Study on mass transfer characteristics for Cr (VI) removal by adsorption onto residual black toner ink

This study was aimed to assess the adsorption capacity of residual black toner ink (RBTI) for the removal of heavy metal Cr (VI), ions in batch mode. To achieve this objective, the effects of different experimental parameters viz., initial Cr (VI) concentration, adsorbent dose, initial pH of solution and temperature on Cr (VI) uptake were studied. The kinetic parameters were evaluated using model equations of Lagergren (pseudo first order), pseudo second order, and Weber and Morris. The Langmuir, Freundlich, Dubinin–Radushkevich isotherms were fitted to experimental data for establishing the adsorption equilibrium. Calculation of thermodynamic parameters (ΔGº, ΔHº, ΔSº) was also done to demonstrate the nature of adsorption. Thermodynamic parameters (ΔGº= −2.5885 kJ/mol, ΔHº= 282.74 kJ/mol, ΔSº= 0.9574 kJ/mol.K) revealed that adsorption of Cr (VI) using RBTI was endothermic, spontaneous and increased with temperature. To investigate the physical and chemical properties of RBTI, SEM‐EDX and FTIR analyses were done. The maximum adsorption capacity of RBTI for Cr (VI) removal was found to be 13.98 mg/g. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1022–1029, 2017