Atmospheric pressure plasma as a tool for decontamination and functionalization of wooden surfaces

Possible applications of plasma technology on wooden surfaces have been investigated by new research projects. There are different initial situation: The residuals of several timber preservatives, based on organo-chlorine compounds, are a high challenge for human protection, storage and wood restoration. Among the most common organo-chlorine substances that have been used as pesticides in the past are Dichlorodiphenyltrichloroethane (DDT), Lindane and Pentachlorphenol (PCP). Lindane and PCP are toxic and/or carcinogenic and all are considered to constitute several environmental hazards. The pesticides were widely used for the treatment of trusses in private homes, churches, castles as well as of furniture or wooden artefacts. This creates the necessity to develop efficient and economically viable methods for removing the harmful biocides from the contaminated timbers without damaging the original materials. For the gentle removal of biocide residuals (so-called blooming of mainly DDT crystalline forms) atmospheric pressure plasma was used as a cleaning tool for the first time. For selected working conditions the removal of up to 75% DDT contamination could be achieved on plain timber surfaces. Using atmospheric pressure plasma jets (APPJ) it is also possible to create thin films (~ 50 – 200 nm) with different functionalities such as hydrophilicity, hydrophobicity or antimicrobial properties. To create antimicrobial effects active agents were embedded into silicon dioxide films matrices. Antimicrobial tests showed high effects of these films towards bacteria strains such as Escherichia coli and Staphylococcus aureus. An effect towards mold fungi was low using films containing only one active agent. However, significant improvements in activity were achieved by the combination of active agents. This paper will address the production of samples, analytic methods and open questions about decontamination and functionalization of wooden surfaces by using atmospheric pressure plasma.