The conversion of industrial waste into adsorbent for wastewater treatment is desirable as it promises cost-effective adsorbent and reduces waste productions. Adsorption of the 4-nitrophenol by recycled carbon black (rCB) and modified rCB (MCB) was investigated in this research to determine their adsorption capacity by varying various parameters: initial concentration, pH, contact time and adsorbent dosage. The surface morphology, surface chemistry, iodine adsorption number and ash content of both samples were also analysed. The adsorption characteristic of 4-nitrophenol was determined by equilibrium and kinetic studies. Equilibrium isotherm was tested by using Langmuir and Freundlich models. The maximum adsorption capacity of 4-nitrophenol onto rCB and MCB was found to be 7.46 mg/g and 21.83 mg/g, respectively. The adsorption kinetic data of both rCB and MCB fit better to pseudo-second-order kinetic model. This study also demonstrated MCB adsorbent better capability to remove 4-nitrophenol compounds in neutral and basic environments.
