Study On The Acid Hydrolysis Technology Of Straw To Produce Small Molecular Carbon Fertilizer By Hydrothermal Method

Biomass energy,known as the fourth largest energy source in the world,is a renewable resource with abundant reserves.Crop straw is a vital part of biomass energy.Our country is a big agricultural country with abundant reserves of crop straw resources.Organic carbon,which has the advantages of high water-solubility,quick effectivity and easy absorption,etc.,can significantly promote the growth of crops.Using crop straw as raw materials for preparing small molecular carbon fertilizers not only promotes the high-value utilization of straw,but also reduces the environmental pollution caused by excess straw.In this paper,cotton pulp as pure cellulose was firstly studied theoretically to explore the process and mechanism of acid hydrolysis under hydrothermal condition.On this basis,the main agricultural wastes,bagasse and corn stalk,in southern and northern China were selected to explore effects of the acid hydrolysis under hydrothermal condition.It will provide the basis for preparing small molecular carbon fertilizer by hydrothermal acid hydrolysis method of crop straw.The thesis achieved the following research results:（1）The acid hydrolysis process of cotton pulp was studied by single factor experiment and orthogonal experiment.The process conditions obtained from single factor experiment were the reaction time of 2.0 h,the reaction temperature of 180℃,the concentration of sulfuric acid 6.0 mol·L^-1,and the solid-liquid mass ratio of 1:14.The results of orthogonal test showed that the order of the influence of each factor on the content of organic matter in the acid hydrolyzate is solid-liquid ratio>acid concentration>reaction time>reaction temperature,in which the influence of solid-liquid ratio was significantly greater than the other three factors.The order of the influence of each factor on the yield of organic matter was reaction time>acid concentration>reaction temperature>solid-liquid ratio.The optimized process conditions were the reaction time of 2.0 h,the reaction temperature of 185℃,the acid concentration of 6.0 mol·L^-1,and the solid-liquid ratio of 1:12.Under these conditions,the content of organic matter in the acid hydrolyzate was 51.42±1.07 g·L^-1,and the yield of organic matter was 46.33±0.77%.（2）The acid hydrolysis process of corn stalk was studied by single factor experiment and orthogonal experiment.The process conditions obtained from single factor experiment were the reaction time of 1.5 h,the reaction temperature of 180℃,the concentration of sulfuric acid 6.0 mol·L^-1,and the solid-liquid mass ratio of 1:14.The results of orthogonal test showed that the order of the influence of each factor on the content of organic matter in the acid hydrolyzate was solid-liquid ratio>reaction time>reaction temperature>acid concentration.The order of the influence of each factor on the yield of organic matter was reaction time>solid-liquid ratio>acid concentration>reaction temperature,in which the influence of reaction time was significantly greater than the other three factors.The optimized process conditions were the reaction time of 1.5 h,the reaction temperature of 180℃,the acid concentration of 6.0 mol·L^-1,and the solid-liquid ratio of 1:12.Under these conditions,the content of organic matter in the acid hydrolyzate was 36.92±0.33 g·L^-1,and the yield of organic matter was 31.56±0.32%.（3）The acid hydrolysis process of bagasse was studied by single factor experiment and orthogonal experiment.The process conditions obtained from single factor experiment were the reaction time of 1.5 h,the reaction temperature of 180℃,the concentration of sulfuric acid 6.0 mol·L^-1,and the solid-liquid mass ratio of 1:14.The results of orthogonal test showed that the order of the influence of each factor on the content of organic matter in the acid hydrolyzate was reaction time>solid-liquid ratio>reaction temperature>acid concentration.The order of the influence of each factor on the yield of organic matter was reaction time>acid concentration>reaction temperature>solid-liquid ratio,in which the influence of reaction time was significantly greater than the other three factors.The optimized process conditions were the reaction time of 0.5 h,the reaction temperature of 175℃,the acid concentration of 5.5 mol·L^-1,and the solid-liquid ratio of 1:14.Under these conditions,the content of organic matter in the acid hydrolyzate was 31.65±0.25 g·L^-1,and the yield of organic matter was 30.14±0.28%.