Metal extraction from Cetraria islandica (L.) Ach. lichen using low pH solutions

Extraction of metals (K, Al, Ca, Mg, Fe, Cu, Ba, Zn, Mn and Sr) from dry Cetraria islandica (L.) Ach. lichen was performed using solutions similar to acid rain (solution A H2SO4-HNO3-(NH4)2SO4 and solution B H2SO4- -HNO3-(NH4)2SO4-NH4NO3). The pH values of these solutions were 2.00, 2.58, 2.87, 3.28, and 3.75. Five consecutive extractions were performed with each solution. In all solutions, the extracted metal content, except Cu and Ca, was the highest in the first extract. The highest percentage of the metals desorbed in the first extraction was obtained using solutions with low pH values, 2.00, 2.58, and 2.87. The lowest percentage in the first extraction was obtained using solutions with pH 3.28 and pH 3.75, indicating influence of the H+ ion on the extraction. According to the results obtained, the investigated metals form two groups. The first group includes K, Al, Ca, Mg, and Fe. They were extracted in each of the five extractions at each of the pH values. The second group includes Ba, Zn, Mn, Cu, and Sr, which were not all extracted at each pH value. The first group yielded three types of extraction curves when the logarithms of extracted metal amounts were plotted as a function of the number of successive extractions. These effects indicate that three different positions (centers) of metal ion accumulation exist in the lichen (due to sorption, complex formation, or other processes present in the tissues). Ispitivana je ekstrakcija metala K, Al, Ca, Mg, Fe, Cu, Ba, Zn, Mn i Sr sorbovanih u uzorcima lisaja Cetraria islandica (L.) Ach. kiselim rastvorima (rastvor A H2SO4-HNO3-(NH4)2SO4 i rastvor B - H2SO4--HNO3-(NH4)2SO4-NH4NO3) slicnim kiselim kisama. pH vrednosti rastvora su iznosile 2,00; 2,58; 2,87; 3,28 i 3,75. Uradjeno je pet sukcesivnih ekstrakcija sa svakim rastvorom. Najuspesnije su prve ekstrakcije navedenim rastvorima, osim kod Cu i Ca. Najveci procenat desorpcije metala je prvim ekstrakcijama kada se koriste rastvori niskih pH vrednosti 2,00; 2,58 i 2.87. Nizi procenti kod prvih ekstrakcija su dobijeni koriscenjem rastvora pH 3,28 i 3,75 sto ukazuje na uticaj H+ jona na ekstrakciju. Ispitivanja su pokazala da se desorbovani metali mogu podeliti u dve grupe. Prvoj grupi pripadaju K, Al, Ca, Mg i Fe, koji se desorbuju svim ekstrakcijama rastvorima svih pH vrednosti. Drugoj grupi pripadaju Ba, Zn, Mn, Cu i Sr koji nisu desorbovani svim ekstrakcijama i pri svim pH vrednostima. Logaritamska zavisnost sadrzaja metala u funkciji od broja desorpci