Adsorption Behavior of Reactive Turquoise Blue KN-G in Aqueous Solutions on a Novel Spherical Lignin-based Adsorbent

摘要

A novel spherical lignin-based adsorbent, denoted as SLBA, was prepared using alkali lignin as a raw material which was provided by a masson pine pulp mill in Fujian, China. Then an investigation was conducted regarding the adsorption behavior of a reactive dye (Turquoise Blue KN-G) from aqueous solutions with the above new spherical lignin-based adsorbent containing the quaternary ammonium cat-ionic group. Moreover, various affecting factors on the adsorption were optimized. It was found that the adsorption of reactive Turquoise Blue KN-G on the adsorbent was found to be initially pH and concentration dependent. The concentration helped to increase the equilibrium adsorption capacity. With an increase in solution pH ranging from 3 to 8, the removal percentage increased sharply from 12.3 % to 98.6 % , and at pH= 10, the removal rate reached 100% . The adsorption process followed the Langmuir adsorption isotherm, i.e. , C_e/q_e = 0.0002136 + 0.001225C_e. Moreover, R_L , a dimensionless separation factor of an equilibrium parameter, was 8.711 x 10~(-4) , which was far less than 0.1 indicating the favorable adsorption. The saturated adsorption capacity was 816.3 mg/g, and the total breakthrough removal capacity was 761 mg/g, which prevailed over the commercial activated carbons evidently. The reactive Turquoise Blue KN-G adsorbed on SLBA could be recovered with a mixture of alcohol, dicyandiamide-formaldehyde polycondensate and HC1 aqueous solutions. And, the maximum desorption efficiency could reach 98.7%.