Citric Acid Removal from Aqueous Solution with Layered Aluminum Hydroxide Crystals

Aluminum hydroxide is a compound with diverse crystalline structures, some of which demonstrate the ability to remove chemicals from aqueous solutions. In this research, aluminum hydroxide with the Bayerite structure was synthesized and used to remove Citric Acid (CA). This structure was not modified under the reaction conditions where CA ranged from 2 to 6 mg of CA in 20 mL of water, the temperature ranged from 30 to 90 °C, and time ranged from 8 to 24 h. The constants in the Freundlich model indicated that adsorption is the phenomenon governing the CA capture by aluminum hydroxide. According to infrared spectroscopy data, adsorption of CA was produced by the hydrogen bond of hydroxyl groups in aluminum hydroxide with either carboxylate or carboxylic groups in CA. The highest removal of CA was 92.12% and the temperature was the only factor with an effect on the percentage of CA removal.