Efficient Removal of Dibenzothiophene from Liquid Oil and Cr(VI) from Waste Water Using Tea Waste-Derived Magnetic Activated Carbon Nanocomposite

A magnetic-activated carbon nanocomposite was synthesized through the ZnCl2–FeCl3 activation of tea waste residue by optimizing the synthesis conditions. The typical nanocomposite was created at 600°C for 1 h, employing a 1 : 1 activator: feed soaking ratio. The BET surface area, FESEM, VSM, pore volume, XRD, and EDX of the nanocomposite were identified. The nanocomposite had a specific surface area of 928.77 m2/g and a 2.80 nm mean pore diameter, demonstrating its mesoporosity. Dibenzothiophene adsorption from model oil (200 ppm dibenzothiophene /hexane) and Cr(VI) from an aqueous solution (200 mg/L) were tried by this adsorbent. The maximum elimination efficiency of dibenzothiophene from the solution was 99.02%, utilizing 0.35 g of the nanocomposite at 25°C for 30 min. Simultaneously, the highest elimination efficiency of Cr(VI) from aqueous solution amounted to 97.50%, implementing 0.20 g of the nanocomposite at 25°C for 120 min. Also, the nanocomposite ascertained its ability to remove S-compounds from real gasoline fuel and Cr(VI) from its solution in actual water. Adsorption of pollutants from their liquid phases by the nanocomposite fitted best with the Langmuir adsorption isotherm and the pseudo-2nd-order model. The reusability studies of the spent adsorbent showed its activity even after 5 reuse cycles with an efficiency exceeding 91.0%. In conclusion, the nanocomposite originated from waste tea residue can be recommended as a potential adsorbent to strip various pollutants from different liquid phases.