Flax shive as a source of activated carbon for adsorption of methylene blue

Abstract

The application of carbon as an adsorbent is a well-known method of removal of chemical pollutants, including dyes, from waste waters. However, a lot of attention is now being paid to improving the adsorbent efficiency and searching for cheap precursors for activated carbon (AC) production. In this work, AC is obtained from flax shive by its physical and chemical activation with KOH. The pyrolysis process and mechanism of KOH activation are studied using thermogravimetric analysis. The methods of X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and low-temperature nitrogen adsorption are used to determine the AC characteristics. The AC ability to adsorb the methylene blue (MB) dye is studied. The effect of the properties of the synthesized AC on the MB equilibrium adsorption capacity is analyzed. The maximum BET surface area of the AC is equal to 1832.2 m2/g, which means its values lie in the range typical of industrial activated carbons. The maximum equilibrium adsorption capacity of MB is 464.2 mg/g. The AC adsorption capacity depends on the cellulose content in the flax shive and pore size distribution over the carbon matrix. The use of lignocellulosic biomass, namely flax shive, in the AC production is associated with solving environmental problems, such as agricultural waste recycling and disposal.

Keywords:

• Activated carbon
• flax shive
• KОН activation
• methylene blue
• adsorption–desorption isotherm
• morphology
• pyrolysis
• thermogravimetric analysis
• characterization