Biodegradation of new quaternary ammonium compounds in treated wood by mould fungi

The degradation of seven potential wood preservatives based on imidazolium compounds (ICs) and quaternary ammonium compounds (QACs) with a modified anion structure by mould fungi was determined using soil-block method. Experiments were carried out on Scots pine (Pinus sylvestris L.) wood. Two-phase titration and high-performance liquid chromatography (HPLC) method were used to detect and quantify the degradation products. The performed soil-block tests showed that the ICs and QACs with alkoxymethyl substituents were leached from the experimental wood when in contact with moist soil and revealed their fungal detoxification by mould fungi, especially by Gliocladium roseum. The degree of biological decomposition of new compounds was higher than didecyldimethylammonium chloride and didecylmethylpoli(oxyethyl)ammonium propionate. The observations of the colonization by mould fungi were made using the scanning electron microscope (SEM). Decay of treated wood by mould fungi showed its tolerance to QACs.