Oxalic acid-modified activated carbons under hydrothermal condition for the adsorption of the 2-butanone.

Abstract

Growing volatile organic compound (VOC) emission will cause air pollution and further threaten human health. Activated carbon is widely applied to treatment of VOCs in virtue of lower cost and excellent adsorption ability. In this work, the adsorption capacity of polarity VOCs on activated carbon is improved by oxalic acid (H2C2O4) hydrothermal modification. After 2M H2C2O4 modification, the adsorption capacity of 2-butanone rose from 312.60 to 345.98mg/g, and the time reaching saturation adsorption became shorter. BET results showed that both the specific surface area and total pore volume of 2M H2C2O4-modified activated carbon increased by 3.32% and 3.9%, respectively. Both FTIR and XPS characterization confirmed variation of the surface oxygen-containing functional groups (SOFGs), while quantitative analysis via Boehm titration showed the significant increase of total acidity (61.36%), particularly the carboxyl content increased by 96.28%. The results indicated modification process can not only change the pore structure but also the SOFGs of activated carbons. The dynamic adsorption curves conform to the Bangham kinetics model, indicating that the adsorption of 2-butanone on both activated carbon is controlled by the diffusion in the pore channel. The adsorption data was also modeled by the internal particle diffusion model, and the internal diffusion adsorption stage is the rate-controlling step. The stability before and after adsorption and the cycling performance were studied.