TiO_(2)-SiO_(2)改性香蕉皮生物炭对水中二氯喹啉酸吸附性能研究

A study on the adsorption of quinclorac in water using TiO_(2)-SiO_(2) modified banana peel biochar

为了寻找有效去除污水中二氯喹啉酸(QNC)的方法,以农业废弃物香蕉皮为原料,磷酸、TiO_(2)和SiO_(2)为活化剂,制备了TiO_(2)-SiO_(2)改性香蕉皮生物炭(Ti-Si-BC)。采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(FTIR)、比表面积法(BET)和元素分析(EDS)等手段对改性前后生物炭的物理化学性质进行表征,研究了Ti-Si-BC对QNC的吸附机理以及接触时间、初始浓度、温度和吸附剂用量等因素对吸附效果的影响。结果表明:磷酸、TiO_(2)和SiO_(2)的协同改性显著提高了生物炭的比表面积并增加了吸附点位。在QNC初始浓度为60 mg·L^(-1)时,Ti-Si-BC对QNC的吸附率是天然香蕉皮生物炭(BC)的2.5倍。Ti-Si-BC对QNC的吸附动力学过程更符合准二级动力学模型,说明吸附包括表面的物理吸附和内部的化学扩散。等温吸附过程更符合Freundlich模型,说明吸附为非均相多层吸附。热力学结果表明该吸附为吸热的自发反应。Ti-Si-BC对QNC吸附的机理主要包括孔隙填充、静电和氢键等作用,其吸附效果较BC明显提高,具有良好的应用潜力。

To find an effective method of removing quinclorac(QNC)from polluted water,TiO_(2)-SiO_(2) modified banana peel biochar(Ti-Si-BC)was prepared from banana peel(agricultural waste)and modified using phosphoric acid,TiO_(2),and SiO_(2).Scanning electron microscopy(SEM),X-ray diffraction(XRD),fourier-transform infrared spectroscopy(FTIR),specific surface area method(BET),and elemental analysis(EDS)were used to characterize the physical and chemical properties of the modified and pristine biochar.The adsorption mechanism of Ti-Si-BC on QNC and the effects of contact time,initial concentration of QNC,temperature,and amount of adsorbent on the adsorption effect were studied.The results showed that the synergistic modification of phosphoric acid,TiO_(2),and SiO_(2) significantly increased the specific surface area and adsorption sites of biochar.When the initial concentration of QNC was 60 mg·L^(-1),the adsorption rate of Ti-Si-BC on QNC was 2.5 times that of natural banana peel biochar(BC).The adsorption kinetics of QNC on Ti-Si-BC was more in line with the quasi-second-order kinetic adsorption model,which included physical adsorption on the surface and internal chemical diffusion.The isothermal adsorption process was more consistent with Freundlich model,which is a heterogeneous multilayer adsorption.Thermodynamic results showed that the adsorption of QNC on Ti-Si-BC was a spontaneous and endothermic reaction.Void filling,electrostatics,and hydrogen bonding were the main mechanisms for the removal of QNC through Ti-Si-BC adsorption.The adsorption capacity of Ti-Si-BC was significantly improved compared with that of BC,indicating that Ti-Si-BC had a good application prospect for the removal of QNC in water.