Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon
| Autor: | Tatsuya Iida, Motoi Machida, Tatsuru Goto, Yoshimasa Amano |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Langmuir
Nitrogen Surface Properties Inorganic chemistry chemistry.chemical_element 02 engineering and technology 010402 general chemistry 01 natural sciences chemistry.chemical_compound Adsorption Nitrate Drug Discovery medicine Surface charge Point of zero charge Nitrates Aqueous solution Water General Chemistry General Medicine 021001 nanoscience & nanotechnology Carbon 0104 chemical sciences Solutions chemistry 0210 nano-technology Activated carbon medicine.drug |
| Zdroj: | CHEMICAL & PHARMACEUTICAL BULLETIN. 64:1555-1559 |
| ISSN: | 1347-5223 0009-2363 |
| Popis: | Activated carbon (AC) has been widely applied for adsorptive removal of organic contaminants from aqueous phase, but not for ionic pollutants. In this study, nitrogen doped AC was prepared to increase the adsorption capacity of nitrate from water. AC was oxidized with (NH4)2S2O8 solution to maximize oxygen content for the first step, and then NH3 gas treatment was carried out at 950°C to aim at forming quaternary nitrogen (N-Q) species on AC surface (Ox-9.5AG). Influence of solution pH was examined so as to elucidate the relationship between surface charge and adsorption amounts of nitrate. The results showed that Ox-9.5AG exhibited about twice higher adsorption capacity than non-treatment AC at any initial nitrate concentration and any equilibrium solution pH (pHe) investigated. The more decrease in pHe value, the more adsorption amount of negatively charged nitrate ion, because the surface charge of AC and Ox-9.5AG could become more positive in acidic solution. The oxidation and consecutive ammonia treatments lead to increase in nitrogen content from 0.35 to 6.4% and decrease in the pH of the point of zero charge (pHpzc) from 7.1 to 4.0 implying that positively charged N-Q of a Lewis acid was created on the surface of Ox-9.5AG. Based on a Langmuir data analysis, maximum adsorption capacity attained 0.5-0.6 mmol/g of nitrate and adsorption affinity was 3.5-4.0 L/mmol at pHe 2.5 for Ox-9.5AG. |
| Databáze: | OpenAIRE |
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