| The presence of heavy metal ions in the environment is harmful to humans,plants and animals.As a representative of heavy metal ions,lead has been used by people for a long time.People exposed to lead for a long time may suffer from impaired memory,prolonged reaction time,and decreased understanding ability.According to the newly implemented pollutant discharge standard for lead-acid battery industry,the emission limit of total lead content in waste water pollution discharge standard shall not be higher than 0.5 mg/L.In the field of heavy metal wastewater treatment,traditional water treatment methods cannot meet the requirements of relevant discharge standards.The traditional adsorption reaction device is an adsorption column reactor.The disadvantages of this reactor include long reaction processing time,inability to treat large quantities of wastewater,and slow industrial application.This subject mainly studied the adsorption characteristics of 732(sodium type)resin on Pb(Ⅱ)under high gravity field.Through single factor analysis,the best process conditions for the removal of lead ions by 732(sodium type)resin under high gravity field were obtained..Provide process and technical route for mass treatment of wastewater from lead-acid battery production.This paper studies the adsorption characteristics of different adsorbers and different adsorbents on lead ions.It was found that 732(sodium type)resin in the rotating packed bed had the best removal effect on free lead ions from the solution.The results of lead ion removal by resin in four different reactors were analyzed by kinetic simulation.It was found that the kinetic simulation was in accordance with the pseudo-first-order kinetic model.Under certain objective conditions,the reaction rate constants from high to low are as follows: rotating packed bed,adsorption column reactor,magnetic stirring reactor and ultrasonic reactor.Comparing the removal efficiency of three different adsorbents in rotating packed bed for free lead ion in solution,it is found that the order of their adsorption effect for lead ion is 732(sodium type)resin,columnar activated carbon and 4A molecular sieve.From the overall adsorption process of three adsorbents,the adsorption effect of resin on lead ion is longer than that of other two adsorbents and the final adsorption capacity is also significantly higher than that of the other two adsorbents.In this paper,the rotating packed bed was selected as the adsorption reactor.732(sodium type)resin was used as the adsorbent to explore the removal effect of free lead ion in the solution.The purpose is to explore a new process route for high gravity ion exchange technology.Through single factor experiment,the optimum process condition of 732(sodium type)resin in rotary packed bed for removing free lead ions from solution was explored.The results showed that under the condition of initial liquid concentration of 100mg/L,the optimal adsorption conditions were as follows: solid-liquid ratio of 0.5 g/L,liquid flow rate of 40L/h,high gravity factor of 81.97(900 r/min),initial liquid p H of 4.0,temperature of 323 K.When the reaction time is 30 min,the removal rate can reach 50 %,the adsorption capacity is 99.35mg/g and the reaction equilibrium time is 210 min.Under these conditions,the removal rate of free lead ions from the solution by resin is more than 95 %.In conclusion,the results show that the high gravity rotating packed bed can reduce the thickness of liquid film,reduce the mass transfer resistance between liquid and solid and enhance the liquid-solid mass transfer.It has good industrial application potential and strong applicability by increasing the liquid-solid contact area and shortening the reaction time to reach equilibrium.Isothermal adsorption model,thermodynamic analysis and kinetic analysis were carried out on the adsorption process data of 732(sodium type)resin in rotating packed bed for free lead ions in solution.The Langmuir isotherm equation and Freundlich isotherm equation were used to analyze the experimental data and the results show that the Langmuir isotherm equation has better fitting effect on the experimental data.It shows that the reaction of 732(sodium type)resin with lead ions in the rotating packed bed is a monolayer surface ion exchange reaction.The conclusion of thermodynamic analysis is as follows.The adsorption process of 732(sodium type)resin and lead ion in the rotating packed bed was endothermic reaction.The reaction is a process of increasing the degree of confusion.The reaction is spontaneous.The pseudo-firstorder dynamics model,pseudo-second-order dynamics model and weber-morris model were used to simulate the dynamics data.The results show that the removal process of lead ions by732(sodium type)resin in the rotating packed bed has a good fit with the pseudo-first-order kinetic model,which again confirms that the reaction is a surface-dominated process.The original resin,contaminated resin and regenerated resin were characterized by FTIRATR,SEM and EDS The adsorption-desorption process of 732(sodium type)resin in rotary packed bed for free lead ions in solution is further understood theoretically,which provides a foundation and support for further theoretical research of high gravity ion exchange technology. |
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