Anthropogenic activities alter the natural flow of materials and introduce novel chemicals into the
environment thereby causing serious soil and water pollution. Indeed, many industries produce aqueous
effluents containing toxic substances, especially heavymetals. The presence of these contaminants in the
environment is a great issue because of their toxicityand bioaccumulation ability which affect human life
and the environment. Various physicochemical and biological techniques have been used to remove the
heavy metals from waste waters, including chemical precipitation, ion exchange, chemical coagulation,
electrolytic methods, membrane processes, and adsorption.
Biochar is a carbonaceous material obtained from the pyrolysis of plant and animal biomasses. Due to its
high porosity, it could be a potential alternative to the existing conventional technologies for the removal
and/or recovery of metal ions from aqueous solutions.
The aim of this work was the chemical-physical characterization of biochar produced from chicken manure
(CM), conifers and poplar wood wastes in order to assess their ability in the removal of heavy metal from
aqueous solutions.
Chemical-physical characterization of the different CM chars was conducted by cross polarization magic
angle spinning (CPMAS)
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C NMR spectroscopy and NMR relaxometry together with a comparative study
between the removal efficiencies of Cu(II), Ni(II) andPb(II) from synthetic wastewater by using adsorption
onto biochars surfaces.
From adsorption studies, it was observed that conifer biochar did not significantly adsorbed metals. This
behavior is probably due to his own chemical characteristics, since it’s quite hydrophobic and probably its
surface lacks functional groups able to bind ions.
Conversely, chicken manure biochar proved to have the highest removal efficiencies for all the metals
considered, in the order Pb(II)>Cu(II)>Ni(II) ions.
In conclusion, different chars have different physicochemical characteristics so they should be addressed to
different uses. For example, conifer char should not be used for remediation since it’s not effective in
removing inorganic metals from aqueous solutions.
The most effective in remediation was chicken manure biochar, probably thanks to the presence of
nitrogen on its surface. In fact, nitrogen has a free electronic doublet/pair able to interact with cation.
Finally, char metals absorption involves both a physical and a chemical mechanism and further studies
should be addressed to explain it
