Sodium Dichloroisocyanurate (NaDCC), a stabilized chlorine disinfectant, is a safe and efficient pool chemical that effectively kills bacteria, viruses and algae in the pool. As for the swimming pool issue, you can refer to: Sodium Dichloroisocyanurate: The Guardian of Swimming Pool Water
Review the History of NaDCC
- In 1774, people discovered the bleaching properties of chlorine in aqueous solution;
- In 1785, people started to use unstabilized chlorine, that is, KClO solution;
- Bleaching powder appeared in 1789;
- And calcium hypochlorite appeared in 1799.
Unstabilized chlorine, including bleaching water, bleaching powder and calcium hypochlorite, has lots of serious shortcomings: high impurity content, short shelf life, poor transport and storage safety. These problems still exist today. However, stabilized chlorine with high purity, long shelf life, convenient transport, and high storage safety appeared much later, which was first synthesized around the early 20th century, and the commercialized production of NaDCC was around the 1960s.
how to synthesize NaDCC
There are three main methods for the synthesis of NaDCC Chemical: method via neutralization of dichloroisocyanuric acid, method via salt-forming of trichloroisocyanuric acid and method via chlorination of sodium hypochlorate (NaClO). These three methods have their own characteristics and are suitable for different production conditions and needs.
01/ Method via Neutralization of Dichloroisocyanuric Acid
Stephen J Kovalsky of FMC Corp. invented this method in 1966
The method usually consists of two steps. First, mix cyanuric acid with NaOH aqueous solution at 1:2, and then add Cl2 to obtain dichloroisocyanuric acid. The filter cake is obtained by centrifugal filtration. After that, the filter cake is washed with pure water to clean the residual sodium chloride, and add a certain amount of pure water and NaOH solution. After filtering and drying, NaDCC white solid is finally finished. The reaction formula is as follows:
(CHNO)3 + 2NaOH + 2Cl2 → H(CNO)3Cl2 + 2NaCl + 2H2O
H(CNO)3Cl2 + NaOH → Na(CNO)3Cl2 + H2O
02/ Method via Salt-forming of Trichloroisocyanuric Acid
James P. Brennan of Clearon Corp. invented this method in 1974
The method is to mix cyanuric acid and NaOH solution at a rate of 1:3 to obtain cyanuric acid trisodium salt, then through Cl2, centrifuge filtration to obtain trichloroisocyanuric acid. Then, the filtered trichloroisocyanuric acid, cyanuric acid and NaOH solution are mixed at a ratio of 2:1:3, and carry out the replacement reaction at a temperature of 30 ~ 40 ℃. Finally, NaDCC is obtained by cooling, filtration and drying. The reaction formula is as follows:
(CHNO)3 + 3NaOH + 3Cl2 → (CNO)3Cl3 + 3NaCl + 3H2O
2(CNO)3Cl3 + (CHNO)3 + 3NaOH → 3Na(CNO)3Cl2 + 3H2O
The above two methods not only have low raw material consumption, but the synthesized product also has the high purity feature, but the acidic reaction environment will corrode the equipment, which has high equipment requirements and high investment costs.
03/ Method via Chlorination of Sodium Hypochlorate (NaClO)
In 1974, S Berkowitz of Olin Corp. reacted cyanuric acid with sodium hydroxide to obtain sodium cyanurate, then added Cl2 into sodium cyanurate solution and got sodium dichlorosisocyanurate. Nowadays, this method has become the basis of almost all NaDCC production processes.
In 1978, S Berkowitz (he was job-hopping to FMC Corp. at that time) developed a new approach on this basis:
The NaClO method is to add Cl2 into NaOH solution to produce a high concentration of NaClO solution, and then react with cyanuric acid to produce sodium dichloroisocyanurate. There are two ways to treat the mother liquor of sodium dichloroisocyanurate after separation.
One is to add Cl2, which can convert the generated NaOH into NaClO and continue to participate in the reaction to improve the utilization rate of raw materials:
2NaOH + 2Cl2 → NaClO + NaCl + H2O
2(CHNO)3 + 3NaClO + Cl2 → 2Na(CNO)3Cl2 + NaCl + 3H2O
The other is to drop hydrochloric acid to neutralize generated NaOH:
(CHNO)3 + 2NaClO →Na(CNO)3Cl2 + NaOH + H2O
NaOH + HCl → NaCl + H2O
The characteristics of the method are that the reaction liquid is approximately neutral, which has not high the requirement of equipment investment, and the mother liquid of sodium dichloroisocyanurate can be used to produce trichloroisocyanuric acid, improving the utilization rate of raw materials. However, there is high demand of NaClO concentration, otherwise the purity of the product will be low. So this method has not been popularized.
Nowadays, with the development of science and technology and the improvement of technological level, we have developed better technology to produce NaDCC with excellent performance, which is inseparable from the contributions made by predecessors in chemical industry. In retrospect, it was the brilliant chemical pioneers who made chlorine disinfectants easy to obtain, protecting us from viruses and germs. In the future, we can certainly do better and stronger on the basis of our predecessors.
If you are interested in NaDCC, please feel free to contact us. We are the largest NaDCC chemical manufacturer in China, so as to provide stable supply and cost-effective products with high quality.