Preparation of Mesoporous Carbon from Sodium Lignosulfonate by Hydrothermal and Template Method and Its Adsorption of Uranium(VI)

A novel adsorbent of mesoporous carbon with high specific surface area was successfully prepared by hydrothermal and template method, using sodium lignosulfonate (LSs) as a raw material and cetyltrimethylammonium bromide (CTAB) as a template agent. The mesoporous carbon was characterized by SEM, TEM, BET, FTIR, and XPS. The formation mechanism of the mesoporous carbon was analyzed. The adsorption of uranium­(VI) on the mesoporous carbon from the simulated aqueous solution and actual radioactive wastewater was respectively investigated. The optimum conditions for U­(VI) adsorption were determined by studying experimental variables including pH, contact time, sorbent dose, initial concentration, and temperature. The results indicated that the maximum adsorption capacity of the mesoporous carbon for U­(VI) in the simulated aqueous solution and actual radioactive wastewater was respectively 109.46 mg/g at pH 5.5 and 328.15 K and 195.6 mg/g at pH 5.5 and the initial U­(VI) concentration of 189.75 mg/L. The adsorption data could be well described by the pseudo-second-order model and Freundlich isotherm model. The adsorption of U­(VI) on the mesoporous carbon was an endothermic and spontaneous process. The adsorption mechanism may be a complex chemical reaction between uranium and the oxygen-containing functional groups on the mesoporous carbon