尿素/烟酰胺改性活性炭的制备及其甲醛吸附性能的研究

Preparation of Urea/Nicotinamide Modified Activated Carbon and Its Formaldehyde Adsorption Performance

以椰壳活性炭为原料,尿素和烟酰胺为改性剂,通过浸渍法制备改性活性炭(ACN),探讨了改性活性炭的物理化学性质对其吸附气相甲醛的影响。通过扫描电子显微镜(SEM)观察改性前后活性炭的表面形貌,通过低温氮气吸附测定活性炭的孔隙结构,采用X射线光电子能谱(XPS)分析活性炭表面元素组成及官能团结构。研究结果表明:改性后活性炭的表面和孔结构中出现负载颗粒,其比表面积和总孔容积相对于改性前有所下降,但表面酰胺类和季铵类结构为主的含氮官能团、酸酐及内酯类■结构为主的含氧官能团数目显著增加。质量分数为9%的尿素溶液和质量分数为0.5%的烟酰胺溶液共同改性的活性炭样品(ACN3)对气态甲醛的吸附性能最好,平衡吸附量达到0.042 9 mg/g,较原活性炭(0.026 7 mg/g)提高60.67%,是商用活性炭的2~3倍。

Modified activated carbon(ACN)was prepared via dipping method with coconut shell activated carbon as precursor and urea and niacinamide as modification agents. Effects of surface chemical properties and pore structure on the adsorption performance of formaldehyde were investigated. The surface morphology, pore structure and surface functional groups were characterized by using scanning electron microscopy, N2 adsorption isotherm and X-ray photoelectron spectroscopy, respectovely of carbon. The results revealed that the loaded particles appeared on the surface and pore of the modified activated carbon, the specific surface area and total pore volume of the modified activated carbon decreased and the number of amide and quaternary ammonium functional groups and lactone class ■ oxygen functional groups increased. As the mass fractions of urea solution was 9% and the mass fractions of nicotinamide was 0.5%, the modified activated carbon ACN3 had the most excellent adsorption capacity with the equilibrium adsorption capacity of 0.042 9 mg/g,which was 60.67% higher than that of the original activated carbon(0.026 7 mg/g), and was 2-3 times of commercial activated carbon.