| The diosgenin solid waste originate from Yellow Ginger after extracting diosgenin. Most of the saponin solid waste is piled or burned arbitraryly, This untreated residue not only occupy a large of land, destroy the soil ecological balance, but also bring water pollution and dust pollution, which have threatened the existent environmnet of human being. More importantly, it cause resources to be wasted.Thus it is of great significance for its comprehensive utilization.Levulinic acid, which has good reactive activity, is an important green platform chemical. Levulinic acid is always prepared by acid hydrolysis under the condition of high temperature and high pressure, so the problem exists in the corrosion for the equipment. The paper aim at keeping the preparation of levulinic acid under normal temperature and pressure conditions.Based on the residual containing a lot of cellulose material characteristics, this paper uesd dilute acid as catalysis in order to find the optimium conditions for levulinic acid producion from diosgenin solid waste. Based on this, studides were carried on the preteratment to gian the best method, so as to provide theoretical basis for comprehensive utilization of diosgenin solid waste and prudction of levulinic acid. The results were as follows:(1) Study on the components of the diosgenin solid waste showed that the percent of cellulose is 17.05, percent of lignin is 10.40, percent of hemicellulose is 24.02, percent of starch is 33.69 and 4.35 percent of water.(2) By using single factor experiment method, the acid catalysis were used to detect the effects of catalytic acid, acid volume fraction, reaction temperature, reaction time, liquid-solid ratio and granularity on levulinic acid production from diosgenin solid waste at atmospheric pressure. Single factor experiment indicated that sulfuric acid concentration, reactive time and liquid-solid ratio were main factors for hydrolysis of diosgenin solid waste, with the granularity in the range of 20~60 mesh has little influence. The optimum conditions were: concentration of sulfuric acid 4%, the liquid-solid ratio 12﹕1(mL/g), the reaction time 10 h, the granularity 20 mesh, in 100℃water-bath temperature, with the levulinic acid yield 18.54%.(3) Basted on single factor experiment method, response surface experiments design by Box-Behnken of four factors and three levels were conducted, factors such as sulfuric acid volume fraction, reaction time, liquid-solid ratio and granularity. Data fitting of multiple factor experiment indicated that interaction of sulfuric acid concentration, reactive time and liquid-solid ratio were impotant. The rusults also showed that theoretical yield of 20.67% was obtained at 4.5% sulfuric acid volume fraction, 18﹕1 of liquid-solid ratio, 12.5 h of reaction time and 60 mesh of granularity in 100℃water-bath temperature.(4) The pretreatment method included that dilute hydrechloric acid, dilute sulfuric acid, sodium hydroxide, ammonia, alkaline hydrogen peroxide, steam explosion and cellulase. The results showed that by pretreatment of dilute hydrechloric acid, dilute sulfuric acid and ammonia, the yield of levulinic acid did not change, which kept at 19.45%. by pretreatment of steam explosion, cellulase and alkaline hydrogen peroxide, the yield of levulinic acid had little change, which increased to 19.98% from original 19.35% by steam explosion, from 19.35% to 22.12% by cellulase and from 19.35% to 22.31% by alkaline hydrogen peroxide. After sodium hydrexide pretreatment, the yield of levulinic acid improved obviously, which increased 4.77% by 24.12% from original 19.35%.
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