Experimental study on treatment of Pb ion wastewater by alkali fusion modified steel slag

Abstract

A modified steel slag adsorbent was prepared with composite modifier(NaOH or Al(OH)3+fly ash) at high temperature. The effects of alkali melting temperature, alkali melting time and alkali doping on the adsorption performance of Pb(Ⅱ) was investigated. Chemical composition, mineral composition, microstructure and pore size was analyzed with XRF, XRD, SEM, BET and other methods. The heavy metal leaching toxicity, regeneration ability and selectivity of the modified steel slag prepared under the optimal conditions were investigated. The results showed that the best adsorption of Pb(Ⅱ) was achieved under the conditions of 700 ℃ alkali melting temperature, 4 h alkali melting time and 100∶10∶20 mass ratio of steel slag, fly ash and Al(OH)3. There was not new crystal in the modified steel slag, but the original crystal structure was destroyed, and porous aluminum silicate salt with certain activity was formed. Loose fine molten particles were accumulated on the surface of steel slag, and pore size was concentrated in the range of 5-20 nm. Under the combined effect of pore adsorption, chemical precipitation and ion exchange, the removal rate of Pb(Ⅱ) from wastewater reached 98.15%. The modified steel slag adsorbent had better regeneration and selectivity, which was a green and safe heavy metal ion adsorbent.

Keywords

• steel slag
• modified
• removal
• lead ion