The Adsorption Properties Of Ethylenediamine Silica Gel Materials On Cu2+Ions

Based on the early work of our laboratory, we carry out the static adsorption and fixed bed dynamic adsorption experiment on ethylenediamine grafted silicone materials (EDA/SiO2), and deal with the experimental data based in the existing model, get the results as follows:This undertaking studies the adsorption behavior of EDA/SiO2to copper ion through static test and examines how the pH value of the solution, adsorbent dosage, time and the initial concentration of solution influence the adsorption properties of materials. Study found that the best adsorption pH is4.0of the EDA/SiO2to copper. In the constant concentration, with the adsorbent dosage increasing the adsorption capacity dropping and the removal rate increasing at first then constant. In experment we determine the adsorption thermodynamic dates, fitting it with Freundlich and Langmuiir isothermal equation we find that both Freundlich and Langmuir are suitable to describe the adsorption process of EDA/SiO2to copper ion. The result of researching the adsorption dynamic datas with Boyd liquid membrane diffusion equation, the pseudo-first-order and the pseudo-second-order model show that the pseudo-second-order model has higher fitting precision, the linear correlation are all larger than0.99, the fitting parameter equilibrium adsorption Qe,calc is very close to experimental Qe,exp, relative error are all less than5.76%, so the pseudo-second-order model is more suitable to describe the adsorption process of EDA/SiO2to copper ion.Fixed bed dynamic experiment mainly examine the influence of the flow rate, the initial solution concentration and the adsorbent dosage(the bed layer height) to breakthrough curve, then we find that smaller rate, larger initial concentration and higher column height can improve the saturate adsorption capacity of EDA/SiO2to copper ion. The result of the competitive adsorption between Cu2+and Zn2+researching show that there are competitive phenomenon existing, and Cu2+has great competitive ability. The repeatability test show that after six times adsorption the breakthrough curve has small change, so EDA/SiO2silica gel can use repeatedly. In addition, we study the influence of the desorption agent concentration in the repeatability test, and find that the desorption time shorten with the desorption agent concentration increasing, determine hydrochloric acid as the desorption agent and concentration of0.5mol·L-1.Fitting and analysising the breakthrough with Yoon-Nelson, BDST, Yan and Thomas models, the results show that BDST, Yan and Thomas models are all suitable to describe the dynamic adsorption behavior of EDA/SiO2to heavy metal ion.According to Thomas analysising we get the relationship among Q, Co, m, kTh and qo, the function relationship of m, C0and q0:q0=0.0234Co/m+0.2573and kTh=0.0081Q+0.0029with Q and kTh we establish has good prediction effect to experiment, error is small.