Prince Sayungki, Lya Sulistyioning Rahayu, Tasrikin Agustianto, Oktaviani Oktaviani, Erik Budi Santiko, Muryanto Muryanto, Mirza Ardella Saputra, Atanu Kumar Das, Gagus Ketut Sunnardianto, Roni Maryana
Lignin holds strong potential as a sustainable adsorbent for heavy-metal remediation. In this work, lignin was isolated from oil palm empty fruit bunches (OPEFB) and processed into nano/submicron particles through ball milling, solvent shifting, and ultrasonication. To explore chemical functionalization, the nanolignin was subjected to a Mannich-type reaction with triethylamine (TEA), a tertiary amine. Characterization by CHN elemental analysis and FTIR confirmed the successful incorporation of nitrogen groups into the lignin structure. Adsorption performance toward Pb2+ ions was evaluated for both unmodified and aminated lignin nanoparticles using batch tests with ICP-OES analysis. Particle size was successfully reduced to 286 nm after ultrasonication, confirming effective nanostructuring. Moreover, among the tested samples, solvent-shifted nanolignin achieved the highest Pb2+ removal (83.9%), while aminated lignin showed a lower efficiency (74.2%). Density functional theory (DFT) - nudged elastic band (NEB) method was applied to investigate the adsorption mechanism. The results showed that Pb adsorption on lignin proceeds with a barrierless resulting exothermic nature with the adsorption energy of around −0.33 eV by forming Pb-phenolic hydroxyl groups of lignin. In contrast, nitrogen on lignin introduces a moderate value of activation barrier of around 1.5 eV at the transition state but resulting more exothermic final adsorption energy of about −1.3 eV. Pb migrating from above the N-doped aromatic ring in the initial state to strong Pb–O binding with phenolic oxygens in the final state. These findings provide novel mechanistic insight into the fundamental limitations of bulky tertiary amines in lignin functionalization for Pb2+ adsorption. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Department of Engineering, Airlangga University, East Java, Surabaya, 60111, Indonesia; Department of Chemistry, Brawijaya University, East Java, Malang, 65145, Indonesia; Department of Chemical Engineering, University of Indonesia, West Java, Depok, 16424, Indonesia; Research Center for Radiation Process Technology – Research Organization for Nuclear Energy, Jl. Lebak Bulus Raya No. 49 Pasar Jum'at, Jakarta Selatan, 7002, Indonesia; Research Centre for Catalysis, National Research and Innovation Agency, South Tangerang, 15314, Indonesia; Research Center for Molecular Chemistry, National Research and Innovation Agency (BRIN-Indonesia), South Tangerang, 15314, Indonesia; Cellulose Technology, Department of Sustainable Materials and Packaging, RISE Research Institutes of Sweden, Hörneborgsvägen 10, Domsjö, Örnsköldsvik, 892 50, Sweden; Research Center for Quantum Physics, National Research and Innovation Agency (BRIN-Indonesia), South Tangerang, 15314, Indonesia
