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Fasā, Iran

Arshadi M.,Islamic Azad University at Fasa | Amiri M.J.,Fasa University | Gil A.,Public University of Navarra
Journal of Colloid and Interface Science | Year: 2014

This paper reports the preparation of three new Schiff base ligands modified SiO2Al2O3 mixed oxide adsorbents, and their use for removal of Pb(II) and Cd(II) from aqueous solutions. Equilibrium and kinetic models for Pb(II) and Cd(II) sorption were applied by considering the effect of the contact time, initial Pb(II) and Cd(II) concentrations, effect of temperature, and initial pH. The contact time to attain equilibrium for maximum adsorption was 120min. These heterogeneous Schiff base ligands were found to be effective adsorbents for the removal of heavy metal ions from solution, with Si/Al-pr-NH-et-Npyridine-2-carbaldehyde having a high adsorption capacity for Pb(II) and Cd(II) ions from aqueous solution. The adsorption of heavy metal ions has been studied in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, confirming chemical sorption as the rate-limiting step of adsorption mechanisms and not involving mass transfer in solution, which were confirmed by techniques of DS UV-vis and FT-IR. The thermodynamic parameters (δG, δH and δS) indicated that the adsorption of Pb(II) and Cd(II) ions were feasible, spontaneous and endothermic between 25 and 80°C. © 2014 Elsevier Inc. Source

Rostami A.,Shiraz University | Habibagahi G.,Shiraz University | Ajdari M.,Fasa University | Nikooee E.,Shiraz University
International Journal of Geomechanics | Year: 2015

The soil-water retention curve (SWRC) is the relationship between the suction values and water content of the soil. This curve has one or more branches depending on the suction imposition paths, and represents one of the most important properties of unsaturated soils. In this paper, by using a percolation approach and introducing a trial-and-error process, a randomly distributed pore network model is first calibrated using experimental data corresponding to the main drying branch of the SWRC. The influence of the stress state on the pore-size distribution of the network is further studied. The calibrated network model is used to predict the main wetting and scanning branches of the SWRC. Piston-type and cooperative fillings are used as the two wetting mechanisms. The proposed method facilitates modeling pore networks with large numbers of pores covering a wide range of suction values (full saturation through the residual degree of saturation). The results indicate that with an increase in the applied stress, micropores and macropores are affected. However, it is the change in the macropores that strongly influences the SWRC. Also, it is possible to predict the wetting and scanning branches of the SWRC with reasonable accuracy once the model is calibrated when using the main drying curve. © 2014 American Society of Civil Engineers. Source

Gharbavi K.,Shahid Chamran University | Badehian H.,Fasa University
AIP Advances | Year: 2015

Full potential linearized augmented plane waves method with the generalized gradient approximation for the exchange-correlation potential was applied to calculate the optical properties of (7, 7) single walled carbon nanotubes. The both x and z directions of the incident photons were applied to estimate optical gaps, dielectric function, electron energy loss spectroscopies, optical conductivity, optical extinction, optical refractive index and optical absorption coefficient. The results predict that dielectric function, ε (ω), is anisotropic since it has higher peaks along z-direction than x-direction. The static optical refractive constant were calculated about 1.4 (z-direction) and 1.1 (x- direction). Moreover, the electron energy loss spectroscopy showed a sharp π electron plasmon peaks at about 6 eV and 5 eV for z and x-directions respectively. The calculated reflection spectra show that directions perpendicular to the tube axis have further optical reflection. Moreover, z-direction indicates higher peaks at absorption spectra in low range energies. Totally, increasing the diameter of armchair carbon nanotubes cause the optical band gap, static optical refractive constant and optical reflectivity to decrease. On the other hand, increasing the diameter cause the optical absorption and the optical conductivity to increase. Moreover, the sharp peaks being illustrated at optical spectrum are related to the 1D structure of CNTs which confirm the accuracy of the calculations. © 2015 Author(s). Source

Seed germination is the most important stage of plant life that is influenced by various environmental factors e.g., salinity-stress. Seed priming can increase plant tolerance against salinity. A laboratory experiment of completely randomized design with three replicates was carried out to investigate the effect of seed priming with different sources of potassium ( K) on germination and seedling-characteristics of corn under salinity stress conditions. Treatments consisted of three levels of K nano chelate (0, 1.5 and 3%), three levels of K sulfate (0, 1.5 and 3%) and five levels of salinity (0, 0.5, 1, 1.5 and 2% prepared from equal equivalents of NaCl and CaCl2). Seed priming increased germination-percentage (GP) and rate (GR), plumule-fresh-weight (PFW), radicle-fresh-weight (RFW) and plumule-dry-weight (PDW), significantly. The highest GR and GP were observed in seeds primed with 1.5% K-nano-chelate without any salinity-stress. Whereas, the lowest-value of the aforementioned traits were obtained in non-primed-seeds subjected to the highest-level of applied-salinity, i.e., 2%. By increasing salinity-levels, mean-germination-time (MGT) of primed and non-primed seeds increased. However, the effect of salinity on primed-seeds was less than that of non-primed-seeds. The highest PFW was obtained with priming of seeds with 1.5% K-nano-chelate at salinity-level of 0.5%. Whereas, its lowest-value was obtained in seeds primed with 3% K-nano-chelate at salinity-level of 2%. The effect of salinity on PDW of primed-seed with K-nano-chelate or K-sulfate was less than that of non-primed-seeds. Seed-priming with low level (1.5%) of applied K-nano-chelate or K-sulfate increased radicle-length (RL); whereas, high-level (3%) of applied K-nano-chelate or K-sulfate was not effective, significantly. Our findings emphasis seed-priming is a useful way to increase seedling-tolerance under salinity stress conditions. Source

Parvizi H.,Shiraz University | Sepaskhah A.R.,Shiraz University | Ahmadi S.H.,Fasa University
Agricultural Water Management | Year: 2014

We investigated the effect of different irrigation and fertilizer regimes on yield of 9-year old pomegranate trees during 2011 and 2012. The experimental design was a split plot as complete randomized blocks with three replications. The main plots contained five irrigation treatments as irrigating one side of trees with 50% and 75% of ETC (DI50, DI75); irrigating alternate sides of trees with 50% and 75% of ETC (PRD50, PRD75) and full irrigation (FI) that received 100% ETC. The sub-plots were three types of fertilizer including sheep manure; M (50Mgha-1), chemical; CF (Urea: 120, diammonium phosphate: 75 and potassium sulfate: 60kgha-1) and foliar; FF (Ecoquel Micromix: 1kgha-1 dissolved in 1000L water, Defender Calcium and Futop: 2 L mixed in 1000L water) fertilizer. Results showed that in comparison with the FI treatment, the PRD75 and PRD50 with 25% and 50% less applied water increased the fruit yield by 5.6-8.3% and decreased it by 15.8-17%, respectively. All DI and PRD irrigation treatments had positive effects on water productivity (WP) compared with FI. The PRD strategies showed the superior results in increasing the fruit load, unit weight and diameter of fruit and decreasing the fruit cracking compared to DI strategies. Fertilizers including microelements (M and FF) resulted in higher fruit yield and loading and lower fruit cracking; while, fertilizers, including macroelements (M and CF), were more effective in enhancing the unit weight of fruit. Therefore, the PRD75 strategy in combination with M is highly recommended for pomegranate orchards in semi-arid areas due to the positive impact on fruit yield, loading, WP, unit weight of fruit and fruit cracking. Also, the DI75 strategy could be used for conserving additional water where the extra cost of the PRD strategy in drip irrigation is considerable. © 2014 Elsevier B.V. Source

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