NaHCO3活化荞麦皮生物炭对碘帕醇的吸附

采用NaHCO₃活化荞麦皮生物炭，优化得到生物炭0.25N-BCm（NaHCO₃）：m（荞麦皮）=0.25：1]，通过SEM、BET、XRD、Raman、FTIR和XPS等方法进行表征，分析NaHCO₃对生物炭理化性质的影响，探究其对非离子型碘代X射线造影剂碘帕醇（IPM）的吸附性能和机制.结果表明，与荞麦皮生物炭相比（BC），NaHCO₃活化生物炭的结构缺陷程度更高（比表面积和孔体积分别由480.40 m²·g^-1和0.29 cm³·g^-1增至572.83 m²·g^-1和0.40 cm³·g^-1，I_D/I_G是BC的1.22倍），表面含碳和含氧官能团数量发生显著变化，极性增强（N+O）/C由0.15增至0.24]，能够有效吸附IPM，0.25N-BC对IPM最大吸附量达到74.94 mg·g^-1，是BC （7.88 mg·g^-1）的9.51倍.拟二级吸附动力学和Langmuir、Freundlich等温线模型可很好地拟合0.25N-BC对IPM的吸附，吸附过程主要以化学吸附和单层、非均质多层吸附为主；孔隙填充、氢键、π—π和n—π相互作用是0.25N-BC吸附IPM的主要机制.对比不同碱KOH、Na₂CO₃、NaHCO₃、KHCO₃和Ca （HCO₃）₂]活化荞麦皮生物炭对IPM的吸附，0.25N-BC吸附效率高，达到吸附平衡时间短，能有效去除实际水体（二沉池出水和湖水）中IPM的残留，并具有良好的循环使用性能，吸附-解吸3次后对IPM的去除率仍保持在74.91%.研究表明NaHCO₃活化荞麦皮生物炭是一种绿色有效，可持续去除含碘有机物的优良吸附剂.

Adsorption of Iopamidol by NaHCO3-activated Buckwheat Biochar

NaHCO₃-activated buckwheat biochar was studied, and an optimal biochar of 0.25N-BC m(NaHCO₃):m(buckwheat bark)=0.25:1]was selected. SEM, BET, XRD, Raman, FTIR, and XPS methods were applied to analyze the effects of NaHCO₃ on the physicochemical properties of buckwheat biochar. The adsorption properties and mechanism of NaHCO₃-activated buckwheat biochar for iopamidol(IPM), a nonionic iodol X-ray contrast agent, were also investigated. The results showed that compared with buckwheat skin biochar(BC), NaHCO₃-activated biochar had higher structural defects(surface area and pore volume increased, respectively, from 480.40 m²·g^-1 and 0.29 cm³·g^-1 to 572.83 m²·g^-1 and 0.40 cm³·g^-1, with I_D/I_G being 1.22 times that of BC), the carbon and oxygen functional groups on the BC surface changed significantly, and the polarity increased (N+O)/C from 0.15 to 0.24]. The maximum adsorption capacity of 0.25N-BC for IPM was 74.94 mg·g^-1, which was 9.51 times that of BC(7.88 mg·g^-1). The pseudo-second-order adsorption kinetics and Langmuir and Freundlich isotherm models could well fit the adsorption of 0.25N-BC for IPM. The adsorption processes were mainly chemical, monolayer, and heterogeneous multilayer adsorption. Pore filling, hydrogen bonding, π-π, and n-π interactions were the main mechanisms of 0.25N-BC adsorption for IPM. Comparing the activated buckwheat biochar by different bases KOH, Na₂CO₃, NaHCO₃, KHCO₃, and Ca(HCO₃)₂], 0.25N-BC exhibited high adsorption capability and short equilibrium time and could effectively remove the IPM residue in the actual water(secondary sedimentation tank effluent and lake). The removal rate of IPM remained at 74.91% after three adsorption-desorption cycles. The results showed that NaHCO₃-activated buckwheat biochar was a green, effective, and sustainable adsorbent for the removal of iodine-containing organic matter.