title: Effects of feedstock and pyrolysis temperature on biochar adsorption of ammonium and nitrate.
abstract: Biochar produced by pyrolysis of biomass can be used to counter nitrogen (N) pollution. The present study investigated the effects of feedstock and temperature on characteristics of biochars and their adsorption ability for ammonium N (NH4(+)-N) and nitrate N (NO3(-)-N). Twelve biochars were produced from wheat-straw (W-BC), corn-straw (C-BC) and peanut-shell (P-BC) at pyrolysis temperatures of 400, 500, 600 and 700°C. Biochar physical and chemical properties were determined and the biochars were used for N sorption experiments. The results showed that biochar yield and contents of N, hydrogen and oxygen decreased as pyrolysis temperature increased from 400°C to 700°C, whereas contents of ash, pH and carbon increased with greater pyrolysis temperature. All biochars could sorb substantial amounts of NH4(+)-N, and the sorption characteristics were well fitted to the Freundlich isotherm model. The ability of biochars to adsorb NH4(+)-N followed: C-BC>P-BC>W-BC, and the adsorption amount decreased with higher pyrolysis temperature. The ability of C-BC to sorb NH4(+)-N was the highest because it had the largest cation exchange capacity (CEC) among all biochars (e.g., C-BC400 with a CEC of 38.3 cmol kg(-1) adsorbed 2.3 mg NH4(+)-N g(-1) in solutions with 50 mg NH4(+) L(-1)). Compared with NH4(+)-N, none of NO3(-)-N was adsorbed to biochars at different NO3(-) concentrations. Instead, some NO3(-)-N was even released from the biochar materials. We conclude that biochars can be used under conditions where NH4(+)-N (or NH3) pollution is a concern, but further research is needed in terms of applying biochars to reduce NO3(-)-N pollution.
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Xiapu
authors.initials: X
authors.lastname: Gai
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China; United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Pasture Systems and Watershed Management Research Unit, University Park, Pennsylvania, United States of America.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Limei
authors.initials: L
authors.lastname: Zhai
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Shen
authors.initials: S
authors.lastname: Liu
authors.affiliation: Institute of Agro-Environmental Protection, Ministry of Agriculture, Tianjin, China.
authors.forename: Tianzhi
authors.initials: T
authors.lastname: Ren
authors.affiliation: Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Liu
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds / Q000737:chemistry* / Q000378:metabolism; D056804:Biofuels; D018533:Biomass; D002606:Charcoal / Q000737:chemistry*; D004553:Electric Conductivity; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning / Q000379:methods; D009566:Nitrates / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D064751:Ammonium Compounds; D056804:Biofuels; D009566:Nitrates; C540010:biochar; D002606:Charcoal; D009584:Nitrogen