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Aim: The removal of heavy metals from drinking water is one of the highest impact challenges in the water and wastewater industry. For this purpose, the use of methods such as solid phase extraction followed by the use of selective adsorbents is considered as one of the most important issues in the water and wastewater industry.
Method: In this research, in order to remove the polluting and toxic heavy metal cadmium from water in the water treatment industry, Fe₃O₄ nanoparticles with a diameter of 10 nm have been synthesized. In order to make these nanoparticles resistant to corrosion and erosive factors of the environment, they are covered with a silica shell and afterwards with the aim of removing cadmium ions from aqueous solutions, the surface of Fe₃O₄@SiO₂ nanoparticles is modified with 1,4-dihydroxyanthraquinone molecules. The synthesized nanoparticles are characterized in order to evaluate the efficiency of these nanoparticles in separating cadmium ions soluble in water has.
Results: The synthesized and functionalized magnetic nanoparticles have an effective surface area of 378 m²/g with black color and spherical morphology. The effects of the parameters of the amount of nano adsorbent, pH of the solution, various concentrations of the solution and test time in the removal of divalent cadmium ions are investigated. According to the experimental data, the optimal values for the absorption process at pH 7 by using 18 mg of adsorbent in 50 ml of cadmium solution with an initial concentration of 0.35 mmol/L lead to the removal of cadmium ions with a maximum absorption of 92% at ambient temperature in a period of 35 minutes. Moreover, the recyclability and reusability of Fe₃O₄@SiO₂-DAQ in the adsorption-desorption process of cadmium ion is investigated using a magnetic magnet, and the results confirm that this synthetic nanocomposite is an effective adsorbent with excellent performance in order to remove divalent cadmium ion from aqueous solutions.
 

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Allium stipitatum is one of the most important plants native to Iran, which has a special position in food basket of people because of its many healing properties. In this study, effect of a proposed combined microwave-hot air method on kinetics and physical properties of Allium stipitatum was investigated. In the proposed method, after applying microwaves (600, 750 and 900W), samples were subjected to combined microwave-hot air drying process. Results showed that Logarithmic model with values of R² =0.996 and RMSE=0.002 was the best one to model drying kinetics of Allium stipitatum slices under the proposed method. In addition, drying curves analysis showed that the more microwave power, the less drying time and the more process rate. Moreover, in the combined section, effect of microwave power will be dominant due to higher energy. The optimum operating point to achieve the lowest moisture content and drying time ocuured at primary power of 900W and combined conditions of 450W at 80°C. Increasing microwave power increased effective moisture diffusivity from 0.167×10^-8 to 0.283×10-8 m²/s and decreased average activation energy from 17.429 to 2.074 kJ/mol. The optimum operating conditions in terms of appearance quality (colorimetry) were related to drying at microwave power of 900W and combined conditions of 450W and 80°C, which was introduced as proposed optimum point. In general, the proposed combined method compared to microwave method alone, was an efficient method in ordrt to keep the product quality characteristics and its use in drying Allium stipitatum is recommended.