Elimination of a basic dye in liquid waste: an alternative to recycle siliceous by-products of kaolin in the adsorption process of methylene blue

The siliceous Kaolin by-product (GO sand) obtained from the TAMAZERT deposit (northeast of Algeria) was used as adsorbent to remove the organic cationic methylene blue (MB) dye from textile industry wastewater. Physicochemical characterization revealed that the by-product is mainly silica with a specific surface area of approximately18 m².g⁻¹. The influence of some physicochemical parameters, such as adsorbent dose, initial dye concentration, contact time, solution pH, and temperature, on the adsorption of MB by the siliceous adsorbent waste was highlighted. The kinetic study showed that the pseudo-second order model is better suited to describe the adsorption of MB on the GO sand than the pseudo-first order model. Boyd’s model indicated that intraparticle diffusion was the limiting step in the adsorption process. The adsorption mechanism obeys the Langmuir model much more (R² > 0.98) than those of Freundlich and Temkin. The increase in temperature was found to promote dye retention. Furthermore, the determination of the thermodynamic parameters ( \(\Delta {H}^{0}, \Delta {S}^{0}, \Delta {G}^{0}\) $\mathrm{\Delta }{H}^0,\mathrm{\Delta }{S}^0,\mathrm{\Delta }{G}^0$ ) disclosed that the adsorption process was endothermic and spontaneous. This study demonstrates that GO sand adsorbent can be recycled as an effective adsorbent for dye removal from industrial effluents.