| In this paper,all-steel tire waste tire rubber particles are selected,and carbon black is prepared by pyrolysis in a self-designed three-stage continuous pyrolysis reactor,and then ball milled carbon black is prepared by ball milling modification,and the adsorption experiment of sulfamethoxazole is carried out.The effect of pyrolysis temperature and residence time on the properties of pyrolysis carbon black was studied,and ball milled carbon black under a series of ball milling conditions was prepared,and the surface characteristics of ball milled carbon black were characterized.The adsorption capacity and the related adsorption mechanism of the waste tires provide a new idea for the resource utilization of waste tires and the high-value utilization of pyrolysis carbon black.The main conclusions are as follows:(1)Physical and chemical properties and pyrolysis characteristics of waste tire rubber particles: tire pyrolysis can be divided into four stages: the first stage is the evaporation of water and the decomposition of plasticizers;the second stage is the decomposition of NR(natural rubber).;The third stage is the decomposition of SBR(styrene butadiene rubber)/BR(cis-butadiene rubber);in the fourth stage,a small weight loss is observed above 600°C,and a small amount of ash is decomposed.Pyrolytic carbon black contains 23.04% ash,which is far greater than the standard of commercial carbon black(ash content < 0.5%).The high ash content greatly limits the commercial utilization of pyrolytic carbon black.Higher content of metal elements such as Fe element and Zn element and non-metallic elements such as Si element.The specific surface area of pyrolytic carbon black is 85.67 m2/g,the proportion of micropore pore volume is less than 10% of the total pore volume,and the average pore diameter is 21.2 nm.(2)Analysis of three-stage pyrolysis characteristics of waste tire rubber pellets:Within the scope of the experimental conditions,for the all-steel tire rubber pellets used in the experiment,the yield of pyrolysis carbon black is about 35%.When the pyrolysis conditions are changed,the performance indicators of pyrolysis carbon black do not change significantly,and the basic properties of the obtained pyrolysis carbon black are roughly similar to those of N660,but the iodine absorption value is 4-5 times higher than the index value of N660,and the ash content is obvious.higher than N660.In addition,through TGA,FTIR,SEM,XRD and other characterization methods,it is found that the surface characteristics of the two are also similar,but the surface organic residues of pyrolysis carbon black are higher than that of N660.The performance results of carbon black under different working conditions show that the use of three-stage stepped heating pyrolysis can significantly reduce the residual amount of organic matter on the surface of pyrolysis carbon black,and at the same time achieve higher oil yield and higher quality carbon black,which is beneficial to waste tires resource utilization.The experimental results show that the device can produce carbon black that meets the national standard.(3)Ball-milling modified pyrolytic carbon black to prepare ball-milled carbon black: The ball-milling modification method was selected to successfully modify the pyrolytic carbon black.The modification results show that the ball milling modification treatment can significantly reduce the particle size of pyrolytic carbon black,the average particle size is reduced from 120.30 μm to 1.09 μm,and the d90 value is also reduced from 278.50 μm to 2.08 μm.However,too long ball milling time will lead to agglomeration of carbon black particles,and the optimal ball milling time is 2 h.The specific surface area of the prepared ball-milled carbon black was about 2.53 times that of the original carbon black without ball-milling treatment(the specific surface area increased from 88.31 m2/g to 223.73 m2/g).The specific surface area of the ball-milled carbon black and the original carbon black was sorted The order is: BM2 > BM5 >BM10 > BM1 > BM0.5 > C,the micropore volume increases from 0.0025 cm3/g to0.0433 cm3/g,an increase of 16.32 times,the micropore volume of each sample is sorted as follows: BM2 > BM5 > BM10 > BM1 > BM0.5 > C.Among them,the BET specific surface area of BM2 is the largest,which is 223.73 m2/g,and the microporosity is 45.34%.Ball milling treatment can increase the number of C-O,C=O,-COOH and other oxygen-containing functional groups of pyrolytic carbon black to a certain extent,and the content of C-O,C=O,-COOH and other oxygen-containing functional groups increases from 31.43% to 36.16%.(4)To study the adsorption performance and adsorption mechanism of sulfamethoxazole by ball milled carbon black and pristine carbon black: The adsorption experiment of sulfamethoxazole was carried out with the pyrolysis carbon black before and after ball mill modification.The experimental results showed that the removal rate of sulfamethoxazole by pyrolysis carbon black before and after ball milling increased from 1.54% to 47.48%,and the maximum adsorption capacity increased from 1.93mg/g to 59.37 mg/g.The maximum adsorption amount of oxazole reached 30.76 times that of pristine carbon black.The order of adsorption capacity for sulfamethoxazole is:BM2 > BM5 > BM10 > BM1 > BM0.5 > C.The adsorption capacity is not only related to the specific surface area,but also affected by the pore structure of the material and the oxygen-containing functional groups on the surface.The adsorption amount was59.37 mg/g.The isotherm adsorption process of sulfamethoxazole by ball milled carbon black conformed to the Langmuir isotherm adsorption model.The adsorption process proceeded rapidly within the first 10 min and reached the adsorption equilibrium within600 min.The adsorption kinetics fit the pseudo-second-order adsorption kinetic model.The fitting results of the particle diffusion model show that the adsorption process is affected by many factors.Ball milling can improve both the diffusion rate of the first stage and the diffusion rate of the second stage,but the improvement effect on the first stage is more obvious,that is,Increase the diffusion rate of sulfamethoxazole molecules from water to the adsorbent surface.The adsorption of sulfamethoxazole by ball milled carbon black is related to both micropores and mesopores,and the effective adsorption pore size is between 1.5 and 2.1 nm.Ball milling can significantly increase the proportion of pore structures in this range,thereby improving the adsorption capacity of ball-milled carbon black to sulfamethoxazole.For the adsorption of sulfamethoxazole,the pore adsorption of the material(depending on the specific surface area of the material)and the electron acceptor-donor mechanism between the adsorbent and the adsorbate are the main adsorption mechanisms,in addition to the π-π bond interaction and Hydrogen bonding also has a certain influence on the adsorption.For ball-milled carbon black and sulfamethoxazole,the oxygen-containing functional groups(such as C-O and C=O)on the surface of ball-milled carbon black are electron donors,while the aromatic ring structure of sulfamethoxazole is an electron acceptor.Ball milling can increase the specific surface area,provide more effective adsorption sites,and also increase the oxygen-containing functional groups on the surface of pyrolysis carbon black,and enhance the electron donor-acceptor interaction between the ball-milled carbon black and sulfamethoxazole molecules.In turn,the adsorption capacity of the ball milled carbon black is enhanced. |
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