Preparation of activated petroleum coke for removal of naphthenic acids model compounds: Box-Behnken design optimization of KOH activation process

• Published in: Journal of environmental management Vol. 211; pp. 63 - 72
• Main Authors: Niasar, Hojatallah Seyedy, Li, Hanning, Das, Sreejon, Kasanneni, Tirumala Venkateswara Rao, Ray, Madhumita B., Xu, Chunbao (Charles)
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2018
• Subjects: Adsorption capacity; KOH activation; Leaching of metals; Naphthenic acids; Optimization; Petroleum coke; Adsorption capacity; Leaching of metals; KOH activation; Naphthenic acids; Petroleum coke; Optimization
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2018.01.051

This study employed Box-Behnken design and response surface methodology to optimize activation parameters for the production of activated petroleum coke (APC) adsorbent from petroleum coke (PC) to achieve highest adsorption capacity for three model naphthenic acids. Activated petroleum coke (APC) adsorbent with a BET surface area of 1726 m2/g and total pore volume of 0.85 cc/g was produced at the optimum activation conditions (KOH/coke mass ratio) of 3.0, activation temperature 790 °C, and activation time 3.47 h). Effects of the activation parameters on the adsorption pefromances (adsortion capaciy and kinetics) were investigated. With the APC obtained at the optimum activation condition, the maximum adsorption capacity of 451, 362, and 320 (mg/g) was achieved for 2-naphthoic acid, diphenylacetic acid and cyclohexanepentanoic acid (CP), respectively. Although, generally APC adsorbents with a higher specific surface area and pore volume provide better adsorption capacity, the textural properties (surface areas and pore volume) are not the only parameters determining the APC adsorbents’ adsorption capacity. Other parameters such as surface functionalities play effective roles on the adsorption capacity of the produced APC adsorbents for NAs. The KOH activation process, in particular the acid washing step, distinctly reduced the sulfur and metals contents in the raw PC, decreasing the leaching potential of metals from APC adsorbents during adsorption. •The optimum conditions for KOH activation of petroleum coke (PC) was obtained.•The obtained optimum activation conditions: 790 °C, KOH/PC mass ratio 3:1, 3.47 h.•The sulfur and metals of PC can be significantly removed by KOH activation.•Adsorption capacity of activated PC was significantly high for naphthenic acids.•The APC adsorbents can be used for treatment of oil sands process-affected water.