载铜活性炭的制备及其气相苯吸附性能的研究

Preparation of Copper Loaded Activated Carbon and Its Adsorption Performance of Gaseous Benzene

在椰壳活性炭表面浸渍CuCl_(2),经二次炭化、活化工艺制得改性活性炭,当CuCl_(2)质量分数为0.3%、0.4%、0.5%和0.7%时,制得的改性活性炭分别标记为AC_(3)、AC_(4)、AC_(5)和AC_(7)。通过扫描电镜(SEM)、N_(2)吸附-脱附、X射线衍射(XRD)和X射线光电子能谱(XPS)对改性活性炭进行表征,在常温动态吸附装置中考察改性活性炭对气相苯的吸附-脱附性能。研究结果表明:改性后活性炭表面酸性含氧官能团减少,且铜在活性炭表面及孔隙内部主要以CuO和Cu_(2)O形式存在,随着浸渍CuCl_(2)质量分数的增加活性炭比表面积降低、孔容积减小,但微孔比表面积和比例提高,其中AC_(5)的微孔比表面积为733.20 m^(2)/g,微孔比例达到72.99%。改性活性炭AC_(5)对气相苯吸附性能最佳,对5 mg/L苯的平衡吸附量为356.40 mg/g,平衡吸附时间118.80 min,较原料活性炭(AC_(raw))均提高了33.38%,吸附性能优于有机气体滤毒盒(3M-3301 CN型和3M-6001 CN型)活性炭。AC_(5)经5次吸附-脱附循环测试后,吸附性能仍能保留80%左右。载铜活性炭通过苯分子中π键与Cu^(2+)中空d轨道发生络合作用,将活性炭对气相苯的吸附作用由物理吸附为主转化为物理-化学联合吸附,从而提高吸附性能。

The modified coconut shell activated carbons were prepared by loading CuCl_(2),carbonization and CO_(2) activation.The Cu-loaded activated carbons were labeled as AC_(3),AC_(4),AC_(5),and AC_(7) to represent the mass fractions of cupric salt solutions 0.3%,0.4%,0.5%and 0.7%,respectively.The Cu-loaded activated carbons were characterized by means of N_(2) adsorption isotherm,SEM,XRD and XPS.Their dynamic adsorption-desorption performance was measured by the gravimetric method.After modification,the acidic oxygenated groups on the surface of activated carbon decreased.The results showed that cupric salt existed in two forms,i.e.,CuO and Cu_(2)O.It was found that the presence of Cu loading led to the decreasing of surface area and pore volume of modified sample,and the increasing of the surface area and proportion of micropore.AC_(5) showed the largest values of the surface area(733.20 m^(2)/g)and proportion(72.99%)of micropore.Furthermore,AC_(5) had the optimal equilibrium adsorption capacity(356.40 mg/g)which increased by 33.38%compared to the raw sample,and the optimal equilibrium adsorption time(118.80 min)which increased by 33.38%.Moreover,the adsorption performance of AC_(5) was better than the activated carbons in the organic gas filter cartridge(3M-3301 CN and 3M-6001 CN).After five cycles of adsorbents regeneration test,80%of adsorption capability was still able to be reserved.The Cu-loaded activated carbons improved the adsorption performance by transforming the style from physical adsorption to physical-chemical adsorption through complexation ofπ-bonds in benzene with hollow d-orbitals in Cu^(2+).