Ziziphus jujuba stones treated with phosphoric acid H₃PO₄ was used as a biosorbent to remove methylene blue dye (MB) from aqueous solution under various operating conditions. The effect of the experimental parameters such as temperature (10-40 °C), pH (2-12), contact time (10-360 min), initial concentration (50-150 mg / l), salt, humic acid and Isoelectric point have been studied .The sorption kinetic uptake for MB by Ziziphus jujuba stones at various initial dye concentrations was analyzed by non-linear method using pseudo-first, pseudo-second, pseudo-nth order and intraparticle diffusion models. It was found that the pseudo-nth order kinetic model was the best applicable model to describe the sorption kinetic data. MB adsorption on biosorbent followed the linear Langmuir isotherm. The calculated values of ∆G⁰ and ∆H⁰ indicated the spontaneous and endothermic nature of the adsorption process.

Key words: methylene blue, phosphoric acid, adsorption.

References

[1]      F. Deniz, R.A. Kepekci, Dye biosorption onto pistachio by-product: A green environmental engineering approach, J. Mol. Liq. 219 (2016) 194–200.

[2]  F. Temesgen, N. Gabbiye, O. Sahu, Biosorption of reactive red dye (RRD) on activated surface of banana and orange peels: Economical alternative for textile effluent, Surf. Interfaces. 12 (2018) 151–159. doi:10.1016/j.surfin.2018.04.007.

[3]  T.R. Moro, F.R. Henrique, L.C. Malucelli, C.M.R. de Oliveira, M.A. da Silva Carvalho Filho, E.C. de Vasconcelos, Adsorption of pharmaceuticals in water through lignocellulosic fibers synergism, Chemosphere. 171 (2017) 57–65.

[4]       E.F. Lessa, M.L. Nunes, A.R. Fajardo, Chitosan/waste coffee-grounds composite: An efficient and eco-friendly adsorbent for removal of pharmaceutical contaminants from water, Carbohydr. Polym. 189 (2018) 257–266.