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Synthesis of Superabsorbents Based on Agar and Modified Agar and Investigation of their Applications in Controlled Release of Potassium Nitrate as a Sample of Ionic Fertilizers

Afjeh, Sofieh | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40061 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Pourjavadi, Ali
  7. Abstract:
  8. This thesis focouses on the preparation and super-swelling behavior of two superabsorbent hydrogel. In the first section, a new superabsorbent hydrogel based on agar was prepared and the effect of the ratio of some components(AA, AAM, MBA, APS and agar) on the swelling capasity of the hydrogel was studied. Maximum water absorbency of the optimized final product was found to be 614.5 g/g in distilled water. The structure of the hydrogel was characterized by FT-IR method and morphology of the samples was examined by scanning electron microscopy(SEM). Swelling behavior properties of optimized hydrogel sample in different swelling medium were investigated. In the second section, we report the synthesis of agarose-based hydrogels and investigation of their swelling properties. Acrylic groups were inserted onto agarose backbone by a homogeneous synthesis of agarose monomers with three different degrees of substitution (DS). The radical copolymerization of acrylated agarose (ACAG) with acrylic acid (AA) and 2-hydroxy ethyl acrylate (HEA) was carried out in an aqueous solution using ammonium persulfate (APS) as an initiator. Infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were carried out to confirm the chemical structure of the hydrogel. Their equilibrium swelling degree was evaluated in various conditions. The absorbency under load (AUL) and dynamic swelling kinetics of the hydrogel were also studied. Finally, the hydrogels were loaded with potassium nitrate and its potential for controlled release of potassium nitrate was investigated by measuring conductivity of ion-released medium
  9. Keywords:
  10. Hydrogel ; Agar ; Acryloyl Chloride ; Acrylic Acid ; Potassium Nitrate

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