The principle of cyanide removal mainly involves converting cyanide in wastewater into non-toxic or low toxicity substances through chemical reactions. The specific process is divided into two stages: incomplete oxidation and complete oxidation.
Author: Marisa
The principle of cyanide removal mainly involves converting cyanide in wastewater into non-toxic or low toxicity substances through chemical reactions. The specific process is divided into two stages: incomplete oxidation and complete oxidation.
1. alkaline chlorination process
Alkaline chlorination is one of the main methods for breaking cyanide. The principle is to use oxidants such as chlorine gas or sodium hypochlorite to oxidize cyanide. The specific steps are as follows:
1)Incomplete oxidation stage: In this stage, cyanide (CN ⁻) reacts with hypochlorite (OCl ⁻) to form cyanuric acid (CNCl), which is then hydrolyzed to form cyanate (CNO ⁻). The rate of this reaction is influenced by pH value, temperature, and effective chlorine concentration. The higher the pH value, water temperature, and effective chlorine concentration, the faster the hydrolysis rate.
2)Complete oxidation stage: In this stage, cyanate (CNO ⁻) is further oxidized and decomposed into carbon dioxide (CO ₂) and nitrogen (N ₂). This step ensures that cyanide is completely converted into non-toxic substances.
2. Other processing methods
In addition to alkaline chlorination, there are other treatment methods such as electrolytic oxidation, activated carbon adsorption, ion exchange, ozone, and ferrous sulfate. These methods each have their own advantages and disadvantages, for example, the electrolytic oxidation method has complex equipment but good treatment effects, while the activated carbon adsorption method is simple to operate but requires regular replacement of adsorbents.
3.application area
The principle of breaking cyanide is widely used in the treatment of electroplating wastewater. The cyanide containing wastewater generated during the electroplating process contains highly toxic free cyanide and other heavy metal ions. By cyanide treatment, these toxic substances can be converted into non-toxic substances, ensuring that wastewater meets discharge standards.