Abstract
Rice straw-derived cellulose (RSC) with purity of 92 wt.% was successfully extracted from rice straw by a novel and facile strategy, which integrated the C2H5OH/H2O autocatalytic process, dilute alkali treatment and H2O2 bleaching process. Influencing factors of the cellulose extraction were systematically examined, such as ethanol concentration, alkali concentration, H2O2 bleaching process and so on; the optimal extraction conditions of cellulose was determined. A series of rice straw-derived cellulose acetate (RSCA) with different degree of substitution (DS) were prepared by the acetylation reaction; the effects of Ac2O/cellulose ratio, reaction temperature and reaction time on the acetylation reaction were investigated. Results of FTIR and XRD analysis demonstrated that highly purified RSC and RSCA were prepared comparing with the commercial cellulose and cellulose acetate. Solubility analysis of RSCA with different DS indicated as-prepared RSCA with DS of 2.82 possessed the best solubleness, which was suitable for electrospinning. Moreover, the flexible RSCA fibrous membrane was easily fabricated by a facile electrospinning method. Our proposed method provided a strategy for realizing the high-value utilization of waste rice straw resource, as prepared RSC and RSCA can be used as chemical raw material, and electrospun RSCA fibrous membrane has various applications in medical materials, food packaging, water purification and so on.
Highlights
Crop straw is rich in resources and extensive in use, and annual output is about 900 million tons in China
As it is known that rice straw is mainly composed of cellulose (40–50%), hemicellulose (20–30%) and lignin (10–18%) [10], cellulose is trapped in a hemicellulose-lignin matrix, which makes its separation extremely difficult [11,12]
We develop a novel and facile strategy for realizing the high-value utilization of waste rice straw resource, which integrates the C2H5OH/H2O autocatalytic process, dilute alkali treatment and H2O2 bleaching process
Summary
Crop straw is rich in resources and extensive in use, and annual output is about 900 million tons in China. The solvent of ethanol can effectively dissolve lignin and separate cellulose and hemicellulose [16]. Rehman et al extracted lignocellulose from crude corn straw by employing the mixed solvent of n-hexane, ethanol and deionized water, followed by a multi-step process of weak alkali treatment and complete chlorine-free bleaching. Rosa et al successfully separated cellulose from rice husk by means of a chlorine-free procedure, on the basis of the whole cellulose content expected for rice husk; this method resulted in a yield around 74%, in which the effect of ethanol was examined [17]. The RSCA suitable for electrospinning with a DS value of 2.82 is screened out, and the electrospun RSCA fibrous membrane is successfully fabricated, which has various applications in medical materials, food packaging, water purification and so on
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