Anionic Surfactant Adsorption on Activated Carbons Produced from Lignin and Modified with Cellulose Sulfoacetate

Abstract

This work is devoted to studying the adsorption of sodium dodecyl sulfate (SDS) and sodium N-lauryl sarcosinate (NLS) on activated carbons produced from hydrolytic lignin using laboratory and pilot setups. Commercially available activated carbons produced by “Sorbent” Ltd. and SKT-3 are used for comparison. The surface of the activated carbons is modified (hydrophilized) by cellulose sulfoacetate (CSA) adsorption from aqueous solutions. Amounts of surfactants adsorbed on the activated carbon surface are determined from their radioactivity using tritium-labeled compounds. It has been found that the maximum adsorption of anionic surfactants is higher on activated carbons obtained from lignin. Adsorption values in the saturation region are 1.7 and 1.5 mmol/g for SDS and NLS on activated carbons obtained from lignin and 0.8 mmol/g for both surfactants adsorbed on commercial carbons. It has been shown that the preliminary application of CSA does not affect the maximum adsorption of NLS at its high concentrations; however, it reduces its adsorption in the initial region of the isotherm. Adsorption of CSA and its ability to be retained on the surface of the activated carbons is also studied. Tritium-labeled CSA has been used to show that the isotherm of its adsorption on activated carbon obtained from lignin is S-shaped beginning from a concentration of 0.5 g/L and reaches a maximum value of 25 mg/g. In the presence of NLS, the polymer is desorbed from the carbon surface by more than 50%.