Study On The Removal Of Phaeocystis And The Preparation Of Slow-release Drug With Isothiazolone

In recent years, Phaeocystis red tide occurs frequently in the Southern and eastern Sea of China, resulting in destruction of marine ecological environment and economic losses. So study on controlling red tide makes significant sense in protection of ecological environment and development of economy.This biocidal effect of isothiazolone on the Phaeocystis globosa in different phase was studied. When the cell density scale of the algae was 1000 cell/mL, the algaecide could restrain the growth and propagation of the algae only with the concentration of 0.05 mg/L. When the growth and propagation of the algae was restrained by the algaecide completely, the concentration of algaecide and the cell density scale showed the direct ratio and the linear relationship was good (R~2=0.982).The biocidal mechanic of isothiazolone to Phaeocystis globosa was also studied. The structure of cell wall was not destroyed by the algaecide. So we could know: after being contacted with the algae, the algaecide could penetrate the cell wall and reacted with the protein directly, damaging the function of cell and killing the cell at last.Furthermore, we blended the isothiazolone with the high polymer, such as chitin, chitosan and poly (vinyl alcohol), and prepared the slow-release drug films. The slow-release performance of these films and the factors influence the slow-release performance of films were also studied. The time that algaecide need to release out from film completely was between 20 min and 48 h, indicating all of the drug films had the slow-release property. The weight ratio of algaecide to carrier, the thickness of film and the cross-linked degree of film were the key factors affecting the releasing performance of films. The higher weight ratio of algaecide to carrier, the shorter time which algaecide need to release out completely; the thicker the film is, the longer time which algaecide need to release out completely; the higher cross-linked degree, the longer time which algaecide need to release out completely. The key mechanic of slow-release was subject to the diffusion controlled release system and swelling controlled release system.The result of this article showed that isothiazolone was an excellent algaecidethat could react with the Phaeocystis in short time and restrain the growth of algae with low concentration. What is more, the algaecide could mix with other carrier and been prepared into slow-release film, which not only increased effect of algaecide but also avoided the problem of higher concentration in part sea.