The invention relates to a continuous preparation method for sodium dichromate crystal solution. The method comprises the following steps of: (1) first-step electrolysis: electrolyzing alkali sodium chromate solution serving as anode raw material solution and sodium hydroxide solution serving as cathode raw material solution in a continuous preparation device for the sodium dichromate crystal solution with a filter at the temperature of 70 DEG C to obtain neutral sodium chromate solution and oxygen at the anode and obtain sodium hydroxide solution and hydrogen at the cathode; filtering the neutral sodium chromate solution to obtain anode raw material solution for the second step, and introducing the anode raw material solution to a next continuous preparation device for the sodium dichromate crystal solution without the filter; and (2) second-step electrolysis: electrolyzing the anode raw material solution obtained in the step (1) and the sodium hydroxide solution serving as cathode raw material solution at the temperature of 70 DEG C to obtain the sodium dichromate crystal solution and oxygen at the anode and obtain the sodium hydroxide solution and hydrogen at the cathode. The method greatly shortens the process, realizes continuous production and effectively improves the production efficiency by using the continuous preparation device for the sodium dichromate crystal solution.

Continuous preparation method for sodium dichromate crystal solution

The invention discloses a method for producing sodium dichromate through cationic membrane electrolysis. The method comprises the following steps: mixing a 20-40% industrial sodium chromate solution and a 23-50% sodium dichromate solution to obtain a mixed feed liquid with a volume ratio of sodium dichromate to chromate being equal to (1.5:1)-(5:1); introducing the mixed feed liquid into an anode chamber and introducing a sodium hydroxide solution with mass concentration of 27-30% into a cathode chamber; switching on direct currents, wherein the current density is controlled to be 2-4kA/m , the electrolysis temperature is 70-90 DEG C, the pressure difference between the cathode chamber and the anode chamber is 200-500mmH2O, the anode feed temperature is 50-85 DEG C, and the cathode feed temperature is 55-90 DEG C; and after electrolysis, obtaining sodium dichromate and oxygen gas in the anode chamber, and obtaining sodium hydroxide and hydrogen gas in the cathode chamber.

Method for producing sodium dichromate through cationic membrane electrolysis

The invention relates to a method for continuously preparing sodium dichromate by an ionic membrane electrolysis. The method comprises the following steps of: firstly, neutralizing industrial alkaline sodium chromate solution, removing impurities, and collecting filtrate serving as feed solution of electrolysis process; secondly, introducing the filtrate into an anode chamber in a one-membrane two-chamber ionic membrane electrolyzer, and introducing sodium hydroxide solution into a cathode chamber, wherein anions and cations migrate to the anode and the cathode respectively under the action of an electric field, sodium dichromate acidizing fluid is obtained in the anode chamber, high-concentration sodium hydroxide solution is obtained in the cathode chamber, and hydrogen and oxygen are produced on a positive electrode and a negative electrode respectively; and finally, performing evaporation concentration and natural cooling crystallization on the sodium dichromate acidizing fluid to separate out dehydrate sodium dichromate products. The method has the advantages of short process, low cost, high purity of the obtained sodium dichromate products, near 100 percent of raw material utilization rate, and high economic value of byproducts.

Method for continuously preparing sodium dichromate by ionic membrane electrolysis

The invention relates to a process unit for glutathione. The process unit comprises an electrolytic cell (1), a cathode (4), an anode (5), a power source (6) and a diaphragm (14). The diaphragm (14) is located in the middle of the electrolytic cell (1) to divide the electrolytic cell (1) into a negative electrolytic cell body (2) and a positive electrolytic cell body (3). The cathode (4) is arranged in the negative electrolytic cell body (2). The anode (5) is arranged in the positive electrolytic cell body (3). A negative electrode of the power source is connected with the cathode (4), and a positive electrode of the power source is connected with the anode (5). The process unit further comprises a cathode liquor storage tank (9), an alkali liquor storage tank (10) and a neutral salt solution storage tank (11). The cathode liquor storage tank (9), the alkali liquor storage tank (10) and the neutral salt solution storage tank (11) are connected with the negative electrolytic cell through pipelines. The process unit further comprises an acid liquor storage tank (12) and an anode liquor storage tank (13). The acid liquor storage tank (12) and the anode liquor storage tank (13) are connected with the positive electrolytic cell body (3) through pipelines. The process unit is suitable for preparing glutathione.

Process unit for glutathione

The invention provides a method for removing sodium or potassium by electrodialysis in a vanadium-containing solution. The method specifically comprises the following steps: adding the vanadium-containing solution into an electrodialysis device, wherein the vanadium-containing solution is taken as an anode solution and a dilute sodium hydroxide or potassium hydroxide solution is taken as a cathode solution; a cation exchange membrane is used as a diaphragm at the middle, adopting a stainless steel cathode and a ruthenium coated titanium anode, performing electrodialysis under direct current voltage of 2-4.5V, and stopping electrolysis when the pH value of solution in an anode chamber reaches 6-7, thus obtaining the vanadium-containing solution with sodium or potassium removed. According to the method provided by the invention, sodium or potassium in the vanadium-containing solution can be reduced to below 1/5 of that of the original solution, and the shortcomings of great acid consumption and a large amount of waste acid liquid of an existing vanadium precipitation process are solved to the greatest extent; in the process, produced substances are high-value products, and the cathode solution can be recycled; the process flow is simple and easy to operate, can be industrialized easily, and can be carried out in an unattended way; and the method has the advantages of better environmental, social and economic benefits.

Method for removing sodium or potassium by electrodialysis in vanadium-containing solution

The invention provides a method for preparing sodium bichromate dihydrate (Na2Cr2O7.2H2O) by using an ion-membrane electrolytic method. The method is as follows: a one-membrane two-room electrolytic cell assembly is formed by using a cation-exchange membrane, a negative electrode and a positive electrode; sodium chromate alkali solution is introduced into an anode chamber. Dilute sodium hydroxidesolution is introduced into a cathode chamber; after direct current is connected, negative ions and positive ions respectively move to the anode chamber and the cathode chamber under the action of anelectric field; the positive ions enters into the cathode chamber by a positive ion membrane, thus obtaining alkali liquor in the cathode chamber; sodium acid chromate solution is obtained in the anode chamber; simultaneously, the negative electrode and the positive respectively output hydrogen and oxygen; sodium bichromate dihydrate products are dissolved out by evaporating and cooling off the sodium acid chromate solution. The Sodium bichromate dihydrate products prepared by the method has high purity; the utilization rate of the raw materials is close to 100%; byproduct sodium hydroxide has high economic value; no waste materials containing chromium are recycled or discharged in the production process; therefore, the method is safe and environment friendly.

Method for preparing sodium dichromate dehydrate by ionic membrane electrolysis method

The utility model relates to a continuous preparation device of sodium dichromate crystalline liquid, which comprises a direct current power supply, an anode chamber, a cathode chamber, a anode liquid storage tank I, a cathode liquid storage tank I, a anode liquid storage tank II and a cathode liquid storage tank II, wherein the direct current power supply is respectively connected with the anode chamber and the cathode chamber, and a cation exchange film is arranged between the anode chamber and the cathode chamber. The continuous preparation device is characterized in that the top ends of the anode chamber and the cathode chamber are respectively connected with the anode liquid storage tank I and the cathode liquid storage tank I through a gas-liquid separator, and the bottom ends of the anode chamber and the cathode chamber are respectively connected with the anode liquid storage tank II and the cathode liquid storage tank II through a peristaltic pump and a constant-temperature tank. The utility model can realize continuous production and can improve the production efficiency.

Meida Chen

Papers

Method for preparing sodium dichromate dehydrate by ionic membrane electrolysis method

Continuous preparation method for sodium dichromate crystal solution

Continuous preparation device of sodium dichromate crystalline liquid

Method for continuously preparing sodium dichromate by ionic membrane electrolysis