| The surface of iron and steel usually produces a layer of oxide skin,that is the phenomenon of corrosion in the process of production and the use.It is necessary to deal with the surface,in order to improve the quality of iron and steel,maintain good appearance and prolong the service life of steel.Using pickling method to remove it,it will produce acid waste water.Acid pickling waste water discharges without treatment directly,not only causing considerable harm to the environment,but also wasting metal and acid in the waste water.Therefore,the recovery of acid pickling waste-water can bring economic benefits to the enterprise,and protect the environment.Acid pickling wastewater contains a lot of iron ions.If separating the iron ion from the acid,and realizing the recycling of metal ions and acid,it is a subject with high industrial application value.In this paper,the ion exchange resin method is used to remove the iron ions from acid pickling wastewater and recycle the acid.By comparing the concentration of iron ions in solution at different time in two kinds of resins that is D001 and 201×7 resin,the D001 resin is selected as the resin in this paper.Through the static adsorption,the adsorption process of iron ion in the acid pickling wastewater by D001 resin is studied,and the adsorption thermodynamics and kinetics of the process are analyzed.The dynamic adsorption process is studied by small scale dynamic adsorption.Based on the study of static and dynamic desorption and regeneration of resin,the kinetics and regeneration conditions are analyzed.What?s more,through the use of waste acid after removing iron,the new cleaning acid is arranged to treat the steel surface in order to recovery and utilization of acid.Research shows:1.Static adsorption experiments show that:D001 strong acid cation exchange resin is selected as the working resin,and the resin achieves saturation after 60min in the adsorption.The temperature has little effect on the adsorption of resin,which choosing the room temperature as the working condition.In the adsorption process,the initial concentration of iron ions in the solution should not be too high.2.The study of adsorption mechanism shows that:Langmuir adsorption isotherm equation can reflect the adsorption process of D001 resin to iron ions better.H>0 shows that heating-up is favorable to adsorption.?G<0 shows that the reaction can proceed spontaneously.The adsorption process can be well fitted by the pseudo-second-order equation,and the main control step is the intraparticle diffusion,and the apparent activation energy of adsorption is6.045kJ/mol.3.Dynamic adsorption experiments show that:It is better for the adsorption to choose which the flow rate is between 1.5 and 2BV/h and initial waste acid dilutes 2 times that the initial concentration of acid is about20mg/mL.The resin is not need to completely wash to neutral that can be washed by 2BV of water before the next adsorption process.4.Regeneration experiments show that:hydrochloric acid with concentration between 10%and 15%and dosage between 34BV is used as a recycling agent in the static experiment at room temperature.Regeneration time is about 60min.The desorption rate constant is 0.1012 min-1,and the apparent activation energy is 7.826kJ/mol at room temperature.3BV and mass fraction about 10%of hydrochloric acid can be selected,working at room temperature for 2 hours through dynamic test.Adsorption capacity and regeneration degree of the resin are stable.5.The experiment that reusing acid pickling waste water after treatment shows that:It meets the requirement of new cleaning acid which contain outflow liquid that concentration of iron ion below 10mg/mL and additional acid of concentrated sulfuric acid,hydrochloric acid and phosphoric acid.The effect of this cleaning acid to clean rust iron is better. |
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