Research On The Adsorption Of Water Premeable Cement-Based To Heavy Metal Ions

With the development of the city traffic ,there is not only emission of automobile exhaust , but also the serious heavy metal pollution . And the heavy metal pollution has the characteristics of protracted nature,concealment,irreversibility and non-degradablility. Cement-based materials are the essential and the extensive materials on the construction of the city-roads. So it is important to research hydration products and shape characteristic of cement system , and the mechanism of the adsorbing heavy metal ions . This paper researches rules of adsorbing heavy metal ions (Cu²⁺,Cd²⁺,Zn²⁺,Pb²⁺) by cement system,complex cement-based materials with adsorbents (fly ash,bentonite,diatomite,zeolite) with the same ratio of 10%.With microstructure analysis techniques ,for example , the ICP,XRD,SEM-EDS, and the paper researches the rules and mechanisms of adsorbing heavy metal ions by different-systems cement (Portland cement and Aluminoferriter cement),the cement-based materials with different absorbents and on the different external conditions , like the pH and the flow rate . Through simulate the design procedures of concrete's mix proportions , and according to the parameters of compressive strength and permeability coefficient , the paper designs the mix proportion that suitable for the two systems-cements . We design a set of water permeable device by ourselves , and through determinate the permeability coefficient of cement-based materials directly , and we could research the influent of flow rate on the adsorption capacity of water permeable cement-based materials .The results show that , the water permeable cement-based materials made by Portland cement and Aluminoferriter cement have good compressive strength and permeability coefficient . And these two kinds of cement could adsorb heavy metal ions well , The adsorption efficiency of Aluminoferriter cement is better than Portland cement . And the adsorption efficiency of water permeable cement-based materials with adsorbents is better than the pured cement-based materials . The Portland cement-based materials with different adsorbents have simulated adsorption rules , and the order of adsorption capacity to heavy metal ions is Pb²⁺,Cu²⁺>Cd²⁺,Zn²⁺ ; but the order of the influents of four kinds of adsorbents on Aluminoferriter cement-based materials is fly ash > zeolite > bentonite > diatomite . and the order of adsorption capacity to heavy metal ions is Zn²⁺>Pb²⁺>Cu²⁺>Cd²⁺ . The results show that , With the increasing pH , the stabilizing capacity of Aluminoferriter cement-based materials to Pb²⁺ is better than others . And when the flow rate of 25L/h and 75L/h , the adsorption capacity is better .