Studies On The Preparation Of Gluconic Acid From Glucose

Gluconic acid and its ramifications, which are the important and multifunctional organic chemicals, have been attracting a wide range of attention in the fields of chemengineering, food, medicine and pharmaceutical industry, etc. The major problems such as complicated machining processes, long acting cycle, low purity of products, high working cost are found in the process of preparing gluconic acid. This thesis searches for new green processes which have the advantages of low manufacturing cost, short production cycle, and high selectivity for the products.A new test was performed in a non-thermal piasma reactor to prepare D-gluconic acid from D-glucose by using dielectric barrier discharge (DBD) plasma under ambient temperature and pressure. The results of the test showed that under test conditions D-glucose was oxidized to D-gluconic acid in air without catalyst. The influence of process condition on the yield of D-gluconic acid was investigated. The results indicated that the yield of D-gluconic acid decreased with the elevation of D-glucose concentration. The yield of D-gluconic acid increased with the increase of flow rate or reaction time. The yield of D-gluconic acid had the same change trend, ascend in first and descend at last with the increase of applied voltage or discharge gap. When the concentration of D-glucose was 0.1 mol/L, applied voltage was 4200 V, frequency was 10 KHz, discharge gap was 14 mm, the flow rate was 1.55 mL/min and the reaction time was 8.31 s, the yield of D-gluconic acid was 94.45%.The research showed that the dehydration reaction of glucose occurred in DBD nonthermal plasma reactor after the addition of CuSO4. The main products are LG (approximately 76.55%) and 1,6-Anhydro-.beta.-D-glucofuranose (approximately 21.26%) under given reaction conditions.It was found that the D-glucose was oxidized to D-gluconic acid by ozone without catalyst under microwave irradiation. The influence of process condition on the yield of D-gluconic acid was investigated. The results from laboratory experiments showed that the yield of D-gluconic acid decreased with the elevation of D-glucose concentration. The yield of D-gluconic acid increased first and then decreased with microwave power, irradiation time and air flow rate increasing. The optimum reaction conditions were obtained by orthogonal experimental design: concentration of D-glucose was 400mmol/L, flow rate of air was 2465mL/min, microwave power was 210 W, microwave time was 15 min.