Treatment of anhydrous DMF

Dimethylformamide; Dimethylformamide; N,N-Dimethylformamide; DMF; CAS: 68-12-2 Physical and chemical properties: A colorless liquid with a mild amine odor. Molecular formula C3-H7-N-O. Molecular weight 73.10. Relative density 0.9445 (25°C). Melting point -61°C. Boiling point 152.8°C. Flash point 57.78°C. Vapor density is 2.51. Vapor pressure 0.49 kPa (3.7 mmHg at 25°C). Autoignition temperature: 445°C. The explosive limit of the vapor-air mixture is 2.2–15.2 %. Mixes well with water and common organic solvents. It can catch fire and explode in the presence of open flames or high temperatures. It reacts violently with concentrated sulfuric acid and fuming nitric acid, and may even explode. DMF is essentially a neutral solvent; it remains stable during distillation at normal pressure in the absence of acidic or alkaline substances. At temperatures above 350°C, DMF begins to decompose into dimethylamine and formic acid. When DMF is exposed to strong sunlight, dimethylamine can also be formed; if OH- ions are present in an aqueous DMF solution, dimethylamine and formate ions are produced

At present, our company is handling the wastewater treatment for a DMF manufacturing enterprise. After more than a month of trial tests. It was found that treating this wastewater is extremely difficult. The pilot-scale process adopted by our company is raw water -- chemical dosing -- hydrolysis -- chemical dosing followed by air flotation -- three-phase aerobic treatment. During the testing, it was found that the raw water of this wastewater had good stability, with a COD level around 4000, and fluctuations within approximately 500. PH7。 The temperature can be controlled; the temperature of the wastewater without heat exchange is around 60-80 degrees, while after heat exchange it can be reduced to around 20 degrees. The settleable SS in the raw water is very high; after 10 minutes of static settling, the color intensity can be significantly improved. However, the effect of this SS on COD is not very significant. Therefore, in the tests conducted with chemical addition for removal, the COD removal efficiency was only around 5%. The BOD of the raw wastewater is around 1300–1500, the ammonia nitrogen level is about 100, and the TN value is very high. After hydrolysis, the pH of this wastewater increased, and the ammonia nitrogen level was measured at around 350. However, after hydrolysis, the BOD is only around 200. The reason for the decrease in BOD after hydrolysis may be the effect of increased ammonia nitrogen, but I’m puzzled as to how it is possible to degrade more than 1000 units of BOD. The effluent after hydrolysis can stabilize at around 1000 after aerobic treatment. The removal efficiency for the entire pilot test was 75%. Since the BOD of the aerobic effluent is already below 20. It is estimated that using multi-stage aerobic treatment cannot reduce COD. Currently, we are exploring other methods to effectively reduce COD in order to meet the company’s requirements. The initial wastewater treatment facilities for this company were designed by Zhejiang Academy of Environmental Sciences. The design institute’s treatment method is a multi-stage OA method. Raw water -- Adjustment -- Heat exchange -- Oil separation -- O1 -- A1 -- Intermediate sedimentation tank -- O2 -- A2 -- O3 -- A3 -- O4 -- A4 -- O5 -- Final sedimentation tank. Based on the design parameters provided by Zhejiang Environmental Engineering Institute, we feel that this institute does not actually have the capability to handle such wastewater; some of the parameters are as follows: Q=4000, retention tank, HRT of 2 days, aerobic HRT of 2.5 days. Such a conservative design simply cannot meet the required standards. In the design, the institute based its approach solely on the fact that the wastewater has some degree of biodegradability and a high TN level; the proposed design scheme does indeed enable effective denitrification through reverse digestion, as can be seen from the scheme itself. Furthermore, passing through the aerobic stage before entering section A can effectively improve the biodegradability of the wastewater. But in reality, they had no idea what the actual nature of that wastewater was. The current operating conditions are due to the fact that in tank O1, 60% removal efficiency can be achieved for the raw water; as a result, the COD level of the aerobic-treated water is around 1600, while the ammonia nitrogen level is around 300. However, in the subsequent treatment units, up to the effluent from the final sedimentation tank, the COD level rises to 1800, and the ammonia nitrogen level ranges from 400 to 500. Does anyone have any information regarding DMF? I would be very grateful if you could share it with me~~ Thank you so much.

I have experience with related wastewater treatment; feel free to contact me at zzb@sunresin.com if needed

I have done this before; there are mainly two methods: add the material with insufficient moisture content to the DMF in the reaction vessel, incorporate about 1% magnesium shavings, raise the temperature for reflux, and once it meets the requirements, add 0.5% sodium persulfate to evaporate the DMF (be careful not to make it too dry, to prevent the peroxides from decomposing). Another method is to add sodium wire to the substandard DMF in batches while stirring; once it becomes qualified, sodium persulfate is added as well to evaporate the DMF – and that’s it!