Partition of biocides between water and inorganic phases of renders with organic binder.

The use of biocides as additives for building materials has gained importance in the recent years. These biocides are applied, e.g., to renders and paints to prevent them from microbial spoilage. However, these biocides can leach out into the environment. In order to better understand this leaching, the partition of biocides between water and inorganic phases of render with organic binder was investigated. The partition constants of carbendazim, diuron, iodocarb, isoproturon, cybutryn (irgarol), octylisothiazolinone, terbutryn, and tebuconazole towards minerals typically used in renders, e.g. barite, calcium carbonate, marble, kaolinite, and talc were determined. Partition constants for calcium carbonate varied between 0.2mLg (diuron) and 5.2mLg (iodocarb), respectively. The results for barite and kaolinite were in a similar range and usually the compounds with high partition constants for one mineral also had high values for the other mineral. No sorption to marble at all was found. From all minerals investigated, only talc showed high partition for all studied biocides. Partition constants for talc varied from 21.3mLg (iodocarb) to 683.7mLg (tebuconazole), respectively. The comparison with render-water distribution constants of two artificially made renders showed that the distribution constants can be estimated based on partition constants of compounds for individual components of the render.