Vladimír Frišták

Sorption and desorption of pertechnetate on biochar under static batch and dynamic conditions

The objective of this study was the utilization of three different biochars for pertechnetate removal from aqueous solutions. Biochars were prepared by slow pyrolysis from different feedstocks, characterized by BET, acid–base titration, SEM, XRD and FTIR and tested for their pertechnetate sorption using batch and dynamic techniques. Effect of various physico-chemical parameters such as contact time, pH and the presence of different ions in the solution on the sorption of pertechnetate onto biochars was investigated. Perrhenate as an analogue of pertechnetate was used for modeling of adsorption isotherms.

Sludge of wastewater treatment plants as Co2+ ions sorbent

Sludges produced in huge amounts by wastewater treatment plants (WWTP) display high fertility properties; however, the presence of heavy metals restricts their use for agricultural purposes. Sorption capacity of sludge is generally much higher and it can also be considered as a cheap sorbent of heavy metals. The paper describes cobalt sorption by dried activated sludge (DAS) obtained from the aerobic phase of a WWTP. DAS was characterized by FT-IR spectroscopy, cation exchange capacity (CEC), and atomic absorption spectrometry (AAS) analysis. Sorption capacity of DAS (Qeq) increased with the initial concentration (C0) of Co2+ (CoCl2) within the range from 100 μmol g−1 to 4000 μmol g−1, reaching 15 μmol g−1 and 200 μmol g−1, respectively. The maximum uptake capacity (Qmax) at pH 6.0 calculated from the Langmuir isotherm model was (256 ± 9) μmol g−1 for Co2+ ions. Obtained Q values were dependent on pH within the range from 3.0 to 7.0. Competitive effect of other bivalent cations such as Ni2+ in Co2+ sorption equilibrium was confirmed; which is in agreement with the hypothesis of the decisive role of ion-exchange mechanism in metal sorption. The obtained data are discussed from the point of view of potential utilization of sludges as sorbents, i.e. in non-agricultural application.

Effect Of Wood-Based Biochar And Sewage Sludge Amendments For Soil Phosphorus Availability

Abstract This study investigated the effects of two biochars (pyrolysed wood chips and garden clippings) on phosphorus (P) availability in a heavy-metal contaminated soil poor in phosphorus. Short-term 14-days incubation experiments were conducted to study how applications of biochars at different rates (1 and 5 %) in combination with (1:1) and without dried sewage sludge from a municipal waste water treatment plant (WWTP) affected the content of soil extractable P. For P-availability analyses deionized water, calcium acetate lactate (CAL), Mehlich 3 and Olsen extraction protocols were applied. In addition, the content of total and mobile forms of potentially toxic heavy metals (PTHM) was studied. Application of both biochars caused a significant decrease of PTHM available forms in sewage sludge amended soil samples. The concentration of total and available P increased with higher biochar and sewage sludge application rates.

Sorption separation of cobalt and cadmium by straw-derived biochar: a radiometric study

Biochar prepared from Triticum aestivum straw (SB) was used to investigate the sorption separation of Cd2+ and Co2+ ions in single and binary systems. The maximum adsorption capacity of SB was higher for Cd2+ ions and the process was strongly pH dependent. Adsorption data in the binary system Cd2+–Co2+ were well described by the extended Langmuir model and the values of affinity parameter b indicate a higher affinity of SB to Cd2+ in comparison with Co2+ ions. The mechanisms for the removal of Cd and Co by biochar were evidenced by the different instrumental analyses as well as by chemical speciation modeling. Elemental mapping of SB revealed spatial distributions of cobalt and cadmium on biochar surfaces. The role of functional groups in metal sorption was confirmed by FTIR. Results demonstrate that SB is a promising heavy metal-immobilizing agent for contaminated soils or water.

The Response of Artificial Aging to Sorption Properties of Biochar for Potentially Toxic Heavy Metals

Abstract This paper evaluates the effect of simulated conditions of artificial aging on sorption capacity of two types of biochar. These were produced by slow pyrolysis from different feedstock - beech wood chips (BC A) and garden green waste residues (BC B). Cadmium served as a model for potentially toxic metals. Twenty freeze-thaw cycles were used to simulate physical aging. The determination of biochar physicochemical properties showed main changes in CEC and SA values of aged sorbents. The maximum sorption capacities of aged BC A sorbent were higher by about 26 % and aged BC B sorbent by about 20% compared to Qmax of non-aged biochar. Qmax of aged BC B peaked at 9.4 mg g-1 whereas BC A sorbed significantly less Cd. FT-IR analyses confirmed the changes in structural composition and content of functional groups on biochar surfaces. The artificial physical aging model was assessed as an efficient tool for investigation of natural weathering conditions.

SIMULTANEOUS AND SEQUENTIAL EXTRACTION PROTOCOLS AS TOOLS FOR DETERMINATION OF ZINC BIOAVAILABILITY IN DRIED ANAEROBIC SLUDGE

Abstract Production of unsettleable sewage sludge with high water content is one of the problems of intensification of industrial activities and environmental protection. Sewage sludge with low toxic metals concentrations can be utilized as fertilizer and soil conditioner in agriculture. For determination of metal bioavailability, a wide range of extraction protocols and fractionation analyses can be used. We studied the distribution and quantified the leaching and bioavailability of zinc from dried anaerobic sludge by simultaneous, multi-step and three different sequential extraction protocols. For determination of zinc, the galvanostatic stripping chronopotentiometry (SCP) and electrothermal atomic absorption spectrometry (ETAAS) were used. The distribution of Zn in sequential extraction protocols was determined using a fivestep chemical fractionation procedures (BCR, Tessier and Van Hullebusch protocols). The potential bioavailability (0.9% NaCl, 0.1 mol/dm3 HCl, 0.1 mol/dm3 HNO3, 0.1 mol/dm3 CH3COOH, 0.1 mol/dm3 Na2EDTA, 0.1 mol/dm3 CaCl2, 0.1 mol/dm3 MgCl2, 0.1 mol/dm3 (NH4)2C2O4.H2O extraction) and pseudo total (aqua regia extraction and ETAAS analyses) content of Zn in sludge was determined. The amount of aqua regia extractable zinc in sludge samples was 650 ± 12 mg/kg (d.w.). We found out that the zinc was extractable from anaerobic sludge in first hour of contact time for all tested agents. Zinc was extracted with highest efficiency by 0.1 mol/dm3 (NH4)2C2O4.H2O, 0.1 mol/dm3 HCl and 0.1 mol/dm3 Na2EDTA. Sequential extraction protocols showed that the maximum extractable amount of zinc 126.3 ± 2.6 mg Zn / kg d.w. was bound to organic matter and sulfides. High concentrations of zinc in residual fractions were leachable under extraction conditions of strong acids only.

APPLICATION OF ISOTOPIC DILUTION AND SINGLE-STEP EXTRACTIONS FOR LABILE SOIL ZINC DETERMINATION

Abstract Concentration of available zinc from soils is the primary concern in assessment of its toxicity or essentiality for plants. This study evaluates the changes in chemical extractable Zn from three Slovak typical soils with simultaneous extractions as tools of zinc bioavailability. We found out that extractability of binding zinc decreased in order Na2EDTA, Mehlich 3, Mehlich 2, NH4NO3 and CaCl2 for all soil samples. Using flow-through stripping chronopotentiometry (SCP) and atomic absorption spectrometry (GFAAS) we found out that maximum of soil zinc was removed by organic ligands. Lability of Zn determined by isotopic dilution method using 65Zn and γ-spectrometry showed the significant decrease of isotopic exchangeable zinc fraction (E-value) with decrease of soil reaction. Obtained E-values of uppermost soil horizons showed the zinc lability ranged from 20 to 39%. Our research confirmed the effect of soil reaction, composition and physico-chemical characteristics to Zn lability. For further assessment of zinc bioavailability is needed to find the correlation and effects of structural changes and aging in studied soils

Evaluation of Mn bioaccumulation and biosorption by bacteria isolated from spent nuclear fuel pools using 54Mn as a radioindicator

Abstract Bioaccumulation and biosorption characteristics of Mn2+ ions by both dead and living, non-growing biomass of Gram-positive bacteria Kocuria palustris and Micrococcus luteus isolated from spent nuclear fuel pools were compared. The radioindicator method using radionuclide 54Mn was applied to obtain precise and reliable data characterizing both processes as well as manganese distribution in bacterial cells. Manganese was mainly found on the surface (biosorption) of live cells of both bacteria and surface sorption capacity increased with Mn concentration in solution. Only 10.0% (M. luteus) and 6.3% (K. palustris) of uptaken Mn were localized in the cytoplasm (bioaccumulation). Biosorption of Mn by dead bacterial biomass was a rapid process strongly affected by solution pH. Maximum sorption capacities Qmax calculated from the Langmuir isotherm and characterizing Mn binding represented 316±15 μmol/g for M. luteus and 282±16 μmol/g for K. palustris. Results indicate that living, non-growing cells showed a higher efficiency of Mn removal than dead biomass. Based on FTIR spectra examination with aim to characterize the surface of K. palustris and M. luteus cells, we confirmed that the phosphate and carboxyl functional groups are involved in manganese sorption onto cell surface by both live and dead bacterial biomass.

Correction to: Sorption separation of Eu and As from single-component systems by Fe-modified biochar: kinetic and equilibrium study

Unfortunately, the address of Barbora Micháleková-Richveisová is wrong in the published article. The correct address is given below as number 6.

Pyrolysis Products as Soil Fertilizers: Screening of Potentially Hazardous Aromatic Compounds

Abstract This study investigated the concentrations of polycyclic aromatic hydrocarbons (PAHs) in pyrogenic carbonaceous materials (PCM) produced from three waste materials during slow pyrolysis at 400 and 500°C. As feedstocks bone meal (BM), biogas slurry (BC) and chicken manure (CM) were used. As potentially problematic substances 1- and 2- methylnaphthalene were analysed as indicators for methylated hydrocarbons in pyrolysis products. The phytotoxic effect of soil amendments was evaluated by a standard cress germination test with Lepidium sativum L. The analysis showed higher concentrations of the sum of 16 US-EPA PAHs in samples produced at lower temperature and in samples produced from biogas slurry. Concentrations of 1- and 2-methylnaphthalene showed similar trends with concentrations in a range of 35-205% of the sum of 16 PAHs. Germination tests showed inhibition effects of products from biogas slurry when applied in concentrations of ≥ 10 % to standard substrate. Apparently pyrolysis of biogas slurry requires special attention to avoid accumulation of PAHs and methylated naphthalenes.