皇竹草生物炭的结构特征及其对Cr(Ⅵ)的吸附性能

Structural feature and chromium(Ⅵ)adsorption of biochar derived from Pennisetum hydridum

以皇竹草茎秆为原料,在限氧控温（300、500、700℃）条件下制备生物炭,研究该生物炭的结构特征及其对Cr（Ⅵ）的吸附行为。结果发现,随着热解温度的升高,皇竹草生物炭的产率下降,而灰分、p H呈上升趋势;电镜扫描（SEM）观察可见不同热解温度下所制备的生物炭结构相似,均具多孔和管状结构,但在700℃条件下所制备的生物炭相对300℃下制备的生物炭孔壁变薄,且孔壁有附着物,切面有突起结构。三种温度下制备的皇竹草生物炭对溶液中的Cr（Ⅵ）都具有较好的吸附作用,且500、700℃下制备的生物炭比300℃下制备的生物炭具有更好的吸附效果。在0~1 h之间,三种热解温度下制备的生物炭对铬的吸附量均随着时间的延长而快速增加,当吸附至1 h时,基本达到饱和状态,随后吸附量无明显变化。

This research investigated the structural feature of biochar derived from Pennisetum hydridum under hypoxia conditions at three pyrolysis temperatures（300 ℃, 500 ℃, and 700 ℃）and its chromium（Ⅵ）adsorption. Results showed that increasing pyrolysis temperature decreased the biochar production rates, but increased ash content and p H values. Scanning electron microscopy showed that the hole wall of the biochar prepared at 700 ℃ was thinner, with more attachments and protuberances inside than that at 300 ℃. All three biochars had good adsorption of Cr（VI）, with adsorption capacity being higher at 500 ℃ and 700 ℃ than at 300 ℃. The adsorption of Cr（VI）by biochars increased quickly and reached saturation after 1 h, and remained no obvious changes after that.