Study On The Removal Of Cadmium From Micro-polluted Raw Water By Hydrochloric Acid Activated Attapulgite

In recent years,along with the rapid growth of Chinese GDP and the large improvement of the life quality,enterprises and individuals both have a more higher requirement to the quantity and quality of water,but the frequency and intensity of accidental heavy metal pollution events tends to increase in China,cadmium pollution is one of them The traditional craft takes less effect on processing the slightly cadmium polluted water,so we urgently need to find a new way to solve this problem.Natural attapulgite is very rich in reserves and widely distributed in our country,which is often usedn water treatment field as adsorbent because of its large specific surface area.It is well known that natural attapulgite contains many impurities and its purity is low,many scholars,at home or abroad,usually carry on some relevant modifications to improve its adsorption performance.This paper studied the removal efficiency of Cd2+ in slightly cadmium polluted water in a series of tests,using the attapulgite which is activated by HC1 as adsorbent.the tests comprises two parts:static and dynamic.The specific research contents mainly include the follows:The determination of the best influential factors of HCl activated attapulgite;studied on removing efficiency and mechanism of Cd2+ on activated attapulgite;studied on the factors influencing Cd2+ removing efficiency from simulated water sample by using HC1 activated attapulgite:PH values and original concentration of Cd2+;the dynamic experinents on the efficiency for removal of and influencing factors in simulated water sample by the filter column filled with HC1 activated attapulgite were studied(the influencing factors:the flow velocity,original concentration of Cd2+ and filter layer thickness).The results of static experiment show that the HC1 activated attapulgite on Cd2+removal effect in the micro-polluted raw water is significantly higher than the natural attapulgite.The optimum influencing factors of HC1 activated attapulgite:the best acid leaching concentration is 3mol/L,the best leaching temperature is 60?,the best activation time is 2.0h;the two kinds of attapulgite,that is natural attapulgite and HC1 activated attapulgite,remove Cd2+ in the micro-polluted raw water,the results show that the removal e?ffect of Cd2+ by HCl activated attapulgite in the simulated water sarrples is best;in the static experiment,Through carried out the experiment data curve fitting of HC1 activated attapulgite removing Cd2+ in the micro-polluted raw water,the fitting results show that the HC1 activated attapulgite on the adsorption of Cd2+ is accordance with Langmuir isotherm adsorption model and the fitting correlation coefficient RL2 = 0.954,HC1 activated attapulgite on the adsorption of Cd2+ in the micro-polluted raw water belongs to single molecular layer adsorption.HC1 activated attapulgite on the adsorption of Cd2+ in the micro-polluted raw water is accorda,ce with adsorption dynamic equation of Lagergren,the fitting correlation coefficient R12 ?0.955.The results of dynamic experiment show that when the filter column diameter is 2.5cm,the filter speed is 4ml/min,the concentration of Cd2+ is 0.4mg/L,HC1 activated attapulgite filter layer thickness is 100cm,HC1 activated attapulgite filter layer on the removal effect of Cd2+ in the micro-polluted raw water is best.In practical application,As long as the control of filter speed to the filter column is good,and selectting appropriate filter layer thickness,HCl activated attapulgite is used as filter processing of Cd2+ in the micro-polluted raw water is feasible and effective.