriers, silica stands out for structural stability, dispersibility, and surface reactivity. When using cer...
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Nanotechnology has been studied on environmental remediation processes to foster greater photocatalysts efficiency and reuse in wastewater. This study investigated the photocatalytic efficiency and viability of niobium pentoxide (Nb 2 O 5) nanoparticles decorated with magnetic ferrite (cobalt ferrite (CoFe 2 O 4) or magnesium ferrite (MgFe 2 O 4))...
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Here, we investigated the feasibility of immobilizing phytase onto zeolite modified with iron(II) ions, for application in the feed and food sectors. Zeolites have excellent physical-chemical characteristics, ion exchange capacity, and can act as dietary supplements. The phytase immobilization yield was up to 73 % at pH 7 and ionic strength of 100...
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This work described the acquisition of immobilized ZnO semiconductors using the slip casting technique, for application as reusable photocatalysts in the degradation of Rhodamine B. The influence of the heat treatment temperature (800ºC, 900ºC and 1000ºC) on the physical, thermal, microstructural, and photocatalytic properties was investigated. All...
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Hydroxyapatite (HA) is an inorganic material with high ability to interact with proteins and has been recently explored as a support for enzyme immobilization. However, there are still some drawbacks concerning the recovery of these biocatalysts, which could be overcome using magnetic supports. Cobalt ferrite (CoFe2O4) is a purely magnetic material...
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Several studies reported that modifying CuO with CuWO4 can increase its photoactivity. In this study, copper and tungsten heterostructure materials were synthesized via a simple sol-gel method using ammonium paratungstate. The temperature’s influence (300, 500, 700, and 900 °C) was analyzed in the structural, morphological, microstructural, and opt...
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The elucidation of photocatalysis and adsorption mechanisms in the pollutant removal, as well as the efficiency for each process, provide key information for polluted water remediation. In this respect, the present study analyzed the application of nanomaterials based on niobium pentoxide (Nb 2 O 5) and hydroxyapatite (HAP) during Prozac ® and 4-(t...
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TiO2 nanoparticles were efficiently doped with Mn applying microwave-assisted synthesis method. Anatase phase was confirmed by XRD pattern, which did not exhibit the peaks associated with MnOx contamination. Raman spectroscopy showed a displacement of up to 5 cm-1 in the O-J o u r n a l P r e-p r o o f Ti-O vibrational mode, suggesting that Ti was...
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Copper oxide (CuO) has been broadly used in different technological and biological applications. However, based on the literature review, there are few reports describing the synthesis of tungsten doped copper oxide and its biological applications, although CuO and W (tungsten) based nanomaterials have been reportedly already synthesized. In this s...
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Water pollution caused by heavy metals ions has been gaining attention in recent years, increasing the interest in the development of methodologies for their efficient removal focusing on the adsorption process for these purposes. The current challenge faced by adsorption processes is the adequate adsorbent immobilization for removal and reuse. Thu...
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Poly(lactic acid) (PLA) is a versatile, bioabsorbable, and biodegradable polymer with excellent biocompatibility and ability to incorporate a great variety of active agents. Silver sulfadiazine (SDZ) is an antibiotic used to control bacterial infection in external wounds. Aiming to combine the properties of PLA and SDZ, hydrotalcite ([Mg–Al]‐LDH) w...
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Photocatalysis is a promising alternative for the decontamination of effluents. In this paper, immobilized ZnO-based photocatalysts were obtained by pressing and by slip casting. The cylindrical pieces were heat treated at 800°C. The samples were characterized by the method based on the principle of Archimedes, XRD, FTIR, Raman, diffuse reflectance...
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α-Fe2O3 samples were manufactured by means of the polymeric precursor method. The powders were sintered and calcined at temperatures of 300–700 °C for 2 h, respectively. In the X-ray diffraction results, the formation of the rhombohedral phase without secondary phases was exhibited. The size of the particle increased after calcination at 700 °C, ex...
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Alginate (ALG) is an abundant, biocompatible, regenerative, and nontoxic polysaccharide that has potential applications in tissue engineering. Silver sulfadiazine (SDZ) is a topical antibiotic used to control bacterial infection in burns. Aiming to combine the intrinsic alginate characteristics and silver sulfadiazine antimicrobial properties, hydr...

Citations

... Thus, innovative technologies, particularly nanotechnology, may be valuable in managing the post-harvest losses of vegetables more effectively, through ecofriendly approaches. Various nanoformulations, including nanoemulsions, nanocomposites, nanospheres, nano-bubbles and nanocapsules, are used for the post-harvest management of vegetables (de Oliveira Filho et al., 2022;Kumera et al., 2021). These nanomaterials have major advantages in safety, decreasing flow of gases, maintenance of optimum moisture and increased shelf-life of vegetables (Watson et al., 2011). ...
... Porous alumina ceramics are widely employed in catalyst carriers, molten metal filters, heat protection systems, heat exchangers, biomaterials, and other fields due to their high melting point, high corrosion resistance, controlled permeability, high surface area, and low density [3,[7][8][9][10]. The pore sizes, morphology, and degree of interconnection are also crucial factors affecting the potential applications of these materials [11,12]. ...
... On the other hand, some materials such as 2-nitrobenzyl, coumarin, azobenzene, or 7-nitroindoli have the ability for photolysis through photocleaving, photoswitchable, or photo-reductive properties [154]. When such up-conversion materials are included with the nanomaterials and the active drug, they can release the active material in controllable fashion by converting light from longer wavelength to shorter wavelength (for example near infrared to ultraviolet), sometimes targeted with suitable surface moieties [155]. ...
... None of these bands were detected in the spectra of the ZnO ceramics, which proves the absence of CMC residues in them, as well as the purity of all ceramics and materials investigated. All ceramics showed a Zn-O deformation band at approximately 416 cm -1 , typical of the vibrational band found for the M-O bond 38,39 . Figure 8 shows the results of the DRS analysis for the heat-treated compositions at (a) 800 ºC/2 h and (b) 1000 ºC/2 h and Table 3 presents the textural analysis (B.E.T. method) and the band gap results obtained for compositions 60/3, 65/1, 65/3 and 70/1, heat-treated at 800 ºC/2 h and 1000 ºC/2 h. ...
... The bottom-up and top-down routes are general methodologies for obtaining nanometric scale materials. The production of nanoparticles via bottom-up occurs through the molecular properties of self-organization [10][11][12] as in hydrothermal 13,14 , precipitation [15][16][17] , and polymeric precursors 11,18,19 synthesis. While in the top-down approach, particles are reduced to the nanometer scale 12, 20-22 by applying force, such as milling methods 23 . ...
... Similarly, an increase in the number of heterojunction layers from 1 to 7 in the T80-Z40 membranes led to an increase in the kinetic constant of photo-electrocatalytic degradation from 28.9 to 63.9 × 10 − 3 min − 1 for paracetamol and 5.1 to 31.2 × 10 − 3 min − 1 for atrazine. The heterojunction between TiO 2 and ZnO layers provides coupling effects between the semiconductor metal oxides, which provide high surface area and intimate contact, leading to efficient separation of photo-induced charge carriers, as explained in detail in previous work [72]. Furthermore, the process of photoelectrocatalysis (PEC) facilitates further charge separation as the conductive SS support drains the photo-generated electrons from the nanoscale heterojunction layers to the cathode via the external circuit upon electrification [73]. ...
... The immobilization process can modify the stability of the enzyme at different pH, due to the interactions between the enzyme and the support. In addition, media loading can affect the catalytic activity of the immobilized enzyme by causing the pH of its microenvironment to be different from the pH of the reaction medium, either favoring or hindering catalysis [35]. Hence, the immobilization had a positive effect on the enzyme activity, depending on the pH at which activity was measured. ...
... Co3O4-4%Ni SG, Co3O4-4%Ni HT, and Co3O4-4%Ni+rGO SG achieved a total ATZ removal of 58, 66, and 68%, respectively, which represents an improvement of up to 17% compared to the 51% removal observed for photolysis in 30 min. When separating the adsorption contribution, the photocatalytic degradation reached the highest values for Co3O4-4%Ni SG and Co3O4-4%Ni HT (~53% for both), showing that adsorption represents an essential contribution to the ATZ removal as can be verified for other emerging contaminants [23,24], due to more molecule-catalyst interactions near the surface of the material. Figure 8b shows the concentration of the byproduct HAT formed by dehalogenation followed by hydroxylation of the ATZ halogenated carbon [25]. ...
... Some methods aim to eliminate and/or reduce these types of consequences. One of these methods is heterogeneous photocatalysis, which is considered an advanced oxidative process (AOP) and aims to use catalytic materials, usually semiconductors, capable of degrading chemicals contained in wastewater upon irradiation [6][7][8][9]. For this purpose, the semiconductor material is excited, causing electrons to pass from the valence band (VB) to the conduction band (CB), forming pairs of electrons and holes that are used together with reactive species for photochemical degradation of organic compounds [10][11][12]. ...