Rapidly increasing environmental pollution by potentially toxic elements (PSE) poses a
serious threat and at the same time encourages the development of effective, sustainable
ways of remediating contaminated sites. In my diploma thesis, I compared the efficiency
of immobilization of PSE with three different adsorbents, namely animal biochar (ABC),
vegetable biochar (CG) and hydroxyapatite (HAp). After 24 hours of exposure of
different combinations of nitrate solutions to the adsorbents, I monitored changes in pH
and redox potential in their extracts. Using the quantitative analysis method ICP-OES,
we measured the concentrations of metals (lead, cadmium and zinc) and leached elements
(calcium and phosphorus) in the extracts. We also determined the concentrations of total,
organic and inorganic carbon. The results revealed the action of the adsorbents through
various mechanisms. ABC exhibited remarkable buffering capacity, as pH values rose to
the neutral to slightly basic range despite the presence of metals. This behaviour is closely
related to the leaching of inorganic carbon, which neutralizes acidic solutions. ABC also
demonstrated structural stability by eliminating minimum concentrations of organic
carbon, which were further reduced in the presence of metals. HAp had no significant
effect on the pH of the extracts, but acted primarily through the release of calcium and
phosphate ions, which bound to PSE and immobilized them. Commercially available CG
proved to be an effective material. Lead was almost completely immobilized in all
systems and was preferred over the other two metals, cadmium and zinc. The research
confirms that biochar of animal origin represents a safer and more stable alternative for
mitigating environmental pollution from PSE.
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