Desorption study and reusability of raw and H 2 SO 4 modified jujube shells ( Zizyphus lotus ) for the methylene blue adsorption

In the study, the raw jujube shells of Zizyphus lotus (RJS) and the chemically modified adsorbent with sulphuric acid H2SO4 (SAMJS) were tested as promising adsorbents for removing methylene blue (MB) dye from aqueous solution. After the adsorption, the influence of operating parameters like different eluents,eluent volume andconcentration, contact time, and temperature on MB desorption from the MB-loaded raw jujube shells (MB-RJS) andthe modified adsorbent (MB-SAMJS) was studied. Desorption equilibrium efficiencies of MB form MB-RJS and MB-SAMJS were 92.88 % and 96.94 % at 50 min and 24 °C, respectively. Kinetic data were obtained very well with a second-order model. The calculated thermodynamic suggests that the MB desorption from MB-RJS and MB-SAMJS is spontaneous and endothermic. The regeneration and desorption studies demonstrated the reusability of RJS and SAMJS for four adsorption–desorption cycles with approximately 73.12 % and 84.08 % of MB removalusing 0.5 M HNO3, respectively.