Mechanism Research Of Dyeing Sludge Catalytic Pyrolysis Based On TG-FTIR And PY-GC/MS

A large number of dyeing sludge in our country are extremely dangerous and harmful.This paper describes the characteristics and resource utilization protential of the dyeing sludge,and the current situation and development trend of the sludge treatment methods at home and abroad.Sludge drying and pyrolysis are both promising ways of sludge recycle,which can realize stabilization,reduction,harmless and recycling of sludge,at the same time,the sludge pyrolysis products has enormous protential of material utilization and can be used quantivative,it has important significance in theory and application.This paper mainly studies the CaO how to influence the dyeing sludge drying in the mcrocosmic,as well as catalytic pyrolysis mechanism and the analysis of gaseous product of the dyeing sludge.In this paper,an apparent drying experiment with different quality ratio of CaO and dyeing sludge?0,100,80,50,20,10 g Cao/kg sludge?at temperature of 160? was conducted several experiments,and the directional random walk model was used to study the microcosmic influence of CaO to the dyeing sludge drying.The results show that there is digestion and disassociation effect of CaO in the drying process of dyeing sludge,at the same time CaO can influence the pore structure of dyeing sludge and change its spectral dimension.Using the mechanism function g?a?=1-?1-a?^1/2lationship between drying rate and time,we found that the drying rate of dyeing sludge was influenced by the digestion and dissociation of CaO and change of pore structure of dyeing sludge,CaO input increase can improve the drying rate significantly in the range of 0²0g CaO wet sludge while in the range of 80¹00g CaO wet sludge,no significant improvement was observed.Moreover,in the range of 20⁸0g CaO wet sludge,increasing the input of CaO will decrease the drying rate during which an inhibition point exists.On the other hand,CaO worsens the thermal conductive ability of dyeing sludge,considering the sludge drying process and thermal process,the best quality ratio is 80 g Cao/kg sludge,that is m?sludge?: m?CaO??28?1:12.5.Using thermogravimetric analyzer?TG?to analysis the pyrolysis mechanism of dyeing sludge and the influence of different alkali catalyst?CaO,BaCO₃,Na₂CO₃ and K₂CO₃?,different ratio?mixtures of dyeing sludge and catalyst according to the quality ratio of 10:1,12.5:1 and 20:1,and CaO added with50:1 and 100: 1?and different heating rate?10 K/min,20 K/min and 40 K/min?on the dyeing sludge catalytic pyrolysis and calculate the apparent activation energy.The results show that CaO can reduce the volume,improve pyrolysis index and reduce the apparent activation energy of the dyeing sludge obviously;Under the heating rate of 20 K/min,catalyst is CaO,for example,to add more CaO,the smaller the of remaining quality percentage of the dyeing sludge;12.5 CaO,for example,the faster heating rate,the bigger residual mass percentage of the dyeing sludge,the temperature of the third weightlessness peak corresponds to the more lag.Thermogravimetric combined with thermal imager?TG-FTIR?was adapted to study the pyrolysis gas product of dyeing sludge with alkali catalyst,the study found that in the whole pyrolysis process of dyeing sludge,add CaO,BaCO₃ and K₂CO₃ can improve useful product(CO,C-H?hydrocarbons,methane?,C-O?ether,alcohol,phenol?and C=O?ketone,aldehyde,acid,amide?,reduce the useless products?CO₂,SO₂,HCN,NH₃,HNCO?,the effects of CaO and BaCO₃ are remarkable.The thermal cracking-chromatography mass spectrometry?PY-GC/MS?was used to further analyze gaseous product composition of the dyeing sludge catalytic pyrolysis.The results show that the sludge pyrolysis gas composition consists of aromatic hydrocarbon,nitrogen compounds,sulphur compounds,fatty hydrocarbon and carboxylic acid five categories.Alkali metal catalyst can promote fat hydrocarbon cyclization reaction generated aromatic hydrocarbon,promote fat acid decarboxylation reaction generating hydrocarbon,can also promote the decomposition of protein,nitrogen production increases.