Abstract: Although research on metal adsorption via biochar has gained intensive attention over the last decade, the reaction mechanisms responsible for metal adsorption remain uncertain. This is the first work that provides direct evidence on the identification of Ni(II), Zn(II), and Cu(II) adsorption mechanisms on pineapple leaf biochar (PLB) using surface characteristics analyses, including X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscope (FTIR), and scanning electron microscope with energy-dispersive X-ray spectroscope (SEM-EDS). Indispensable parameters, including temperature, ionic strength, and pH, affect much on adsorption. From Langmuir isotherm fitting, the maximum adsorption capacity of PLB for Ni(II), Zn(II), and Cu(II) are 44.88, 46.00, and 53.14 mg g-1, respectively, surpassing all biochars reported in the literature. Findings of surface characterization techniques coupled with cation released during adsorption, cation exchange, and surface complexation mechanisms were proposed. PLB is reusable and remains sufficient adsorption capacity even six consecutive cycles via pressure cooker regeneration. With high regenerability and ultrahigh adsorption capacity, PLB defines itself as a promising cost-effective adsorbent for future applications in metal-laden wastewater.
This study also provides framework for understanding how metal ions react with biochar.

Biography: Professor Chih-Huang Weng is the Chairman of Department of Civil Engineering at I-Shou University, Taiwan. He also served as vice-president of North Kaohsiung Community University, Taiwan. He received his MS and Ph.D. degrees in 1990 and 1994, respectively, from the Department of Civil Engineering of The University of Delaware, USA. He has published over 100 journal articles with around 7050 citations, 43 h-index and 80 i10-index in google scholar database. Based on the 2020 updated science-wide author databases of standardized citation indicators (https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000918), his publication citation was listed on the top 1% and ranked at 263rd among 42482 authors in the category of Engineering, Environmental. He was listed in the World’s Top 2% Scientists based on 2021 Sandford University published an update database of the most widely cited scientists in different disciplines. He has earned number of awards and honors, including the National Innovation Award by the Research Center for Biotechnology and Medicine Policy, Taiwan. He is serving as the Associate Editor of Environmental Geochemistry and Health (Springer, since 2020) and on the Editorial Board Panel Member of Coloration Technology (Wiley, since 2013). He has also served as a Guest Editor of SCI journals, such as Agricultural Water Management (V. 174, Aug. 2016 (https://doi.org/10.1016/j.agwat.2016.06.012) and Environmental Science and Pollution Research (V. 26, issue 30, Oct. 2019 (https://doi.org/10.1007/s11356-019-06281-w); V. 27, issue 31, Oct. 2020 (https://doi.org/10.1007/s11356-020-09994-5), V. 28, issue 34, Sep. 2021 (https://doi.org/10.1007/s11356-021-15004-z), V. 29, issue 9, Feb. 2022 (https://doi.org/10.1007/s11356-021-17392-8). He has also organized and chaired several international conferences. His main research interests focus on using advanced oxidation processes and adsorption for the treatment of wastewater and bacteria inactivation, ground water modeling, and application of electrokinetic technologies to soil remediation/sludge treatment/activated carbon regeneration.