Cyanobacterial biosorption of Cr(VI): Application of two parameter and Bohart Adams models for batch and column studies

The present investigation was aimed at analyzing the potential utility of Lyngbya putealis HH-15, an indigenous cyanobacterium isolated front a metal contaminated site as a biosorbent of Cr(VI) from aqueous solutions using static and dynamic mode studies. Surface adsorption of the metal at specific binding sites on the algal biosorbent was confirmed through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) spectral analysis. Kinetic model was applied to study the adsorption process. Intraparticle diffusion plot of the data indicated the involvement of both surface sorption and intraparticle diffusion. Six two-parameter equations (Langmuir, Freundlich, Temkin, Flory-Huggins, Dubinin-Radushkevich, D-R and Brunauer, Emmer and Teller, BET isotherms) were applied to model the equilibrium sorption data on both free and immobilized form of the cyanobacterial biosorbent. In continuous flow column experiments effects of bed height (5-10 cm). Mow rate (1-3 mL/min). and initial metal ion concentration (5-20 mg/L) on breakthrough time and adsorption capacity of the immobilized biosorbent were studied. The data generated was developed into a model based on empirical relationship of the Bohart-Adams model. The column regeneration studies were also performed using 0.1 M HCl for five cycles. The high chromium removal ability and regeneration efficiency of this biosorbent suggest its applicability in industrial processes and data generated would help in further upscaling of the adsorption process. (c) 2008 Elsevier B.V. All rights reserved.