| The production process of petrochemical industry is accompanied by the production of a large amount of waste sulfuric acid.If such waste sulfuric acid discharge will bring great harm to human health and living environment,it must be properly disposed or reused.In this paper,the waste sulfuric acid containing petroleum organic impurities produced in the production process of petrochemical plants was taken as the research object.The preparation of waste sulfuric acid by using kaolin,activated carbon,modified organic bentonite as adsorbent,and leaching of manganese carbonate was studied.The COD value of manganese ore leachate was used as an evaluation index.Single factor experiment was used to investigate the effect of reaction temperature,dosage of adsorbent,reaction time,stirring rate on the removal of organic impurities in the waste sulfuric acid system.In addition,the response surface experiment or orthogonal experiment was used to further optimize the reaction process to obtain better technological conditions and to explore its adsorption mechanism.The thermodynamics and kinetics and regeneration and reuse tests of activated carbon adsorption were also studied.(1)As a sorbent,kaolin was used to explore the effects of reaction temperature,reaction time,kaolin dosage,agitation rate,particle size,and initial concentration of waste sulfuric acid on the removal rate of waste sulfuric acid COD through single factor experiments.The initial concentration is 15.04mol/l.The adsorption experiments were optimized by orthogonal experiment.The optimum conditions for the adsorption of waste sulfuric acid from kaolin are as follows:reaction temperature35°C,reaction time 60min,kaolin dosage 4.2g,stirring rate 350(r/min),particle size180um,parallel experiment under this condition,the average COD removal rate is87.23%.(2)Activated carbon was used as an adsorbent.The effects of reaction temperature,reaction time,kaolin dosage,agitation rate,particle size,and initial concentration of waste sulfuric acid on the removal rate of COD from waste sulfuric acid were investigated through single factor experiments.The response surface method obtained a better process for the purification of waste sulfuric acid by activated carbon.The second-order multiple mathematical model of the process is established by the response surface method:Y=86.44+1.52A+2.04B+5.44C+0.58AB+0.84AC+0.32BC-2.09A2-1.91B2+0.78C2,the optimum process conditions are:adsorption temperature74°C,activated carbon 3.9g,adsorption time 34 min,initial concentration of waste sulfuric acid 4.70mol/L,stirring rate 100r/min,parallel under better process conditions The experimental results show that the average COD removal rate reached 92.01%.The adsorption activation energy Ea is 14.95k J/mol,?H and?S are 12.20k J/mol and-283.73J/mol·k,respectively.The kinetic fitting results show that the adsorption process conforms to the second-order kinetic equation.(3)Experiments of modified bentonite-activated carbon as an adsorbent,fixed amount of activated carbon,adsorption temperature 74°C,adsorption time 34min,initial concentration of waste sulfuric acid 4.70mol/L,stirring rate was 100r/min.Bentonite was modified with sodium carbonate(Na2CO3)and cetyltrimethy-lammonium bromide(CTMAB)to prepare cetyltrimethylammonium bromide(CTMAB).On the basis of single factor experiments,the response surface method was used to optimize the process of treating bentonite by organic bentonite,and a quadratic mathematical model of the process is established:Y=+88.04+6.31A-0.57B+2.15C-0.27D-0.93AB-0.54AC-0.70AD+0.045BC+0.69BD-2.27CD-2.01A2-7.11B2-3.07C2-1.76D2.The optimum process conditions are:reaction temperature29°C,organic bentonite dosage 5.8g,reaction time 49 min,stirring rate was 90 r/min,initial concentration of waste sulfuric acid was 11.120 mol/L,and particle size of organic bentonite was 96 um.The possible adsorption mechanism is that the modified bentonite has the effect of ion exchange with waste sulfuric acid during the adsorption process. |
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