TY - JOUR
T1 - Influence of pigments on phototransformation of biocides in paints
AU - Urbanczyk, Michal M.
AU - Bester, Kai
AU - Borho, Nicole
AU - Schoknecht, Ute
AU - Bollmann, Ulla E.
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2019/2/15
Y1 - 2019/2/15
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.
AB - 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 - Construction materials
KW - Indirect photolysis
KW - OIT
KW - Terbutryn
UR - http://www.scopus.com/inward/record.url?scp=85055027557&partnerID=8YFLogxK
U2 - 10.1016/j.jhazmat.2018.10.018
DO - 10.1016/j.jhazmat.2018.10.018
M3 - Article
C2 - 30343174
AN - SCOPUS:85055027557
VL - 364
SP - 125
EP - 133
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
SN - 0304-3894
ER -