Activated Carbon Obtained from Cardboard Tube Waste of Immersion Thermocouple and Adsorption of Methylene Blue

Thermocouple sensors which use cardboard tubes are used as thermal insulators to measure the temperature of liquid steel. After its use, the material is discarded, causing high waste of the cardboard tube of the immersion thermocouple (CTW). Thus, this study aimed to use it as a precursor for the production of activated carbon (AC-CTW) by activation with H3PO4. A CHN analyzer estimated the carbon, hydrogen, and nitrogen contents of CTW. CTW and AC-CTW were characterized by FTIR, XRD, TGA, and SEM. Besides, AC-CTW was also characterized by XRF, zeta potential, and BET. The batch adsorption of MB onto AC-CTW was tested at various times of contact, temperature, adsorbent dosage, solution pH, and initial solution concentrations. Adsorption mechanisms were investigated using kinetic models, isothermal models, and thermodynamic studies. Elementary CTW analysis showed carbon content of 39.29