Adsorption behaviour of bromophenol blue from the aqueous solution on Labeo bata fish scale, a bio-waste material

Abstract

The processed protein-rich scales of <em>Labeo bata</em> fish have been characterized as cycloid pattern from the scanning electron and atomic force microscopic images. The scales when used for the bromophenol blue (BPB) adsorption from aqueous phases show the good BPB removal performance at <em>p</em>H 4.8 (&plusmn; 0.1). The kinetic data acquired at that <em>p</em>H fits well both with the pseudo-second order and the Weber-Morris kinetic equations. Arrhenius activation energy (E_a = 4.20 kJ. mol^-1) as well as temperature dependent kinetic parameter (A = 75.56 g. mg^-1. min^-1) which are estimated indicate the facile BPB adsorption. The data of adsorption equilibriums describe the Freundlich model very well. Thermodynamics shows that the BPB adsorption by the fish scale is spontaneous (∆G⁰ = negative, ∆H⁰ = -21.49 kJ. mol^-1 and ∆S⁰ = + 27.75 J.mol^-1.K^-1). The BPB adsorption by the tested fish scale has taken place with electrostatic mechanism.