负载镁香蕉茎秆基生物质炭的制备与表征

Preparation and Characterization of the Magnesium-loaded Biochar from Banana Stem

利用废弃的香蕉茎秆制备了一种负载镁的生物质炭吸附剂。以磷为目标污染物,采用Box-Behnken响应曲面法研究了MgCl_2浓度、碳化温度和碳化时间对磷吸附量的单独作用及交互影响作用,并建立了数学模型。结果表明,所建的数学模型对实验数据拟合度高,自变量对响应值的影响次序为:MgCl_2浓度>炭化温度>炭化时间,MgCl_2浓度与炭化温度交互影响显著;最佳工艺条件为MgCl_2浓度1.15 mol/L,炭化温度430℃,炭化时间4 h。模型预测最佳吸附量q_e为38.67 mg/g,验证实验结果q_e为39.27 mg/g,预测值与测定值偏差率为1.55%。在吸附磷后的负载镁生物质炭的X射线衍射谱图上,出现了磷酸氢镁(MgHPO_4·3H_2O)的特征衍射峰。

A magnesium-loaded biochar adsorbent was prepared from wasted banana stem for the removal of phosphorus from aqueous solution. The Box-Behnken response surface method was applied to optimize its preparation condition, including MgC12 concentration, carbonization temperature and carbonization time. The results demonstrated that the mathematical model could fit the experimental data very well and the significance of the influence factors followed the order as MgC12 concentration 〉 carbonization temperature 〉 carbonization time. The interactive influence between the MgCI2 concentration and the carbonization temperature was significant. Under the optimal preparation condition of the MgC12 concentration of 1.15 mol/L, the carbonization temperature of 430 ~C and the carbonization time of 4h, the absorption capacity of phosphorus was experimentally determined to be qe=39.27 mg/g, which agreed well with the predicted qe of 38.67 mg/g with 1.55% deviation. The characteristic diffraction peaks of magnesium phosphate hydrate （MgHPO4·3H2O） were detected in the XRD pattern of the magnesium-loaded biochar after phosphorus adsorption.