| Nowadays,there are a large number of small and medium-sized steel processing enterprises in China.Produce a large amount of pickling waste hydrochloric acid solution every year.However,considering the economic factors,it is impossible to treat acid pickling waste liquor by direct roasting method like large iron and steel enterprises.Ion exchange method is widely used in water treatment.Metal ions in waste hydrochloric acid solution are replaced by exchange groups in ion exchange resin when treating waste hydrochloric acid solution.Thus regeneration of hydrochloric acid.In this paper,ion exchange resin was used to adsorb iron ions from acid pickling waste hydrochloric acid solution in electroplating industry,so as to regenerate hydrochloric acid,so as to lay a foundation for industrial application.In this paper,simulated acid pickling waste hydrochloric acid solution was taken as the research object,and ion exchange resin was used to adsorb iron ions in waste hydrochloric acid solution to regenerate hydrochloric acid.Through static experiment,response surface optimization experiment,dynamic experiment and regeneration experiment,the adsorption capacity of resin for iron ion was studied,and the kinetics and thermodynamics were studied.The adsorption process of resin was analyzed by BET determination,and the following conclusions were obtained:(1)In static experiments,chlorine dioxide was used as oxidant to oxidize iron ions in acid pickling waste hydrochloric acid solution.The addition of oxidant was 36.972 g/L,and the oxidation effect reached 99.83% after 15 minutes of reaction.The adsorptive capacity of D201 resin and 201*7 resin for total iron ions under single factor conditions was investigated.The experimental results showed that the adsorption capacity of D201 resin reached 141.62mg/g at initial iron ion concentration of 0.3 mol/L,hydrochloric acid of 9 mol/L,temperature of 30 C and reaction time of 240 min.The experimental results show that the adsorption capacity of 201*7 resin reaches 93.30 mg/g at initial iron ion concentration of 0.25 mol/L,initial hydrochloric acid of 9 mol/L,temperature of 30 C and reaction time of 240 min.By comprehensive comparison,D201 resin was selected to treat total iron ions in waste hydrochloric acid solution.(2)Through response surface optimization experiment and analysis by Design-expert8.0.6 software,the optimum experimental conditions for D201 resin to adsorb waste hydrochloric acid solution containing iron were obtained as follows: adsorption time 180 min;hydrochloric acid concentration 7.8 mol/L;iron ion concentration 0.35 mol/L;temperature 35 C.The total iron ion adsorption capacity was 149.186 mg/g.The adsorption capacity of D201 resin was 153.128mg/g,and the deviation was 2.64%.The experimental results were in good agreement with the simulated values.(3)The adsorption mechanism of D201 resin and 201*7 resin was analyzed:The results of thermodynamic and kinetic experiments show that the adsorption of iron ions by D201 resin and 201*7 resin in waste acid solution is monolayer surface adsorption,and the adsorption process belongs to spontaneous endothermic chemical reaction.Particle diffusion is the main rate control step for D201 resin and 201*7 resin to adsorb iron ions in acid pickling waste hydrochloric acid solution.BET results show that the main rate control step of D201 resin adsorption is particle diffusion.The apparent activation energy of D201 resin is22.54KJ/mol and that of 201*7 resin is 33.36KJ/mol,which indicates that the adsorption rate of iron ion in waste acid by D201 resin is faster.(4)In dynamic experiments,the running velocity and aspect ratio of D201 resin have an effect on the penetration volume and the penetration curve.Experiments show that the optimum operating speed is 5 mL/min,the ratio of height to diameter is 5:1,and the running volume is 5 BV.(5)In the regeneration experiment,D201 resin saturated with adsorption was regenerated by secondary deionized water.The regeneration effect could reach 96.83% by downstream regeneration and controlling the inlet water velocity of 10 mL/min.Static pipe string regeneration method,running volume 1.5BV,regeneration effect reached 99.4%.Considering comprehensively,static column regeneration method was chosen to regenerate D201 resin with saturated adsorption,and regenerated desorption liquid was used to treat pickle wastewater,which had good flocculation effect.(6)Two columns in series were used to adsorb the waste hydrochloric acid solution containing iron.The concentration of iron ion in the effluent was basically 0 at the first 180 mL.When the effluent was 300 mL,the removal rate of iron ion was 90.12%,and the acidity was 6.09 mol/L.The acidity of effluent could continue to be used in the acid pickling process. |
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