Simultaneous Adsorptive Removal of Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ Using Raw Norway Spruce Biomass: A Low-Cost and Eco-Friendly Solution for Wastewater Treatment

Ibrahim G. Al-Labadi¹Márk Horváth¹Ayah T. Alkilani²Alaa M. Al-Ma'abreh³Mohammed Bashir⁴Basem E. Keshta⁵Ghadir Hanbali⁶Wail Al Zoubi^7*Mostafa Abukhadra⁸Haifa A. Alqhtani⁹Mohamed Hamdy Eid^10*

• ¹Hungarian University of Agricultural and Life Sciences, Gödöllő, Hungary
• ²University of Petra, Amman, Amman, Jordan
• ³Isra University, Amman, Amman, Jordan
• ⁴Central Queensland University, Rockhampton, Queensland, Australia
• ⁵Tanta University, Tanta, Gharbia, Egypt
• ⁶An-Najah National University, Nablus, Palestine
• ⁷Yeungnam University, Gyeongsan, North Gyeongsang, Republic of Korea
• ⁸Applied Science Private University, Amman, Amman, Jordan
• ⁹Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
• ¹⁰University of Miskolc, Miskolc, Hungary

This study evaluated the unmodified Norway Spruce Wood Residue (NSWR), an abundant lignocellulosic biomass, for the simultaneous removal of Pb²⁺, Cd²⁺, Zn²⁺, and Cu²⁺ from a quaternary aqueous system. A series of batch adsorption experiments were performed to assess the influence of key operational parameters (pH, contact time, adsorbent dose, temperature, particle size, initial concentration), with equilibrium data subsequently fitted to Langmuir and Freundlich isotherm models, and the NSWR characterized using FTIR and EDS analyses. The results demonstrated maximum Langmuir adsorption capacities following the order Pb²⁺ (10.3 mg/g) > Cu²⁺ (7.9 mg/g) > Cd²⁺ (6.3 mg/g) > Zn²⁺ (6.0 mg/g), corresponding to high removal efficiencies (up to 99% for Pb²⁺). Adsorption was rapid initially (~60% removal within 20 min) and favored slightly acidic conditions (pH 5-6) and moderately elevated temperatures (45 °C). The Langmuir model provided an excellent fit to the data (R²≈0.99), indicating favorable monolayer chemisorption, likely driven by a combination of cation exchange supported by EDS and interactions with surface functional groups. Conclusively, unmodified NSWR shows significant promise as an effective, inexpensive, and eco-friendly biosorbent for treating water contaminated with multiple heavy metals, presenting a viable waste valorization strategy for sustainable water management.