Activated Carbon Adsorption Of Hydroquinone Isomers With The Same Score

The adsorption capacity of the benzenediol isomers from solutions over theactivated carbon and modified activated carbon were studied here. The results canprovide the theory base for activated carbon application in separating isomercomponents.This paper used commercially available nutshell-based activated carbon asstarting materials. It was ground to the particle of more than200mesh. Three types ofactivated carbons were prepared from the pristine activated carbon by means of HNO3oxidation, heat treatment under N2atmosphere at600oC and H2atmosphere at900oC.The effect of the adsorption temperature, the pH of the solution as well asthe surface functional groups on the adsorption of benzenediol isomers on4activatedcarbons have been investigated by the batch method.The experimental results show that the order of the adsorption capacity ofisotherms of benzenediol isomers is hydroquinone>catechol>resorcinol. All theadsorption isotherms of benzenediol isomers on activated carbon could be well fittedby Langmuir equation. In the temperature range from25oC to65oC, the adsorptioncapacity of hydroquinone and catechol increases with the increased temperature. Theadsorption amount of resorcinol at25oC is higher than that at45oC and under65oC,indicative of the different adsorption law.The adsorption capacity of hydroquinone and catechol in the neutral and alkalinesolutions was higher than that at the acidic conditions, but the adsorption capacity ofresorcinol in acid and alkaline solution is higher than at the neutral solution.The oxygen-containing surface groups of activated carbon had the negativeeffect on the adsorption of benzenediol isomers, carboxyl group being the mostsignificant. This mainly because of the acidic group enhanced the hydrophilicisty ofactivated carbon and preoccupied the adsorption sites accessible to adsorbatemolecules. When the surface functional groups were removed, the adsorption amountis thus significantly increased.