A green and environmental–friendly method for the removal of the hazardous bromothymol
blue from aqueous solution was considered applying a hydrophilic, biocompatible and biodegradable
natural sorbent of Latvian sphagnum peat moss, applying shaking-dispersive solid-phase extraction.
First, the influence of shaking speed was evaluated at 300, 600, 900 U. Furthermore, the optimum
conditions of dye-adsorption, such as pH, adsorption-equilibrium contact time, adsorbent mass, and
adsorbate initial concentration were investigated. In addition, the adsorption equilibrium isotherms,
thermodynamics, and kinetics were studied. Thus, the optimum removal of bromothymol blue was
concluded at a shaking speed of 600 U. Regarding the dye adsorption at different pH, bromothymol
blue showed two removal maxima at acidic (pH 2.5) and almost neutral (pH 7.5) media, reaching
dye % removal of 80.8 and 88.2 %, respectively, in 120 min of adsorption equilibrium contact time.
Moreover, the dye removal improved reasonably by increasing the concentration and the sphagnum
dose. Additionally, the equilibrium isotherm plot correlated comparably to Langmuir's and Freundlich's
models. Also, the adsorption kinetic study demonstrated a better correlation to pseudo-secondorder
plot than to pseudo-first-order one. Finally, excellent reproducibility in % removal was demonstrated
with RSD values of 2.2 and 2.7% at pH of 7.5 and 2.5, respectively.