Ngatia L W, Hsieh Y P, Nemours D, Fu R, Taylor R W
Center for Water and Air Quality, College of Agriculture and Food Sciences, Florida A&M University, Tallahassee, FL 32307, USA.
Center for Water and Air Quality, College of Agriculture and Food Sciences, Florida A&M University, Tallahassee, FL 32307, USA.
Chemosphere. 2017 Aug;180:201-211. doi: 10.1016/j.chemosphere.2017.04.012. Epub 2017 Apr 4.
Phosphorus (P) eutrophication is a major pollution problem globally, with unprecedented amount of P emanating from agricultural sources. But little is known about the optimization of soil-biochar P sorption capacity. The study objective was to determine how biochar feedstocks and pyrolysis conditions influences carbon (C) thermal stability, C composition and pH and in turn influence the phosphorus sorption optimization. Biochar was produced from switchgrass, kudzu and Chinese tallow at 200, 300, 400, 500, 550, 650,750 °C. Carbon thermal stability was determined by multi-element scanning thermal analysis (MESTA), C composition was determined using solid state C NMR. Phosphorus sorption was determined using a mixture of 10% biochar and 90% sandy soil after incubation. Results indicate increased P sorption (P < 0.0001) and decreased P availability (P < 0.0001) with increasing biochar pyrolysis temperature. However, optimum P sorption was feedstock specific with switchgrass indicating P desorption between 200 and 550 °C. Phosphorus sorption was in the order of kudzu > switchgrass > Chinese tallow. Total C, C thermal stability, aromatic C and alkalinity increased with elevated pyrolysis temperature. Biochar alkalinity favored P sorption. There was a positive relationship between high thermal stable C and P sorption for Kudzu (r = 0.62; P = 0.0346) and Chinese tallow (r = 0.73; P = 0.0138). In conclusion, biochar has potential for P eutrophication mitigation, however, optimum biochar pyrolysis temperature for P sorption is feedstock specific and in some cases might be out of 300-500 °C temperature range commonly used for agronomic application. High thermal stable C dominated by aromatic C and alkaline pH seem to favor P sorption.
磷（P）富营养化是全球主要的污染问题，农业源排放的磷量空前。但关于优化土壤 - 生物炭对磷的吸附能力却知之甚少。本研究的目的是确定生物炭原料和热解条件如何影响碳（C）的热稳定性、C组成和pH值，进而影响磷吸附的优化。生物炭由柳枝稷、葛藤和乌桕在200、300、400、500、550、650、750℃下制备而成。通过多元素扫描热分析（MESTA）测定碳热稳定性，使用固态碳核磁共振测定C组成。在培养后，使用10%生物炭和90%砂土的混合物测定磷吸附。结果表明，随着生物炭热解温度的升高，磷吸附增加（P < 0.0001）且磷有效性降低（P < 0.0001）。然而，最佳磷吸附因原料而异，柳枝稷表明在200至550℃之间存在磷解吸。磷吸附顺序为葛藤>柳枝稷>乌桕。总碳、碳热稳定性、芳香碳和碱度随热解温度升高而增加。生物炭碱度有利于磷吸附。对于葛藤（r = 0.62；P = 0.0346）和乌桕（r = 0.73；P = 0.0138），高热稳定性碳与磷吸附之间存在正相关关系。总之，生物炭具有缓解磷富营养化的潜力，然而，用于磷吸附的最佳生物炭热解温度因原料而异，在某些情况下可能超出农艺应用常用的300 - 500℃温度范围。以芳香碳为主的高热稳定性碳和碱性pH似乎有利于磷吸附。
