Study On Adsorption Of Lead In Wastewater By Modified Montmorillonite

The remediation of wastewater containing Pbo-has attracted much attention due to the harms of PbU-to environrmInt and human health.Montrmorillonite is a kind of layered clay mineral with a large specific surface area,good adsorbability and cation exchange,which exists in nature widely.It has potential application values for the treatment of heavy metal wastewater in industry and life.The main research contents are as follows:(1)In this study,taking two ligands diethylenetriamine and L-lysine as modifiers to modify sodium montmorillonite(Na-MMT),diethylenetriamine modified montmorillonite(DETA-MMT)and L-lysine modified montmorillonite(L-MMT)were prepared under mild reaction conditions.The changes of structure and morphology of montmorillonite after modification were studied by means of XRD,FTIR,TG/DTG,BET and SEM.The characterization results of XRD and FTIR showed that the modifiers were inserted into the montmorillonite layers successfully.(2)The effects of time,pH,initial concentration and temperature on the adsorption capacity of Pb2+ were studied by three kinds of adsorbents of Na-MMT,DETA-MMT and L-MMT.The results showed that the effects of time and temperature on adsorption were small,while pH and initial concentration had a great influence on the adsorption of Pb2F.(3)The adsorption performance of Pb2+ had improved of modified montmorillonite.The maximum adsorption capacity of Na-MMT,DETA-MMT and L-MMT for Pb21 were 31.78mg/g,64.14mg/g and 101.32mg/g respectively.The adsorption process of the three adsorbents on Pb2+ is in accordance with the pseudo-second-order model.The adsorption thermodynamics model showes that the adsorption process of Na-MMT and L-MMT can be described by Langmuir adsorption model.The adsorption process of Pb2+ on DETA-MMT can be described by Freundlich adsorption model.(4)The adsorption of Pb2+ on DETA-MMT and L-MMT exhibited a great adsorption stability.It is hard to be eluted by acid rain in nature,and it will not cause secondary pollution.The order of stability of Pb2+ on adsorbents is DETA-MMT>L-MMT>Na-MMT.The Pb2+adsorbed on modified montmorillonite mostly exists in the form of relatively stable organic matter and sulfide binding state(F-iv).So that the mobility and bioavailability of Pb2+ in nature can be reduced greatly,and it can reduce the harms to environment and human health.