Search results for "erotusmenetelmät"
showing 10 items of 11 documents
Fast pyrolysis of hot-water-extracted and soda-AQ-delignified okra (Abelmoschus esculentus) and miscanthus (miscanthus x giganteus) stalks by Py-GC/MS
2018
Abstract The thermochemical behavior of various samples of okra ( Abelmoschus esculentus ) and miscanthus ( Miscanthus x giganteus ) stalks (initial, hot-water-extracted, and those from sulfur-free delignification) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In all cases, major GC-amenable condensable products were measured semi-quantitatively and classified into several product groups. The formation of these product groups from different feedstock samples with varying mass portions of their structural constituents (carbohydrates and lignin) was investigated at 500 °C and 700 °C with a residence time of 5 s and 20 s. The main product groups were aliphatic comp…
α-Aminophosphonates, Phosphinates, and Phosphine Oxides as Extraction and Precipitation Agents for Rare Earth Metals, Thorium, and Uranium : A Review
2022
α-Aminophosphonates, -phosphinates, and -phosphine oxides are a group of organophosphorus compounds that were investigated as extraction agents for rare earth (RE) metals and actinoids for the first time in the 1960s. However, more systematic investigations of their extraction properties towards REs and actinoids were not started until the 2010s. Indeed, recent studies have shown that these α-amino-functionalized compounds can outperform the commercial organophosphorus extraction agents in RE separations. They have also proven to be very efficient extraction and precipitation agents for recovering Th and U from RE concentrates. These actinoids coexist with REs in some of the commercially im…
Harvinaisista maametalleista ja niiden erotusmenetelmistä
2014
Työn tarkoituksena oli selvittää soveltuvia kemiallisia tekniikoita harvinaisten maametallien erottamiseen sekä luontaisista, että ihmisperäisen teollisuuden lähteistä. Tavoitteena oli saavuttaa hyvä näkemys aiheen historiasta, kehityksestä ja nykytilasta. Harvinaiset maametallit ovat kemiallisesti samankaltainen joukko, johon sisältyvät skandium, yttrium ja lantanoidit. Työssä käydään läpi harvinaisten maametallien keskeinen kemia, käyttö, saatavuus ja maailmanmarkkinoiden asettamat haasteet. Kiinan harvinaisten maametallien tuotanto ja sen aiheuttamat vaikutukset maailmankauppapolitiikkaan ovat merkittäviä, ja työssä korostetaan tällä hetkellä vallitsevaa tilannetta harvinaisten maametall…
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…
Solid phase extraction materials as a key for improving the accuracy of silver nanoparticle characterization with single-particle inductively coupled…
2022
The accurate characterization of silver nanoparticles (Ag NPs) in environmental samples is crucial for understanding the potential impact of these materials on the environment and human health. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) is one of the few techniques available for quantifying NPs at environmentally relevant concentrations. However, the spICP-MS detection of Ag NPs can be interfered with coexisting dissolved analyte causing high background signals, which mask NP signals leading to a significant bias in NP characterization. In this paper, a simple sample pre-treatment procedure for efficient removal of dissolved silver in natural waters is proposed …
Protein recovery as a resource from waste specifically via membrane technology : from waste to wonder
2021
Economic growth and the rapid increase in the world population has led to a greater need for natural resources, which in turn, has put pressure on said resources along with the environment. Water, food, and energy, among other resources, pose a huge challenge. Numerous essential resources, including organic substances and valuable nutrients, can be found in wastewater, and these could be recovered with efficient technologies. Protein recovery from waste streams can provide an alternative resource that could be utilized as animal feed. Membrane separation, adsorption, and microbe-assisted protein recovery have been proposed as technologies that could be used for the aforementioned protein re…
On potential of interactive multiobjective optimization in chemical process design
2006
Interaktiivinen monitavoiteoptimointi soveltuu hyvin teollisen kemian prosessisuunnitteluun. Jussi Hakanen esittelee väitöskirjassaan menetelmään pohjautuvan uuden työkalun, jollaista ei aiemmin ole ollut tarjolla. Hakanen on soveltanut työkalua onnistuneesti useiden kemiallisten prosessien suunnitteluun huomioimalla uudella tavalla enemmän kuin kaksi prosessin käyttäytymiseen vaikuttavaa tavoitetta.Aikaisemmin kemian prosessien suunnittelussa on otettu huomioon enintään kaksi prosessin toimintaan vaikuttavaa ristiriitaista tavoitetta. Hakasen esittelemä lähestymistapa ei rajoita huomioitavien tavoitteiden määrää, mikä mahdollistaa prosessien aiempaa realistisemman suunnittelun. Väitöstyöss…
Method development for determination and recovery of rare earth elements from industrial fly ash
2014
Rare earth elements (REE) are important in numerous high technology applications and in addition their supply risk is high, which gives rise to studying new sources for rare earth elements. Rare earth element concentrations in industrial fly ash samples collected from Finnish power plants, using a mixture of peat and biomass as a fuel, have been determined. Two sample pre-treatment methods, ultrasound- and microwave-assisted acid digestions, have been applied to fly ash samples. Measurement conditions for inductively coupled plasma-optical emission spectrometry (ICP–OES) have been optimized to reach robust plasma conditions and the reliability of the analysis has been investigated by using …
Separation of palladium and silver from E-waste leachate : effect of nitric acid concentration on adsorption to Thiol scavenger
2022
The development of recovery techniques for metals present in low concentrations in E-waste, such as silver and palladium, is important from the aspect of the circular economy. Adsorption of palladium and silver was studied in detail in a batch process with silica-based Thiol scavenger from nitric acid leachate of waste printed circuit boards (PCBs). High adsorption efficiencies of Pd(II) and Ag(I), >97%, were reached in nitric acid concentrations below 3 mol L−1. At higher acid concentrations, adsorption efficiency of Ag(I) decreased drastically which enables the separation of Ag(I) and Pd(II) based on nitric acid concentration in sample solution. Pd(II) and Ag(I) followed pseudo 2nd order …
Application of 3D printed scavengers for improving the accuracy of single-particle inductively coupled plasma mass spectrometry analyses of silver na…
2023
The determination of silver nanoparticles (Ag NPs) with single-particle inductively coupled plasma mass spectrometry can be severely interfered with coexisting dissolved silver causing high background signals, which can lead to inaccurate quantification of NP size and particle concentration. In this paper, chemically active and reusable 3D printed scavengers are applied for highly efficient dissolved silver removal in Ag NP dispersions, allowing more accurate determination of particle concentration and size. Selective laser sintering was used for constructing the porous 3D scavengers constituting of polystyrene used as a supporting material and ion-exchange material SiliaBond Tosic acid (TA…