Sodium gluconate is a chemical agent, which is widely used in construction, textile, water treatment and other industries. It can be used as cleaning agent, cement admixture, retarder, water reducer, water quality stabilizer and food additive. As its use becomes more and more important, more and more people want to make sodium gluconate. What are the methods to make sodium gluconate?

1.生物发酵法。该方法包括真菌发酵和细菌发酵，另外还有固定细胞发酵工艺，其中较普遍采用的是黑曲霉菌发酵制葡萄糖酸钠工艺。该方法具有发酵速度快、发酵过程易于控制、产品易提取等特点，但同时也会出现产品色泽不易控制、无菌化要求程度高等不良现象。

1. Biological fermentation. The method includes fungal fermentation and bacterial fermentation, as well as fixed cell fermentation process, in which Aspergillus niger fermentation for sodium gluconate is widely used. This method has the characteristics of fast fermentation speed, easy control of fermentation process and easy extraction of products, but at the same time, it will also have adverse phenomena such as difficult control of product color and high aseptic requirements.

2.均相化学氧化法。结晶葡萄糖加水溶解后加入催化剂，控制一定的温度，滴加次氯酸钠溶液，同时滴加离子膜液碱来控制反应体系的pH值，使平衡向生成葡萄糖酸钠的方向移动。使用该方法生产葡萄糖酸钠具有转化率高，工艺过程简单，成本低的优点，但是其中间步骤多，副产物多，产物难于分离，因此在应用上受到了限制。

2. Homogeneous chemical oxidation. After the crystalline glucose is dissolved with water, the catalyst is added, the temperature is controlled, the sodium hypochlorite solution is added dropwise, and the ionic membrane liquid alkali is added dropwise to control the pH value of the reaction system, so as to move the balance to the direction of generating sodium gluconate. The production of sodium gluconate by this method has the advantages of high conversion, simple process and low cost, but it has many intermediate steps, many by-products and difficult to separate the products, so its application is limited.

3.电解氧化法。该方法是在电解槽中加入一定浓度的葡萄糖溶液，再加入适宜的电解质，在一定温度、一定电流密度下恒电流电解。其工业参数的确定因加入电解质的不同而异。电解氧化法虽然克服了生物发酵法和均相化学氧化法的某些缺点，但在工业生产中能耗大，不易控制，因此工业化生产中很少采用。

3. Electrolytic oxidation method. The method is to add a certain concentration of glucose solution into the electrolytic cell, then add a suitable electrolyte, and conduct constant current electrolysis at a certain temperature and current density. The determination of industrial parameters varies with the addition of electrolytes. Although electrolytic oxidation method overcomes some shortcomings of biological fermentation method and homogeneous chemical oxidation method, it is rarely used in industrial production because of its high energy consumption and difficult to control.

4.多相催化氧化法。配制一定量的葡萄糖溶液加入于四口烧瓶中，称取适量催化剂加入到此烧瓶中，恒温。该法工艺简单，反应平稳，易于控制，反应条件温和，其葡萄糖转化率在95%左右。

4. Heterogeneous catalytic oxidation. Prepare a certain amount of glucose solution and add it into a four port flask. Weigh an appropriate amount of catalyst and add it to the flask at constant temperature. The process is simple, the reaction is stable, easy to control, the reaction conditions are mild, and the glucose conversion is about 95%.