A green and efficient technology for the degradation of cellulosic materials: Structure changes and enhanced enzymatic hydrolysis of natural cellulose pretreated by synergistic interaction of mechanical activation and metal salt

A new technology for the pretreatment of natural cellulose was developed, which combined mechanical activation (MA) and metal salt treatments in a stirring ball mill. Different valent metal nitrates were used to investigate the changes in degree of polymerization (DP) and crystallinity index (CrI) of cellulose after MA   +   metal salt (MAMS) pretreatment, and Al(NO 3 ) 3 showed better pretreatment effect than NaNO 3 and Zn(NO 3 ) 2 . The destruction of morphological structure of cellulose was mainly resulted from intense ball milling, and the comparative studies on the changes of DP and crystal structure of MA and MA   +   Al(NO 3 ) 3 pretreated cellulose samples showed a synergistic interaction of MA and Al(NO 3 ) 3 treatments with more effective changes of structural characteristics of MA   +   Al(NO 3 ) 3 pretreated cellulose and substantial increase of reducing sugar yield in enzymatic hydrolysis of cellulose. In addition, the results indicated that the presence of Al(NO 3 ) 3 had significant enhancement for the enzymatic hydrolysis of cellulose.