A1 Journal article (refereed)
Preparation and Characterization of Pulp and Paper Mill Sludge-Activated Biochars Using Alkaline Activation : A Box–Behnken Design Approach (2022)

Simões dos Reis, G., Bergna, D., Tuomikoski, S., Grimm, A., Lima, E. C., Thyrel, M., Skoglund, N., Lassi, U., & Larsson, S. H. (2022). Preparation and Characterization of Pulp and Paper Mill Sludge-Activated Biochars Using Alkaline Activation : A Box–Behnken Design Approach. ACS Omega, 7(36), 32620-32630. https://doi.org/10.1021/acsomega.2c04290

JYU authors or editors

Publication details

All authors or editorsSimões dos Reis, Glaydson; Bergna, Davide; Tuomikoski, Sari; Grimm, Alejandro; Lima, Eder Claudio; Thyrel, Mikael; Skoglund, Nils; Lassi, Ulla; Larsson, Sylvia H.

Journal or seriesACS Omega



Publication year2022

Publication date02/09/2022


Issue number36

Pages range32620-32630

PublisherAmerican Chemical Society

Publication countryUnited States

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessOpen Access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/84303


This study utilized pulp and paper mill sludge as a carbon source to produce activated biochar adsorbents. The response surface methodology (RSM) application for predicting and optimizing the activated biochar preparation conditions was investigated. Biochars were prepared based on a Box–Behnken design (BBD) approach with three independent factors (i.e., pyrolysis temperature, holding time, and KOH:biomass ratio), and the responses evaluated were specific surface area (SSA), micropore area (Smicro), and mesopore area (Smeso). According to the RSM and BBD analysis, a pyrolysis temperature of 800 °C for 3 h of holding and an impregnation ratio of 1:1 (biomass:KOH) are the optimum conditions for obtaining the highest SSA (885 m2 g–1). Maximized Smicro was reached at 800 °C, 1 h and the ratio of 1:1, and for maximizing Smeso (569.16 m2 g–1), 800 °C, 2 h and ratio 1:1.5 (445–473 m2 g–1) were employed. The biochars presented different micro- and mesoporosity characteristics depending on pyrolysis conditions. Elemental analysis showed that biochars exhibited high carbon and oxygen content. Raman analysis indicated that all biochars had disordered carbon structures with structural defects, which can boost their properties, e.g., by improving their adsorption performances. The hydrophobicity–hydrophilicity experiments showed very hydrophobic biochar surfaces. The biochars were used as adsorbents for diclofenac and amoxicillin. They presented very high adsorption performances, which could be explained by the pore filling, hydrophobic surface, and π–π electron–donor–acceptor interactions between aromatic rings of both adsorbent and adsorbate. The biochar with the highest surface area (and highest uptake performance) was subjected to regeneration tests, showing that it can be reused multiple times.

Keywordsbiocharcharcoalpulp and paper industrysludgeadsorptionporositycircular economy

Contributing organizations

Ministry reportingYes

Reporting Year2022

JUFO rating1

Last updated on 2024-03-04 at 21:46