The results of proximate and ultimate analysis and surface
properties of the sour cherry stones and activated carbon are given
in Table 1. The carbon content increased after activation process,
and the hydrogen, nitrogen and oxygen contents indicated the
opposite change trend. Since the sulfur content of activated carbon
was below the detection limit, the activated carbon could be used
in adsorption and purification process. This is due to the release of
volatiles during carbonization that results in the elimination of
non-carbon species and enrichment of carbon (Aygün et al.,
2003). Also, activation process led to an increase in fixed carbon
content while decrease in volatile matter content. The ash content
of activated carbon slightly increased by activation process. The
porosity has a strong effect on the adsorption properties of the
activated carbon. The specific surface area of activated carbon
was found to be 1704 m2 g1 and a good deal of the material
(63%) consisted of micropores. The nitrogen adsorption–desorption
isotherms and pore size distribution of activated carbon obtained
from sour cherry stones are presented in Supplementary
Figs. S1a and S1b. The isotherms of activated carbon can be properly
classified as a mixture of type I and type IV isotherms. According
to the International Union of Pure and Applied Chemistry
(IUPAC) classification, type I isotherm can be associated with
microporous structure while type IV isotherm exhibited by the
mixture of microporous and mesoporous material (Angın et al.,
2013a; Sütçü and Demiral, 2009; Foo and Hameed, 2011).