Preparation and characterization of carbons from β-cyclodextrin dehydration and from olive pomace activation and their application for boron adsorption

An activated carbon was prepared by phosphoric activation of olive pomace and further oxidation by nitric acid. Another carbon was obtained from β-cyclodextrin dehydration in concentrated sulfuric acid. A composite of the oxidized activated carbon and the carbon from β-cyclodextrin was prepared. The four materials were characterized by N2 adsorption-desorption measurements, X-ray diffraction, infrared and Raman spectroscopies, elemental analysis, “Boehm” titration and measurements of pH of the point zero charge. The obtained adsorbents were tested for boron adsorption in aqueous solution. Despite their lowest specific surface areas, the composite carbon and the amorphous carbon from cyclodextrin dehydration showed the highest boron adsorption uptake (1.41 and 1.68 mg·g−1) compared to the raw (1.05 mg·g−1) and oxidized (0.95 mg·g−1) activated carbons. The surface chemistry particularly rich in phenolic groups was responsible for the high boron adsorption uptake of the carbon composite and the amorphous carbon, both prepared through cyclodextrin dehydration.