Abstract: The adsorption behavior of Cr(Ⅳ) on Mg-Al hydrotalcite compounds(Mg-Al HTlc) was investigated in the metal-organic pollutant system of Cr(Ⅵ) and p-cresol. The results suggest that in the adsorption of Cr(Ⅵ) on HTlc is in the pseudo-second-order reaction and follows Langmuir isothermal adsorption equation; p-cresol can reduce the adsorption velocity but can increase the adsorption capacity of Mg-Al HTlc to adsorb Cr(Ⅵ) from water. Cr(Ⅵ) and p-cresol exhibit a competitive effect. On the one hand, the competitive effect is dependent to the concentration ratio of p-cresol to Cr(Ⅵ), the adsorption capacity of Mg-Al HTlc toward Cr(Ⅵ) can be increased by decreasing the pH value due to the adsorption of p-cresol on HTlc. The competitive ability of p-cresol decreases relatively with the increase of Cr(Ⅵ) concentration and the removal rate of Cr(Ⅵ) increases significantly when the mass concentration ratio of Cr(Ⅵ) to p-cresol is larger than 3. In addition, the adsorption capacity decreases with increasing temperature.

Key words: Mg-Al hydrotalcite compounds, Cr(VI), p-cresol, adsorption