Laccase Degradation Of PAHs In Waste Frying Oils And Oil Deodorizer Distillates

Polycyclic aromatic hydrocarbons(PAHs)are a class of persistant pollutant that broadly present in food and environment.Their threat towards human health received more and more attention in recent years.One of the effective approaches to degrade and control PAHs is biodegradation.This thesis selected waste frying oils(WFO)and oil deodorizer distillates(ODD)as samples to degrade PAHs.We conducted enzymatic degradation experiment using laccase from Aspergillus niger.The main approaches and results are as followed:First of all,we used a two-time liquid-liquid extraction followed by a two-time solid extraction pretreatment to seperate PAHs and their oxygenated derivatives(oxygenated PAHs,OPAHs)from 13 WFO and five ODD samples for gas chromatography-triple quadrupole-mass spectrum(GC-QQQ-MS)determination in quality and quantity.As a result,total light PAH(LPAHs)concentrations in WFO varied from 17.32-165.32 μg/kg;toal heavy PAH(HPAHs)concentrations were 1.22-393.66 μg/kg;total OPAH concentrations were 1.34-47.26 μg/kg.For ODD,total LPAH,HPAH and OPAH concentrations were 53.39-115.08,12.56-145.35 and 9.49-148.71μg/kg,respectively.The intra-day and inter-day relative deviations of this method were 3.54-11.98 % and 6.64-15.98 %,respectively.Recovery rate varied from 55.01-129.23 %.Secondly,the enzymatic degradation experiment showed that laccase could successfully degrade phanthrene(Phe),anthracene-9,10-dione(ATQ)and 9-fluorenone(9FO),whose maximum degradation rates after 48 h were24.95%,62.88% and 70.02%,respectively.Laccase could as well reduce ATQ and 9FO in ODD,and it was capable of degrading Ant to a certain degree.In the end,we discussed and proposed possible degradation pathways for PAHs.We analysed and compared the chromatogram of treatment group and control group after enzymatic degradation experiment.Unsaturated acid ester,long-chain alkene,phytosterols and tocopherols were degraded to different degree,while the content of small molecule epoxides and olefine aldehydes increased.