The Composition And Antimicrobial Activity Of The Pyrolysis Liquid From MDF Contained UF Resin

In order to explore the composition characteristics and the antimicrobial activity to bacteria and mold of the pyrolysis liquid containing UF resin.In this paper,four kinds of MDF pyrolysis liquid prepared from 300-600℃ were chose.The basic physicochemical properties were evaluated and GC-MS was used to analyze the composition characteristics.Then the antimicrobial activity was evaluated by experiments of antibacterial circle,minimal inhibitory concentration and mycelial growth inhibition rate.Finally,the pyrolysis liquid was separated into three groups by acid extraction method.For the separated groups,the antimicrobial experiment and composition analysis experiment were carried out.The main conclusions are as follows:(1)The pH values of the pyrolysis liquid were alkaline,and the alkali contents were positively correlated with the increase of pH values.There was small difference between the densities of pyrolysis liquids,and the densities were close to and slightly larger than the density of water.The water contents of pyrolysis liquid were between 62%-71%.Four kinds of the pyrolysis liquid all contained N heterocyclic substances,substances containing-NH2,-NH-,N=N,phenols,esters,acids and other substances,substances containing N was the main material in pyrolysis liquid.And it was the main reason that caused the pyrolysis liquid to be alkaline.With the increase of temperature,the content of heterocyclic compounds containing N increased gradually,and the content of-NH2,-NH-and N=N decreased.(2)Overall,the antimicrobial effect of four kinds of pyrolysis liquid on Escherichia coli was better than Staphylococcus aureus.For Escherichia coli,the antimicrobial effect of pyrolysis liquid prepared from 300 and 600℃ was best,then followed by pyrolysis liquid prepared from 500℃,pyrolysis liquid prepared from 400℃ was the last.For Staphylococcus aureus,the inhibition effect of pyrolysis liquid gradually increased with the increase of temperature.In general,to the two bacteria,the antibacterial circle of pyrolysis liquid prepared from 600℃ was largest,and close to 30mm.The minimal inhibitory concentration of pyrolysis liquid prepared from 600℃ was minimum,which was 0.81%.The antimicrobial effect of four kinds of pyrolysis liquid on Trichoderma viride and Aspergillus niger was close to each other.For Trichoderma viride,the pyrolysis liquid prepared from 600℃ had the best antimicrobial effect,the inhibition rate was 51.28%,followed by the pyrolysis liquid prepared from 300 and 500℃,and finally,the pyrolysis liquid prepared from 400℃ had the weakest antimicrobial effect.In the case of Aspergillus niger,the best antimicrobial effect was obtained at pyrolysis liquid prepared from 600℃,the inhibition rate was 51.35%,which was followed by the pyrolysis liquid prepared from 500℃,then followed by the pyrolysis liquid prepared from 300℃,and finally,the pyrolysis liquid prepared from 400℃ had the weakest antimicrobial effect.(3)Four kinds of pyrolysis liquid were separated into alkaline,neutral and acid groups by acid-base extraction.Substances that in alkaline group were almost pyrazines,pyridines and other heterocyclic compounds containing N.Substances that in acidic group were almost phenols and acids.As for the neutral group,the composition was relatively messy,contained a small amount of phenols,pyrazine,pyridine and N heterocyclic substances.For Escherichia coli and Staphylococcus aureus,the largest antibacterial circle was obtained at the acid group,followed by the alkaline group,the antibacterial circle of the neutral group was smallest.Compared with groups separated from 300 and 400 ’C,the antimicrobial effect of the alkaline and acid groups separated from 500 and 600℃ was better.For viride and Aspergillus niger,there was little difference between the mycelial growth inhibition rate of alkaline and acid groups,and the mycelial growth inhibition rate of acid group was slightly larger than the alkaline group.Neutral group had the minimum mycelial growth inhibition rate.Acid and alkaline groups separated from 500℃ had the maximum mycelial growth inhibition rate and best antimicrobial effect.