Characterization of candle soot obtained from combustion of candle wax for the removal of methylene blue

Abstract

Carbonaceous candle soot (CS) was prepared from combustion of candle wax in the laboratory. Thus prepared material has been characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). Surface area, methylene blue number (MBN), and iodine number (IN) were also investigated. EDX clearly showed high carbon content. XRD exhibited well defined graphitic domain structure. Oxygen functionality has been observed on the surface by FTIR. The specific surface area of CS, was found to be 242.46 m²/g. Thus prepared CS was used for the removal of dye from aqueous solution by batch adsorption studies. Methylene Blue (MB) was used as a model dye. The adsorption parameters such as contact time, initial concentration of MB and adsorbent dosage, and pH were also examined. The optimum pH was found to be 10 while optimum time and adsorbent dose was found to be 2 hrs and 0.25 g/L respectively. After optimizing parameters, CS as an adsorbent have been used to remove MB where a significant 97% MB adsorption was observed. To evaluate adsorption behaviors of CS, different adsorption isotherm models have been tested. Langmuir isotherm and Temkin isotherm model revealed the chemisorption type of adsorption perceived in CS. The maximum monolayer coverage (Q_m) was found to be 17.95 mg/L with the dimensionless separation factor R_L ˂ 1 indicating a favorable sorption condition. Therefore, it might be an impressive alternative for the treatment of colored wastewater discharged from many industrial outlets including textile.