Synthesis, Characterization, Applications, and Toxicity of Lead Oxide Nanoparticles

Over the past few years, the interest of material scientists for metal and metal oxide nanoparticles (NPs) is increasing dramatically because of their unique physicochemical characteristics such as catalytic activity and optical, electronic, antibacterial, and magnetic properties which depend on their size, shape, and chemical surroundings. Recently, several new routes of synthesis of lead monoxide (PbO) nanoparticles have been used, such as chemical synthesis, calcination, sol-gel pyrolysis, anodic oxidation, solvothermal method, thermal decomposition, chemical deposition, laser ablation, and green methods. Essentially, for the structural characterization of lead oxide nanoparticles, several spectroscopic, microscopic, and thermogravimetric methods of analysis are used. Lead oxide has been widely utilized in batteries, gas sensors, pigments, ceramics, and glass industry. Furthermore, lead oxide nanoparticles are graded as toxic and dangerous for the human health and environment. Therefore, there is an urgent need to develop new approaches and standardized test procedures to study the potential hazardous effect of nanoparticles on the human health and environment. The aim of this chapter is to provide an overview of the recent trends in synthesis of lead oxide nanoparticles, their characterization, possible applications, and toxicity

DESIGN OF HETEROGENEOUS PHOTOCATALYSTS FOR SELECTIVE OXIDATION OF ALCOHOLS

My doctoral activity deals with oxidative photocatalysis. This is based on the use of photosensitive materials, it employes molecular oxygen as oxidant and it operates under mild temperature and pressure conditions. In particular, I worked on the preparation and characterization of photocatalytic heterogeneous systems containing the decatungstate anion W10O324- or the complex Fe(III) meso-tetrakis (2,6-dichlorophenyl) porphyrin. The photocatalytic properties of these photocatalysts were evaluated in the selective oxidation of aliphatic alcohols. The chosen polyoxoanion and porphyrin have many similarities because both of them absorb in the near UV (λ > 300 nm) and their primary photochemical processes involve the reduction of the metal centre (tungsten or iron), the simultaneous oxidation of the alcohol and the closure of photocatalytic cycle by molecular oxygen. The (nBu4N)4W10O32 was incorporated into silica matrix by sol-gel procedure and two heterogeneous systems were obtained with loadings of 10% and 30%. Their photocatalytic properties were compared in the oxidation of primary and secondary aliphatic alcohols (1-pentanol, 2-pentanol, 3-pentanol, 1-heptanol, 4-heptanol, 2,6-dimethyl-4-heptanol). Photoexcitation (λ > 300 nm) led to the selective conversion of alcohols to the corresponding carbonylic products, with a mass balance higher than 90%. The system with 10% of loading, which is characterized by a pronounced micro- and mesoporous structure, favored the selective adsorption of primary aliphatic alcohols with respect to the homologous secondary compounds, so allowing the reaction between the photoexcited decatungstate and the less hindered OH group. The system with loading of 30% was less selective; that is attributed to its lower porosity and to the fact that part of the immobilized decatungstate was not caged inside silica but weakly adsorbed on its surface and, therefore, easily accessible to all substrates. Photoexcitation of Na4W10O32 dissolved in water led to the formation of OH• radicals which, in turn, were able to oxidize glycerol. This substrate was chosen as a model of polyfunctional alcohol and because its selective transformation is a process of great industrial interest. While the photocatalytic process in solution was scarcely selective, incorporation of Na4W10O32 in a silica matrix provided a heterogeneous system with good selectivity and stability: 90% of the products were carbonylic compounds and CO2 was formed only in negligible amounts. The surface played a fundamental role, favoring adsorption of glycerol, increasing its local concentration near the decatungstate and, thus, facilitating its reaction with the photogenerated OH• radicals. Iron (III) meso-tetrakis (2,6- dichlorophenyl)porphyrin, properly silanized, was linked covalently on the surface of a mesoporous MCM-41 material. The possible effects of the morphology of the solid support on the selectivity of the photooxidation of 1,4-pentandiol were considered. The mesoporous photocatalyst, due to its large surface area, is able to disperse the iron porhyrin. The diol coordinates to iron, but contrary to what occurs in solution, can not act as a bridge between two complexes. This prevents the formation of inactive oligomers. The photocatalytic system presented a good selectivity in the oxidation of the diol in the primary position, with accumulation of 4-hydroxypentanal. It is noteworthy that there is no evidence of formation of products of further oxidation

Effect of Temperature Extraction on the Potassium and Calcium Content in the Lemon and Orange Water Peel Extracts

The aim of this study is to examine the effect of temperature extraction on the potassium (K) and calcium (Ca) contents in orange and lemon peel extracts. The extractions were done at 62 ºC and 92 °C for 15 minutes and atmospheric pressure in distilled water. The fruit peel content in the extraction mixture was 5 % (w/v) in all samples. Calcium (Ca) and potassium (K) concentrations have been determined by flame photometric method. This research has revealed that by increasing the temperature of extraction, in particular, the concentration of Ca and K concentrations increased as applied extraction temperatures increased. The concentration of potassium is higher than the concentration of calcium in orange and lemon extracts, respectively. The concentration of K was 308 mg/l at 62 ºC and 361 mg/l at 92 ºC in lemon extracts, while in orange extracts the concentration of K was 476 mg/l at 62 ºC and 483 mg/l at 92 ºC. The concentration of Ca was 70.8 mg/l at 62 ºC and 71.9 mg/l at 92 ºC in lemon extracts, while in orange extracts the concentration of Ca was 91 mg/l at 62 ºC and 93.6 mg/l at 92 ºC. These results confirm that both citrus could be a very valuable source of potassium and calcium which are needed micronutrients to ensure the water and electrolyte balance and to build and maintain strong bones, proper function of muscles and nerves

Determination of essential nutrients and cadmium in the white quinoa and amaranth seeds

Micronutrients are trace elements required in very small amounts in the diet. Metals such as copper (Cu), iron (Fe), and zinc (Zn) are essential nutrients that are required for various biochemical and physiological functions. Cadmium, which is considered as systemic toxicant that is known to induce multiple organ damage, even at lower levels of exposure, has been also determined. Therefore, in this paper the concentrations of Cu, Fe, Zn and Cd have been determined in the white quinoa and amaranth by ICP-MS analysis. Concentrations of all examined metals were higher in the amaranth. This research has shown that amaranth and white quinoa could be good sources of essential micronutrients. The concentration of cadmium in amaranth was very close to maximum permitted concentration in food

Quality assessment and health safety of natural spring water

In this paper the natural spring water was investigated. The sample of spring water was taken at the beginning of July 2019 in Tuzla, Bosnia and Hercegovina (BIH), which is consumed by the local population. The source of in-vestigated spring water is located above salt mine. All parameters of health safety were analysed by the methods of laboratory tests regulated by the State regulation on natural mineral and natural spring waters ”Official Ga-zette BiH” No. 26/10 and 32/12, i.e. physical-chemical and microbiological analysis was performed. The results of the study showed that water is not for drinking because it contains higher concentrations of ammonium ion (NH4+) which is 0.89 mg/L, nitrite (NO2-) 2.20 mg/L and sulphate (SO42-) 398.34 mg/L, and coliform bacteria are isolated. The pH value of 9.07 indicate that this spring water is alkaline. The concentrations of iron (Fe2+) 0.007 mg/L and manganese (Mn2+) 0.0144 mg/L are within the allowed limit values while the concentration of lead (Pb2+) 0.0088 is at the upper maximum allowable value. The results of this research indicate that water in this untreated state is not for drinking

Micro- and nano-encapsulation in food industry

Encapsulation can be defined as a process of entrapping one substance within another substance producing particles with diameters of a few nm to a few mm. The entrapped material is usually a liquid, but may be a solid or a gas. The main reason of using encapsulation is the fact that some nutrients do not remain in the food for a significant amount of time or may react with the other food components causing undesirable effects. It is possible to use micro- and nanoencapsulation techniques. The first one, microencapsulation, is a technology that can improve the retention time of the nutrient in the food and allow controlled release at specific times, during food consumption or in the intestinal gut (microencapsulation of vitamin). Nanoencapsulation has the potential to protect sensitive bioactive food ingredients from unfavourable environmental conditions, enhance solubilisation, improve taste and odour masking, and enhance bioavailability of poorly absorbable function ingredients. In this review, some relevant aspects of encapsulation methodologies, coating materials and their uses in food technology were discussed

POSITIVE ASPECTS OF NANOTECHNOLOGY ON AGRICULTURAL SUSTAINABLE DEVELOPMENT: APPLICATION OF NANOPARTICLES AND FIBERS FOR INCREASING AGRICULTURAL YIELD

Recently, nanotechnology is widely used in agriculture with the aim of achieving high agricultural yields. Due to the unique surface and physicochemical properties, nanomaterials can be used to deliver nutrients to plants via nanoparticles, for the synthesis of nanopesticides, nanofungicides, and to design nanosensors for the detection of very low concentrations of pesticides and other contaminants. Excessive use of pesticides and fertilizers causes the loss of soil biodiversity and the development of resistance to pathogens. Nenoencapsulation of fertilizers, pesticides and herbicides is used for slow and specific dosed release of nutrients as well as agrochemicals. This paper discusses the applications of nanotechnology and their positive effect in agriculture in relation to the common methods used so far