Effect of Microwave Irradiation on the Solution of Amino Acid Chromium Complexes

In recent years, microwave technology has been applied more and more in tanning, however there is still a lack of research on the effect of microwave irradiation on the interaction between chromium complex and amino acids. In the study, the influences of microwave irradiation on the reactions were studied by selecting four kinds of characteristic amino acids in collagen, aspartic acid, hydroxyproline, lysine and glycine, to provide new knowledge on tanning process. The solution of chromium complex reacted with amino acid was heated by microwave as a sample and by water bath heating under the same conditions as a control. During the process, the pH variation and UV-Visible absorption spectrum were used to determine the influence of microwave on the reaction between amino acids and chromium complex. The results demonstrated that both microwave irradiation and water bath could accelerate the reaction rate and promote the stability of the amino acid chromium complex. However, the microwave irradiation had much more obvious effects on these changes than the water bath, indicating that microwave irradiation could promote the reaction between amino acid and chromium complex further and make the formed amino acid chromium complex more stable. In addition, microwave had stronger effect on improving the reaction when the polarity of amino acid was larger. In short, this study would provide some hints for understanding how microwave affects chrome tanning and might be useful to apply microwave in tanning in future.