Study On Modified Activated Carbon And Its Adsorption Of Pb(Ⅱ) And Ni(Ⅱ) In Wastewater

With the rapid development of automobile industry,in the process of automobile production,a large number of wastewater containing heavy metal ions will be produced in the painting process,which will cause serious environmental and health problems and waste a large amount of metal resources if not properly treated.The adsorption and recovery of heavy metal ions in wastewater with adsorbent is a good treatment method.In this experiment,the automobile coating wastewater Pb（Ⅱ）,Ni（Ⅱ）as the object of study,using activated carbon as the adsorbent,using the single factor experiment method to study the pH value,adsorption time,ion concentration and adsorption temperature conditions,on the activated carbon in Pb（Ⅱ）,Ni（Ⅱ）single ion and the two mixed ion system under the adsorption performance to explore.In this paper,the adsorption properties of seven activated carbons were studied,including coconut shell carbon（YAC,YAC-Zn and YAC-Mn）before and after modification,fruit shell carbon（GAC and GAC-Mn）before and after modification,coffee grounds activated carbon（KAC-1）prepared in Muffle furnace and coffee grounds activated carbon（KAC-2）prepared in tube furnace.The surface morphology,elemental composition,phase structure,functional groups and specific surface area of seven activated carbons were studied by SEM,EDS,XRD,FT-IR and BET characterization.SEM and EDS tests were conducted on the adsorbed activated carbon to compare the morphologic changes and the changes of the elements before and after adsorption.In the single factor experiment,when the initial solution pH,adsorption time is 12h,solution ion concentration is 100mg/L,and temperature is 55℃,the adsorption capacity of modified YAC-Zn and YAC-Mn for Pb（Ⅱ）becomes about 2.00 times and2.43 times,respectively,compared with the original YAC before modification.The adsorption capacity of Ni（Ⅱ）was 1.73 times and 2.21 times,respectively.The adsorption capacity of GAC-Mn on Pb（Ⅱ）and Ni（Ⅱ）was 4.28 times and 4.37 times respectively compared with that before modification,indicating that the modification effect was more obvious.For coffee grounds,compared with the activated carbon（KAC-1）prepared in the Muffle furnace,the adsorption capacity of KAC-1 for Pb（Ⅱ）and Ni（Ⅱ）is 15.09 times and 6.20 times of that of KAC-2,respectively,and the adsorption capacity of Kac-1 is much greater than that of KAC-2.Based on the adsorption data of activated carbon in Pb（Ⅱ）and Ni（Ⅱ）single-ion systems,the quasi-first-order kinetic model,quasi-second-order kinetic model,intra-particle diffusion model,Langmuir adsorption isotherm model,Freundlich adsorption isotherm model and adsorption thermodynamic model were fitted to explore the adsorption mechanism.In addition,the adsorption capacity of seven activated carbon in the mixed ion system of Pb（Ⅱ）and Ni（Ⅱ）was studied under the conditions of four factors.The experimental results show that the adsorption capacity of Pb（Ⅱ）and Ni（Ⅱ）under the mixed ion system is smaller than that under the single ion system.Then the adsorption experiment was carried out on the adsorbed activated carbon.HCl,HNO₃and EDTA-2Na solution were used as desorption agents to explore the recycling capacity of activated carbon.