Search results for "talteenotto"
showing 10 items of 25 documents
RAVITA Technology : new innovation for combined phosphorus and nitrogen recovery
2018
Abstract Present phosphorus (P) recovery technologies mainly contain P recovery from sludge liquor or ash. These types of technologies are suitable for large wastewater treatment plants (WWTPs) with enhanced biological phosphorus removal (EBPR), digestion and/or incineration. In Finland and other Nordic countries, strict P discharge limits require chemical precipitation, thus EBPR alone is not sufficient. Ammonium recovery from wastewater, on the other hand, is not so often discussed. However, recovery from WWTP reject waters would decrease the energy demand of ammonium synthesis by Haber-Bosh technology and the energy demand of the WWTP's biological process. Helsinki Region Environmental S…
Valorization potential of technical lignins from Norway spruce (Picea abies) via pyrolysis
2022
Analytical pyrolysis (Py-GC/MS) on mg-scale of Norway spruce (Picea abies)-derived kraft lignin, ethanosolv lignin, and dried lignin-rich soda-anthraquinone (AQ) black liquors was studied at 500 °C to compare the valorization potential of these materials, focusing on the type and yield of condensable pyrolysis products. Of particular interest was the relatively selective formation of guaiacol (2-methoxyphenol) from the dried soda-AQ black liquors in contrast to the formation of complex phenolic product mixtures from the pyrolysis of the kraft and ethanosolv lignins. It was shown that this finding could be attributed to differences in composition and structure as was assessed by various NMR …
Lignin recovery from spent alkaline pulping liquors using acidification, membrane separation, and related processing steps: A Review
2019
The separation of lignin from the black liquor generated during alkaline pulping is reviewed in this article with an emphasis on chemistry. Based on published accounts, the precipitation of lignin from spent pulping liquor by addition of acids can be understood based on dissociation equilibria of weak acid groups, which affects the solubility behavior of lignin-related chemical species. Solubility issues also govern lignin separation technologies based on ultrafiltration membranes; reduction in membrane permeability is often affected by conditions leading to decreased solubility of lignin decomposition products and the presence of colloidal matter. Advances in understanding of such phenomen…
Use of nanostructures as oxygen carriers in chemical looping combustion
2013
The usage of fossils fuels has increased carbon dioxide emissions, and the carbon dioxide is responsible for global warming and sea level rising. One of the most promising ways of carbon capturing from the power plants is chemical looping combustion (CLC). CLC is based on the alternating oxidation and reduction reactions on the air and fuel reactors. Oxygen and energy needed for combustion between the reactors is transferred by an oxygen carrier. Oxygen carrier is usually made of metal or metal oxide. One big hindrance towards commercial use of CLC is slow reaction kinetics of oxygen carriers. One possible solution for the problem is to replace the conventional carriers by nanoscale oxygen …
Influence of a Cu–zirconia interface structure on CO2 adsorption and activation
2021
CO2 adsorption and activation on a catalyst are key elementary steps for CO2 conversion to various valuable products. In the present computational study, we screened different Cu–ZrO2 interface structures and analyzed the influence of the interface structure on CO2 binding strength using density functional theory calculations. Our results demonstrate that a Cu nanorod favors one position on both tetragonal and monoclinic ZrO2 surfaces, where the bottom Cu atoms are placed close to the lattice oxygens. In agreement with previous calculations, we find that CO2 prefers a bent bidentate configuration at the Cu–ZrO2 interface and the molecule is clearly activated being negatively charged. Strain…
Computational studies of chemical looping combustion materials and CO₂ activating surfaces
2016
Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate
2020
AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen pero…
Elektroniikkajätteen typpihappoliuotus ja metallien talteenotto
2017
Tämän pro gradu -tutkielman kirjallisessa osassa käsitellään elektroniikkajätettä ja metallien talteenottoa. Erityisesti talteenottomenetelmissä keskitytään typpihappoliuoksiin, sillä kokeellisessa osassa tutkimuksen kohteena oleva liuos on typpihappo. Näiden lisäksi tarkastellaan tutkimuksen kannalta merkittävien metallien; kuparin (Cu), nikkelin (Ni), lyijyn (Pb), tinan (Sn), hopean (Ag), sinkin (Zn) sekä palladiumin (Pd) fysikaalisia ja kemiallisia ominaisuuksia. Tutkielmassa tuodaan myös esille elektroniikkajätteen ympäristövaikutukset sekä sen taloudellinen merkitys maailmassa. Elektroniikkajäte on maailman nopeinten kasvava jätefraktio. Tämä on saanut useat tahot heräämään tähän kasva…
Jalometallit ja niiden talteenotto
2016
Tämän pro gradu -tutkielman kirjallisessa osassa käsitellään jalometallien ominaisuuksia ja esiintyvyyttä. Myös jalometallien yleisimpiä yhdisteitä ja käyttökohteita teollisuudessa selvitetään. Jalometallien talteenottomenetelmistä esitellään varsinkin klassiset saostusmenetelmät, neste-nesteuutto ja ioninvaihto. Näistä painotetaan ioninvaihtomenetelmien esittelyä, sillä tutkielman kokeellisessa osassa tutkittiin jalometallien talteenottoa ioninvaihdolla. Kirjallisessa osassa esitellään myös lyhyesti induktiivisesti kytketyn plasma-emissiospektrometrin (ICP-OES) rakennetta ja käyttöä. Tutkielman kokeellisessa osassa tutkittiin jalometallien talteenottoa synteettisestä uuttoliuoksesta, hyödy…
Recent progress in metal-organic frameworks (MOFs) for CO2 capture at different pressures
2022
Global climate change ensued by the rise in atmospheric CO2 levels is one of the greatest challenges our planet is facing today. This worldwide distress demands technologies that can contribute to our society toward “negative carbon emissions”. Carbon capture and storage (CCS) technologies are in in important role for capturing CO2 from existing emission sources, such as industrial and energy production point sources, before new more prominent modifications to the energy infrastructure can be implemented. Recently, alongside point source capture, direct air capture (DAC) processes have emerged as highly sought-after technologies that are able to capture CO2 from the ambient air. Alongside t…