正交试验法探讨单酸降解纤维素的最佳条件

Research for the optimun conditions of degrading plant fiber or cellulose with single acids by cross experiments

正交试验法探讨了乙酸、草酸、盐酸、硫酸等单酸降解植物纤维素的最佳条件。研究结果表明 ,乙酸降解纤维素时 ,影响因素的主次顺序为 :A >B >C ,最佳组合为A3B1C2 。即乙酸浓度为 30 % ,温度4 0℃ ,反应 1 5h为最佳条件 ,验证性试验结果表明 ,单用乙酸能使纤维素降解成葡萄糖的转化率达4 2 2 %。而草酸影响因素的主次则为A >C >B ,最佳组合为A2 C1B2 。即草酸浓度 10 % ,70℃酸解 1h为最佳条件。在此条件下 ,转化率可达 4 0 8%。对于盐酸影响因素的主次为A >B >C ,最佳组合为A3B3C1。即在 2 0 %盐酸 ,10 0℃酸解 1h的条件下 ,转化率可达 4 2 8%。而硫酸影响因素的主次顺序为B >A >C ,最佳组合为A3B3C1。即在 4 0 %硫酸 ,10 0℃反应 1h的最佳条件下能使转化率达 4 0 9%。研究还发现 ,乙酸、草酸、盐酸、硫酸降解纤维素特性不同。乙酸、草酸同属有机酸 ,但因二者的酸性、挥发性、溶解性等不同 ,致使温度、时间两因素对纤维素降解的影响相差很大。盐酸、硫酸属无机强酸 ,都要求高温短时 ,但随着浓度的升高 ,转化率呈下降趋势 ,且二者的下降幅度不同 ,硫酸大于盐酸。

The optimunm conditions of degrading plant fiber of cellulose with single acids such as acetic acid, oxalic acid, hydrochloric acid and sulphuric acid were studied by cross experiments. The results showed that the influential extent is:A>C>B,the best combination is A3B1C2,that is, the optimal conditions of discomposing cellulose with acetic acid are 30% acetic acid, 40℃ for 1.5 hrs. Further experiment indicated that the ratio of cellulose to glucose reached 42.2%. As for oxalic acid, the primary and secondary order affecting degradation is A>B>C,the best combination is A2B2C1,that is,the optimal conditions are 10% oxalic acid,70℃ for 1.0hr. The ratio reached 40.8% under the condition. the influential extent are A>B>C,B>A>C,respectively while hydrolyzing cellulose with HCl,H 2SO 4.The best combinations are all A3B3C1.However, the optimal conditions are not same. The former is 20% HCl, at 100℃ for 1.0 hr while the latter is 40% H 2SO 4, 100℃ for 1.0 hr.Thr rates are up to 42.8% ,40.9% under their respective optimal conditions. Although acetic acid and oxalic acid are all organic acids, because of the differences of their acidity, volatility and solubility, the impact on cellulose degrading by the two factors of temperature and time differ greatly. HCl and H 2SO 4 are all strong inorganic acids, all demand high-temperature and short-time when applying to breaking down cellulose, but with the increasing concentration of acids, the transferring rates of cellulose to glucose tend to decrease, and the decreasing extent of H 2SO 4 is bigger than HCl.