Parametric Study and Optimization for the Co-Pyrolysis of Plastic Waste and Spent Coffee Ground for Biochar Production using Response Surface Methodology

• Published in: Chemistry Africa 2024-07, Vol.7 (5), p.2749-2765
• Main Authors: Aljomard, Haif, Inayat, Abrar, Jamil, Farrukh, Khalil, Abdelrahman K. A., Ghenai, Chaouki, Kalfat, Rafik
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Inorganic Chemistry; Organometallic Chemistry; Original Article
• ISSN: 2522-5758; 2522-5766
• DOI: 10.1007/s42250-024-00907-4

This study focuses on enhancing the sustainability of waste management by investigating the optimization of biochar production from lignocellulosic solid waste and plastic waste. The essential process of transforming spent coffee grounds (SCG) and Polyethylene terephthalate (PET) into valuable resources is explored through an innovative co-pyrolysis approach, blending these diverse feedstocks. Response surface methodology (RSM) and a face-centered central composite design (FCCD) were employed to identify the key parameters influencing biochar production performance, including feedstock blending ratio, pyrolysis temperature, and heat treatment duration. The study conducted an in-depth analysis using thermogravimetric analysis (TGA), ultimate and proximate analysis, as well as scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM/EDS) for surface morphology and elemental analysis of both raw and pyrolyzed materials. Optimization results indicate that a maximum co-pyrolyzed biochar yield of 71.33% was achieved at a temperature of 350 °C and a residence time of 30 min, with a SCG: PET blending ratio of 25:75% (w/w%). Conversely, the same blending ratio resulted in the lowest biochar yield when temperature and pyrolysis time were set at 450 °C and 90 min, respectively. The findings reveal a negative correlation between temperature and biochar yield, with higher temperatures leading to a decrease in yield. Furthermore, the study underscores the significance of co-pyrolysis by comparing it to the pyrolysis of a single raw material (SCG), which yielded only 37.90% under the same conditions as the co-pyrolysis of blended material. This highlights the superior efficacy of co-pyrolysis in processing high yield and multi-blended feedstock, emphasizing its importance in sustainable waste management practices.