Preliminary Study On Pyrolysis Resource Technology Of Seafood Processing Sludge

Seafood farming and processing in many coastal areas is one of the important pillar industries in China,which makes a noticeable contribution for local economic development.However,it also caused many environmental problems,and the sludge which was produced by it is particularly prominent.In this paper,a preliminary study on the technology of pyrolysis and utilization of seafood processing sludge was conducted.The conditions on the physical and chemical properties of pyrolysis solid products(pyrolytic carbon)were mainly investigated in the pyrolysis process.Further study on heavy metal adsorption was also carried out and its effect on heavy metal(Pb,Cu,Cd and Cr ions)adsorption was explored.The researching results were as follows:The pyrolyzed biochars were characterized by methods of TG-DTG,elemental and industrial analyses,N2 adsorption/desorption,and FTIR.The preparation conditions on the physical and chemical characteristics of biochars were obtained.The results showed that:(1)With the increasing pyrolysis temperature(over the range from 450 ? to 650 ?),the biochar yield decreased,the specific surface area of biochar first increased then decreased,p H value(8.5~9.5)increased.(2)Pyrolysis treatment can significantly improve the specific surface area of sludge,and it reached 85.35 m2/g when the condition of the maximum specific surface area was 450 ?-60 min.(3)Pyrolysis temperature also has an important influence on the chemical properties of biochars by increasing the pyrolysis temperature the atomic ratio of C/H and C/N increased,the quantity of oxygen-containing functional groups and alkyl radical decreased,which indicated that high-temperature biochar possess is a more complete aromatic structure.(4)Pyrolysis residence time had a manifest effect on the performance of biochar,which shows that pyrolysis charcoal yield is lower and p H value is higher at 60 min than 30 min,while the change of specific surface area and chemical property is obvious at different temperature.In this experiment,the adsorption of Pb(?),Cu(?),Cd(?)and Cr(?)on biochars were studied which prepared by different pyrolysis process.Results indicated that:(1)Biochar indeed achieved an excellent adsorption performance,the adsorption of Pb(?)among that were the best,the 500 ?-60 min biochar had the highest adsorption capacity among all biochars to remove Pb(?),which reached 381.68 mg/g.(2)The biochars maximum adsorption of Cr(?)(87.11 mg/g)was greater than the original sludge(42.43 mg/g);the maximum adsorption of biochars to Cd(?)(73.80 mg/g)was slightly lower than the original sludge(92.25 mg/g);and the adsorption capacity of biochars to Cu(?)had little difference with the original sludge.(3)Sorption thermodynamics conformed to Langmuir model with perfect fitness.The sorption kinetics which conformed to a pseudo-second-order reaction were very well.(4)The mechanism of biosorption of heavy metals biochar mainly involves the complexation of acidic functional groups on the surface of biochar,ion exchange and surface precipitation.It indicates that the adsorption characteristics of biochar on heavy metals are closely related to the pyrolysis temperature.