TY - JOUR A1 - Urbanczyk, M.M. A1 - Bester, K. A1 - Borho, N. A1 - Schoknecht, Ute A1 - Bollmann, U.E. T1 - Influence of pigments on phototransformation of biocides in paints N2 - Biocides are commonly applied to construction materials such as facade renders and paints in order to protect them from microbial spoilage. These renders and paints are exposed to weathering conditions, e.g., sunlight and rain. Pigments are interacting intensively with the spectrum of the incoming light; thus, an effect of paint pigments on phototransformation rates and reaction pathways of the biocides is hypothesized. In this study, the phototransformation of four commonly used biocides (carbendazim, diuron, octylisothiazolinone (OIT) and terbutryn) in four different paint formulations differing solely in pigments (red and black iron oxides, white titanium dioxide, and one pigment-free formulation) were investigated. Paints surfaces were irradiated under controlled conditions. The results show that biocides degrade most rapidly in the pigment-free formulation. The degradation in the pigment-free formulation followed a first-order kinetic model with the respective photolysis rate constants: kp,Diuron=0.0090 h−1, kp,OIT=0.1205 h−1, kp,Terbutryn=0.0079 h−1. Carbendazim concentrations did not change significantly. The degradation was considerably lower in the pigment-containing paints. The determination of several phototransformation products of terbutryn and octylisothiazolinone showed different transformation product ratios dependent on the pigment. Consequently, pigments not only reflect the incoming light, but also interact with the biocide photodegradation. KW - OIT KW - Terbutryn KW - Indirect photolysis KW - Construction materials PY - 2019 U6 - https://doi.org/10.1016/j.jhazmat.2018.10.018 SN - 0304-3894 VL - 364 SP - 125 EP - 133 PB - Elsevier AN - OPUS4-46328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Uhlig, S. A1 - Colson, B. A1 - Schoknecht, Ute T1 - A mathematical approach for the analysis of data obtained from the monitoring of biocides leached from treated materials exposed to outdoor conditions N2 - Leaching processes are responsible for the release of biocides from treated materials into the environment. Adequate modeling of emission processes is required in order to predict emission values in the framework of the risk assessment of biocidal products intended for long-term service life. Regression approaches have been applied to data obtained from the long-term monitoring of biocide emissions in experiments involving semi-field conditions. Due to the complex interaction of different underlying mechanisms such as water and biocide diffusion and desorption, however, these attempts have proven to be of limited usefulness e at least, for the available biocide emission data. It seems that the behavior of the biocide emission curve depends to a considerable extent on whichever underlying mechanism is slowest at a given point in time, thus limiting the amount of biocide available for release. Building on results obtained in the past few years, the authors propose a criterion for determining which mechanism controls the leaching process at a given point in time based on the slope of the log-log emission curve. In addition, a first-order approximation of this slope value is presented which displays advantages both in terms of computability and interpretability. Finally, an algorithm for the determination of breakpoints in the slope of the log-log emission curve is presented for the demarcation of phases within which one mechanism acts as a limiting factor. KW - Biocides KW - Leaching KW - Weathering KW - Mathematical analysis PY - 2019 U6 - https://doi.org/10.1016/j.chemosphere.2019.04.102 SN - 0045-6535 SN - 1879-1298 VL - 228 SP - 271 EP - 277 PB - Elsevier AN - OPUS4-47886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -