Abstract:

To utilize waste resource and protect environment, eggshells were processed into calcium acetate by direct reaction with acetic acid. The preparation process for calcium acetate was optimized using a four-factor quadratic general rotary unitized design and response surface methodology. The interactions between acetic acid concentration and reaction temperature or reaction time had significant effect on calcium acetate yield. Acetic acid concentration of 6 mol/L, reaction temperature of 79.38℃, reaction time of 5.98 h and material/liquid ratio of 1:5 were found optimum. Under these optimum conditions, the maximum calcium acetate yield was 98.48%. Orthogonal array design was used to optimize the process for magnesium removal from the prepared product, and the results showed that the optimal process conditions were as follows: CaO amount 0.5 g, reaction temperature 65 ℃ and reaction time 15 min and the purity of the purified product under these conditions was 99.79%. According to X-ray diffraction analysis, the final product is calcium acetate.

Key words: eggshell, comprehensive utilization, calcium acetate, egg processing