Change of the surface and structure of activated carbon as a result of HNO3 modification

Abstract

In the paper the chemical modification of activated carbon was presented. The activated carbon was modified by nitric acid. For the tested activated carbons, the following physical and chemical properties were determined: bulk density, pH of the water extract, and effective diameter of the grains. Elemental and technical analyses were performed. The pore distribution was determined using mercury porosimetry. Low-temperature nitrogen isotherms were used to analyze the microporous structure. The chemical properties of the surfaces of the tested adsorbents were interpreted by means of the Boehm method. The water vapor adsorption isotherms at 303 K were determined and the adsorption capacity towards methanol was tested using the desiccator method. Thermogravimetric tests were used and, at the same time, the released oxidizing gases from the tested samples were analyzed using a mass spectrometer. As a result of the modification, activated carbon enriched with acidic oxygen functional groups was obtained. The resulting modified activated carbon showed worse structural parameters (when compred to umodified activated carbon), however it was characterized by a higher adsorption capacity in relation to polar adsorbates such as water and methanol, especially in the low pressure range.

Removal of Divalent Copper Ions from Aqueous Solution using <i>Sorghum bicolor</i> L. Stem Waste as an Effective Adsorbent

“…In addition, the surface looks smoother and less messy. Adding HNO 3 to This adsorbent shows changes in the surface structure when HNO 3 modifies the sorghum stem [25]. The presence of small holes or pores that are formed due to the addition of HNO 3 gives a large surface area [26].…”

Activated Carbons as Effective Adsorbents of Non-Steroidal Anti-Inflammatory Drugs

“…Moreover, they are characterized by non-toxicity, a highly developed porous structure, and low production costs, which encourage their use. Of course, the efficiency of removing pollutants from aqueous solutions is influenced by a number of factors that relate not only to the properties of the adsorbent but also to the characteristics of the adsorbate (e.g., solubility, particle diameter, pKa, and charge) as well as the adsorption conditions (e.g., pH, temperature, mixing speed, and the presence of accompanying substances) [8][9][10][11][12][13][14][15].…”