| Coal gasification slag is a type of solid waste produced from coal gasification,and the main disposal methods are stacking and landfill at present,which causes great pollution to the environment.In addition,ammonia nitrogen is one of the main pollutants in water bodies,and its treatment is an important field for water pollution control.In this paper,the residual carbon in the coal gasification fine slag was recovered by flotation,and the physical and chemical properties of residue carbon are studied.Then,a three-dimensional electrocatalysis system is constructed to treat ammonia nitrogen wastewater with the flotation residue carbon as the particle electrode,achieve the purpose of “ using waste to treat waste ”,aiming to realize the high-value utilization of coal gasification slag,and provide a theoretical basis for the application of the electrocatalytic technology of residue carbon particle electrode of coal gasification slag.The main conclusions are as follows:(1)The microemulsion was served as collector to flotation coal gasification fine slag,and the influence of the content of surfactant HLB(hydrophile-lipophile balance),S:K(mass ratio of surfactant to kerosene)and cosurfactant content of the microemulsion collector on the flotation effect of coal gasification fine slag were investigated.The optimal ratio of microemulsion collector was obtained as follows: surfactant HLB of the microemulsion collector was 8,S:K=1:5,and the mass fraction of cosurfactant was 20%.When its dosage is10 kg/t,the combustible recovery rate up to 53.55%.At the same time,the adsorption mechanism of collector in flotation was explored,and the results showed that the adsorption process of microemulsion and coal gasification fine slag was the synergistic effect of Van der Waals force and hydrogen bond,and the surface hydrophobicity of coal gasification fine slag was improved after microemulsion.(2)In order to explore the feasibility of the flotation residual carbon from gasification slag as particle electrode,the physicochemical and electrochemical properties of the residue carbon particles were analyzed,which showed that the residue carbon had a high specific surface area,and the pore structure was mainly mesoporous.The residual carbon is partially graphitized,which has a certain conductivity.In addition,the residual carbon particle electrocatalysis system has a lower resistance,which will accelerate the charge transfer rate.Under the same conditions,the removal rate of ammonia nitrogen in the three-dimensional electrocatalysis system was 19.82% higher than that in the two-dimensional electrocatalysis system,which indicated that the residual carbon particles have a certain catalytic ability.In the residual carbon particle electrode cycling test,the removal rate of ammonia nitrogen only decreased by 5.3% when residue carbon particles were reused for 5 times,which showed the residual carbon particles have high stability.Therefore,it is feasible for residual carbon particles to be used as particle electrodes.(3)In the experiment of designing feasible electrocatalysis reactors and optimizing operating conditions,the effects of particle dosage,initial p H of wastewater and electrolysis voltage on the three-dimensional electrocatalysis removal of ammonia nitrogen were studied.Through response surface method,the optimal operating conditions were obtained as follows:the electrolysis voltage was 16 V,the p H was 8.43,the particle dosage was 1.43 g/L,and ammonia nitrogen removal rate up to 95.49%.Under different particle dosages,initial p H and electrolysis voltage conditions,the removal of ammonia nitrogen follows first-order reaction kinetics. |
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