Study On Two Forms Of RPFC-Ⅰ Ion Exchange Fibers For Treating Low Concentration Pb(Ⅱ) Containing Wastewater

Pb（Ⅱ）is the most typical heavy metal pollutant in water pollution.The use of ion exchange technology for adsorption treatment has become one of the main research directions,with adsorbents being the core of ion exchange technology.RPFC-Ⅰfiber have the advantages of large adsorption capacity and fast adsorption rate.However,there is currently no in-depth research on RPFC-Ⅰfibers for low concentration Pb（Ⅱ）containing wastewater.This article modifies RPFC-Ⅰfibers into Na-RPFC-Ⅰfibers and H-RPFC-Ⅰfibers,and analyzes the surface structure and chemical groups of the two forms of RPFC-Ⅰfibers before and after adsorption using equipment such as Zeta potential,scanning electron microscopy（SEM）,and Fourier transform infrared spectroscopy（FTIR）.Furthermore,the static and dynamic adsorption properties of the two forms of RPFC-Ⅰfibers are studied,Finally,the dynamic adsorption process of Pb（Ⅱ）on H-RPFC-Ⅰfibers was further explored through dynamic adsorption experiments,and H-RPFC-Ⅰnon-woven fabrics were applied to simulate Pb（Ⅱ）containing wastewater and the effluent from the secondary sedimentation tank of the standardized urban sewage treatment plant.The specific research results are as follows:（1）From the Zeta potential,it can be concluded that when the p H is between 2.4 and 10.0,the Na-RPFC-Ⅰfiber surface carries negative charges.When the p H is between 3.6 and 10.0,the H-RPFC-Ⅰfiber surface carries negative charges,both of which exhibit electrostatic adsorption on Pb（Ⅱ）.From SEM,it can be seen that the surface structure of the two modified forms of RPFC-Ⅰfibers is rough,and there are some grooves and micropores with many adsorption sites.According to FTIR analysis,the adsorption of Pb（Ⅱ）by two forms of RPFC-Ⅰfibers is the result of the combined action of carboxyl and amino groups,with carboxyl groups dominating.（2）The static adsorption experiment results of two forms of RPFC-Ⅰfibers for Pb（Ⅱ）show that with the increase of fiber dosage,the adsorption amount decreases and the removal rate increases.When the p H is between 3.0 and 5.0,the adsorption capacity and removal rate increase.When the p H is between 5.0 and 9.0,the adsorption capacity and removal rate decrease.When the water temperature is between 10 and 30℃,the adsorption capacity and removal rate increase with the increase of temperature.Under the conditions of 0.02 g of RPFC-Ⅰfiber dosage,p H 6.5,temperature 20℃or 10℃,and Pb（Ⅱ）wastewater concentration of 0.32 mg·L^-1,the fitting results of the quasi first order kinetic model and quasi second order kinetic model indicate that the removal process of Pb（Ⅱ）by the two forms of RPFC-Ⅰfiber conforms to the quasi second order kinetic model.Under the same conditions,the Langmuir model and Freundlich model were used to fit the isothermal experimental data,and it was found that the Langmuir model had a better fitting effect.After four regeneration experiments,the two forms of RPFC-Ⅰfibers still have ideal removal effects on Pb（Ⅱ）,with the removal rate of Na-RPFC-Ⅰfibers decreasing by up to 2.6%;The removal rate of H-RPFC-I fiber decreased by a maximum of 10.1%.（3）The dynamic adsorption experiment shows that the penetration time decreases with increasing initial concentration,shortens with increasing flow rate,and prolongs with increasing temperature.The adsorption capacity increases with the increase of initial concentration,slightly decreases with the increase of flow rate,and increases with the increase of temperature.The Thomas model and Yoon Nelson model both have good fitting effects on the adsorption breakthrough curve.The Thomas model can be used to describe the dynamic adsorption process and calculate the saturated adsorption capacity of the adsorbent.The Yoon Nelson model can be used to predict the time required for adsorption to reach 50%.After two repeated regeneration experiments,the dynamic regeneration performance of the two forms of RPFC-Ⅰfibers is stable.（4）Through the H-RPFC-Ⅰfiber dynamic experiment,it can be concluded that under the selected experimental conditions,the upper limit value of the space velocity in the ion exchange column is 700 min-1.Choosing a dynamic adsorption H-RPFC-Ⅰfiber dosage of 0.10 g,i.e.at the penetration point,0.10 g of H-RPFC-Ⅰfiber can treat 14160 m L(0.50 mg·L^-1)of Pb（Ⅱ）containing wastewater.Design the pilot ion exchange column using experimental parameters fitted with a flow rate of 30 m L·min^-1.（5）The dynamic adsorption effect of H-RPFC-Ⅰnon-woven fabric on experimental simulated Pb（Ⅱ）containing wastewater is better than that of H-RPFC-Ⅰfiber on this wastewater;The dynamic adsorption effect of H-RPFC-Ⅰnon-woven fabric on experimental simulated Pb（Ⅱ）containing wastewater is better than that of H-RPFC-Ⅰnon-woven fabric on the dynamic adsorption effect of secondary sedimentation tank effluent of standardized urban sewage treatment plants.