Maria Stefani, Valentino Bervia Lunardi, Alchris Woo Go, Kuan-Chen Cheng, Hsien-Yi Hsu, Shin-Ping Lin, Artik Elisa Angkawijaya, Hui-Wen Lin, Wiyanti Fransisca Simanullang, Chang-Wei Hsieh, Shella Permatasari Santoso, Suryadi Ismadji
Spent coffee grounds (SCG) are an abundant yet underutilized lignocellulosic waste with a high potential for sustainable valorization in environmental applications. Addressing the limitations of conventional pyrolysis for carbon material production, this study aims to develop an integrated biorefinery approach to convert SCG into a sulfonated carbon adsorbent (S-char) while co-producing value-added byproducts. Unlike conventional pyrolysis, which requires high temperatures and post-synthesis activation, the proposed simultaneous carbonization-sulfonation (SCS) process enables in situ functionalization at significantly lower temperatures (100–180 °C). Through sequential delipidation, acid hydrolysis, and SCS, the process achieves three key outcomes: (1) lipid recovery, (2) fermentable sugar production, and (3) functionalized S-char with superior adsorption properties. The resulting S-char exhibited a methylene blue (MB) adsorption capacity of 103.6 mg/g, fivefold higher than conventional pyrolyzed char, owing to its engineered sulfonate groups and optimized porosity. Characterization confirms enhanced surface acidity (2.59 mmol H+/g) and preserved mesoporous structure, enabling efficient dye removal through combined electrostatic, π-π, and hydrogen bonding interactions. This approach maintains environmental sustainability, with an E-factor (31.4) comparable to traditional pyrolysis despite its performance advantages—the cascade process addressing waste management and resource recovery challenges. By simultaneously producing high-performance adsorbents and biorefinery co-products, this work establishes a blueprint for sustainable biomass conversion with applications in wastewater treatment, biofuel production, and circular bioeconomy strategies. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
Chemical Engineering Department, Faculty of Engineering, Universitas Katolik Widya Mandala Surabaya, Jl. Kalijudan 37, Surabaya, East Java, 60114, Indonesia; Chemical Engineering Master Program, Faculty of Engineering, Universitas Katolik Widya Mandala Surabaya, Jl. Kalijudan 37, Surabaya, East Java, 60114, Indonesia; School of Engineering, University of San Carlos - Talamban Campus, Gov. M. Cuenco, Cebu, 6000, Philippines; Institute of Biotechnology, National Taiwan University, #1 Roosevelt Rd., Sec. 4, Taipei, 10617, Taiwan; Graduate Institute of Food Science and Technology, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei, 10617, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, 91 Hsueh-Shih Rd., Taichung, 40402, Taiwan; Department of Optometry, Asia University, 500, Lioufeng Rd., Wufeng, Taichung, 41354, Taiwan; School of Energy and Environment, Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, 518057, Hong Kong; Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, Hong Kong; School of Food Safety, Taipei Medical University, 250 Wu-Hsing Street, Taipei, 11031, Taiwan; Ph.D. Program in Drug Discovery and Development Industry, College of Pharmacy, Taipei Medical University, 250 Wu-Hsing Street, Taipei, 11031, Taiwan; Research Center of Biomedical Device, Taipei Medical University, 250 Wu-Hsing Street, Taipei, 11031, Taiwan; Center for Sustainable Resource Science, RIKEN, Yokohama, 230-0045, Japan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Research Center for Catalysis, National Research and Innovation Agency, Jakarta, 10340, Indonesia; Department of Food Science and Biotechnology, National Chung Hsing University, South Dist., Taichung City, 40227, Taiwan; Department of Medical Research, China Medical University Hospital, North Dist., Taichung City, 404333, Taiwan; Collaborative Research Center for Zero Waste and Sustainability, Jl. Kalijudan 37, East Java, Surabaya, 60114, Indonesia; Department of Food Science, Fu Jen Catholic University Hospital, China Medical University, Taichung, Taiwan