Carbonized waste biomass as a sorbent in the recycling of macro- and microelements from the contaminated environment

Dissertation thesis offers a comprehensive look at the use of materials based on biochar in case of sorption separation of anionic and cationic contaminants, the impact of aging on the sorption properties of biochar and its further application in the form of soil additives as a source of nutrients for plants. The conclusions of the dissertation can be summarized as follows: Biochar prepared by slow pyrolysis from cobs (BCA), garden waste (BCB), and oak wood chips (BCC) has a low efficiency in the separation of PO₄³⁺ anions from aqueous solutions. Modification of biochar by Fe-impregnation significantly increased uptake of PO₄³⁺ anions. In all three cases of the modified biochar showed higher sorption capacity for PO₄³⁺ anions (IBC A 55 times more, IBC B 20 times more, IBC C 12 times more) compared to the non-modified samples. The maximum sorption capacity Q_max was found in case of IBC C (3.201 ±0.187 mg/g). Sorption of PO₄³⁺ anions by impregnated biochar has been affected by the reaction pH, contact time and initial concentration of PO₄³⁺ in solution. SEM/EDX analysis confirmed the binding of Fe on the surface of biochar assuming that during the modification is formed a layer of Fe²⁺/Fe³⁺ in the form of oxides. This modification enables sorption of PO₄³⁺ anions by electrostatic forces to the positively charged functional groups on the biochar surface. In case of metal cations sorption, we took into account the fact that the heavy metals are present in the real environment together with other cations and anions affecting the sorption process. Therefore, the sorption separation of Cd²⁺ and Co²⁺ ions by wheat biochar (SBC) was performed in single and binary system. In single metal system, the maximum sorption capacity of biochar (Q_max) calculated from the Langmuir isotherm was significantly higher for Cd²⁺ ions (193±10 mmol/g) compared to the Co²⁺ ions (89±1.8 mmol/g). In binary system was observed at various molar ratios of [Cd]:[Co] a significant effect of Cd²⁺ ions on Co²⁺ sorption, which indicates a higher affinity of SBC toward Cd²⁺ ion. Sorption process is greatly influenced by the pH of the solution and metal chemical speciation. At lower pH was the competition for sorption sites between H⁺ and Cd²⁺ or Co²⁺ ions. At pH 8 was observed maximum sorption of Co and Cd, which is related to precipitation. SEM/EDX and FTIR analysis confirmed that the main mechanisms of Co and Cd sorption were related to the charged and uncharged functional groups of biochar and metal ion precipitation. Other possible binding sites provides the presence of minerals (sylvite, calcite, apatite) in biochar. Effect of simulated physical aging of biochar samples BCB and BCC on the sorption separation of Cd²⁺ ions highlighted the positive impact of aging on the sorption capacity of both biochar samples. The maximum sorption capacity of the aged biochar A-BCB was higher by 20% and A-BCC by 26% compared to the values Q_max of unmodified biochar. Changes in temperature led to a change in values of CEC and SA. FT-IR analysis confirmed the changes in the structure and content of the functional groups on the surface of the aged biochar. Ageing simulation is a powerful tool for assessing the real physical and chemical effects on the sorption efficiency of biochar applied to the environment (especially soil application). Pyrolysis products based on municipal activated sludge (AKBC) and industrial waste water treatment plants (PAKBC) were prepared by slow pyrolysis (430 grad C). Pyrolysis process increased nutrient content in biochar, while there was a decrease in the concentration of PAHs. Extraction with DTPA confirmed the reduced pollutant availability in biochar. Application of pyrolysis products to phosphorus deficient soils containing potentially toxic substances caused reduction in metal mobility and increased of total phosphorus content in the soil. Obtained knowledge of dissertation thesis indicate that biochar can be applied not only in the process of sorption separation of contaminants (anions and cations). Thermochemical conversion of sewage sludge is possible to obtain stable and valuable type of soil additive with 2- or 3 times higher phosphorus content. Moreover, the pyrolysis process of sewage sludge besides the closure of phosphorus cycle in the environment can significantly reduce the mobility of inorganic contaminants and eliminate organic and biological contaminants present in the sludge. (author)