Adsorbent And The Adsorption Mechanism Of Gaseous Trace Elemental Mercury Modified Vermiculite

The mercury is a kind of violently poisonous,highly volatile substance and permanent accumulation virulent material in organism and the food chain.It has been more attention in the environmental protection domain.Coal combustion is a major source of atmospheric mercury pollution.After investigated some domestic and foreign technologies of removing Hg⁰,a new method of removal gas-phase elementary mercury was put forward,such as cheap vermiculite adsorbents.Through the vermiculite adsorbents manufacture,mainly discussed the different concentrations of hydrochloric acid and ferric chloride impregnating vermiculite on the adsorption effects.Finally elect optimal vermiculite modified by HCl or FeCl₃.The experimental study of fixed-bed of two vermiculites adsorbing vapour-gas Hg⁰ from flue gases has been investigated in this paper.The experimental results show that: Modified vermiculite adsorbed the gaseous state Hg⁰.The adsorption effects are related to the entrance mercury concentration,adsorption reaction temperature and the difference of absorbent pellet size.The adsorption amounts could be improved when increasing the entrance mercury,but the removal efficiency of Hg⁰ is to come down.The adsorption efficiency could be improved when improving the temperature of the adsorption or reducing diameter of the sorbents.But the adsorbents sizes are not suited of more little.At last modified vermiculite put up to contrast with active carbon.Results show that the removal effect of modified vermiculite is better than active carbon at relative high temperature.And the the temperature of combustion of flue-gas is more high after passing through several heat exchangers.So modified vermiculite can be forecasted that they are very valuable at the actual application.Vermiculite and HCl modified vermiculite were determined by X-ray powder diffraction(XRD).The results show that the structure spectroscopy of HCl modified vermiculite was changed obviously.The fist is the structure spectroscopy,the second is the diffraction intensity;The space of interbedded crystal(d)about the modified vermiculite was increased relatively,and some structure spectroscopy are disappear,which is because the acid dissolving the organic and abio-organic impurity,dredging the hole,making the wafer space between vermiculite accretion.The result approved that the adsorption effect was getting better after the vermiculite modified.Introduced some of the basic mathematical models,established kinetic equations,and carried on the fitting to the experiment data,obtained the adsorption equilibrium constant, the theory biggest adsorptive capacity,the heat of adsorption and the adsorption speed equation under the different reaction temperature.The concrete data indict that the temperature 25℃,q_max= 7.65^* 10^-6g/g,k=4.0664^* 10⁴ m³/g,△H=3.54KJ/mol;At the temperature 70℃,k = 2.5596^* 10⁴ m³/g,q_max=1.3034^* 10⁵ g/g,△H=5.44 KJ/mol;At the temperature 140℃,k=2.1620^* 10⁴ m³/g,q_max= 1.7883^* 10^-5g/g,△H=7.11 KJ/mol.And the modified vermiculite 4^# of hydrochloric acid to Hg⁰ adsorption speed equation shows as follow:q = q_e[1 - exp(-22.9267t^1.0638)]。...