Adsorptive interaction of ortho-phenylenediamine with commercial activated carbon in presence of Indole and vice versa: synergistic/antagonistic evaluation

Ortho-phenylenediamine (OPD) and Indole are nitrogenous organic compounds. Ortho-phenylenediamine has been reported to be an endocrine disrupting chemical and is genotoxic in nature, whereas, Indole is mutagenic and carcinogenic. OPD and Indole both all together are present in effluents of several industries, and their simultaneous (binary in the present study) adsorption equilibrium data are required in designing the adsorption system/reactor for separation. Therefore, in the present work, simultaneous adsorption study for adsorption of OPD and Indole from their binary solution, on to low cost commercial grade activated carbon was conducted. Adsorption experiments were performed at 288–318 K, and simultaneous equilibrium adsorption data (binary data in the present study) were collected. Further, various multicomponent competitive isotherms [Langmuir (extended), Freundlich (extended), Sheindorf–Rebuhn–Sheintuch and competitive Redlich–Peterson (modified)] were used to validate the experimental equilibrium isotherm data, and parameters of various isotherms were calculated. Moreover, synergistic/antagonistic effects were also evaluated. Freundlich (extended) and Sheindorf–Rebuhn–Sheintuch isotherm models best represented the experimental data.