Soil Chemistry and Pollution
Samira Alvani; ُSaeid Hojati; Ahmad Landi
Abstract
Introduction Pollution of the environment to heavy metals is one of the major problems of today's world. Following the development of industries, as well as increasing agriculture in response to the growing population, the overuse of chemical fertilizers, mining activities, the production and disposal ...
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Introduction Pollution of the environment to heavy metals is one of the major problems of today's world. Following the development of industries, as well as increasing agriculture in response to the growing population, the overuse of chemical fertilizers, mining activities, the production and disposal of waste waters and sewage sludge, etc., the entry and accumulation of heavy metals in the environment has increased. There are several methods for removing heavy metals from wastewaters. Among the common methods for removal of heavy metals, adsorption, in particular using inexpensive natural adsorbents, due to the ease of implementation and high efficiency is a cost-effective and economical technique. Palygorskite is a fibrous mineral common in clay fractions of soils of arid and semi-arid regions of the world. Although there are several studies applying palygorskite as a suitable mineral for cleaning of wastewaters, however, few studies have been carried out to evaluate the ability of nanosized particles of such clay minerals for removal of heavy metals from the environment. Therefore, this study was conducted to measure the ability of palygorskite nano- and micro-sized particles to adsorb lead and copper from aqueous solutions. Materials and Methods: Kinetic experiments were carried out at 11 different contact times (5, 10, 20, 30, 60, 120, 240, 480, 720, 1440, and 2880 min) using solutions containing 150 mg / l of lead and copper elements at pH=5. Palygorskite used in this study was purchased from Tulsa Co., Spain Then, micron (Results and Discussion The results illustrated that in the so-called samples as nanosized palygorskite, about 50% of the particles in the sample was found smaller than 100 nm in size, and in this case no samples of particle size of 100 nm and smaller were observed in those so-called palygorskite microparticles. The results indicated that by increasing the contact time and reducing the mineral particle sizes from micron to nanoscale, more amounts of lead and copper heavy elements adsorbed onto the mineral. This is due to an increase in the exposure of active sites on the adsorbent surfaces by the pollutant. When the data were fitted with the pseudo first order, pseudo second order and intraparticle diffusion kinetic models, it was revealed that the pseudo second-order kinetic model with a determination coefficient (R2) of 0.99 was the best model describing kinetics of study. Besides, the lower values of the chi-square (ᵡ2) in fit with the pseudo-second-order kinetic model as compared to those in the pseudo first-order model show a greater similarity between the pseudo-second-order kinetic model and the experimental data. The isotherm of Pb and Cu adsorption was also studied using Langmuir and Freundlich adsorption models. It was observed that the data had a better coordination with the Langmuir model with a determination coefficient of 0.99. By increasing the initial concentration of the lead and copper in the solution, their distribution coefficient (Kd) decreases. This suggests that although with increasing initial concentration of lead and copper, their adsorption increased by palygorskite mineral, however, by increasing the initial concentration of heavy metals, the remaining concentration of these elements also increased. The results also illustrated that both micro- and nanoparticles of palygorskite show more affinity to adsorb lean than copper from solutions. Conclusion: In general, it can be concluded from this study that adsorption of lead and copper by palygorskite nanoparticles depends on the contact time and the adsorbent size. Besides, the use of this mineral could be considered as a suitable, feasible and environmentally friendly way to remove lead and copper from aqueous solutions.
Plant Nutrition, Soil Fertility and Fertilizers
Ali Abdolahi; Mehdi Taghavi; Mojtaba Norouzi masir; Abdolamir Moezzi
Abstract
Nanotechnology has created a range of new applications in different stages of agriculture. The application of Nano-fertilizers for plants is of vital importance because of its unique properties, such as the specific surface and high reactivity. Many studies have investigated the effect of metal nanoparticles ...
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Nanotechnology has created a range of new applications in different stages of agriculture. The application of Nano-fertilizers for plants is of vital importance because of its unique properties, such as the specific surface and high reactivity. Many studies have investigated the effect of metal nanoparticles on yield and concentration of elements in the plant. The present study was conducted with the aim of investigating the effects of Functionalized Iron Oxide Nanoparticles (FIONPs) on plant yield, concentration and uptake of Zinc in root and shoots of wheat under greenhouse cultivation in a calcareous soil. Materials and Methods This study was conducted in the greenhouse condition as a randomized complete design with three replications. Treatment consisted of functionalized iron oxide nanoparticles (Hydroxyl: OH, Carboxyl: COOH and Amine: NH2) each at three levels (100, 200 and 300 mg.kg-1), ZnSO4 (40 kg.ha-1) and Control. During the experiment, some parameters such as the plant height and chlorophyll index were measured. At the end of the cultivation period, dry weight and Zn concentration of root, shoot and grain was determined using Atomic absorption apparatus (Perkin elmer A_Analyst 200 model). Likewise, content of soil available Zn was measured using DTPA. Results The amount of available zinc in all levels of iron oxide nanoparticles, except Amine iron oxide nanoparticles (at levels of 200 and 300 mg / kg), was significantly (p < 0.01) increased compared to control. The maximum amount of soil available Zn were observed in levels of 300, 200 and 100 mg.kg-1 Carboxyl iron oxide nanoparticles with 83.64, 70.91 and 63.64% increment compared to control, respectively. Effect of treatments of functionalized iron oxide nanoparticles and zinc sulfate on chlorophyll content, plant height and dry weight of shoots was significant (p < 0.01). The maximum yield of root and shoot was obtained at the level of 300 mg.kg-1 of Carboxyl iron oxide nanoparticles with 34.74 and 25.1% increment compared to control, respectively. The maximum grain yield was observed at the level of 300 mg.kg-1 of Carboxyl iron oxide nanoparticles with 36.51% increment compared to control. The maximum chlorophyll content was obtained in Carboxyl iron oxide nanoparticles (at level of 300 mg. kg-1) with 11.38% increment compared to control. The maximum of Zinc concentration in root, shoot and grain was observed at the level of 300 mg.kg-1 carboxylic oxide nanoparticles with 103.62, 159.26 and 26.87% increment compared to control, respectively. Conclusions The results showed that application of FIONPs improved soil pH and subsequently available zinc of soil. Also, nanoparticles increased the yield, concentration and uptake of zinc in root, shoots and grain of wheat. Therefore, based on the obtained results from this study, it can be said that use of new strategies such as nanoparticles can be useful in improving soil conditions and bioavailability of Micronutrient like Zinc and reducing chemical fertilizers.