核桃壳生物炭小球对雌激素污染物的吸附机制

为探究生物炭小球对雌激素污染物的吸附机制，以农业废弃物核桃壳为原材料，在400 ℃下热解碳化制备生物炭，与黏土、碳酸氢钠、硅酸钠混合制备生物炭小球。采用ESEM观察、比表面积测定、红外光谱对其表面结构和组成进行表征，并将其用于对雌酮(E1)、雌二醇(E2)和雌三醇(E3)的吸附去除研究。分别考察了吸附时间、溶液pH、生物炭小球投加量以及雌激素初始浓度对吸附效果的影响，并通过颗粒内扩散、等温吸附、吸附动力学探讨其吸附机制。结果表明：生物炭小球对雌激素的吸附平衡时间为15 min；投加量为1 g、pH为5、初始浓度为2 500 μg·L-1时平衡吸附量最大；颗粒内扩散模型研究结果表明吸附机制包括分配作用和表面吸附；准二级动力学可较好地描述生物炭小球对雌激素的吸附过程；生物炭小球对雌激素的吸附过程符合Freundlich等温吸附模型。所制备的生物炭小球对雌激素污染物具有较好的去除效果，在环境治理方面具有一定的应用前景。

Adsorption mechanism of estrogenic pollutants on biochar pellets made from walnut shell

In order to explore the adsorption mechanism of estrogenic pollutants, the biochar was prepared through pyrolyzation and carbonization of the agricultural wastes walnut shell at 400 ℃, then it was mixed with clay, sodium bicarbonate and sodium silicate to prepare the biochar pellets. The surface structure and composition of these pellets were characterized by ESEM observation, specific surface area measurement and infrared spectroscopy, respectively. The performance of these pellets on the adsorption of estrogens estrone (E1), estradiol (E2) and estriol (E3) was studied. Experiments were conducted at different adsorption time, biochar pellets dosage, solute pH and initial estrogen concentration, and the adsorption mechanism was investigated through isothermal adsorption, intraparticle diffusion, adsorption kinetics. Results showed that the adsorption of estrogenic pollutants on biochar pellets reached equilibrium after 15 min. The maximum equilibrium adsorption capacity occurred at the dosage of 1 g, pH=5 and initial estrogen concentration of 2 500 μg·L-1. The fitting results of the particle diffusion model indicated that the adsorption mechanisms were partition and surface adsorption. Quasi-second-order kinetics could well describe the adsorption process of estrogen on biochar pellets. And the adsorption data at different initial estrogen concentrations fitted to Freundlich adsorption isotherms. The biochar pellets had a good performance on estrogen pollutants removal. Therefore, it has a certain application prospect in environmental governance.