Transforming spent coffee grounds into sulfonated char: an eco-innovative method using a refined simultaneous sulfonation-carbonization process
Journal
Biomass Conversion and Biorefinery
Journal Volume
15
Journal Issue
24
Start Page
30775
End Page
30794
ISSN
2190-6815
2190-6823
Date Issued
2025-09-01
Author(s)
Stefani, Maria
Lunardi, Valentino Bervia
Go, Alchris Woo
Hsu, Hsien-Yi
Lin, Shin-Ping
Angkawijaya, Artik Elisa
Lin, Hui-Wen
Simanullang, Wiyanti Fransisca
Hsieh, Chang-Wei
Santoso, Shella Permatasari
Ismadji, Suryadi
Abstract
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.
Subjects
Biochar
Carbonaceous adsorbent
Carbonized material
Hydrolysis residue
Simultaneous sulfonation carbonization
Publisher
Springer Science and Business Media LLC
Type
journal article