Study On The Removal Of Hydrogen Sulfide By Carbide Slag Modified Bentonite-Based Adsorbents

Hydrogen sulfide（H₂S）gas is a toxic and harmful gas that can limit tail gas recycling,cause equipment corrosion,and even endanger human health.Carbide slag is a harmful but valuable solid by-product produced in the coal chemical industry when producing acetylene,polyvinyl chloride（PVC）and other products,the main component is calcium hydroxide（Ca（OH）₂）,and also contains a small amount of other metal oxides,has the advantages of high alkalinity,good activity,small particle size,etc.,but because the carbide slag does not have a rich pore structure.It cannot be used directly as a filler alone for the adsorption and removal of H₂S.Bentonite is a non-metallic mineral with montmorillonite as the main mineral component,its excellent stability and good adsorption properties make it can be used as an excellent carrier.In this paper,we summarize the H₂S removal methods at home and abroad,and use carbide slag as the active component to prepare carbide slag modified bentonite adsorbent for H₂S removal.In this study,the composite calcium-based adsorbent of carbide slag modified with bentonite was prepared by wet mixing and impregnation methods,and the adsorption performance of the adsorbent on H₂S was investigated.The adsorption performance of the composite adsorbent was investigated.The effects of the preparation conditions（raw material ratio,roasting temperature and roasting time）and adsorption operation conditions（adsorption temperature and air velocity）on the adsorption performance of the gas were investigated.The results of TG/DTA,N₂-BET,FTIR,Raman,XRD,XRF and XPS were used to optimize the composition and structure of the adsorbent.The adsorption kinetics and thermodynamics of the composite adsorbent were studied to investigate the purification and removal mechanism of H₂S on the adsorbent.The results showed that the wet mixing method was more suitable for the preparation of the carbide slag type composite bentonite adsorbent than the impregnation method.The H₂S adsorption effect of the composite adsorbent prepared from bentonite,carbide slag and water in a suitable ratio of 5:3:5 was best after 24 h of static aging,drying（10h at 100℃）and then roasting（2 h at 450℃）.The optimum adsorption reaction temperature was 95℃and the volume air velocity was 833 h^-1.The adsorption process of H₂S followed the Freundlich adsorption isotherm equation and Bangham adsorption kinetic model.There is a strong interaction between the carbide slag and the bentonite carrier,which reduces the specific surface area of bentonite and increases the number of active sites.The adsorption process is chemisorption by the action of multiple chemical reactions,and H₂S is finally adsorbed as Ca S and Ca SO₄·2H₂O to fill the mesopores and macropores of the composite adsorbent.