Evaluation of corn-cob biochar as a packing material

The corn-cob was pyrolyzed at 400 °C to prepare biochar and was used as a supporting material for microbial immobilization. The biochar was sterilized before use by autoclaving for 15 min at 15 psi (121 °C) to ensure that microbes were not involved during the adsorption process. FT-IR analysis by KBr pellet technique was performed to assess the presence of functional groups in biochar before and after adsorption using the Thermofisher Scientific, Nicolet IS10 in ATR mode (with the 16-scan speed in the mid-IR range of 400–4000 cm⁻¹). CHNS analysis was carried out to determine the composition of existing elements in biochar, such as carbon, hydrogen, nitrogen, and sulfur (Elementar Analysen Systeme, Germany/Vario EL). SEM analysis (JEOL JSM-6084LV) determines the surface morphology of the biochar. Biochar porosity, surface area, and adsorption volume were evaluated using a BET analyzer (Quanta chrome/AUTOSORB-1).

The corn-cob biochar (CC-biochar) has also been examined for the adsorption and desorption of the Indanthrene Blue RS dye packed in the column. For adsorption experiments, 2.5 g of CC-biochar was added with Indanthrene Blue RS (100 mg L⁻¹) to 100 mL of MBM. The flasks were incubated in an isothermal shaker (120 rpm) at room temperature. The samples were withdrawn at a regular time interval (30 min) for 4 h. The supernatant was then centrifuged at 8000 rpm for 10 min. The percentage of dye removal was measured spectrophotometrically at 520 nm. The desorption experiments were carried out by subsequently drying and transferring the spent CC-biochar sample into NaCl solution (100 mL) (Voudrias et al.⁴⁴). The flasks were incubated in an isothermal shaker, and the study was carried out as specified in adsorption experiments. The final concentrations of desorbed dye were determined spectrophotometrically at 520 nm.