| 1. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Influence of hydrothermal carbonization conditions on the porosity, functionality, and sorption properties of microalgae hydrochars
- 2023
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Green microalgae is a possible feedstock for the production of biofuels, chemicals, food/feed, and medical products. Large-scale microalgae production requires large quantities of water and nutrients, directing the attention to wastewater as a cultivation medium. Wastewater-cultivated microalgae could via wet thermochemical conversion be valorised into products for e.g., water treatment. In this study, hydrothermal carbonization was used to process microalgae polycultures grown in municipal wastewater. The objective was to perform a systematic examination of how carbonization temperature, residence time, and initial pH affected solid yield, composition, and properties. Carbonization temperature, time and initial pH all had statistically significant effects on hydrochar properties, with temperature having the most pronounced effect; the surface area increased from 8.5 to 43.6 m2 g−1 as temperature was increased from 180 to 260 °C. However, hydrochars produced at low temperature and initially neutral pH generally had the highest capacity for methylene blue adsorption. DRIFTS analysis of the hydrochar revealed that the pH conditions changed the functional group composition, implying that adsorption was electrostatic interactions driven. This study concludes that un-activated hydrochars from wastewater grown microalgae produced at relatively low hydrothermal carbonization temperatures adsorb methylene blue, despite having low surface area.
|
|
| 2. |
-
Filtration materials for groundwater : a guide to good practice
- 2016
-
Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Ground water is a source for drinking and industrial water supply and pollution created by active industrial sites which often cause social, health, and environmental problems. This groundwater eventually drains into adjacent water sources. Filtration Materials for Groundwater: A Guide to Good Practice presents the up-to-date technology of purification of polluted ground water, its treatment for industrial and human needs and the remediation of polluted sites.The book examines:Types of pollutants in ground water including the main inorganic and organic pollutants and their behaviour.Filtration materials for water treatment and principles of their choice. How to choose suitable filtration materials according to targeted compounds and estimate its efficiency.Technologies for ground water treatment.Cost and risks estimation of treatment facilities. Lifetime, risks and cost estimation of technology.Examples of modern ongoing facilities for ground water treatment and polluted sites remediation.This book is of interest to scientists and engineer who deal with the problem of purification of ground water for different purposes and the remediation of polluted sites.
|
|
| 3. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Comparative environmental assessment of end-of-life carbonaceous water treatment adsorbents
- 2020
-
Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 302
-
Tidskriftsartikel (refereegranskat)abstract
- This study evaluates and compares the environmental impacts arising from the disposal of different carbonaceous sorbents used for wastewater treatment. Three different adsorption materials were considered, i.e. activated carbon, biochar and hydrochar, and three end-of-life management approaches, i.e. incineration, regeneration and landfilling. The highest overall environmental impact was of Carcinogenic effects and Freshwater Ecotoxicity due to emissions of heavy metals during production of all types of sorbents. The use of materials with higher adsorption capacities and regeneration of carbonaceous materials were considered and shown to be an efficient way for reducing the overall environmental impacts of the different adsorbents. The compensation of fossil fuel incineration by using recovered heat led to negative impacts in all categories. Recirculation of HTC process water reduced the impact on Freshwater Ecotoxicity and Eutrophication.
|
|
| 4. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Fractionation and size-distribution of metal and metalloid contaminants in a polluted groundwater rich in dissolved organic matter
- 2016
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 318, s. 194-202
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the concentration levels, fractionation and molecular weight distribution (MWD) of dissolved organic matter (DOM) and metals (V, Cr, Co, Ni, Cu, Zn, As, Cd, Sn, Ba, Hg and Pb) in a polluted groundwater from an industrial area in Northern Sweden. DOM was mainly recovered in the hydrophobic acidic and hydrophobic neutral sub-fractions (45 and 35%, respectively) while most metals were found in the acidic sub-fractions (46–93%) except for V, Fe and As, which were predominant in the basic sub-fractions (74–93%) and Cd in the neutral ones (50%). DOM exhibited a broad MWD in groundwaters, usually from 5 to 200 kDa and was dominated by high molecular weight hydrophobic acids, low molecular weight hydrophilic acids and hydrophilic neutral compounds. Most of the studied metals (Fe, Cr, Co, Sn, Ba, Hg) were associated with the high molecular weight DOM fraction (ca. 40–100 kDa). Cu, Pb, Zn, Cd and Ni interacted with a broad range of DOM size fractions but were still most abundant in the high molecular weight fraction. Few metal/metalloids (As, V and Cr in some cases) presented a very weak affinity for DOM and presumably existed predominantly as “free” inorganic ions in solution.
|
|
| 5. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
On the leaching of mercury by brackish seawater from permeable barriers materials and soil
- 2015
-
Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 3:2, s. 1200-1206
-
Tidskriftsartikel (refereegranskat)abstract
- Soils at former pulp, paper and chemical plants in the subarctic (boreal) zone, including Canada, Scandinavia, Russia, and parts of the USA, are often contaminated with organic pollutants and heavy metals, of which mercury is one. The soil- and ground-water at these sites is often rich in dissolved organic matter (DOM), particularly fulvic substances. Permeable barriers are sometimes used to limit the migration of pollutants with groundwater and protect nearby aquatic environments. These are installed downstream of the source, generally close to the receiving water body. In cases when such barriers have been installed close to the sea, concerns have been raised that the seawater may back-flush the barrier and release mercury, often a key contaminant, in the form of stable chloride complexes.Intrusion of seawater into coastal groundwater reservoirs has previously been shown to result in dissolution of mercury from soil. Less is known about the ability of brackish water, present in estuaries or brackish seas, to mobilize mercury from soil or from barrier materials. We therefore investigated the effect of artificial brackish seawater (6.3‰ salinity) on the sorption and desorption of mercury from different barrier materials (activated carbon, fly ash, lignite, torrified material, peat, and iron powder).The mercury was found to be associated with the high molecular weight fraction of groundwater DOM and it was concluded that the mercury was removed (sorbed) as relatively strong DOM-complexes. Chloride ions did not seem to form aqueous complexes with mercury to any great extent and artificial brackish seawater did not desorb mercury from the contaminated soil or from the studied barrier materials.
|
|
| 6. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Removal of contaminants of emerging concern from multicomponent systems using carbon dioxide activated biochar from lignocellulosic feedstocks
- 2021
-
Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 340
-
Tidskriftsartikel (refereegranskat)abstract
- Adsorption of six contaminants of emerging concern (CECs) – caffeine, chloramphenicol, carbamazepine, bisphenol A, diclofenac, and triclosan – from a multicomponent solution was studied using activated biochars obtained from three lignocellulosic feedstocks: wheat straw, softwood, and peach stones. Structural parameters related to the porosity and ash content of activated biochar and the hydrophobic properties of the CECs were found to influence the adsorption efficiency. For straw and softwood biochar, activation resulted in a more developed mesoporosity, whereas activation of peach stone biochar increased only the microporosity. The most hydrophilic CECs studied, caffeine and chloramphenicol, displayed the highest adsorption (22.8 and 11.3 mg g−1) onto activated wheat straw biochar which had the highest ash content of the studied adsorbents (20 wt%). Adsorption of bisphenol A and triclosan, both relatively hydrophobic substances, was highest (31.6 and 30.2 mg g−1) onto activated biochar from softwood, which displayed a well-developed mesoporosity and low ash content.
|
|
| 7. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Use of biochar and Moringa oleifera in greywater treatment to remove heavy metals and contaminants of emerging concern
- 2023
-
Ingår i: Bioresource Technology Reports. - : ELSEVIER. - 2589-014X. ; 24
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated the combination of biochar derived from carbonized local feedstock and Moringa oleifera seed extract-based flocculant, a novel combination in the context of greywater treatment missed in the previous studies, with a focus on the removal of organic contaminants (caffeine, chloramphenicol, trimethoprim, carbamazepine, diclofenac, and bisphenol A) and heavy metals (Cr(VI), As(III), Co(II), Ni(II), Cu(II), Zn(II), and Pb(II)). The research focused on the optimization of dosage, application procedure, and relevance to greywater (presence of humic acids, clay, and surfactants).The order of application was found to impact organic compound removal, with the initial application of the flocculant, followed by biochar, being the more effective approach. The combined use of biochar and flocculant positively impacted the removal of heavy metals but impeded the removal of organic pollutants. The presence of humic acids, clay, and surfactants affected the flocculation process, which impeded the removal of heavy metals and organic pollutants.
|
|
| 8. |
- Kozyatnyk, Ivan, 1982-, et al.
(författare)
-
Valorization of Humic Acids by Hydrothermal Conversion into Carbonaceous Materials : Physical and Functional Properties
- 2019
-
Ingår i: ACS Sustainable Chemistry and Engineering. - Washington : American Chemical Society (ACS). - 2168-0485. ; 7:2, s. 2585-2592
-
Tidskriftsartikel (refereegranskat)abstract
- Humic acids (HAs) represent an economic and environmental challenge in water treatment, as they have the propensity to foul membranes and create toxic byproducts when interacting with chlorine. To overcome this, HAs were submitted to hydrothermal carbonization to convert them into an easy to remove, valuable carbon material. The result was a carbonaceous material which was easy to filter/dewater compared to HAs with a char yield of 49 +/- 1.8 wt %, and with 46.6 1.4 wt % ending up in the water phase, 2.2 +/- 0.2 wt % in the tar, and the rest in the gaseous fraction. The molecular weight distribution of the organic matter in the water pre-and post-HTC indicated that the structure was broken into several different fragments with a lower molecular weight than that initially present. Physicochemical analysis of the material via elemental analysis, X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and solid-state nuclear magnetic resonance indicated that under hydrothermal carbonization, the aromatic structure of HAs condensed. Carboxylic acids groups were also lost from the surface of HAs, with ether and alcohols increasing because of their loss. The morphology of the obtained material had an amorphous macrostructure consisting of many smaller light lamellar carbon fragments. Finally, the hydrothermal treatment increased the surface area from 0.4 to 103.0 m(2) g(-1).The porosity is located in the mesoporous range of 10-80 nm with a maximum peak at 50 nm.
|
|
| 9. |
- Latham, Kenneth G., et al.
(författare)
-
Impact of Temperature and Residence Time on the Hydrothermal Carbonization of Organosolv Lignin
- 2022
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier. - 0165-2370 .- 1873-250X. ; 166
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we have investigated how pure lignin extracted from birch and spruce via a hybrid organosolv/steam explosion method reacts under hydrothermal carbonization (HTC) to produce hydrochar, a product that has found applications in environmental remediation, energy storage and catalysis. We subjected thirteen lignin samples obtained from birch and spruce under different extraction conditions to HTC at 260 ℃ for four hours. The yield of hydrochar varied between the different extraction conditions and source, although no clear correlation between extraction conditions and yield could be observed. For instance, lignin from birch pretreated in 60%v/v ethanol for 15 minutes resulted in a hydrochar yield of 39 wt%. Increasing the time to 30 and 60 resulted in a hydrochar yield of 27 wt% and 23 wt%, respectively. This suggested that small changes in the organosolv reaction conditions might produce highly structurally different lignin, resulting in the difference in HTC yield. Thus, we chose a subset of four lignin samples to investigate in-depth, subjecting these samples to a range of hydrothermal reaction temperatures and residence times. Solid State NMR and FTIR analysis indicated that the most significant structural changes occurred below 230 ℃ resulting in the breaking of C-O- linkages. Increasing the temperature or time had minimal impact, with no further C-O- linkages broken and no changes to the ring structure of C-C groups. Size exclusion chromatography indicated that the degree of micro and macromolecules in the liquid product varied significantly with lignin source and HTC reaction conditions. Overall, this study demonstrated that lignin has a large reaction range where it produces a very chemically similar solid product, with the only major difference being the yield of material. This is important for industry, as it indicates that a similar solid product can be easily achieved independently of extraction conditions allowing the HTC reaction to be tuned towards extracting the maximum benefit from products contained in the liquid.
|
|
| 10. |
- Latham, Kenneth G., et al.
(författare)
-
Self-generation of low ash carbon microspheres from the hydrothermal supernatant of anaerobic digestate : Formation insights and supercapacitor performance
- 2021
-
Ingår i: Chemical Engineering Journal Advances. - : Elsevier. - 2666-8211. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- This work provides the first observations of and insights into the self-generation of carbon microspheres from the supernatant after hydrothermal carbonization of anaerobic digestate has been completed and the hydrochar removed. Solid State NMR and XPS revealed that the carbon microspheres were comprised of decomposed fragments of proteins, carbohydrates and lignin. The carbon microspheres were significantly lower in ash content (3.1%), compared to the hydrothermal solid (41.2%) and precursor (25.2%) and their formation reduced the total organic carbon load of the supernatant. The low ash content allowed them to be easily activated, achieving a surface area of 1711.0 m2 g−1, compared to 51.4 m2 g−1 for the activated hydrothermal solid and 12.8 m2 g−1 for the activated precursor. The microcarbon spheres achieved a specific capacitance from cyclic voltammetry of 86 F g−1 at 100 mV s−1 to 176 F g−1 at 1 mV s−1, while the gravimetric capacitance was 42 F g−1 at 25 A g−1 and 140 F g−1 at 0.5 A g−1 in 0.5 M Li2SO4 and a 1.8V potential window. Overall, this study highlights the importance of exploring this new product and its valorisation potential for the hydrothermal carbonization of ash-rich precursors.
|
|
