Preparation of highly developed mesoporous activated carbon by H4P2O7 activation and its adsorption behavior for oxytetracycline

Preparation of highly developed mesoporous activated carbons from renewable source Arundo donax Linn was performed using H4P2O7 as activator. The influences of chemical impregnation ratio (mass of H4P2O7:A. donax Linn), activation temperature and soaking time on the properties (yield, BET surface area, pore volume and surface functional group) of activated carbon were investigated. The optimal activated carbon (ALAC) was characterized by scanning electron micrograph (SEM), N2 adsorption/desorption isotherms, X-ray photoelectron spectrometry (XPS) and oxytetracycline (OTC) adsorption experiments. Results showed that the pore development was significant at temperatures > 400 °C, and reached a maximum BET surface area (1463 m2/g) at 600 °C and maximum total pore volume (1.24 cm3/g) at 500 °C. At a low impregnation ratio of 0.4, BET surface area and pore volume could reach as high as 1150.69 m2/g and 0.59 m3/g. Both BET surface area and pore volume initial increase followed by a decrease after reaching a maximum, with the maximal surface area was obtained at an impregnation ratio of 0.75 and maximal pore volume at 1.0. BET surface area and mesopore volume reached maximum after 10 h of soaking. Acidic surface groups followed the order of: strong acidic groups > weak acidic groups > intermediate acidic groups. Low activation temperature was favorable to the formation of acidic surface functional groups. With the increase of soaking time, the acidic surface functional initial increase was followed by a gradual decrease and finally tended to level off.