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Investigation of Operating Parameters for Thorium Adsorption from Wastewater by Using of Radiated Grafting Polymeric Adsorbents in Packed Bed Column

Kazzazi, Sina | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55172 (46)
  4. University: Sharif University of Technolog
  5. Department: Energy Engineering
  6. Advisor(s): Outokesh, Mohamad; Torab Mostaedi, Meysam; Asadollahzadeh, Mehdi; Torkaman, Rezvan
  7. Abstract:
  8. Today, the pollution of heavy metals in wastewater and surface waters, which is a global environmental problem, has increased with the expansion of various industrial activities. Heavy metals cause serious health problems due to their accumulation in human and animal tissues. Thorium, is a radioactive element with an atomic number of 90 that is widely used in the optics, aerospace, metallurgy and chemical industries, in the manufacture of high-strength alloys, in UV photocells, and especially in the nuclear industry. The primary sources of radioactive wastewater include nuclear power plants, nuclear energy industry research centers, medical institutions, industrial production, universities, and research institutes. Assessing the adverse health effects of thorium (Th4+) requires a slightly different approach to chemicals because radioactive elements begin to emit electromagnetic radiation after entering the living organism.In this study, the adsorption of thorium metal using a radiated grafting polymeric adsorbent in continuous and batch systems has been investigated. In the first stage, optimization of adsorbent synthesis with parameters, solvent to monomer ratio, gamma-ray dose, and monomer composition ratio, in the second stage, optimization of adsorption conditions in a batch system with parameters, pH, initial ion concentration, and contact time, the parameters affecting the adsorption process in the continuous system including the initial ion concentration, bed height, and inlet flow were investigated. For optimization, EXPERIMENTAL DESIGN software and surface response method were used. Under optimal synthesis conditions, the ratio of solvent to monomers was 43.43 to 56.57, the dose was 20 kg gamma, and the ratio of acrylonitrile (AN) to acrylic acid (AAc) was 53.75 to 46.25. The adsorption and graft percentages for the optimal adsorbent were 99.97 and 70.1%, respectively. Also, the optimal adsorption conditions were determined at a concentration of 61.07 mg /L, contact time of 3.77 hours, and pH 6.5. The adsorbent adsorption capacity was 58.9 mg/g under optimal conditions. The Freundlich isotherm was better matched to the experimental data, and the adsorption process followed a second-order kinetic model. In the continuous part, the optimal conditions were observed at a 25 mg/L concentration, a bed height of 9 cm, and a flow rate of 2.5 mL/min. Also, the data were in good agreement with the Clark model
  9. Keywords:
  10. Heavy Metals ; Thorium ; Adsorption ; Experimental Design ; Packed Bed Column ; Radiation Grafted Polymer

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