垫料生物炭对Cd2+的吸附性能

以发酵床废弃垫料和秸秆为原料，采用限氧热解法制备不同温度（300、400和500℃）下的垫料生物炭（D300、D400和D500）和秸秆生物炭（S300、S400和S500），通过X-ray能谱仪、扫描电镜、傅里叶变换红外光谱仪等手段表征其物理化学性质，研究不同吸附时间、Cd2+浓度和初始pH下垫料生物炭对Cd2+的吸附性能，并与秸秆生物炭进行比较。结果表明，D300和D400的吸附过程较符合准二级动力学模型，D500的吸附过程更符合颗粒内扩散模型，吸附时间以30 h为宜；垫料生物炭对Cd2+的等温吸附实验更符合Freundlich模型，400℃制备的垫料生物炭对Cd2+的吸附效果最好；D300和D400对Cd2+的吸附能力受pH的影响较大，D500对Cd2+的吸附能力受pH的影响较小，pH在4.5~7.5之间吸附效果较好。秸秆生物炭吸附Cd2+到表观平衡所用的时间在20 h左右，而最大吸附量比垫料生物炭多2.727 mg·g-1。

Adsorption properties of Cd2+ by bedding materials derived-biochar

We herein report the generation of six types of biochar (D300, D400, D500, S300, S400, S500) from bedding materials and rice straw at pyrolysis temperatures of 300℃, 400℃, and 500℃, followed by the analysis of their structural characteristics by X-ray spectrometry, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). We also investigated Cd2+ adsorption on biochar in aqueous solution. Adsorption on D300 and D400 fit well with a pseudo-second-order kinetic model, while adsorption on D500 fits well with the intraparticle diffusion model. In addition, an optimal adsorption time of 30 h and an optimal adsorption temperature of 400℃ were determined. Indeed, the adsorption of Cd2+ on biochar can be better described by the Freundlich model. Furthermore, adsorption on D300 and D400 was affected by solution pH to a greater extent than D500, with an optimal pH of 4.5-7.5 being determined. Finally, the Cd2+ optimal adsorption time of straw derived-biochar was 20 h, while the maximum adsorption capacity was 2.727 mg·g-1 greater than that of the bedding material-derived biochar.