title: Adsorption of ammonium in aqueous solutions by pine sawdust and wheat straw biochars.
abstract: Ammonium (NH4+) is a common form of reactive nitrogen in wastewater, and its discharge to water bodies can lead to eutrophication. This study was conducted to understand NH4+adsorption mechanisms of pine sawdust and wheat straw biochars in aqueous solutions and the factors affecting NH4+removal. Biochars were produced by pyrolysing pine sawdust at 300 °C (PS300) and 550 °C (PS550) and wheat straw at 550 °C (WS550). Pseudo-second-order and Redlich-Peterson models best fitted the adsorption data. The PS300 showed the highest NH4+adsorption capacity (5.38 mg g-1), followed by PS550 (3.37 mg g-1) and WS550 (2.08 mg g-1). Higher H/C and O/C ratios of PS300 (0.78 and 0.32, respectively) indicated the greater presence of functional groups on the biochar's surface as compared to PS550 (0.35 and 0.10, respectively) and WS550 (0.36 and 0.08, respectively), resulting in different NH4+adsorption through electrostatic interactions. The dominant mechanism for NH4+adsorption by the biochars was likely chemical bonding and electrostatic interaction of NH4+with the surface functional groups. Lower pyrolysis temperature resulted in a higher NH4+adsorption capacity by the pine sawdust biochar. At the same pyrolysis temperature (550 °C), the biochar made with pine sawdust as the feedstock had a higher NH4+adsorption capacity than biochar made from wheat straw. We conclude that biochars can be efficient absorbents for NH4+removal from wastewater, and the removal efficiency can be optimised by selecting different feedstocks or the pyrolysis condition for biochar production.
authors.affiliation: Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada.|Department of Rural and Biosystems Engineering, Chonnam National University, Gwangju, 61186, Republic of Korea.
authors.forename: Hye In
authors.initials: HI
authors.lastname: Yang
authors.affiliation: Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Kangyi
authors.initials: K
authors.lastname: Lou
authors.affiliation: Department of Basic Sciences, Faculty of Health Sciences, The Open University of Sri Lanka, Nawala, Nugegoda, 10250, Sri Lanka.
authors.forename: Anushka Upamali
authors.initials: AU
authors.lastname: Rajapaksha
authors.affiliation: Korea Biochar Research Center & School of Natural Resources and Environmental Science, Kangwon National University, Chuncheon, 24341, Republic of Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: Aquatic and Crop Resource Development Portfolio, National Research Council of Canada, Ottawa, ON, K1N 5A2, Canada.
authors.forename: Anthony O
authors.initials: AO
authors.lastname: Anyia
authors.affiliation: Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada. scott.chang@ualberta.ca.
authors.forename: Scott X
authors.initials: SX
authors.lastname: Chang
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D009584:Nitrogen; D028223:Pinus; D013696:Temperature; D014908:Triticum; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification; D014934:Wood
chemical_list: D064751:Ammonium Compounds; D002606:Charcoal; D009584:Nitrogen; D062065:Wastewater; D014874:Water Pollutants, Chemical; C540010:biochar
keywords: Ammonium adsorption; Black carbon; Charcoal; Isotherm; Kinetics; Wastewater treatment