为了充分利用葵花籽的工业生产副产物，该文以葵花籽壳为原料，采用硫酸水解法制备葵花籽壳纳米纤维素。通过单因素试验研究了酸解温度、酸解时间、硫酸质量分数和液料比4个因素对纳米纤维素得率的影响，应用响应面法对工艺参数进行优化，并对制备得到的纳米纤维素进行了透射电镜（transmission electron microscopy，TEM）、红外光谱（Fourier transform infrared spectroscopy，FT-IR）和X-射线衍射（X-ray diffraction，XRD）等分析。结果表明：当酸解温度为42℃、酸解时间为83.71 min、硫酸质量分数为59.97%、液料比为12.33：1时，预测得出纳米纤维素得率为31.67%，验证试验纳米纤维素得率为31.31%。制备的葵花籽壳纳米纤维素呈棒状，直径为10～30 nm，长度为150～300 nm，仍然具有纤维素的基本化学结构，结晶度较高，属于典型的纤维素Ⅰ型结晶结构。该文研究结果可以为葵花籽的综合利用提供参考。%Nanosized single crystal cellulose is often called whisker. Nano-whisker or nanofibrils can be prepared from various sources, such as natural fibers, agricultural by-products, and marine animals. Nano-whiskers are characterized by excellent mechanical properties, high specific surface area, high length-diameter ratio, environmental friendliness, and low cost. Because of these properties, nano-whiskers are used in many fields and attract growing attention by researchers in the world. In China, the agricultural product processing industry yields abundant cellulose waste. Thus, it becomes meaningful to find out a better resolution to ‘agricultural cellulose waste’. In this study, nano-cellulose was prepared by a sulphuric acid hydrolysis method and with shells of sunflower seeds as raw material. The effects of four factors (e.g. acid hydrolysis temperature, sulfuric acid concentration, acid hydrolysis time, and liquid to material) on nano-cellulose yield were investigated by single-factor tests. The preliminary results showed that the optimal conditions were: acid hydrolysis temperature at 40℃; sulfuric acid concentration at 60%; hydrolysis time at 90 min; liquid to material ratio at 12:1. The results of single-factor tests showed that the nano-crystalline cellulose (NCC) yield was maximized to 26.72% at the acid hydrolysis temperature 40℃. The yield of NCC was maximized to 29.89% at the sulfuric acid concentration of 60%, to 30.09% at the acid hydrolysis time of 90 min, or to 25.33% at the liquid to material of 12:1. Based on the single-factor test, the process parameters were optimized by a response surface method. A quadratic polynomial model was built, and then its effectiveness and the interactions between different factors were analyzed. Also the microstructure of the nano-cellulose as-prepared was investigated by transmission electron microscopy (TEM), particle size distribution, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Results showed that the importance degrees of all factors on yield of NCC rank as follows: Acid hydrolysis temperature > acid hydrolysis time > liquid to material > sulfuric acid concentration. The optimal process conditions were as follows: acid hydrolysis temperature at 42℃, acid hydrolysis time at 83.71 min, sulfuric acid concentration at 59.97%, and liquid to material ratio at 12.33:1. Under these conditions, the highest yield of NCC was 31.67%, which was validated to be 31.31%. SEM and particle size distribution analysis showed that the NCC from shells of sunflower seeds was rod-like and partially aggregated. The diameter was measured to be 10 - 30 nm, and length was 150 - 300 nm. FT-IR showed that NCC still possessed the basic chemical structure of cellulose and did not have functional group variation. XRD showed that NCC possess a typical cellulose I crystal structure and their crystallinity degree was obviously higher the crystallinity degree. This study provided some reference for the comprehensive utilization of sunflower seeds.
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