Preparation Of Adsorbent From Coal Gasification Fine Slag For Treatment Of Semicoke Wastewater And Its Adsorption Mechanism

Coal gasification fine slag is a solid residue produced by incomplete combustion of coal under high temperature and pressure in the process of coal gasification production.It is usually stacked as solid waste,causing serious land waste and environmental pollution.However,coal gasification fine slag has certain hardness and porosity,rich pore structure and certain specific surface area,which can be used in metallurgical industry,environmental protection materials and other fields with high value.Yulin City’s high-quality coal resources derive high-quality blue charcoal products,which are important raw materials for the metallurgical industry.However,a large number of"three high"wastewater with high Chemical oxygen demand(COD),high volatile phenol and high ammonia nitrogen will be produced during its processing,which will cause great harm to the ecological environment and need to be treated urgently.First of all,the raw material used in this paper is coal gasification fine slag,which uses its porous characteristics and adsorption capacity to prepare adsorbent after gravity sedimentation flotation upgrading,to study its adsorption capacity for characteristic pollutants in semicarbon wastewater and reveal its adsorption mechanism.The results showed that the removal rate of COD in simulated wastewater reached 90%when the p H value of refined coal gasification slag was 8,the experimental temperature was 20℃,the adsorption time was 20 min,and the dosing ratio was 1:4.However,under the optimal conditions,the removal rates of COD,volatile phenol and ammonia nitrogen are 69%,57%and 47%respectively when the fine slag of coal gasification is used to treat the semicoke wastewater,and the adsorption capacity is poor.This is due to the complex components of pollutants in the wastewater from semicarbon,which interfere with their adsorption effect,resulting in insufficient adsorption capacity of fine slag from coal gasification for upgrading.Secondly,the refined coal gasification slag was modified.The results showed that the removal rates of the three were increased to 94%,91%and 85%respectively after p H was 9,dosing ratio was 1:4,and adsorption at 20℃for 30 minutes.The main reason is that the modified treatment significantly increased the specific surface area of the adsorbent from112.90 m~2/g to 606 m~2/g,effectively increasing the adsorption active site of pollutant molecules.In addition,the saturated adsorption modified coal gasification fine slag can be regenerated through the"methanol high temperature treatment method".After 8 times of reuse,the removal rates of COD,volatile phenol and ammonia nitrogen in the wastewater from the semicarbon still remain above 62%,56%and 50%,showing good reproducibility.Finally,the kinetics and thermodynamics of the adsorption process of COD in the treatment of semicarbon wastewater by modified coal gasification fine slag were studied.The research data of adsorption kinetics shows that the adsorption process data of modified coal gasification fine slag is close to the Langmuir contour line temperature and related subjects equation,with a small relative error,and conforms to the quasi first order kinetics model.The adsorption capacity changes nonlinearly with time.Thermodynamic study shows that the adsorption process of modified coal gasification fine slag for pollutants in semicoke wastewater is exothermic and spontaneous.