Empty cotton boll crop-residue and plastic waste valorization to bio-oil, potassic fertilizer and activated carbon – A bio-refinery model

• Published in: Journal of cleaner production 2021-03, Vol.290, p.125738, Article 125738
• Main Authors: Patel, Himanshu, Mangukiya, Hiren, Maiti, Pratyush, Maiti, Subarna
• Format: Article
• Language: English
• Subjects: Activated carbon; Alternative fuel; Bio-refinery; Engine performance; Potassic fertilizer; Pyrolysis
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2020.125738

Empty cotton boll and plastic waste (@ 5% w/w) were slow pyrolyzed in a fixed bed pilot scale reactor at 500 °C in vacuum. The proposed bio-refinery model involves: (1) application of bio-oil as alternative fuel in existing engine facility, (2) water leaching of bio-char followed by synthesis of potassic fertilizer, and (3) chemical activation of spent char to porous carbon. Thorough investigation of moisture free bio-oil fuel properties supported its applicability in the engine. Moisture free bio-oil was blended with commercial gasoline in proportions of 10–30% (v/v). The effect of engine functioning parameters: compression ratio, engine load and blend proportion on engine performance and emission was optimized using response surface methodology. Almost 93 wt% of water leachable potassium available in the bio-char was leached out via two stage counter current leaching. Route of selective precipitation using tartaric acid converted ∼98 wt% of potassium available in leachate to potassium nitrate. Porous carbon with surface area of 1381.40 m2/g was derived via chemical activation of spent char at 700 °C in nitrogen atmosphere. The porous carbon showed carbon-dioxide adsorption capacity of 5.1 mmol/g at 25 °C and 1 atm pressure. [Display omitted] •A bio-refinery model based on pyrolysis of crop residue was proposed.•Bio-oil gasoline blend was tested in spark ignition engine.•Engine performance and emission were optimized using response surface methodology.•Biochar was used as a source of potassium and ∼91% of potassium was recovered.•Commercial grade porous carbon was derived using KOH as an activating agent.