Asphaltenes are highly undesirable components present in heavy petroleum residue. Asphaltenes are responsible for their destructive behavior and characteristics leading to depositing in crude pipeline and creating severe problem in refining processes. Asphaltenes are comprised of highly condensed polynuclear aromatics with branched alkane chains and few prominent heteroatoms and metals. Keeping undesirable characteristics of asphaltenes, the asphaltenes were functionalized to develop a novel adsorbent for the adsorption of water pollutants which demonstrated very effective and significant results. The functionalized asphaltenes were characterized by FTIR, SEM and elemental analysis and found to contain higher amounts of oxygen atoms and carbonyl and hydroxyl functional groups. The effect of pH, adsorbent dose, dyes concentration, reaction temperature and contact time parameters were studied. The adsorption isotherms fitted well the Langmuir, Freundlich, Temkin as well as Lagergren models. The adsorption isotherm data of BPB and MO were in good conformity with all models studied, however, BPB was more closely fits with Freundlich and Temkin isotherm while MO was more closely fits with Langmuir and Lagergren models thereby implying that the adsorption occurred as a monolayer as well as a heterogeneous surface adsorption. The calculated maximum adsorption capacity for Langmuir model were 7.44 and 2.24 mmol/g for BPB and MO respectively. Several adsorption kinetic models were fit with experimental data and pseudo second-order kinetic model was found to be best fitting model. The separation factor (RL) values found between 0 - 1 that indicates the favorability of the adsorption process on adsorbent surface. The thermodynamic parameters were calculated and the respective values for BPB and MO dyes were found to be ΔG° (-11.808 and -14.057 KJ/mol), ΔH (8.509 and 6.460 KJ/mol) and ΔS (65.954 and 66.613 J/K.mol) which exhibited that the adsorption of dyes on functionalized asphaltenes was spontaneous, endothermic with increased randomness. The functionalized asphaltene showed high adsorption capacity with highly efficient removal for BPB and MO dyes.

Functionalized asphaltenes used for the adsorption of water pollutants

254th National Meeting (2017)

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