Preformed Amide-containing biopolymer for Improving the Environmental Performance of Synthesized Urea–formaldehyde in Agro-fiber Composites

Investigations have continued for production high performance agro-based composites using environmentally acceptable approaches. This study examines the role of adding amide-containing biopolymers during synthesis of urea–formaldehyde (UF) on properties of adhesive produced, especially its adhesion potential. The environmental performance of UF-resin synthesized in the presence of modified amide-containing biopolymer was evaluated by evaluating the free-HCHO of both adhesive (during processing) and of the eventual engineered composite product. Also, the benefits of this synthesis-modified adhesive in enhancing the bondability of sugar-cane fibers used in engineered composite panels was evaluated and compared to using UF-resin. The results obtained show that, static bending of the produced composites varied from 27.7 to 33.13 N/mm² of modulus of rupture (MOR) and from 2860 to 3374 N/mm² of Modulus of Elasticity (MOE); while for internal bond (IB) it’s varied from 0.64 to 0.866 N/mm². Based on the ANSI and EN Standards modified UF-based agro composites produced meet the performance requirements for high grade particleboards with respect to static bending strength. These agro-based composite also tested out as having free-HCHO values of ~13 mg/100 g board.     

Effects of Filler Content and Compatibilizing Agents on Mechanical Behavior of the Particle-Reinforced Composites

The study was carried out to investigate the effects of filler content and two different compatibilizing agents (Eastman G-3003 and G-3216) on the mechanical properties of polypropylene reinforced with corn stalk and wood flour. In the sample preparation, three levels of filler loading (30, 40 and 50 wt%) and one level of compatibilizing agent content (2.5 wt%) were used. For overall trend, with addition of both grades of the compatibilizing agents, tensile and flexural properties of the composites significantly improved, as compared with the pure PP. Tensile and flexural properties reach a maximum at 40 wt% filler content and gradually decrease with a further increase in wood particle content. The composites treated with G-3003 gave better results in comparison with G-3216. This could be caused by the high melt viscosity of G-3003. In general, corn stalk flour filled composites showed superior mechanical properties.     

Effects of Preparation Parameters on Properties of Soy Protein-Based Fiberboard

The effects of manufacturing parameters on mechanical properties of medium density fibreboard (MDF) bonded with modified soy protein-based glue were studied to find an appropriate manufacture technology. Physical properties of MDF made with different amount of wax emulsion were measured. Results indicated that water repellent had no obvious influence on physical properties of soy protein-based MDF boards. The fiberboards bonded with soy protein-based glue showed stronger water resistance properties than those bonded with urea–formaldehyde (UF) resins. Furthermore, the soy protein-based MDF boards had good quality [25.2% 24 h soak thickness swell (TS), 29.9 MPa modulus of rupture (MOR), 3130 MPa modulus of elasticity (MOE)], which met requirements of Chinese national standard. Practical processing parameters were obtained by orthogonal experiment, i.e., glue content 8.0%, hot-press temperature 200 °C, and hot-press time 150 s.     

Preparation and Properties of Starch/Nanosilicate Layer/Polycaprolactone Composites

Starch nanocomposites have been prepared using mineral clay. Montmorillonite, kaolin and a surface-modified montmorillonite by dimethyl (hydrogenated tallow alkyl) ammonium cation were used. Starch-g-PCL nanocomposites have been prepared with graft polymerization through in situ ring-opening polymerization of ε-caprolactone in the presence of starch, Sn(Oct)₂ (Tin(II) 2-ethyl hexanoate) as an initiator/catalyst and silicate layers. In fact, the related composites were prepared in solution method, bulk polymerization and in situ polymerization methods with introducing the mineral clay. The effect of kind of clay on d-spacing of silicate layers was investigated and the obtained nanocomposites were analyzed using X-ray diffraction. The obtained compounds were characterized by Fourier transform infrared (FT-IR). Morphology of the prepared nanocomposites was investigated using scanning electron microscopy and DSC enhanced the study of thermal behaviour of the prepared composite compounds.     

Potential of microalgae as biopesticides to contribute to sustainable agriculture and environmental development

The loss of yields from agricultural production due to the presence of pests has been treated over the years with synthetic pesticides, but the use of these substances negatively affects the environment and presents health risks for consumers and animals. The development of agroecological systems using biopesticides represents a safe alternative that contributes to the reduction of agrochemical use and sustainable agriculture. Microalgae are able to biosynthesize a number of metabolites with potential biopesticidal action and can be considered potential biological agents for the control of harmful organisms to soils and plants. The present work aims to provide a critical perspective on the consequences of using synthetic pesticides, offering as an alternative the biopesticides obtained from microalgal biomass, which can be used together with the implementation of environmentally friendly agricultural systems.     

Trace elements and microbiological parameters in farmed Nile tilapia with emphasis on muscle,water, sediment and feed

Fish may bioaccumulate contaminants from the aquatic environment and extend them to the food chain provoking risks to human health. This study evaluated the microbiological parameters of the pond´s water and trace elements concentrations in samples of water, sediment, feed and muscle of farmed Nile tilapia used for human consumption in southern Brazil. A total of 240 fish were collected from 12 tilapia farms. Sediment, tank water and dry ration used in the animals' diet were collected for analysis. Analysis were performed by Energy Dispersion X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Induced Coupled Plasma Optical Emission Spectrometer (ICP-OES), and Atomic Absorption Spectrometer (AAS-VGA). In addition, the microbiological analysis of the water was carried out. The concentrations of Se, I, Fe, Cu and Zn in fish muscle were higher than the recommended by the Brazilian legislation, considering the advised daily intake for adults. The arsenic element had concentrations above the limit stipulated by the present Brazilian legislation, observed in all samples of muscle, sediment and tank water highlighting a possible environmental and fish contamination by the toxic element. Moreover, the arsenic concentration in the water presented a positive correlation (ρ?=?0.33) with arsenic in the muscle, suggesting that tilapia is a good environmental bioindicator, once they properly reflect the levels of arsenic in the water. It is suggested to perform an arsenic speciation for quantification of the inorganic form and accurate assessment of the degree of toxicity in the muscle samples and risks it can bring to human health. Regarding the other potentially toxic elements (Hg, Pb and Cd), and microbiological analysis of water it was verified that the consumption of the fish in question does not raise risks, since the values are within a quality benchmark established by law. The concentration of total and fecal coliforms in pond´s water in the facilities was in agreement with the microbiological indexes required by the legislation of CONAMA class II. Western region presented the lowest concentrations of fecal coliforms when compared to the other regions. There was no significant difference in the microbiological counts of total heterotrophic bacteria, Vibrio spp. and Pseudomonas spp. among the regions.     

Auxinic herbicides induce oxidative stress on Cnesterodon decemmaculatus (Pisces: Poeciliidae)

Environmental Science and Pollution Research - Pesticides might increase the production of reactive oxygen species (ROS). Dicamba (DIC) and 2,4-dichlorophenoxyacetic acid (2,4-D) are auxinic...     

Larvicidal and pupicidal activities of eco-friendly phenolic lipid products from Anacardium occidentale nutshell against arbovirus vectors

Environmental Science and Pollution Research - Aedes aegypti and Culex quinquefasciatus are vectors of diseases that constitute public health problems. The discovery of products capable of...     

BIO_ALGAE 2: improved model of microalgae and bacteria consortia for wastewater treatment

Environmental Science and Pollution Research - A new set up of the integral mechanistic BIO_ALGAE model that describes the complex interactions in mixed algal-bacterial systems was developed to...     

Synthesis of functionalized mesoporous material from rice husk ash and its application in the removal of the polycyclic aromatic hydrocarbons

Environmental Science and Pollution Research - The rice husk ash (RHA) was used as an alternative source of silica for the synthesis of the functionalized mesoporous material, which was used in the...