水合氧化铁对水中酸性品红的吸附-解吸行为研究

 为了有效地去除工业废水中的阴离子型染料,本文以酸性品红为模拟污染物,采用批量吸附-解吸平衡实验,研究了水合氧化铁(FH)对水中酸性品红(AF)的吸附、解吸特性,并就pH值和温度的影响进行了深入研究.实验数据表明,pH值对吸附影响较大,pH值为4.0时,FH对AF的吸附效果最佳,297K时饱和吸附量达到392.2mg·g^-1.Langmuir方程比Freundlich方程更好地描述了FH对AF吸附的行为,表明此吸附是优惠单分子层吸附.FH对AF吸附过程的焓变、熵变和吉布斯自由能数据表明,该吸附是自发、放热的不可逆吸附.FH对AF的解吸也很好地符合Langmuir方程,但表现出一定的滞后效应.滞后效应随溶液中AF初浓度的增加、温度的升高而减弱.不同温度或同一温度、不同初始浓度下,FH对AF的解吸率均低于9%,说明FH对AF吸附具有良好的稳定性.

Adsorption and Desorption of Aqueous Acid Fuchsine on Ferrihydrite

Acid Fuchsine (AF) was selected as a model anionic dye to examine the adsorption-desorption behavior of ferrihydrite to acid fuchsine by using batch equilibration technique. The useful data is provided for the industrial treatment of acid fuchsine and the similar pollutants. The effect of solution pH and temperature on the adsorption of AF onto FH was investigated in detail. The results indicate that ferrihydrite has an optimum condition for the removal of AF at pH 4.0. The maximum adsorption capacity reaches 392.2mg·g^-1 at 297K. Adsorption isotherms of AF at different temperatures are conformed to the Langmuir equation, indicating one monomolecular layer of the coverage on FH surface. The data of Gibbs free energy, enthalpy, and entropy of the adsorption show that the adsorption of AF onto FH is an irreversible, spontaneous, exothermic and chemical process. The AF desorption from FH is also investigated. The isotherms of AF desorption are also conformed to Langmuir equation. The constant values of desorption intensity are much lower than that of adsorption at 297K and 323K with three different concentrations, indicating that AF desorption from FH shows significant hysteretic effect. The hysteretic coefficient decreases with the increase of AF initial adsorbed concentration or temperature. The desorption rates of AF from FH at different initial concentrations or temperatures are below 9%, therefore the adsorption of AF onto FH has the good stability. On the whole, FH is a highly efficient adsorbent for the removal of AF from contaminated water.