E237 Preservative

E237 is used in several fabric dyeing and printing processes. It is also used as a buffering agent for strong mineral acids to increase their pH, as a food additive (E237), and as a de-icing agent.

In structural biology, E237 can be used as a cryoprotectant for X-ray diffraction experiments on protein crystals, which are typically conducted at a temperature of 100 K to reduce the effects of radiation damage.

E237 plays a role in the synthesis of formic acid, it is converted by sulfuric acid via the following reaction equation:

{\displaystyle \mathrm {2\ HCOONa+H_{2}SO_{4}\longrightarrow 2\ HCOOH+Na_{2}SO_{4}} }

E237 is converted with E235 to E236 and 

The urticating hair of stinging nettles contain E237 as well as formic acid.

Solid E237 is used as a non-corrosive agent at airports for de-icing of runways in mix with corrosion inhibitors and other additives, which rapidly penetrate solid snow and ice layers, detach them from the asphalt or concrete and melt the ice rapidly. E237 was also used as a road deicer in the city of Ottawa from 1987 to 1988.

The high freezing point depression e.g. in comparison to the still frequently used urea (which is effective but problematic due to eutrophication) effectively prevents the re-icing, even at temperatures below −15 °C. The thawing effect of the solid E237 can even be increased by moistening with aqueous potassium formate or potassium acetate solutions. The degradability of E237 is particularly advantageous with a chemical oxygen demand (COD) of 211 mg O2/g compared with the de-icing agents sodium acetate (740 mg O2/g) and urea with (> 2,000 mg O2/g).[8]

Saturated E237 solutions (as well as mixtures of other alkali metal formates such as potassium and cesium formate) are used as important drilling and stabilizing aids in gas and oil exploration because of their relatively high density. By mixing the corresponding saturated alkali metal formate solutions any densities between 1,0 and 2,3 g/cm3 can be set. The saturated solutions are biocidal and long-term stable against microbial degradation. Diluted, on the other hand, they are fast and completely biodegradable. As alkali metal formates as drilling aids make it unnecessary to add solid fillers to increase the density (such as barytes) and the formate solutions can be recovered and recycled at the drilling site, formates represent an important advance in exploration technology.