Properties Of Wheat Straw On The Solution Of Lead, Cadmium Ion Adsorption

In this thesis, we used wheat straw as raw materials and prepare it for undistur bed adsorbents. Through the research of adsorption capacity about lead and cadmium, we explored its principles about heavy metal. According to the static and dynamic a dsorption experiment, a lot of exogenous factors to the adsorption effect were investi gated. Balanced adsorption kinetics and thermodynamics related to heavy metal were studied. Agricultural waste such as straw into the remediation of heavy metal pollutio n could provide a scientific basis. The main research results were discussed below.In the use of undisturbed wheat adsorption to lead and cadmium ion static test process, wheat grain size、dosage、initial concentration pH、adsorption time and tem perature were mainly taken into considered. pH had the greatest effect on the adsorpt ion of the two metals greatest impact, we selected the particle size of0.15-0.2mm, the dosing amount (g) of0.2g, pH between2to4, the reaction temperature25℃, concentration of300mg/L as the most suitable reaction conditions in the last. Com bined FTIR spectra with SEM results about Pb2+, Cd2+, chemical adsorption process was inferred. In the choice of adsorption kinetics models, quasi-two kinetic model wa s the most suitable for wheat straw adsorption. Adsorption process by the membrane diffusion and internal diffusion joint was under control. In the adsorption thermodyn amics, the adsorption isotherm was very suitable for the Langmuir equation and Freu ndlich model and conducive for adsorption. For chemically modified straw, both ions adsorption effect increased higher than original wheat straw.In the process of using wheat straw adsorption of lead、cadmium ion dynamic e xperiments, we took the impact of flow and concentration into consider. At a fixed c oncentration of different flow rates and a fixed of flow rate of different concentration s, Pb2+took longer to achieve the breakthrough point than Cd2+. At the same time, t he outflow concentration of Pb2+was lower than Cd2+, indicating that adsorption effe ct of Pb2+was better than Cd2+. This experiment selected6mL/min and30mg/L as the most ideal flow rate and concentration. According to dynamic adsorption model, flow rate had greater impact on reaching the breakthrough point.In the case of identical concentration and competitive adsorption about Pb an d Cd2+, whether it was static or dynamic, adsorption strength had decreased compare d with single-ion. Pb2+was more easily adsorbed than Cd2+in competitive advantage.