Chromium(VI) adsorption by Codium tomentosum

What is it about?

Bioadsorbents are renewable and exhibit excellent adsorption characteristics due to the presence of relevant functional groups that react with metals to form metal-organic complexes. By modifying the functional groups by chemical treatment, the adsorption capacity of the bioadsorbents can be increased. Understanding the kinetics and mechanisms by which enhanced adsorption occurs in biomaterials is essential for the design and manufacture of adsorbent columns for industrial applications. Here we report the adsorption characteristics of Codium tomentosum biomass. Acid treatment of the Codium tomentosum biomass resulted in increased adsorption capacity while base treatment reduced chromium adsorption. However, the base-treated Codium tomentosum biomass exhibits a sigmoidal dose-response curve, when the adsorbent dose was gradually increased. From such curves, it is possible to optimise operating conditions of adsorbent columns. Moreover, the adsorption was conceptualised to follow the Boltzmann distribution in its adsorption energy function. Such concepts are useful in the generalisation of the Langmuir adsorption theory.

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Why is it important?

The results of this study indicated that the generalisation of the Langmuir's adsorption theory for energetically heterogeneous surfaces can be achieved using Boltzmann energy function. Such an approach shall improve our understanding of the theory of adsorption. Moreover, it also implied that the adsorption energy is not uniform at all adsorbing sites. Such energetic heterogeneity can be used for the development of techniques for separation, purification and concentration of trace elements from mixtures or, environmental samples. With further research, it should also be possible to design separation columns for isotopes.

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