Partially pyrolyzed olive pomace sorbent of high permeability for preconcentration of metals from environmental waters

The aim of this work is to develop a preconcentration procedure of Cd2+, Zn2+ and Cu2+ in environmental waters using olive pomace (OP) prior to their determination by flame atomic absorption spectrometry (FAAS). Raw OP as preconcentrating sorbent was found to have low permeability towards the passed water samples and thus long time was needed. Even reducing the vacuum pressure caused cartridge blockage. Novel preconcentrating sorbents of high permeability were then prepared by heat pretreatment under inert atmosphere (partial pyrolysis) of OP at various temperatures (100, 150, 200, 250 and 300 °C). The permeability of OP pyrolyzed at 200 °C (sorbent OP-200) was enhanced 11 times relative to the raw OP, which significantly reduced the time required in the preconcentration process. A preconcentration procedure was optimized using OP-200 as preconcentrating sorbent, in which the detection limits were 42 ng L−1 for Cu2+, 76 ng L−1 for Zn2+ and 172 ng mL−1 for Cd2+. The method was linear within the studied concentration range (2-100 ng mL−1). The proposed method gave recoveries from 83 ± 6 to 103 ± 5% for determination of metals in tap water; and recoveries from 81 ± 6 to 100 ± 6% in well water. The method was validated by comparison with independent method and by analysis of lake sediments LKSD-4 certified reference material.