Pyrolysis Of Heavy Metal Contaminated Water Hyacinth For Bio-oil

Heavy metal pollution hasbecome worse in recent years and plants grown in soilor wastewaterwould absorbheavy metals,which generates quantities of heavy metal contaminated biomass.Heavy metals threaten the health of human beings by food chains.At present, the heavy metal contaminated biomass mainly uses the method of landfilling or burning.However, pyrolysis is a very important kind of biomass energy conversion technology, which not onlycanapply the biomass energy to convert into chemical fuels, but also can reduce the pollution of the environment.The pyrolysisexperiments were performed ina fixed bed reactor chosing heavy metal(Pb, Cr, Cu) contaminated water hyacinth as the research object.The pyrolysis characteristicsof heavy metal contaminated water hyacinthwas studied, including product yield, composition, characteristicsandthe transformation of heavy metalsduring the pyrolysis process in this paper in order to analysis the advantage of the pyrolysis of heavy metal contaminatedbiomass and provide basic research materials forheavy metal contaminatedbiomass utilization.Thermogravimetric analysis shows that the weight loss process is divided into dehydration, rapid weight loss and charring three stages. The major pyrolysis zoneare moved forward with the presence of heavy metals(Pb, Cr, Cu), and the maximum weight loss rate becomesbigger. Kinetic analysis indicates that a first order reaction can be a good fit for the pyrolysis process,and the main activation energy of pyrolysis range increaseswith the presence of heavy metals(Pb, Cr, Cu).The investigation of the fixed bed pyrolysis experiments shows that the optimal pyrolysis temperature of water hyacinth is 500 ?, when maximum yield of pyrolysis oil is 51.7%and lowest acid value is 100.60 mgKOH/g and highest calorific value is28.87 MJ/Kg. The yieldof pyrolysis oilincrease by15.7%and calorific valueincrease by 2.5% and acidvalue decreaseby 24.6% with the presence ofPb; The yield of pyrolysis oil increaseby 13.2% and acid valueincreaseby 2.8% and calorific value decrease by 7.0% with the presence of Cr; The yield of pyrolysis oil increase by 16.2% and acid valuedecrease by 37.7% and calorific value decreaseby 6.6% with the presence of Cu. Pyrolysis oil components analysis shows, the amount of esters decreases and the amount of nitrogen compounds increase with the presence ofPb or Cr or Cu; the amount of alcoholic compounds and phenolic compoundsincrease with the presence of Pb or Cr, but the amount of phenolic compounds is not changed with the presence of Cu; the amount of carboxylic acids increase with the presence of Cr or Cu, but the amount of carboxylic acids is not changed with the presence of Pb. The pyrolysis process of water hyacinth was changed with the presence of heavy metals, which made the composition of the bio-oil different thus increasing the quality of bio-oil. The largest contribution to the improvement of the quality ofbio-oil is Pb, followed by Cu and Cr.The analysis of gas and solid phase productsshows that the yields of gas and solid phase productsand the amount of CO2 decrease, butthe amount of H2 increase with the presence of Heavy metals(Pb, Cr, Cu). After pyrolysis, more than 80% of Pb is kept in the char in the form of PbO; Only more than 64%of Cr is kept in the char in amorphous form; More than 80% of Cu is kept in the char in the form ofzerovalentCu. Heavy metal kept in the oil phaseis50.0 mg/Kgat most whichis very smalland can be negligible.