活性炭的zeta电位对各种染料吸附的影响3．活性炭对阴离子染料洋红的吸附

测定了在不同pH下活性炭吸附阴离子染料洋红的变化规律,发现活性炭表面的电位(ζ对洋红吸附量的影响起着重要作用.当溶液pH小于活性炭的零电位pH(pHZPC=6.2)时,活性炭表面带正电,它对洋红阴离子具有静电引力,而当pH增大时活性炭的ζ电位下降,静电引力减弱,使得吸附量下降;另一方面由于洋红变色(pH3.5橙色,～pH6.8玫瑰红)后,洋红的溶解度增大,所以导致吸附量很快下降并趋于零.通过活性炭对洋红在不同pH下的吸附动力学和吸附热力学参数的估算,进一步揭示了活性炭在不同pH下对洋红的吸附机理.

The Effect of Zeta Potential of Activated Carbon on the Adsorption of Dyes from Aqueous Solution 3.The Adsorption of Anionic Dye Carmine

In the present paper the adsorption of anionic dve carmine (CM) on the activatedcarbon under various pH has been studied, and revealed that the zeta potential of the activat-ed carbon has a large effect on the adsorption capacity of CM.The results show that the zetapotential of the carbon surface is positive when the pH of the suspension is lower than pH_zpc.Therefore, with decreasing zeta potential the electrostatic attraction between anionic dye andthe carbon surface greatly reduces the adsorption capacity.On the other hand the colorchange of CM from orange to rose in the pH range 3.5～6.8 results to the solubility increaseof CM with increasing pH,Therefore,the adsorption capacity is gradually reduced and downto vanish.The adsorption kinetics and thermodynamic parameters as a function of pH havebeen evaluated.The mechanism for adsorption of anionic dve CM on the activated carbon hasalso been studied.