Wet Oxidation of Paper Mill Evaporation Concentrates

Tämän työn tarkoituksena oli tutkia lämpötilan pH:n ja vetyperoksidin vaikutusta kuorimoveden haihdutuskonsentraatin märkähapetuksessa. Kirjallisuusosassa esitellään massan ja paperin valmistusta sekä kuorintaprosessi. Lisäksi tarkastellaan kuoren kemiallista koostumusta, jäteveden ja prosessiveden käsittelymenetelmiä sekä märkähapetuksen periaatteita. Kokeellinen osa käsittää erään suomalaisen paperitehtaan kuorimoveden haihdutuskonsentraatin märkähapetuskokeet. Hapetuskokeet tehtiin useammassa eri lämpötilassa, pH:ssa ja vetyperoksidikonsentraatiossa. Em. muuttujien vaikutusta tutkittiin kemialliseen hapenkulutukseen (COD), biologiseen hapenkulutukseen (BOD), välittömästi saatavana olevan biologiseen hapenkulutukseen (IABOD), orgaaniseen kokonaishiileen (TOC) ja tanniini/ligniini pitoisuuteen. Koetulokset osoittivat, että korkeimmat COD- ja TOC-reduktiot saavutettiin H2O2-katalysoidulla märkähapetuksella jäteveden alkuperäisessä pH:ssa (60 % reduktio COD:lla ja 45 % reduktio TOC:lla lämpötilassa 170 °C ja 0.2 g H2O2/g COD). Toisaalta, parhaat tulokset biohajoavuuden paranemisen suhteen saavutettiin emäksisissä olosuhteissa, jossa 170 °C:ssa saavutettiin BOD/COD-arvo 76 %. Emäksisissä olosuhteissa saavutettiin lähes täydellinen tanniinin reduktio lämpötila-alueella 130-170 °C, mutta näissä lämpötiloissa orgaanisen kuorman alenemista ei havaittu.

Removal of Lipophilic Wood Extractives from TMP Process Waters by Wet Oxidation

Työssä tutkittiin kokeellisesti rasvaliukoisten uuteaineiden poistamista TMP -prosessin vesikierroista märkähapetuksen avulla. Työn tavoitteena oli tutkia mahdollisuudet hyödyntää TMP -prosessissa vallitsevaa korkeaa lämpötilaa rasvaliukoisten uuteaineiden poistamiseen hapettamalla niitä puhtaalla hapella. Kirjallisuusosassa tarkasteltiin märkähapetuksen teknologiaa, reaktiomekanismia, käytettyjä katalyyttejä, käyttökohteita sekä kustannuksia. Kokeita suoritettiin autoklaavireaktorissa lämpötiloissa 140 °C, 160 °C ja 180 °C. Vetyperoksidia käytettiin katalyyttinä lisätyn vetyperoksidin määrän ollessa 100 - 1800 mg/l ja hapen osapaineen ollessa 0 ( typpiatmosfääri) - 15 baria. Kokeissa tarkasteltiin kemiallisen hapenkulutuksen (COD), rasvaliukoisten uuteaineiden konsentraation, orgaanisen kokonaishiilen (TOC) ja värin muutoksia kokeiden aikana eri lämpötiloilla, hapen osapaineilla ja lisätyn vetyperoksidin määrillä. Kokeissa saavutettiin 30 %:n COD:n vähenemä sekä 90 %:n vähenemä rasvaliukoisissa uuteaineissa lämpötiloissa 160 °C ja 180 °C. Lisäämällä vetyperoksidia katalyyttinä saavutettiin lähes sama tulos lämpötilassa 140 °C. Suurin tässä työssä havaittu ongelma oli lisääntynyt värinmuodostus vedessä olevassa hienojakoisessa kiintoaineessa hapetuksen aikana. Tämän vuoksi lisätutkimukset ovat tarpeellisia sen seikan selvittämiseksi, voidaanko muodostunut väri mahdollisesti poistaa massan valkaisussa.

Wet Oxidation of TMP Concentrated Paper Mill Process Water. Kinetics of the reaction

Työn tarkoituksena oli tutkia lämpötilan, paineen, pH:n ja katalyytin vaikutusta paperitehtaan TMP-konsentroidun prosessiveden märkähapetuksessa. Teoriaosio sisältää katsauksen sellu- ja paperiteollisuuteen, jätevesien käsittelyyn, nanosuodatuksen ja märkähapetusprosessin toimintaperiaatteet ja sovellukset hybriditeknologialle nanosuodatus-märkähapetuksessa. Empiirinen osa koostuu märkähapetuskokeista eri lämpötiloissa, paineissa, pH:ssa ja eri katalyyseillä. Työssä tutkittiin näiden vaikutusta kemialliseen hapenkulutukseen (COD), Biologiseen hapenkulutukseen (BOD), Välittömästi saatavana olevan biologisen hapenkulutukseen (IABOD), ligniiniin, täysin orgaanisen hiileen (TOC) ja rasvaliukoisten uuteaineiden (LWEs) pitoisuuteen. Tuloksina kokeellisesta työstä saatiin korkeimmat COD:n alenemat ja BOD/COD (biohajoavuus) suurimmilla lämpötilaolosuhteilla (COD:n alenema 70 % ja BOD/COD 97 % 200 °C:ssa ja hapen 10 bar osapaineella). Tutkimuksessa, jossa selvitettiin hapen osapaineen vaikutusta saatiin tuloksena, että hapen osapaineen kasvu parantaa orgaanisen kuormituksen poistoa: COD poisto oli olosuhteilla130°C, 5bar 5 %, olosuhteilla 130 °C, 15bar 15 %, olosuhteilla 170 °C, 5bar 20 % ja olosuhteilla 170 °C, 15bar 50 %. Lähes täydellinen LWEs –poisto saavutettiin 150 °C ja 10bar olosuhteilla, vaikka tässä lämpötilassa ei saavutettu korkeata orgaanisen kuormituksen poistoa. Emäksinen pH vaikutti suosivan hapettavia reaktioita, koska korkein COD:n poisto saavutettiin näissä olosuhteilla; kuitenkin alkalisen väliaineen tehokkuudelle löydettiin tärkeä lämpötilariippuvuus.

Aluminium fouling and its impact on activated carbon based dioxin and furan removal in a wet scrubber at a co-incineration plant

Dioxins and furans, PCDD/Fs, are highly toxic substances formed in post combustion zones in furnaces. PCDD/F emissions are regulated by a waste incineration directive which relates also to co-incineration plants. Several observations of dioxin and furan enhancements in wet scrub- bers have been reported previously. This is thought to be due to the so-called "memory effect" which occurs when dioxins and furans absorb into plastic material in scrubbers and desorb when ambient circumstances alter significantly. At the co-incineration plant involved, dioxins and furans are controlled with a wet scrubber, the tower packing of which is made of plastic in which activated carbon particles are dispersed. This should avoid the memory effect and act as a dioxin and furan sink since dioxins and furans are absorbed irreversibly into the packing ma- terial. In this case, the tower packing in the scrubber is covered with a white layer that has been found to be mainly aluminium. The aim of this thesis was to determine the aluminium balance and the dioxin and furan behaviour in the scrubber and, thus, the impacts that the foul- ing has on dioxin and furan removal. The source of aluminium, reasons for fouling and further actions to minimize its impacts on dioxin and furan removal were also to be discovered. Measurements in various media around the scrubber and in fuels were made and a profile analysis of PCDD/F and mass balance calculations were carried out. PCDD/F content de- creased in the scrubber. The reduced PCDD/F was not discharged into scrubbing water. The removal mechanism seems to work in spite of the fouling, at least with low PCDD/F loads. Most of the PCDD/F in excess water originates from the Kymijoki River which is used as feeding water in the scrubber. Fouling turned out to consist mainly of aluminium hydroxides. Sludge combusted in the furnace was found to be a significant source of aluminium. Ways to minimize the fouling would be adjustment of pH to a proper lever, installation of a mechanical filter to catch the loose material from the scrubbing water and affecting the aluminium content of the sludge.

Catalytic Wet Oxidation of Paper Mill Debarking Water

The objective of the research was to study the influence of temperature, oxygen pressure, catalysts loading and initial COD concentration of debarking wastewater on the pollutants during the catalytic oxidation. More importantly, how the addition of catalyst affects the wet oxidation process. The whole work was divided into two main sections, theoretical and experimental parts. The theoretical part reviews the pulp and paper industry from wood processing to paper production as well as operations that generate wastes. Treatment methods applicable for industrial pulp and paper mill effluents were also discussed. Wet oxidation and catalytic wet oxidation processes including mechanism, reactions, kinetics and industrial applications were previewed. In the experimental part, catalytic wet oxidation process were studied at 120-180°C, 0-10 bar oxygen pressure, 0-1 g/L catalyst concentration and 1000-3000 mg/L initial COD concentration. Responses, such as Chemical oxygen demand (COD), Total organic carbon (TOC), colour, lignin/tannin, Biochemical oxygen demand (BOD) and pH were measured. In the experiment, the best conditions occurred at 180°C, 10 bar, l g/L catalyst concentration and 3000mg/L initial COD. At these conditions; 74% COD, 97% lignin/tannin, 54% TOC, 90% colour were removed from the wastewater. pH was greatly reduced from 7 to 4.6. Lignin/tannin was removed most. Lignin/tannin showed linear dependency with colour during oxidation. Temperature made the most impact in reducing contaminants in debarked wastewater.

Wet oxidation of recalcitrant lignin waters: Experimental and kinetic studies

The dissertation is based on four articles dealing with recalcitrant lignin water purification. Lignin, a complicated substance and recalcitrant to most treatment technologies, inhibits seriously pulp and paper industry waste management. Therefore, lignin is studied, using WO as a process method for its degradation. A special attention is paid to the improvement in biodegradability and the reduction of lignin content, since they have special importance for any following biological treatment. In most cases wet oxidation is not used as a complete ' mineralization method but as a pre treatment in order to eliminate toxic components and to reduce the high level of organics produced. The combination of wet oxidation with a biological treatment can be a good option due to its effectiveness and its relatively low technology cost. The literature part gives an overview of Advanced Oxidation Processes (AOPs). A hot oxidation process, wet oxidation (WO), is investigated in detail and is the AOP process used in the research. The background and main principles of wet oxidation, its industrial applications, the combination of wet oxidation with other water treatment technologies, principal reactions in WO, and key aspects of modelling and reaction kinetics are presented. There is also given a wood composition and lignin characterization (chemical composition, structure and origin), lignin containing waters, lignin degradation and reuse possibilities, and purification practices for lignin containing waters. The aim of the research was to investigate the effect of the operating conditions of WO, such as temperature, partial pressure of oxygen, pH and initial concentration of wastewater, on the efficiency, and to enhance the process and estimate optimal conditions for WO of recalcitrant lignin waters. Two different waters are studied (a lignin water model solution and debarking water from paper industry) to give as appropriate conditions as possible. Due to the great importance of re using and minimizing the residues of industries, further research is carried out using residual ash of an Estonian power plant as a catalyst in wet oxidation of lignin-containing water. Developing a kinetic model that includes in the prediction such parameters as TOC gives the opportunity to estimate the amount of emerging inorganic substances (degradation rate of waste) and not only the decrease of COD and BOD. The degradation target compound, lignin is included into the model through its COD value (CODligning). Such a kinetic model can be valuable in developing WO treatment processes for lignin containing waters, or other wastewaters containing one or more target compounds. In the first article, wet oxidation of "pure" lignin water was investigated as a model case with the aim of degrading lignin and enhancing water biodegradability. The experiments were performed at various temperatures (110 -190°C), partial oxygen pressures (0.5 -1.5 MPa) and pH (5, 9 and 12). The experiments showed that increasing the temperature notably improved the processes efficiency. 75% lignin reduction was detected at the lowest temperature tested and lignin removal improved to 100% at 190°C. The effect of temperature on the COD removal rate was lower, but clearly detectable. 53% of organics were oxidized at 190°C. The effect of pH occurred mostly on lignin removal. Increasing the pH enhanced the lignin removal efficiency from 60% to nearly 100%. A good biodegradability ratio (over 0.5) was generally achieved. The aim of the second article was to develop a mathematical model for "pure" lignin wet oxidation using lumped characteristics of water (COD, BOD, TOC) and lignin concentration. The model agreed well with the experimental data (R2 = 0.93 at pH 5 and 12) and concentration changes during wet oxidation followed adequately the experimental results. The model also showed correctly the trend of biodegradability (BOD/COD) changes. In the third article, the purpose of the research was to estimate optimal conditions for wet oxidation (WO) of debarking water from the paper industry. The WO experiments were' performed at various temperatures, partial oxygen pressures and pH. The experiments showed that lignin degradation and organics removal are affected remarkably by temperature and pH. 78-97% lignin reduction was detected at different WO conditions. Initial pH 12 caused faster removal of tannins/lignin content; but initial pH 5 was more effective for removal of total organics, represented by COD and TOC. Most of the decrease in organic substances concentrations occurred in the first 60 minutes. The aim of the fourth article was to compare the behaviour of two reaction kinetic models, based on experiments of wet oxidation of industrial debarking water under different conditions. The simpler model took into account only the changes in COD, BOD and TOC; the advanced model was similar to the model used in the second article. Comparing the results of the models, the second model was found to be more suitable for describing the kinetics of wet oxidation of debarking water. The significance of the reactions involved was compared on the basis of the model: for instance, lignin degraded first to other chemically oxidizable compounds rather than directly to biodegradable products. Catalytic wet oxidation of lignin containing waters is briefly presented at the end of the dissertation. Two completely different catalysts were used: a commercial Pt catalyst and waste power plant ash. CWO showed good performance using 1 g/L of residual ash gave lignin removal of 86% and COD removal of 39% at 150°C (a lower temperature and pressure than with WO). It was noted that the ash catalyst caused a remarkable removal rate for lignin degradation already during the pre heating for `zero' time, 58% of lignin was degraded. In general, wet oxidation is not recommended for use as a complete mineralization method, but as a pre treatment phase to eliminate toxic or difficultly biodegradable components and to reduce the high level of organics. Biological treatment is an appropriate post treatment method since easily biodegradable organic matter remains after the WO process. The combination of wet oxidation with subsequent biological treatment can be an effective option for the treatment of lignin containing waters.

Measurement and Improvement of Wet Paper Web Strength

Various strength properties of paper are measured to tell how well it resists breaks in a paper machine or in printing presses. The most often measured properties are dry tensile strength and dry tear strength. However, in many situations where paper breaks, it is not dry. For example, in web breaks after the wet pressing the dry matter content can be around 45%. Thus, wet-web strength is often a more critical paper property than dry strength. Both wet and dry strength properties of the samples were measured with a L&W tensile tester. Originally this device was not designed for the measurement of the wet web tensile strength, thus a new procedure to handle the wet samples was developed. The method was tested with Pine Kraft (never dried). The effect of different strength additives on the wet-web and dry paper tensile strength was studied. The polymers used in this experiment were aqueous solution of a cationic polyamidoamine-epichlorohydrin resin (PAE), cationic hydrophilised polyisocyanate and cationic polyvinylamine (PVAm). From all three used chemicals only Cationic PAE considerably increased the wet web strength. However it was noticed that at constant solids content all chemicals decreased the wet web tensile strength. So, since all chemicals enhanced solid content it can be concluded that they work as drainage aids, not as wet web strength additives. From all chemicals only PVAm increased the dry strength and two other chemicals even decreased the strength. As chemicals were used in strong diluted forms and were injected into the pulp slurry, not on the surface of the papersheets, changes in samples densities did not happen. Also it has to be noted that all these chemicals are mainly used to improve the wet strength after the drying of the web.

The Effects of Some Furnish and Paper Structure Related Factors on Wet Web Tensile and Relaxation Characteristics

The objective of this thesis was to identify the effects of different factors on the tension and tension relaxation of wet paper web after high-speed straining. The study was motivated by the plausible connection between wet web mechanical properties and wet web runnability on paper machines shown by previous studies. The mechanical properties of wet paper were examined using a fast tensile test rig with a strain rate of 1000%/s. Most of the tests were carried out with laboratory handsheets, but samples from a pilot paper machine were also used. The tension relaxation of paper was evaluated as the tension remaining after 0.475 s of relaxation (residual tension). The tensile and relaxation properties of wet webs were found to be strongly dependent on the quality and amount of fines. With low fines content, the tensile strength and residual tension of wet paper was mainly determined by the mechanical interactions between fibres at their contact points. As the fines strengthen the mechanical interaction in the network, the fibre properties also become important. Fibre deformations caused by the mechanical treatment of pulp were shown to reduce the mechanical properties of both dry and wet paper. However, the effect was significantly higher for wet paper. An increase of filler content from 10% to 25% greatly reduced the tensile strength of dry paper, but did not significantly impair wet web tensile strength or residual tension. Increased filler content in wet web was shown to increase the dryness of the wet web after the press section, which partly compensates for the reduction of fibrous material in the web. It is also presumable that fillers increase entanglement friction between fibres, which is beneficial for wet web strength. Different contaminants present in white water during sheet formation resulted in lowered surface tension and increased dryness after wet pressing. The addition of different contaminants reduced the tensile strength of the dry paper. The reduction of dry paper tensile strength could not be explained by the reduced surface tension, but rather on the tendency of different contaminants to interfere with the inter-fibre bonding. Additionally, wet web strength was not affected by the changes in the surface tension of white water or possible changes in the hydrophilicity of fibres caused by the addition of different contaminants. The spraying of different polymers on wet paper before wet pressing had a significant effect on both dry and wet web tensile strength, whereas wet web elastic modulus and residual tension were basically not affected. We suggest that the increase of dry and wet paper strength could be affected by the molecular level interactions between these chemicals and fibres. The most significant increases in dry and wet paper strength were achieved with a dual application of anionic and cationic polymers. Furthermore, selectively adding papermaking chemicals to different fibre fractions (as opposed to adding chemicals to the whole pulp) improved the wet web mechanical properties and the drainage of the pulp suspension.

Improvement of wet and dry web properties in papermaking by controlling water and fiber quality

Pappersindustrin står inför många utmaningar och bör uppfylla krav som ställs av t.ex. marknadstrender och slutanvändare. Snabbare och effektivare processer ställer även större krav på pappersbanans mekaniska egenskaper. Avbrott i produktionen sker inte enbart pga. låg styrka utan orsaken kan även vara en för låg spänning i pappersbanan. De flesta problemen sker vid våtpressen och/eller i början av torkpartiet då papprets torrhalt är 30-70 %. Spänningen hålls inte konstant efter töjning, utan sjunker pga. papprets relaxering, som till största delen sker då pappret flyttas från pressen till torkpartiet. Ur forskningssynvinkel öppnar en smidigt fungerande verksamhet med potentiella energibesparingar upp möjligheterna för förbättring av befintliga processer. I detta arbete undersöktes hur olika faktorer inverkar på fibernätverkets avvattning, initiala våtstyrka och relaxering samt också på slutproduktens mekaniska egenskaper och ytegenskaper. I första delen ändrades processvattnets egenskaper, såsom pH, konduktivitet och ytspänning. Ytspänningen varierades genom tillsatts av ett nonjoniskt ytaktivt ämne, s.k. surfaktant. Fiberegenskaperna modifierades också. Fibern maldes antingen genom en mild eller genom en hård process. Effekten av finmaterial undersöktes genom att tillsätta finmaterial till den ursprungliga massan eller genom att avlägsna finmaterialet från den malda massan. I den sista delen användes en hemicellulosa, som finns i stora mängder i gran, som tillsatsmedel. Förutom naturliga galaktoglukomannaner (GGM), tillverkades också en katjoniserad, en karboximetylerad samt en iminerad, amfifil GGM. Dessa användes i pappersmassa eller sprayades på ytan av ett nybildat ark. Resultaten, som erhölls i denna avhandling, bildar en värdefull kunskapsbas, som kan användas för kontroll och reglering av pappersmaskinens körbarhet och papperskvalitet.

Wet oxidation of biomass for chemical production

Tämän kandidaatintyön tarkoituksena oli tutkia märkähapetusprosessia jätevesien käsittely-menetelmänä ja mahdollisena menetelmänä kemikaalien tuottamiseksi jätevesistä. Erityishuomio on kiinnitetty paperiteollisuudessa syntyviin jätevesiin. Teoriaosassa käsitellään vesikiertoja paperitehtaassa, paperitehtaalla syntyvän jäteveden ominaisuuksia sekä itse märkähapetusprosessia. Märkähapetusprosessissa perehdytään tavalliseen happea käyttävään märkähapetukseen sekä vetyperoksidia käyttävään menetelmään sekä näissä prosesseissa syntyviin väli- ja lopputuotteisiin. Märkähapetus (WO) on terminen hapetusmenetelmä, jolla voidaan käsitellä jätevesiä, jotka ovat liian konsentroituja biologisiin käsittelyihin tai jotka ovat huonosti biohajoavia. Märkähapetuksen tarkoituksena on parantaa molekulaarisen hapen ja orgaanisen aineen välistä kontaktia, jolloin orgaaninen aines pilkkoutuu muodostaen pääasiassa karboksyylihappoja, aldehydejä, hiilidioksidia ja vettä. Märkähapetuksessa hapettavana kaasuna voidaan käyttää joko puhdasta happea tai ilmaa. Vetyperoksidia käyttävässä märkähapetuksessa (WPO) hapettava kaasu on korvattu nestemäisellä vetyperoksidilla. Kokeellisessa osassa tutkittiin orgaanisen aineksen hapetusta käyttäen Fentonin reagenssia, jolloin katalyyttina reaktiossa toimii rautaionit (Fe2+ ja Fe3+) ja hapettimena vetyperoksidi. Hapetettavana jätevetenä käytettiin paperitehtaan hiomolta saatua kiertovettä, TMP-vettä. Hapetuskokeita tehtiin eri vetyperoksidin annoksilla ja katalyytin määrillä eri lämpötiloissa. Hapetuksen jälkeen näytteistä mitattiin kemiallinen hapenkulutus (COD), orgaanisen hiilen kokonaismäärä (TOC) sekä pH. Lisäksi näytteistä määritettiin nestekromatografilla (HPLC) tyypillisten välituotteiden, kuten oksaalihapon, muurahaishapon ja etikkahapon, määrät. Tehdyissä kokeissa COD-arvoja saatiin pienennettyä 50-88 % siten, että suodatetuissa näytteissä muutos oli suurempi kuin suodattamattomissa näytteissä. Lisäksi TOC-arvot laskivat 28-58 %. Tehdyissä kokeissa saatiin myös tuotettua välituotteina karboksyylihappoja, joista etikkahappoa ja oksaalihappoa tuotettiin suurimmat määrät. Myös muurahaishappoa ja meripihkahappoa saatiin tuotettua.

Rhapsody in blue

Soitinnus: trumpetti, orkesteri.

Rhap. in blue

Soitinnus: trumpetti, orkesteri.

Production of Chemicals from Woody Biomass by Wet Oxidation

The production of chemicals from sawdust by wet oxidation has been investigated. Two different concentrations of sawdust; 54054 mg/l and 32683 mg/l were used in the study. The wet oxidation operating conditions were; 175 deg.C – 225 deg.C, 1MPa Oxygen, and 40 minutes to 120 minutes reaction time. Carboxylic acids were among the chemicals produced in the process. The total yield of carboxylic acids was found to increase with temperature. Also, higher yields of carboxylic acids were observed at a lower sawdust concentration. This was probably due to the high oxygen-biomass ratio at lower sawdust concentration. Higher oxygen availability at low sawdust concentration resulted in increased conversion of the sawdust; hence the higher yields of carboxylic acids. At lower sawdust concentration, a total carboxylic acid yield of 25.59 wt% was attained at 200 deg.C and 40 minutes reaction time. At higher sawdust concentration, a total carboxylic acid yield of 15.57 wt% was attained at 200 deg.C and 40-minutes reaction time. The carboxylic acids identified include formic acid, acetic acid, succinic acid and oxalic acid. The optimum temperature for the production of formic acid was found to be 200 deg.C, while the optimum temperature for the production of acetic acid was found to be 225 deg.C. A temperature of 225 deg.C and relatively short reaction time of 10 minutes was found to be the optimal condition for the production of succinic acid. Formic acid was produced in the highest yield, with an optimal yield of 13.69wt %, when the reaction temperature and time are 200 deg.C and 40 minutes respectively. The yield of formic acid was found to decrease significantly when further increasing the temperature to 225 deg.C. This was presumably due to thermal decomposition of formic acid at relatively higher temperature. However, the yield of acetic acid was found to steadily increase with temperature. This is because acetic is more thermally stable than formic acid. The yield of acetic acid did not decrease after the temperature was increased to 225 deg.C. Optimal yield of acetic acid (7.98wt %) was achieved at; 225 deg.C, and 40 minutes reaction time. Succinic acid was produced only at temperatures of 200 deg.C and 225 deg.C. Optimal yield of succinic acid (5.66wt %) was attained under the following conditions; 32683 mg/l, 225 deg.C, 1MPa O2, and 10-minutes reaction time. Oxalic acid was produced in the lowest yield and, less frequently. The optimal yield of oxalic acid (4.02 wt%) was attained at 175 deg.C and 80-minutes of reaction time The Total Organic Carbon (TOC) is found to be higher when increasing the operating temperature, thus suggesting that more organic compounds are formed at higher temperatures. The identified carboxylic acids could only account for less than 30% of the measured COD content of the various wet oxidation samples. This implies that some other unidentified compounds (reaction products) must have been present. In general, wet oxidation seems to be an effective method for converting lignocellulosic biomass into useful chemicals. Relatively higher temperatures have been found to favor the production of carboxylic acids from sawdust.

Recovery and purification of anthocyanins from purple-blue potato

The aim of this work was to study techniques to extract and purify of anthocyanins from purple-blue potato. This topic was determined as a master’s thesis and it was done in collaboration with the Food Chemistry and Food Development Department of University of Turku and Department of Chemical and Process Engineering at Lappeenranta University of Technology. At first, purple-blue potatoes were pretreated in four types of boiled, raw, freeze-dried and dried boiled potato for extraction. They were mixed with aqueous acidified ethanol (ethanol:water:acetic acid 40%:53%:7% v/v) for conventional extraction. Boiled potato was selected as a best pretreated potato. Different ethanol concentration and extraction time were examined and the mixture of 80% in 24 h resulted in maximum anthocyanin content (132.23 mg/L). As conventional extraction method of anthocyanins was non-selective, some of impurities such as free sugars might accelerate anthocyanin degradation. Therefore, to obtain anthocyanins in purified form, adsorption as a promising selective method was used to recovery and isolate anthocyanins. It was carried out with six adsorbents. Among those, Amberlite XAD-7HP, a nonionic acrylic ester adsorbent, was found to have the best performance. In an adsorption column, flow rate of 3 mL/min was selected as the loading flow rate among four tested flow rates. Eluent volume and flow rate were 3 BV of aqueous acidified ethanol (75%, v/v) and 1 mL/min for desorption. The quantification of the total anthocyanin contents was performed by pH-differential method using UV-vis spectrophotometer. The resulting anthocyanin solution after purification was almost free from free sugars which were the major cause for degradation of anthocyanins. The average anthocyanin concentration in the purified and concentrated sample was obtained 1752.89 mg/L.

Blue and Uv-Emitting Upconversion Nanoparticles: Synthesis and (Bio) Analytical Applications.

Rare-earth based upconverting nanoparticles (UCNPs) have attracted much attention due to their unique luminescent properties. The ability to convert multiple photons of lower energy to ones with higher energy through an upconversion (UC) process offers a wide range of applications for UCNPs. The emission intensities and wavelengths of UCNPs are important performance characteristics, which determine the appropriate applications. However, insufficient intensities still limit the use of UCNPs; especially the efficient emission of blue and ultraviolet (UV) light via upconversion remains challenging, as these events require three or more near-infrared (NIR) photons. The aim of the study was to enhance the blue and UV upconversion emission intensities of Tm3+ doped NaYF4 nanoparticles and to demonstrate their utility in in vitro diagnostics. As the distance between the sensitizer and the activator significantly affect the energy transfer efficiency, different strategies were explored to change the local symmetry around the doped lanthanides. One important strategy is the intentional co-doping of active (participate in energy transfer) or passive (do not participate in energy transfer) impurities into the host matrix. The roles of doped passive impurities (K+ and Sc3+) in enhancing the blue and UV upconversions, as well as in influencing the intense UV upconversion emission through excess sensitization (active impurity) were studied. Additionally, the effects of both active and passive impurity doping on the morphological and optical performance of UCNPs were investigated. The applicability of UV emitting UCNPs as an internal light source for glucose sensing in a dry chemistry test strip was demonstrated. The measurements were in agreement with the traditional method based on reflectance measurements using an external UV light source. The use of UCNPs in the glucose test strip offers an alternative detection method with advantages such as control signals for minimizing errors and high penetration of the NIR excitation through the blood sample, which gives more freedom for designing the optical setup. In bioimaging, the excitation of the UCNPs in the transparent IR region of the tissue permits measurements, which are free of background fluorescence and have a high signal-to-background ratio. In addition, the narrow emission bandwidth of the UCNPs enables multiplexed detections. An array-in-well immunoassay was developed using two different UC emission colours. The differentiation between different viral infections and the classification of antibody responses were achieved based on both the position and colour of the signal. The study demonstrates the potential of spectral and spatial multiplexing in the imaging based array-in-well assays.