Study On Modified Of Microporous ZSM-5 And Loaded Ce For Adsorption As(Ⅴ) In Solution

At present,environmental problems of arsenic pollution have been highly concerned around the world.Although the efforts and struggles of predecessors have achieved remarkable results in the treatment of arsenic pollution,the global environmental situation is still grim.Therefore,it is imperative to choose an efficient arsenic removal technology.The arsenic removal technology used in this paper is the adsorption method.In this paper,microporous ZSM-5 has been used as raw material,and the reamed ZSM-5K was obtained by alkali fusion-hydrothermal method through reasonable parameters of the control system.The results show that the optimal conditions for modifying:the mass ratio of ZSM-5 and alkali is 10:1,p H is adjusted to 10.5 when hydrothermal,the hydrothermal temperature is 110°C and the hydrothermal time is 24h.The modified ZSM-5K maintains the skeleton structure of the original ZSM-5 to a certain extent.The research object of this thesis is to simulate the arsenic-containing wastewater for the laboratory.Static adsorption experiments show that Ce/ZSM-5K has higher adsorption efficiency for As（Ⅴ）than Ce/ZSM-5 and other common non-metal-based arsenic adsorbents;when As（Ⅴ）initial concentration is lower than or equal to 5.27 mg/L,the residual concentration of As（Ⅴ）in the wastewater after adsorption is less than 0.5mg/L,which meets the requirements of the Integrated Wastewater Discharge Standard（GB8978-1996）;The experimental data was more suitable for analysis with Freundlich adsorption isotherm model indicates that the adsorption is not a monolayer adsorption,but a surface uneven adsorption,so there may be multiple adsorption mechanisms.Furthermore,the adsorption process is easy to carry out.By calculation,the maximum theoretical adsorption capacity of Ce/ZSM-5K for As（Ⅴ）is 36.49 mg/g（Langmuir）which is in good agreement with the actual adsorption capacity.Under different initial concentration conditions,the adsorption kinetics of As（Ⅴ）by Ce/ZSM-5K accords with the pseudo-second-order kinetic model,which indicates that the“surface reaction”is the adsorption rate limiting step.Thermodynamic studies show that the adsorption is spontaneous and endothermic,and the temperature rise is favorable for the reaction.According to the FT-IR characterization and the p H change of the solution before and after adsorption,the electrostatic attraction is the main adsorption mechanism of Ce/ZSM-5K at low p H.When the p H is neutral or alkaline,the adsorption is mainly SO₄^2-,OH^-.Adsorption is carried out by the action of ion exchange with H₂AsO4^-.