Sodium acetate, also known as sodium ethanoate, comes in two forms: trihydrate sodium acetate and anhydrous sodium acetate. Many people are unfamiliar with sodium acetate, so let's take a closer look. Trihydrate sodium acetate is a colorless, odorless crystalline solid that can be weathered in air and is combustible. It is easily soluble in water, slightly soluble in ethanol, and insoluble in ether. It loses its water of crystallization at 123°C. However, the wet-processed form typically has a vinegar-like odor. Trihydrate sodium acetate is primarily used in the textile printing and dyeing industry, photography, electroplating, as a chemical reagent, and in organic synthesis. It is specifically used in the production of items such as hot water bags, heating pads, foot warmers, and cartoon hand warmers. In the textile industry, it is used as a neutralizing agent to adjust the pH during dyeing, as a color-removing agent in aniline black printing, as a neutralizer in naphthol dye developing solutions, and as a softening agent for sulfur black fabrics. In organic synthesis, it is used as an acetylation auxiliary, in the production of cinnamic acid, and benzyl acetate. In the pigment industry, it is used in the production of direct blue reactive dyes, acid-based pigments, and phthalocyanine blue.
Sodium acetate anhydrous is a white powder or small, flaky crystals. It is hygroscopic and readily soluble in water, soluble in ether, and slightly soluble in ethanol. It has a melting point of 324°C and a relative density of 1.528. Sodium acetate anhydrous is used as a food additive, analytical reagent, mordant, buffer, pharmaceutical excipient, precipitant, and masking agent. It is also used in organic synthesis, photographic chemicals, and as a pigment.
Both sodium acetate trihydrate and anhydrous sodium acetate can be used for cultivating microorganisms in wastewater treatment. The main difference lies in their sodium acetate content: sodium acetate trihydrate has a content of 58-60%, while anhydrous sodium acetate has a content of 99% or higher. For wastewater treatment, sodium acetate trihydrate is generally preferred due to its COD (chemical oxygen demand) content of approximately 450,000, which meets the requirements for cultivating microorganisms and is also more cost-effective. If a higher COD content is required, anhydrous sodium acetate, with a COD content of around 700,000, can be chosen. It offers even better performance in cultivating microorganisms, but it is also more expensive. Therefore, the choice of which sodium acetate to use should be based on the specific water quality and practical needs.