Biochars prepared from nut shells, plum stones, wheat straws, grape stalks and grape husks were tested as potential sorbents for Cd and Pb. Mechanisms responsible for metal retention were investigated and optimal sorption conditions were evaluated using the RSM approach. Results indicated that all tested biochars can effectively remove Cd and Pb from aqueous solution (efficiency varied between 43.8% and 100%). The removal rate of both metals is the least affected by the biochar morphology and specific surface but this removal efficiency is strongly pH-dependent. Results of variable metal removal combined with different optimized conditions explain the different metal sorption mechanisms, where the predominant mechanism is ion exchange. In addition, this mechanism showed very strong binding of sorbed metals as confirmed by the post-desorption of the fully metal-loaded biochars. Finally, these biochars could thus also be applicable for metal contaminated soils to reduce mobility and bioavailability of Cd and Pb.
- MeSH
- adsorpce MeSH
- chemické látky znečišťující vodu analýza MeSH
- chemické modely MeSH
- čištění vody metody MeSH
- dřevěné a živočišné uhlí chemie MeSH
- kadmium chemie MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- mikroskopie elektronová rastrovací MeSH
- olovo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Two experiments were carried out to study the competition for adsorption between trace elements (TEs) and nutrients following the application of nano-maghemite (NM) (iron nano-oxide; Fe2O3) to a soil solution (the 0.01molL(-1) CaCl2 extract of a TEs-contaminated soil). In the first, the nutrients K, N, and P were added to create a set of combinations: potential availability of TEs during their interaction with NM and nutrients were studied. In the second, response surface methodology was used to develop predictive models by central composite design (CCD) for competition between TEs and the nutrients K and N for adsorption onto NM. The addition of NM to the soil solution reduced specifically the concentrations of available As and Cd, but the TE-adsorption capacity of NM decreased as the P concentration increased. The CCD provided more concise and valuable information, appropriate to estimate the behavior of NM sequestering TEs: according to the suggested models, K(+) and NH4(+) were important factors for Ca, Fe, Mg, Mn, Na, and Zn adsorption (Radj(2)=95%, except for Zn with Radj(2)=87%). The obtained information and models can be used to predict the effectiveness of NM for the stabilization of TEs, crucial during the phytoremediation of contaminated soils.
