Abstract
► The effects of pretreatment on the surface chemistry and pore sizes were studied. ► Treated GAC was nitrogen functionalized and alkylated GAC also called modified GAC. ► HNO3 pretreatment caused a slight decrease in surface area and microporosity. ► The nitrogen percentage of modified GAC which pretreated by H2O2 was 4.07%. ► The pyridine of modified GAC which pretreated by urea-formaldehyde resin was 45.88%.
In this paper, granular activated carbon (GAC) from coconut shell was pretreated by HNO3, H2O2 and urea-formaldehyde resin, respectively. Then the obtained materials were functionalized in the same way for nitrogen group, and then alkylated. Effects of pretreatment on the surface chemistry and pore size of modified GACs were studied. Surface area and micropore volume of modified GAC which pretreated by HNO3 were 723.88m2/g and 0.229cm3/g, respectively, while virgin GAC were 742.34m2/g and 0.276cm3/g. Surface area and micropore volume decrease of the modified GACs which pretreated by the others two methods were more drastically. The types of groups presented were analyzed by electrophoresis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). NCH3 group and CN group were detected on the surfaces of these three kinds of modified GACs. Results of XPS showed that the nitrogen functions of modified GAC which pretreated by H2O2 was 4.07%, it was more than that of the others two pretreatment methods. However, the modified GAC which pretreated by urea-formaldehyde resin was fixed more pyridine structure, which structure percentage was 45.88%, in addition, there were more basic groups or charge on the surface than the others.