Parametric study for hydrogel with medium swelling

preparation and characterization

Abstract

Availing medium water swelling hydrogel would significantly contribute to the production of soil conditioner and conductive gels. In the present work, hydrogel was prepared based on corn and potato starches, acrylonitrile (AN) as a grafting monomer and H₂O₂/Fe²⁺ redox system as a source of free radicals. The parameters tested for the preparation were (AN) / starch ratio of 0.3 to 1.6, H₂O₂ dose of 0.03 to 0.21 of starch weight and liquor to solid ratio of 10 to 30. The best conditions for grafting efficiency were obtained at :AN/starch ratio of about 1.4 for corn and potato starches, H₂O₂ dose of about 12% and 15% of starch weight for corn and potato starches, respectively and liquor to solid ratio of 1:10.

The prepared hydrogel at optimum attained conditions was tested for water swelling under different operating conditions. An empirical correlation for hydrogel water retention (WR) was deduced as a function of pH, temperature (T ^oC), electric conductivity (C, as µmho /cm) and time (t, hr) as follows:

WR = [21.5C ^-0.21 – 1.2pH + 0.44T] (t^0.3).

Performance indicators revealed significant water holding capacity in the range of 48 to 56 g/g. Scanning Electronic Microscopy investigations depicted the morphological features of the prepared hydrogel. Electric conductance properties were depicted at different swelling conditions of pH, NaCl concentration and temperature. The process design implications for the proposed hydrogel production are also outlined.