Preparation Of Attapulgite Compound Grains And Their Performance In Purifing Water

This work aim at the serious drinking water pollution, using the attapulgite which have great surface area, chemic stability, good absorbent ability, study the preparing method for compound grains which can absorb the heavy metal, organic pollutions and have anti-bacteria function.The attapulgite compound grains preparation method was studied. Studied the effect of concentration of HC1, the appending quantity of binder and pore former, the temperature of heat treatment to performance of absorbing Cr⁶⁺ and methyl-orange. The optimized preparing method is: firstly, acid activate the attapulgite with 2mol/L HC1, then add the anti-bacterial and other appending agents into the powder, ball the mixture of the powder for 30 min, prepare solution with 4% binder and 2% pore former, prepare grains with the powder and the solution. Drying this grains and bake them at 500℃ for 1.5 h.The compound grains have good absorbent performance on Cr⁶⁺ and methyl-orange. When the concentration of the Cr⁶⁺ is 500Mg/L and the appending quantity is 2g/100ml, the adsorbent percentage is 94%. When the appending quantity is 3g/100ml and the concentration is 100mg/L, the adsorption capacity is 1.2mg/g at pH7. The pH has the trend to pH7 after the water be treated by the attapulgite compound grains.The study to surface area and SEM of compound grains showed that the heat treatment temperature, pore former and acid activating obviously changed the surface area and the pore distribution. The pore volume at 2 nm, 2.5 nm and 20 nm increased. The microstructure of the compound grains was improved. Majority of single fibres pile into a loose and porous grain. The study of X-ray showed that the crystal structure changed after adding pore-former and heat treatment. The grains formed a new peak at d=12.9501 nm. The study of surface free energyshows that above modification increased the surface free energy of the compound grains. The reason that the surface free energy increased is likely the modification increased the absorbent center, then increased the adsorbent performance. The infrared spectra showed that the adsorption on methyl-orange is mainly physical adsorption, and a few chemic adsorption.The anti-bacterial result shows that when the appending percentage of anti-bacterial agent is 2%, the anti-bacterial performance is good, the bacteria killing rate to Escherichia coli reaches 98.7% when the anti-bacterial time is 6 h. The reason that the anti-bacterial performance of this percentage of anti-bacterial agent is good is likely this percentage is the optimum ratio of binder and anti-bacterial agent. But when the percentage of anti-bacteria agent increase continuously, the silver ion will reunite, decrease the anti-bacterial performance.