Obtaining biodegradable blend PLA:starch for the incorporation of micronutrient manganese

The incorporation of particulate fertilizers in polymeric fibers aims to release these active principles from a substrate with a high surface area and biodegradable and biocompatible properties. It also seeks to provide the release thereof, and minimize the effects of leaching, increasing the efficiency of absorption by the roots in direct soil application. Thus, the present study was to interest obtaining a composite biodegradable matrix of acid poly -L- lactic (PLA):starch in the form of fibers, impregnating particulate solids that can act as sources of manganese ions. It is also aimed to assess any improvement in the release of the Mn2+ ions in an aqueous medium by means of variations in the processing of biodegradable blends. PLA fibers were obtained employing the electrospinning method, various solvent systems primarily been studied for obtaining a polymer solution, in order to obtain the best morphological characteristics for the support, such as control of the fiber diameter and porosity. Then there was the addition of different concentrations of starch in order to find the best embodiment of this condition to the fibers. Finally, we performed the inclusion of MnO, MnO2, MnCO3 and MnSO4, to act as sources of manganese ions, in order to observe possible and different interactions of these with the polymer matrix. In the release test, the same concentration of manganese ions 12.5% (w/v) was added experimentally to a medium extractant citric acid 2 % (w/ w) at 25 ° C in a range of 6 days for all the aforementioned precursors. It was observed that the presence of starch in the PLA fiber increased water vapor permeability (WVP) which promotes the degradation of the blend. The incorporation of salts and oxides in the blends PLA:starch used by the process resulted in different effects of the merger, agglomeration and dispersion in the composite due to its grain size and dispersive characteristics in the solvents used. The behavior of salts and manganese oxides embedded in composite promoted the rapid and direct release of assets. The composites PLA:starch is a polymeric support with high surface area which minimizes the effects of leaching allowing direct release of different precursors ion Mn2 + as fertilizer sources.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A incorporação de particulados, fertilizantes, em fibras poliméricas tem como objetivo a liberação destes princípios ativos a partir de um suporte com uma alta área superficial e propriedades biodegradáveis e biocompatíveis. Além disso, visa proporcionar a liberação dos mesmos e minimizar os efeitos de lixiviação, aumentando a eficiência de absorção pelas raízes na aplicação direta no solo. Assim, o presente trabalho teve como interesse a obtenção de um compósito com matriz biodegradável de ácido poli-L-lático (PLA):amido na forma de fibras, com a impregnação de sólidos particulados que possam atuar como fontes de íons manganês. Visou-se também, avaliar o possível melhoramento na liberação dos íons Mn2+ em meio aquoso, por intermédio de variações no processamento das blendas biodegradáveis na forma de fibras. As fibras de PLA foram obtidas empregando-se o método de eletrofiação, sendo primeiramente estudados diferentes sistemas de solventes para a obtenção da solução polimérica, de modo a obter as melhores características morfológicas para o suporte, tais como, controle do diâmetro das fibras e da porosidade. Em seguida, realizou-se a adição de diferentes concentrações de amido, com o intuito de encontrar a melhor condição de incorporação deste às fibras. Por fim, efetuou-se a inclusão de MnO, MnO2, MnCO3 e MnSO4, para atuarem como fontes de íons manganês, com objetivo de observar as possíveis e distintas interações destes com a matriz polimérica. Nos testes de liberação, uma mesma concentração de íons manganês foi adicionada a um meio extrator de ácido cítrico 2%(m/m), a 25ºC, num intervalo de 6 dias para todos os precursores supracitados. A concentração liberada de íons Mn foi analisada por espectrometria de absorção atômica de chama para verificar a disponibilidade do mesmo. Portanto, foram obtidos compósitos poliméricos PLA:amido:Mn com 20% (m/m) de amido, apresentando distribuição de diâmetros médios das fibras variando entre 0,4 à 1,0 um, e com a incorporação experimental de 12,5% (m/m) deste íon na solução polimérica. Foi observado que a presença do amido na fibra de PLA aumentou a permeabilidade ao vapor de água (WVP) o qual favorece a degradação da blenda. A incorporação dos sais e óxidos nas blendas PLA:amido pelo processo utilizado teve como resultado distintos efeitos de incorporação, aglomeração e dispersão no compósito devido as suas características granulométricas e dispersivas nos solventes utilizados. O comportamento dos sais e óxidos de manganês inseridos nos compósitos promoveu a liberação rápida e direta dos ativos. O compósito de PLA:amido é um suporte polimérico com alta área superficial que permite minimizar os efeitos de lixiviação permitindo a liberação direta de diferentes precursores de íon Mn2+ como fontes de fertilizante

Evaluation of Ni-Doped Tricobalt Tetroxide with Reduced Graphene Oxide: Structural, Photocatalysis, and Antibacterial Response

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 showed typical crystallographic planes to cubic phase and particles with inferior diameter to 30 nm. The Ni-Co3O4 + rGO nanocrystals exhibit a band gap value of 2.0 eV. The bactericidal tests for S. aureus and E. coli revealed that the insertion rGO synthesized by the sol–gel method promoted the antimicrobial activity for both microorganisms. Afterward, the photocatalytic assay for the atrazine contaminant showed significant responses to pesticide removal attributed to the simultaneous adsorption and degradation process. In addition, the sol–gel process found a better response to Ni-Co3O4 in the presence of rGO, indicating a nanocomposite superior synergism

A “Zero-Cost” Adsorbing Hydroxyapatite-Based Material from Amazon Fishery Waste for Water Remediation and Nutrient Release for Agriculture

This paper puts forward the use of “low-cost/low-end” hydroxyapatite-based adsorbing materials prepared from Tambaqui fish cleaning residues (i.e., bones) by grinding and/or thermal annealing. The nature of raw materials and treatments practically resulted in a “zero-cost” adsorbent for atrazine pesticide and Co2+ ion remediation in an aqueous solution. Despite the distinctive character of the two contaminants, all adsorptions were found to follow pseudo-second order kinetics and Freundlich isotherm models. Pristine hydroxyapatite proved to be more effective in adsorbing atrazine at low concentrations due to interactions with collagen residues. Conversely, heat-treated materials demonstrated better adsorption performances for cobalt due to the removal of organic residues hindering access to the surface. On the other hand, lower adsorption affinities resulted into a faster and more efficient Co2+ release into water. The different behavior in terms of phosphate and cobalt release shown by the three hydroxyapatite-based absorbents can be exploited for differential liberation of targeted nutrients, with high seed germination rates. Considering circular economic principles, waste-derived hydroxyapatites may be potentially attractive for removing ionic species, minimizing water pollution stemming from heavy industry, and for their subsequent targeted release to edible plants, enhancing agricultural availability of mineral nutrients for soil fertilization