Pyrolysis Characteristics Of Texting Dying Sludge,Red Wood Waste And Their Mixture Based On Microwave Irradiation

Unreasonable disposal of a large amount of solid waste causes serious harm to the environment and human health.According to statistics,China generated 5 billion tons of solid waste annual.Among them,～2 billion tonnes of printing and dyeing wastewater and一 20 million tonnes of textile dyeing sludge(TDS)are produced from textile dyeing industries in my country.TDS is hazardous industry waste and it contains high content of slurry,dyes,auxiliaries,pathogens,heavy metals and other substances.The threat of TDS to environmental health is greater and it is more difficult to deal with.～173 billion tonnes of biomass is generated through photosynthesis,and the application of biomass energy is an indispensable part of achieving the goal of "carbon neutrality".However,most of the biomass energy has not been used rationally,resulting in environmental pollution and waste of energy.In this paper,an automatically designed continuously operated auger reactor under microwave irradiation was used,and two solid wastes TDS and(Red wood sawdust waste)RWW were used as raw materials for pyrolysis and co-pyrolysis.The effects of pyrolysis temperature and mixing ratio of RWW on co-pyrolysis products were investigated.(1)Pyrolysis of TDS alone,as the temperature increased,the N content decreased,while the S content increased in the pyrolysis charcoal,and most of the sulfur-containing compounds were fixed in sludge char.Fe,Ca and P were the most abundant elements in raw materials and sludge carbon,and the content of Fe accounted for more than 27 wt%.Heavy metals(Cr,Ni,Zn and Mn)were mostly fixed in pyrolysis char(83%～100%),and the potential ecological risk is assessed as a mild risk.N-containing substances(70%>)in pyrolysis oil was the main components,mainly including amines,nitriles and pyridines.Pyrolysis of RWW alone,the content of Ca was the most abundant metal element in RWW and pyrolysis char.Oxygen-containing groups was most abundant in pyrolysis oil,and the content of phenolic compounds(>98%)(GC-MS)were produced during pyrolysis at 750℃.(2)When the RWW ratio was 30 wt%,the yield of H2 was significantly increased relative to the theoretical value,indicating that co-pyrolysis could promote the water-gas reaction of the main volatiles,the steam reforming reaction and the secondary tar reaction.Oxygen-containing compounds in oil decreasd with increasing temperature,while nitrogen-containing compounds increased sharply and reach a maximum of 91.23%at 750℃.Among them,carbonyl compounds dropped sharply,while pyridine,amine and nitrile compounds increased with temperature.At 650℃,with the increase of the RWW addition ratio,the content of phenols increased.The content of pyridine in the pyrolysis oil obtained by pyrolysis reached the maximum(33.4%)with the addition of 45 wt%RWW.(3)By comparing experimental results and theoretical calculation results,it is found that co-pyrolysis inhibited the formation of amines and nitriles in oil,and promoted the formation of pyridines and other nitrogen-containing heterocyclic compounds.It shows that co-pyrolysis promoted the formation of N-heterocyclic compounds.(4)SC obtained from the pyrolysis of TDS at 650℃ had a greater sulfur fixation capacity than the co-pyrolysis char.TDS and SC750-30 obtained the highest methylene blue value(372.25 mg/g)and iodine adsorption value(332.42 mg/g),respectively,indicating that adding RWW could improve the microporous properties of pyrolysis char.The specific surface area of TDS was 23.24 m2/g,the value of pore volume was 0.1259 cm3/g,and the value of average adsorption pore size was 21.88 nm.The specific surface area of SC75030 was 47.70 m2/g,the value of pore volume was 0.0735 cm3/g,and the value of average adsorption pore size was 7.41 nm.