Reinforced MFC aerogel for heavy metal ions separation

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Mirco-fibrillated cellulose (MFC) aerogel was reinforced by chitosan. The reinforced MFC aerogel was used as heavy metal ions absorbent. The results showed that the aerogel had good absorption capacity of over 200mg/g for all 4 kinds of heavy metal ions, Cd2+,Zn2+,Pb2+ and Cr6+ in the initial concentration range of 50-1000mg/L. The aerogel had little effect on contact time, but showed dependence on ion initial concentration. The reinforced MFC aerogel is a novel and attractive absorbent for heavy metal ions separation. Micro-fibrillated cellulose (MFC) is isolated from natural cellulose fibers by basically mechanical action after enzyme or chemical pretreatment. MFC has been widely investigated recently due to its sustainable, renewable, and biocompatible nontoxic properties for relatively high physical-chemical stability materials (1-3). These aerogels are based on the hydrogen bond formation between MFC (4). Unfortunately, these hydrogen bonds can be easily destroyed by immersing the aerogels in water, which limited the application of the aerogels. Chemical-crosslinking affords a method for the preparation of cellulose aerogels with high mechanical properties (4-6). Although many efforts have been carried out for the improvement of the mechanical properties of cellulose aerogels, the substances that can provide safe, renewable, and biocompatible nontoxic are more desirable. Regarding to the chemical nature, chitosan and cellulose have similar structure, with the same β-glycosidic linkages, being the main difference the presence of primary amino groups at most of the C-2 positions in chitosan, in place of the hydroxyl groups of cellulose. Much work has been devoted to the study of chitosan blends with cellulose (7-10), poly (vinyl alcohol) (11-13), gelatin (14), collagen (15) and others (7). The evidence of some chitosan-cellulose interactions were found. The chemical reaction of the chitosan amino groups with cellulose carbonyl Groups was proved (3). In the current work, we firstly reported a reinforced MFC aerogel and its application with the addition of chitosan. The aerogels showed mechanical properties improved. Using the reinforced aerogel as absorbent, 4 kinds of heavy metal ions separation were examined in different conditions. The aerogel will have strong potential in heavy metal ions removal.