Flow Rate and Interference Studies for Copper Binding to a Silica-Immobilized Humin Polymer Matrix: Column and Batch Experiments

Batch and column experiments were performed to determine the Cu(II) binding capacity of silica-immobilized humin biomass. For column studies, 500 bed volumes of a 0.1 mM Cu(II) solution were passed through humin packed columns at the flow rates of 1, 1.5, 2, and 3 mL/min. The biopolymer showed an average Cu binding capacity of 12 ± 1.5 mg/g and a Cu recovery of about 96.5 % ± 1.5. The breakthrough points for Cu(II) alone were approximately 420, 390, 385, and 300 bed volumes for the flow rates of 1, 1.5, 2 and 3 mL/min, respectively. The interference studies demonstrated that at low concentrations, the hard cations Ca(II) and Mg(II) did not seem to represent a major interference on Cu(II) binding to the humin biopolymer. The selectivity showed by this biopolymer was Cu(II)>Ca(II)>Mg(II). On the other hand, batch experiments showed that Ca(II) + Mg(II) at 100mM each reduced the Cu(II) binding to 73 %. However, 1000 mM concentrations of Ca(II) and Mg(II), separately and in mixture, reduced the Cu(II) binding to 47 %, 44 % and 31 %, respectively. The results of this study showed that immobilized humin in a silica matrix could represent an inexpensive bio-source for Cu removal from contaminated water, even in the presence of low concentrations of the hard cations Ca(II) and Mg(II)

Sorption kinetic study of selenite and selenate onto a high and low pressure aged iron oxide nanomaterial

The sorption of selenite (SeO32−) and selenate (SeO42−) onto Fe3O4 nanomaterials produced by non microwave-assisted or microwave-assisted synthetic techniques was investigated through use of the batch technique. The phase of both synthetic nanomaterials was determined to be magnetite by X-ray diffraction. The average grain sizes of non microwave-assisted and microwave-assisted synthetic Fe3O4 were determined to be 27 and 25 nm, respectively through use of the Scherrer\u27s equation. Sorption of selenite was pH independent in the pH range of 2-6, while sorption of selenate decreased at pH 5 and 6. The addition of Cl− had no significant effect on selenite or selenate binding, while the addition of NO3− only affected selenate binding to the microwave assisted Fe3O4. A decrease of selenate binding to both synthetic particles was observed after the addition of SO42− while selenite binding was not affected. The addition of PO43− beginning at concentrations of 0.1 ppm had the most prominent effect on the binding of both selenite and selenate. The capacities of binding, determined through the use of Langmuir isotherm, were found to be 1923 and 1428 mg Se/kg of non microwave-assisted Fe3O4 and 2380 and 2369 mg Se/kg of microwave-assisted Fe3O4 for selenite and selenate, respectively

Evaluación de la reacción de doce variedades híbridas de sorgo granífero (Sorghum bicolor (L) Moench) a la inoculación artificial con Macrophomina phaseolina (Tassi) Goid

El presente estudio fue realizado para evaluar resistencia a la pudrición Carbonosa del Tallo, causada por el hongo Macrophomina phaseolina (Tassi) Goid., en doce variedades híbridas de sorgo granifero. El ensayo se condujo en los campos de cultivo de la Escuela Nacional de Agricultura y Ganadería (ENAG), en el departamento de Managua, Nicaragua. El método de inoculacion usado fue el de los palillos (mondadientes) de Young (33). El hongo fue colectado de residuos de cosecha de los campos de la Calera, se cultivo en PDA y se inoculo cuando las plantas tenían 21 días de florecidas, haciendo la evaluación 20 días después de la inoculacion. El diseño utilizado fue el de Latice rectangular, con 3 repeticiones, los tratamiento fueron distribuidos en parcelas subdivididas utilizando en cada repetición 5 plantas inoculadas con el hongo y 5 con ausencia de este. En el análisis estadístico se encontró diferencia entre las variedades al nivel del 5%, y la prueba de Duncan permite la separación de las variedades de acuerdo a la susceptibilidad, considerándose en este estudio preliminar como resistente al hongo el grupo formado por las variedades C-42A, E-57, Dorado Tx y P 8202

Feasibility of using living alfalfa plants in the phytoextraction of cadmium(II), chromium(VI), copper(II), nickel(II), and zinc(II): Agar and soil studies

Trace level concentrations of heavy metals are found everywhere on earth. However, activities such as mining and localized intensive agriculture, have contributed to an undesirable accumulation of toxic metals in many areas worldwide. Current technologies used in the cleaning process of contaminated sites are expensive and frequently not environmentally friendly. Phytoremediation, the use of plants to remove, stabilize, or degrade soil contaminants, is a promising remediation technology, which has several advantages over traditional clean up methodologies. This investigation demonstrated the capabilities of alfalfa (Medicago sativa) to clean up soils contaminated with Cd(II), Cr(VI), Cu(II), Ni(II), and Zn(II). Experiments conducted using agar-based media showed that the concentration of 5 mg/L of these heavy metals, individually, increased the growth of the alfalfa plants. The dose of 10 mg/L of Cr(VI), 20 mg/L of Cd(II), Cu(II) or Ni(II) significantly reduced the germination and development of the alfalfa seedlings. However the plants were able to tolerate 40 mg/L of Zn(II). Plants gown in the agar-based media contaminated with 10 mg/L of Cd(II), Cr(VI), Cu(II), and Ni(II) accumulated in the shoot dry tissues 2,427 mg/kg of Cd, 909 mg/kg of Cr, 757 mg/kg of Cu, and 713 mg/kg of Ni, respectively. However, the plants treated with 40 mg/L of Zn(II) accumulated 4,036 mg/kg of Zn in the shoot dry tissues. In another experiment alfalfa plants were cultivated in a montmorillonite-based medium individually contaminated with the heavy metals indicated above, whose solutions were adjusted at pH 4.5, 5.8, and 7.1. Our results showed that alfalfa plants were able to tolerate 80 mg/L of Cd(II), Cu(II), and Ni(II), and 160 mg/L of Zn(II). Alfalfa plants did not show capabilities to tolerate more than 10 mg/L of Cr(VI) in the cultivation medium. Furthermore, alfalfa plants were able to remove up to 86 mg/kg of Cd(II) and 185 mg/kg of Cu(II) at pH 7.1, as well as 174 mg/kg of Ni(II) at pH 5.8 and 398 mg/kg of Zn(II) at pH 4.5. Experiments conducted in the same substratum using a mixture of 50 mg/kg of Cd(II), Cu(II), Ni(II) and Zn(II) showed that alfalfa plants absorbed more Ni than any of the other metals. The concentrations of Ni in the alfalfa shoot dry tissues were 437 mg/kg, 333 mg/kg, and 308 mg/kg at pH 7.1, 5.8, and 4.5, respectively. The second metal with the highest uptake potential was cadmium since it was found in concentrations of 202, 124, and 132 mg/kg at pH 7.1, 5.8, and 4.5, respectively; while zinc was third, followed by copper. These experiments demonstrated that alfalfa plants successfully compete with the soil matrix for the adsorbed metal cations. Further experiments performed in a silt soil showed that at the growth stage of 20 days, alfalfa plants were able to tolerate up 500 mg/L of Cd(II), Cu(II), and Zn(II). In these conditions, the alfalfa shoot dry tissues accumulated up to 1079 mg/kg of Cd, which represented 26% of the Cd concentrated in the root tissues. This result indicated that alfalfa could be included as a Cd hyperaccumulator species. Also, other experiments performed in the same soil, demonstrated that Zn(II) reduced the toxic effects of Ni(II) to alfalfa plants, which could represent an important information for the use of living alfalfa plants in the phytoremediation of nickel contaminated soils

Do all Cu nanoparticles have similar applications in nano-enabled agriculture?

abstract: Copper-based chemicals have been widely used in agriculture as fertilizers and pesticides. Although these products have been essential to ensure food security, their continuous use has resulted in environmental pollution with detrimental effects for certain living organisms. Efforts have been put in place to reduce pollution derived from Cu application in agriculture. However, there is still a long way to go to reduce agrochemical applications without affecting food security. Copper-based nanomaterials including metallic copper (Cu NPs, nCu) copper oxide (CuO NPs, nCuO) and copper hydroxide [Cu(OH)2 nanowires, nCu(OH)2, Cu(OH)2 NPs] appear as the alternative to replace traditional copper-based agrochemicals. The available literature shows that the three nanomaterials have exhibited capabilities as nanofertilizers or nanopesticides. However, the data is very scattered and, in some cases, inconsistent. This minireview shows the most recent results from investigations about the effects of the three Cu-based nanomaterials in agricultural production. Advantages and disadvantages are discussed and research questions to guide future investigations are stated

Advanced Analytical Techniques for the Measurement of Nanomaterials in Food and Agricultural Samples

Nanotechnology offers substantial prospects for the development of state-of-the-art products and applications for agriculture, water treatment, and food industry. Profuse use of nanoproducts will bring potential benefits to farmers, the food industry, and consumers, equally. However, after end-user applications, these products and residues will find their way into the environment. Therefore, discharged nanomaterials (NMs) need to be identified and quantified to determine their ecotoxicity and the levels of exposure. Detection and characterization of NMs and their residues in the environment, particularly in food and agricultural products, have been limited, as no single technique or method is suitable to identify and quantify NMs. In this review, we have discussed the available literature concerning detection, characterization, and measurement techniques for NMs in food and agricultural matrices, which include chromatography, flow field fractionation, electron microscopy, light scattering, and autofluorescence techniques, among others

Recent insights into the impact, fate and transport of cerium oxide nanoparticles in the plant-soil continuum

The advent of the nanotechnology era offers a unique opportunity for sustainable agriculture provided that the exposure and toxicity are adequately assessed and properly controlled. The global production and application of cerium oxide nanoparticles (CeO2-NPs) in various industrial sectors have tremendously increased. Most of the nanoparticles end up in water and soil where they interact with soil microorganisms and plants. Investigating the uptake, translocation and accumulation of CeO2-NPs is critical for its safe application in agriculture. Plant uptake of CeO2-NPs may lead to their accumulation in different plant tissues and interference with key metabolic processes of plants. Soil microbes can also be affected by increasing CeO2-NPs in soil, leading to changes in the physiology and enzymatic activity of soil microorganisms. The interactions between CeO2-NPs, microbes and plants in the agricultural system need systemic research in ecologically relevant conditions. In the present review, The uptake pathways and in-planta translocation of CeO2-NPs,and their impact on plant morphology, nutritional values, antioxidant enzymes and molecular determinants are presented. The role of CeO2-NPs in modifying soil microbial community in plant rhizosphere is also discussed. Overall, the review aims to provide a comprehensive account on the behaviour of CeO2-NPs in soil-plant systems and their potential impacts on the soil microbial community and plant health

Removal of copper, lead, and zinc from contaminated water by saltbush biomass: Analysis of the optimum binding, stripping, and binding mechanism

Experiments performed on the Cu(II), Pb(II), and Zn(II) binding by saltbush biomass (Atriplex canescens) showed that the metal binding increased as pH increased from 2.0 to 5.0. The highest amounts of Cu, Pb, and Zn bound by the native biomass varied from 48-89%, 89-94%, and 65-73%, respectively. The hydrolyzed biomass bound similar amount of Pb and 50% more Cu and Zn than the native. The esterified biomass had a lower binding capacity than native; however, esterified flowers bound 45% more Cu at pH 2.0 than native flowers. The optimum binding time was 10 min or less. More than 60% of the bound Cu was recovered using 0.1 mM HCl, while more than 90% of Pb was recovered with either HCl or sodium citrate at 0.1 mM. For Zn, 0.1 mM sodium citrate allowed the recovery of 75%. Results indicated that carboxyl groups participate in the Cu, Pb, and Zn binding. © 2007