surface charring
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In this research, the adsorption of two herbicides, alachlor (ALA) and terbuthylazine (TBA), on granular activated carbon (GAC) in the presence of well-characterized peptide fraction of cellular organic matter (COM) produced by cyanobacterium Microcystis aeruginosa was studied. Two commercially available GACs were characterized using nitrogen gas adsorption and surface charge titrations. The COM peptides of molecular weight (MW) < 10 kDa were isolated and characterized using MW fractionation technique and high-performance size exclusion chromatography (HPSEC). The effect of surface charge on the adsorption of COM peptides was studied by means of equilibrium adsorption experiments at pH 5 and pH 8.5. Electrostatic interactions and hydrogen bonding proved to be important mechanisms of COM peptides adsorption. The adsorption of ALA and TBA on granular activated carbon preloaded with COM peptides was influenced by solution pH. The reduction in adsorption was significantly greater at pH 5 compared to pH 8.5, which corresponded to the increased adsorption of COM peptides at pH 5. The majority of the competition between COM peptides and both herbicides was attributed to low molecular weight COM peptides with MW of 700, 900, 1300 and 1700 Da.
- MeSH
- acetamidy analýza chemie MeSH
- adsorpce MeSH
- chemické látky znečišťující vodu analýza chemie MeSH
- dřevěné a živočišné uhlí chemie MeSH
- herbicidy analýza chemie MeSH
- kinetika MeSH
- Microcystis chemie MeSH
- odpad tekutý - odstraňování metody MeSH
- peptidy chemie MeSH
- povrchové vlastnosti MeSH
- triaziny analýza chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Biochar application is a widely investigated topic nowadays, and precisely described biochar parameters are key information for the understanding of its behaviour in soil and other media. Pore structure and surface properties determine biochar fate. However, there is lack of complex, investigative studies describing the influence of biomass properties and pyrolysis conditions on the pore structure of biochars. The aim of our study was to evaluate a wide range of gathered agriculture residues and elevated pyrolysis temperature on the biochar surface properties and pore composition, predicting biochar behaviour in the soil. The biomass of herbaceous and wood plants was treated by slow pyrolysis, with the final temperature ranging from 400 to 600 °C. Specific surface ranged from 124 to 511 cm2 g-1 at wood biochar and from 3.19 to 192 cm2 g-1 at herbaceous biochar. The main properties influencing biochar pore composition were increasing pyrolysis temperatures and lignin (logarithmically) and ash contents (linearly) of biomass. Increasing lignin contents and pyrolysis temperatures caused the highest biochar micropore volume. The total biochar pore volume was higher of wood biomass (0.08-0.3 cm-3 g-1). Biochars of wood origin were characterised by skeletal density ranging from 1.479 to 2.015 cm3 g-1 and herbaceous ones 1.506-1.943 cm3 g-1, and the envelope density reached 0.982 cm3 g-1 at biochar of wheat grain origin and was generally higher at biochars of herbaceous origin. Density was not pyrolysis temperature dependent.
The present study aimed to envisage the effect of physicochemical properties on the performance of Gliricidia sepium biochar (GBC) pyrolyzed at 300, 500, and 700 °C in the removal caffeine (CFN); a pharmaceutical and personal care product, from water. The physicochemical properties of GBC were characterized by proximate and ultimate analysis, BET, SEM, FTIR, and Raman spectroscopy. The adsorption batch experiment was carried out at various pH values (pH 3-10), mixing times (up to 24 h), and initial CFN concentration (10-500 mg/L). The FTIR analysis revealed the loss of polar functional groups on the surface of GBC derived at high temperatures. The red-shifted and blue-shifted Raman peaks indicate the condensation of small molecules on GBC. The GBC derived at 700 °C demonstrated high CFN adsorption capacity (16.26 mg/g) due to its high surface area and aromaticity. The highest adsorption of CFN was occurred at acidic pH range from 3.5 to 4.5 due to the existence of non-specific attraction between CFN and GBC. The kinetics and isotherm experimental data were fitted with Elovich and fractional power kinetic regression, Freundlich, and Temkin isotherm models, which suggested the adsorption of CFN on the GBC by mixed mechanisms; physisorption and chemisorption including π-π interactions, hydrogen bonding, n-π interactions, electrostatic attraction, and electron donor-acceptor attraction. Moreover, both surface area and aromaticity index have demonstrated a high positive correlation for CFN adsorption, signifying the importance of controlling physicochemical properties based on the end-user purpose of biochar.
Japanese knotweed (JK) is considered one of the most problematic invasive plants. Great attention was paid to research any possibilities of reducing its occurrence. This work deals with possibilities of easy transformation of JK into carbon adsorbent (AC), which is usable for sorption of diclofenac and paracetamol. Activated carbons were prepared by microwave heating using H3PO4, NaOH and sodium methanolate as the chemical agents. Characterization of AC's was carried out using BET, ATR-FTIR, SEM, adsorption equilibrium and kinetics experiments. The pseudo-second-order model showed the best similarity criteria for all studied systems adsorbent/adsorbate. The sorption efficiency was influenced by the choice of activating agent, where the π-π interactions between the planes of the obtained adsorbent and the aromatic rings of adsorbate and the interactions between the adsorbate and AC functional groups of the surface played an important role. AC-H3PO4 exhibited highest adsorption capacity for both diclofenac (87.09 mg.g-1) and paracetamol (136.61 mg.g-1).
Phosphorus reduction from wastewater is vital to mitigate eutrophication of receiving waters. In this study, discarded lignocellulose biochar loaded with lanthanum (defined as La-biochar) was applied for phosphate adsorption. Based on the design of response surface methodology, La-biochar displayed a high phosphate adsorption capacity of 36.06 mg P/g, strong pH-compatibility from 3 to 12, favorable selectivity for phosphate among foreign ions (Cl-, SO42-, CO32-, HCO3- and NO3-), excellent reusability with 92.3% desorption efficiency and retained 85% adsorption capacity after five recycles. The adsorption law of La-biochar perfectly matched with the pseudo-second-order model and the Langmuir model. Moreover, real wastewater adsorption experiments indicated the removal of total phosphorus within 20 min. Ligand exchange, electrostatic attraction, and complexation mechanisms contributed to phosphate adsorption on La-biochar. Overall, the La-biochar material could be applied as a potential sustainable building block for the preconcentration of phosphorus for practical pollutant purification.
This paper discusses Cd(II) and Pb(II) sorption efficiency of biochars modified by impregnation with magnetic particles. All selected biochar characteristics were significantly affected after the modification. More specifically, the cation exchange capacity increased after the modification, except for grape stalk biochar. However, the changes in the pH value, PZC, and BET surface after modification process were less pronounced. The metal loading rate was also significantly improved, especially for Cd(II) sorption on/in nut shield and plum stone biochars (10- and 16-times increase, respectively). The results indicated that cation exchange (as a metal sorption mechanism) was strengthened after Fe oxide impregnation, which limited the desorbed amount of tested metals. In contrast, the magnetization of grape stalk biochar reduced Pb(II) sorption in comparison with that of pristine biochar. Magnetic modification is, therefore, more efficient for biochars with well-developed structure and for more mobile metals, such as Cd(II).
This paper evaluates a novel sorbent for the removal of potentially toxic elements, inherent cations, and hetero-chloride from hydraulic fracturing wastewater (FWW). A series of iron-biochar (Fe-BC) composites with different Fe/BC impregnation mass ratios (0.5:1, 1:1, and 2:1) were prepared by mixing forestry wood waste-derived BC powder with an aqueous FeCl3 solution and subsequently pyrolyzing them at 1000 °C in a N2-purged tubular furnace. The porosity, surface morphology, crystalline structure, and interfacial chemical behavior of the Fe-BC composites were characterized, revealing that Fe chelated with CO bonds as COFe moieties on the BC surface, which were subsequently reduced to a CC bond and nanoscale zerovalent Fe (nZVI) during pyrolysis. The performance of the Fe-BC composites was evaluated for simultaneous removal of potentially toxic elements (Cu(II), Cr(VI), Zn(II), and As(V)), inherent cations (K, Na, Ca, Mg, Ba, and Sr), hetero-chloride (1,1,2-trichlorethane (1,1,2-TCA)), and total organic carbon (TOC) from high-salinity (233 g L-1 total dissolved solids (TDS)) model FWW. By elucidating the removal mechanisms of different contaminants, we demonstrated that Fe-BC (1:1) had an optimal reducing/charge-transfer reactivity owing to the homogenous distribution of nZVI with the highest Fe0/Fe2+ ratio. A lower Fe content in Fe-BC (0.5:1) resulted in a rapid exhaustion of Fe0, while a higher Fe content in Fe-BC (2:1) caused severe aggregation and oxidization of Fe0, contributing to its complexation/(co-)precipitation with Fe2+/Fe3+. All of the synthesized Fe-BC composites exhibited a high removal capacity for inherent cations (3.2-7.2 g g-1) in FWW through bridging with the CO bonds and cation-π interactions. Overall, this study illustrated the potential efficacy and mechanistic roles of Fe-BC composites for (pre-)treatment of high-salinity and complex FWW.
This research deals with the removal of Cr(VI), one of the most toxic heavy metal in biological systems, from wastewater by using activated carbon produced via pyrolysis and chemical activation of "Posidonia oceanica". That is the most important and well-studied seagrass species of the Mediterranean Sea. The as produced activated carbon exhibited high specific surface area up to 1563 m2/g and a cumulative pore volume of 0.74 cm3/g, allocated to 74% micro-pores and 26% to meso-macro- pores. The adsorption capacity of Cr(VI) into Posidonia oceanica activated carbon was studied via batch experiments considering the contact time, the initial concentration and the pH parameters. The results were interpreted using four different adsorption kinetic models. The activated carbon material seems to exhibit excellent sorption properties with rapid removal capability for Cr(VI). The estimated maximum uptake capacity at equilibrium stage was ~120 mg/g. Also, the initial adsorption rate ri was dependent on the initial Cr(VI) concentration in aqueous solution and it was from 77 mg/(g*h) to 264 mg/(g*h). The best fitted kinetic model seems to be the Diffusion-Chemisorption model with the rate constant KDC of the Cr(VI) ions transfer from liquid to solid particles extend from 52 to 78 mg/(g*h0.5).
- MeSH
- adsorpce MeSH
- Alismatales * MeSH
- chemické látky znečišťující vodu * analýza MeSH
- chrom analýza MeSH
- dřevěné a živočišné uhlí MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- pyrolýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Středozemní moře MeSH
Spruce wood and Typha (wetland plant) derived biochars pyrolyzed at 350 °C and 600 °C were tested for their sorption affinity for organic pollutants (diclofenac, methylparaben, benzotriazole and sodium 1-decanesulfonate) and nutrients (nitrate, ammonium, phosphate and boron) commonly found in greywater. Batch and column studies combined with molecular dynamics modelling determined the sorption capacity, kinetics, and described the underlying mechanisms. The spruce biochar (600 °C) exhibited the highest sorption capacity mainly for the tested organics. The dynamic test performed for spruce biochar (600 °C) showed that the magnitude of desorption was low, and the desorbed amount ranged between 3 and 11 %. Molecular dynamics modelling (a computational tool for elucidating molecular-level interactions) indicated that the increased sorption of nitrate and boron on spruce biochar (600 °C) could be attributed to hydrophobic interactions. The molecular dynamics shows that predominant adsorption of organic pollutants was governed by π-π stacking, with a minor role of hydrogen-bonding on the biochar surface. In summary, higher pyrolysis temperature biochar yielded greater adsorption capacity greywater borne contaminants and the reaction temperature (10-34 °C) and presence of anionic surfactant had a limited effect on the adsorption of organic pollutants, suggesting efficacious application of biochar in general for greywater treatment in nature-based systems.
Efficiency of advanced wastewater treatment technologies to reduce micropollutants which mediate dioxin-like toxicity was investigated. Technologies compared included ozonation, powdered activated carbon and granular activated carbon. In addition to chemical analyses in samples of effluents, surface waters, sediments, and fish, (1) dioxin-like potentials were measured in paired samples of effluents, surface waters, and sediments by use of an in vitro biotest (reporter gene assay) and (2) dioxin-like effects were investigated in exposed fish by use of in vivo activity of the mixed-function, monooxygenase enzyme, ethoxyresorufin O-deethylase (EROD) in liver. All advanced technologies studied, based on degradation or adsorption, significantly reduced dioxin-like potentials in samples and resulted in lesser EROD activity in livers of fish. Results of in vitro and in vivo biological responses were not clearly related to quantification of targeted analytes by use of instrumental analyses.
- MeSH
- adsorpce MeSH
- biotest MeSH
- chemické látky znečišťující vodu analýza MeSH
- cytochrom P-450 CYP1A1 metabolismus MeSH
- dioxiny chemie toxicita MeSH
- dřevěné a živočišné uhlí MeSH
- játra enzymologie MeSH
- nemoci ryb chemicky indukované MeSH
- odpadní voda analýza MeSH
- regulace genové exprese enzymů MeSH
- ryby MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
