腐殖酸对无定形氢氧化铝吸附锌的影响

Zinc (Ⅱ) commonly exists in drinking water. This paper aims to investigate the effects of humic acid on the adsorption of Zn2+ on amorphous Al(OH)3. Both suspension and well scaled forms of Al(OH)3 were investigated applying ICP-AES determination and Visual MINTEQ calculation. It was found that in solutions without HA, pH had notable effects on the removal of Zn2+. Chemical adsorption mainly took place at pH above 7.5; 1.0 g solid could accumulate about 15.9 mg Zn2+ at 15℃. Because of H+ inhibition, active reaction sites on amorphous Al(OH)3 surface were much less at pH below 7.5. The adsorption of Zn2+ on Al(OH)3 changed gradually from chemical coordination to physical adsorption. Compared with Zn2+, the adsorption of HA on Al(OH)3 suspension was strong. In drinking water with HA coexisting, the adsorption of Zn2+ was enhanced notably; while pH had little effects its removal. Under the bridging effects of HA, Zn2+ could not be detected in solution with HA above 1.0 mg/L, much lower than the standard required level. The adsorption of Al(OH)3 scale for Zn2+ was weak, about 0.2 mg/g. Better management on sediment accumulation and Zn2+ preservation was suggested to control the concentration of Zn2+ residual.