Application of CGP-cross route process for microstructure refinement and mechanical properties improvement in steel sheets

A modified method of severe plastic deformation (SPD) entitled constrained groove pressing-cross route (CGP-CR) was introduced for imposing a high magnitude of equivalent strain of about 2.32 per pass on the sheet form samples. The major benefit of this improved route compared to previous common route was the more homogeneity of strain in the rolling (RD) and transverse (TD) directions of sheets. In this study, low carbon steel samples were used for examination of evolutions in microstructure and mechanical properties during SPD via CGP-CR process. Mechanical properties improvement were measured by tensile and macro hardness tests. The results indicate that CGP-CR process can effectively improve tensile strength; and also, yield stress and hardness of as-received low carbon steel samples were improved up to about 100% after two deformation passes. Also, high magnitude of inhomogeneity can be observed in hardness distribution through first pass of the process which diminishes in the subsequent passes. Microstructural evolutions during process were monitored by optical microscopy observations and X-ray diffraction analysis. The results demonstrate that initial ferritic microstructure with grain size of about 30 μm was refined to a 225 nm cell structure after two passes of CGP-CR process.     

Study of Fe–Co mixed metal oxide nanoparticles in the catalytic low-temperature CO oxidation

Iron–cobalt mixed metal oxide nanoparticles (Co/Fe molar ratio: 1/5) have been prepared by a simple co-precipitation method and employed as catalyst in low-temperature CO oxidation. The prepared catalysts were characterized by thermal gravimetric and differential thermal gravimetric analyses (TGA/DTG), X-ray diffraction (XRD), temperature programmed reduction (TPR), N₂ adsorption (BET) and transmission electron microscopy (TEM) techniques. The results revealed that inexpensive iron–cobalt mixed metal oxide nanoparticles have a high potential as catalyst in low temperature CO oxidation. The results showed that increasing in calcination temperature increased the crystallite and particle size and decreased the specific surface area, which caused a decrease in catalytic activity of prepared catalysts. In addition, the pretreatment conditions affect the catalytic activity and catalyst pretreated under oxidative atmosphere showed the higher activity than those pretreated under reductive and inert atmospheres.     

Removal and recovery of copper and nickel ions from aqueous solution by poly(methacrylamide-co-acrylic acid)/montmorillonite nanocomposites

Nanocomposite hydrogels based on poly(methacrylamide-co-acrylic acid) and nano-sized montmorillonite were prepared by aqueous dispersion and in situ radical polymerization. Optimum sorption conditions were determined as a function of montmorillonite content, contact time, pH, and temperature. The equilibrium data of Cu²⁺ and Ni²⁺ conformed to the Freundlich and Langmuir isotherms in terms of relatively high regression values. The maximum monolayer adsorption capacity of the nanocomposite hydrogel (with 3 wt% montmorillonite content), as obtained from the Langmuir adsorption isotherm, was found to be 49.26 and 46.94 mg g^?1 for Cu²⁺ and Ni²⁺, respectively, at contact time?=?60 min, pH?=?6.8, adsorbent dose?=?100 mg/ml, and temperature?=?318 K. Kinetic studies of single system indicated that the pseudo-second order is the best fit with a high correlation coefficient (R ²?=?0.97–0.99). The result of five times sequential adsorption–desorption cycle shows a good degree of desorption and a high adsorption efficiency.     

Screening for plants and rhizospheral fungi with bioremediation potency of petroleum-polluted soils in a Tehran oil refinery area

The contamination of soils by toxic and/or hazardous organic pollutants, especially with crude oil, is a widespread problem. This study was conducted in a petroleum-contaminated area in a Tehran oil refinery to find petroleum-resistant plants and their rhizospheral fungal strains with bioremediation potency. The plants growing in the oil-polluted area were collected and determined taxonomically. Root samples of the plant species were collected from a polluted area and fungal strains determined by laboratory methods and taxonomical keys. The growth ability of the isolated fungal strains was studied in media containing 1%–15% crude oil. Results showed that seven plant species were of the highest density in the contaminated area: Alhagi persarum, Hordeum marinum, Peganum harmala, Phragmites australis, Prosopis farcta, Salsola kali, and Senecio glaucus. The root-associated fungi were isolated and showed that the fungal variation in the oil-polluted area is higher than that in a non-polluted area. The growth assay of isolated fungal strains showed that all studied fungal strains were able to form colonies at the applied concentrations but Alternaria sp. and Rhizopus sp. were the most resistant ones. Some plants were resistant to oil pollution, which also had positive effects on the fungal strains.     

Seasonal trend and source identification of polycyclic aromatic hydrocarbons associated with fine particulate matters (PM2.5) in Isfahan City,Iran, using diagnostic ratio and PMF model

Environmental Science and Pollution Research - Particulate matters (PMs) and their associated chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) are important factors to evaluate...     

Carbon sequestration via afforestation as a sustainable action to mitigate climate change in Western Iran

Climate change involves increasing atmospheric carbon dioxide concentration which is driven by anthropogenic emissions. Afforestation, which is the establishment of forests on previously non‐forested lands, could be a suitable climate change mitigation strategy. The aim of this research is to evaluate the carbon sequestration capability of the Eucalyptus and Prosopis species in the Reza‐Abad afforestation park in western Iran. For this aim, three stands of any species were selected. For quantitative assessment, a transect was implemented at the length of 100 m. In trees located of transects, the general characteristics of species were measured. Also, for estimating the amount of litter, a sample plot has been measured at the center of the quadrate. These samples were taken from the afforested area, the control area inside the afforested area and another control area outside. In each stand, species were selected randomly and one‐eighth of the whole stand was taken for calculating the percentage of carbon and aerial biomass. Then the aboveground organs were weighted and after the transfer of different plant organs to the laboratory, the conversion factor of carbon sequestration of the plant organs was determined individually by combustion method. Also, soil samples were also collected from two depths of 0–15 and 15–30 cm in each of the cultivated and control parts. The results showed that there is a significant difference between the species and Prosopis has higher carbon sequestration than Eucalyptus. The carbon sequestration among different organs showed a significant difference, carbon sequestration was 19.24 t/ha for Eucalyptus and 18.43 t/ha for Prosopis. After an economic calculation, it was concluded that afforestation has a positive effect on the reduction of atmospheric carbon dioxide. Hence, these results allow decision makers to change land use from desert area to forest, and planting the Prosopis species is more recommendable than Eucalyptus for afforestation in such areas which are economically profitable.     

Positive environmental effects of the coronavirus 2020 episode: a review

Environment, Development and Sustainability - The outbreak of COVID-19 has made a global catastrophic situation that caused 1,039,406 deaths out of 35,347,404 infections, and it will also cause...     

Preparation and characterization of polycaprolactone nanocapsules containing pretilachlor as a herbicide nanocarrier

Polycaprolactone nanocapsules (PCL) containing pretilachlor were prepared, and Fourier transform infrared spectroscopy, atomic force microscopy, and transmission electron microscopy were used for their structural and morphological investigations. The results revealed that the nanocapsules had irregular shape and their particles size was in the range of 70–200 nm. The encapsulation efficiency of pretilachlor was measured as 99.5 ± 1.3% using high-performance liquid chromatography analysis. The physicochemical stability studies over 60 days showed that the nanocapsules were stable in the suspension without any aggregation. The herbicide activity was examined in a pre-emergence manner using barnyard grass as a target plant and rice as a non-target plant. The nanoformulation had no negative effect on rice plant. However, its effect on barnyard grass was significant. The cytotoxicity analysis indicated that the nanocapsulated herbicide is less toxic rather than the commercial formulation. Therefore, encapsulation of pretilachlor in PCL nanocapsules can be used effectively to construct environmentally friendly PCL-herbicide systems in agriculture.

     

Petroleum pollution in mangrove forests sediments from Qeshm Island and Khamir Port—Persian Gulf, Iran

The concentrations of total polycyclic aromatic hydrocarbons (?PAHs) and 22 individual PAH compounds in 42 surface sediments collected from the mangrove forest of Qeshm Island and Khamir Port (Persian Gulf) were analyzed. ?PAHs concentrations ranged from 259 to 5,376 ng?g^?1 dry weight with mean and median values of 1,585 and 1,146 ng?g^?1, respectively. The mangrove sediments had higher percentages of lower molecular weight PAHs and the PAH profiles were dominated by naphthalene. Ratio values of specific PAH compounds were calculated to evaluate the possible source of PAH contamination. This ratios suggesting that the mangrove sediments have a petrogenic input of PAHs. Sediment quality guidelines were conducted to assess the toxicity of PAH compounds. The levels of total PAHs at all of stations except one station, namely Q₆, were below the effects range low. Also, concentrations of naphthalene in some stations exceeded the effects range median.     

Laboratory waste minimization by recovery of silver as nano-silver colloidal dispersion from waste silver chloride

The use of cyclic experiments, where the product of one reaction becomes the starting material for the next experiment, was proposed as an effective protocol for waste minimization in an educational lab. A simple, cheap and pollution-free method was developed for recovering silver as nano-silver colloidal dispersion from waste silver chloride in the laboratories of the Faculty of Health, Safety and Environment. Silver nanoparticles of the size 5–18 nm were recovered in the presence of sodium borohydride as a reducing agent and polyvinylpyrrolidone as a stabilizer agent. The nano-silver particles were studied for their formation, structure, stability and size using UV–Vis spectroscopy, transmission electron microscopy and dynamic light scattering techniques. The antibacterial assays of nanoparticles showed satisfactory results for Escherichia coli ATCC25922, Staphylococcus aureus ATCC 29213, and Acinetobacter baumanii (Clinical isolate). A laboratory experiment was designed in which students synthesize yellow colloidal silver solution from chemical waste silver chloride and estimate particle size using visible spectroscopy.