Study on the efficiency and recyclability of Fenton-MnFe2O4 for the degumming of hemp fibers

Abstract

Traditional alkali degumming (TAL) has been widely used for hemp degumming; however, the produced degumming waste liquid pollutes the environment. For this phenomenon, an improved Fenton oxidation degumming process was developed in this study, that is, MnFe₂O₄ (Fenton-MnFe₂O₄) was added to the Fenton system. The purpose was to reduce the reaction time and the addition of chemical reagents, and reuse the added MnFe₂O₄. The effects of the Fenton-MnFe₂O₄ system on fiber properties (such as residual gum rate, and breaking strength) and the recyclability of MnFe₂O₄ were studied. The results indicated that the hemp fiber could be separated by Fenton-MnFe₂O₄ treatment (5.30% H₂O₂ (w/w), 0.310% FeSO₄·7H₂O (w/w), 0.040% MnFe₂O₄ (w/w), 40.0 °C, 40.0 min). The breaking strength of the refined fiber was 18.22 cN per dtex, and the residual gum rate was 5.47%. Compared with the TAL system, the time was shorter, energy consumption was less and pollution was smaller. In addition, the fiber treated with MnFe₂O₄ after five cycles still showed excellent properties, namely, 15.76 cN per dtex breaking strength and 7.79% residual gum rate, which met the needs of the spinning process. Therefore, Fenton-MnFe₂O₄ show great development potential in hemp fiber degumming.