Water purification with activated carbons (ACs): A short review—Influence of the textural and surface properties of ACs on the adsorptive removal of pollutants—

Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon

“…The oxidized AC (Ox) was then heat treated with pure ammonia gas at 950°C for 5 min to aim at maximizing N-Q species, designated as Ox-9.5AG, because in our previous study the maximum adsorption amount of phosphate anion was observed at 950°C for the heat treated activated polyacrylonitrile (PAN) fiber ranging from 900 to 1000°C. 13) In case of AC, when AC was oxidized as a pretreatment and then treated with melamine and urea at 950°C in an inert atmosphere, N-Q including pyridinic N-oxide (N-X) could be measured in large amounts compared to those without oxidation pretreatment. 18) Finally obtained Ox-9.5AG was washed with pure water for 2 d by Soxhlet extractor and dried in oven at 110°C and stored, and dried again at 110°C every time before use.…”

“…Nitrate in contaminated water can be removed from aqueous phase generally by biological reduction to convert N 2 6) and adsorption to solid surfaces 7) including ion exchange. 8) Adsorptive removal was conducted by chitosan, 9) sepiolite, 10) kaolin, 11) functionalized silica, 12) activated carbon, 13) carbon nanotube (CNT) 14) and many other natural and synthesized materials. 7) In this study commercially available activated carbon (AC) was firstly oxidized so as to maximize oxygen content and then pure NH 3 gas treatment was conducted to increase positively charged quaternary nitrogen (N-Q, N + ) on the carbon surface 15) to improve adsorption affinity and capacity of nitrate anion.…”

“…Prepared AC was compared with the nontreatment original AC in adsorption performance of nitrate and some physical and chemical properties of specific surface area, pore volume, pore size, elemental composition and the pH of the point of zero charge (pH pzc ). For the adsorption of nitrate from water, influence of equilibrium solution pH (pH e ) was principally examined, because pH could be one of the decisive factors affecting adsorption capacity of nitrate 13,16) and probably practical usage. The effect of solution pH e was measured varying initial nitrate concentrations and adsorption isotherms at the same pH e were also estimated to inspect the adsorption capacities and affinities of nitrate at three pH e values.…”

Nitrate Ion Adsorption Characteristics of Activated Carbon Fibers with and without Quaternary Nitrogen Effective for Anion Adsorption

“…Shafeeyan et al showed that acidic functional groups were decomposed as CO/CO 2 and H 2 O by heat treatment. 19) In particular, carboxy groups were decomposed in the range of 100-400 °C. 19) Complete decomposition of carboxy groups can be expected when we perform heat treatment at 950 °C.…”

“…19) In particular, carboxy groups were decomposed in the range of 100-400 °C. 19) Complete decomposition of carboxy groups can be expected when we perform heat treatment at 950 °C. HP555 has only N-Q (trimethylammonium) as an adsorption site.…”