Muurahaishapon käyttö etikkahapon ja propionihapon sovelluksissa

Työssä tutkittiin muurahais-, etikka- ja propionihapon sekä näiden johdannaisten teollisia sovelluskohteita. Työn tarkoituksena oli löytää muurahaishapolle tai sen johdannaisille potentiaalisia käyttökohteita etikka- ja propionihapon sekä näiden johdannaisten teollisista sovelluskohteista. Työssä on laaja kirjallisuuskatsaus, jossa käsitellään muurahais-, etikka- ja propionihapon kemiallisia ja fysikaalisia ominaisuuksia, ekologisia ja korroosiovaikutuksia sekä yleensä orgaanisten happojen antimikrobisia ominaisuuksia. Tämän lisäksi työssä esitellään tarkasteltavien happojen sekä happojohdannaisten markkinat teollisissa sovelluksissa Yhdysvalloissa, Länsi-Euroopassa ja Japanissa. Korvaavuuksien syventävän analyysin avulla pyrittiin löytämään ne sovelluskohteet muurahaishapolle tai sen johdannaisille, joissa ne voisivat olla hinnaltaan kilpailukykyisiä vastaavien etikka-ja propionihapposovellusten kanssa. Mahdollisen korvaavuuden rajaksi asetettiin5 000 tonnia sovelluskohdetta kohti. Kirjallisuustutkimuksen perusteella etikkahapon estereiden (asetaattiestereiden) käyttökohde liuottimien komponentteinavoisi olla potentiaalisin käyttökohde vastaaville muurahaishapon estereille (formiaattiestereille). Asetaattiestereitä on ennustettu käytettävän maailmalla 2 808 000 tonnia vuonna 2006. Niiden pääkäyttöalueet ovat liuottimina pintapäällysteissä kuten maaleissa, lakoissa sekä painomusteissa ja -väreissä. Toistaiseksi formiaattiestereitä on hyödynnetty vain muutamia satoja tonneja lähinnä lääketeollisuuden sovelluksissa välituotteena. Työssä tehtyjen alustavien laskelmien perusteella muurahaishapon esterit ovat hintatasoltaan kilpailukykyinen vaihtoehto vastaaville asetaattiestereille. Diplomityön kokeellisessa osassa etyyliformiaattia valmistettiin menestyksekkäästi laboratoriomittakaavassa. Toinen potentiaalinen uusi tuote on selluloosaformiaattikuitu (SF-kuitu). Selluloosa-asetaattikuitua käytettiin vuonna 2001 845 000 tonnia, josta 79 % kului savukefilttereiden valmistukseen. SF-kuitu on kirjallisuuden mukaan vaihtoehtoinen raaka-aine savukefilttereiden valmistukseen.

Stabilization of the ionic form of weak acid cation exchange resins

Weak acid cation exchange (WAC) resins are used in the chromatographic separation of betaine from vinasse, a by-product of sugar industry. The ionic form of the resin determines the elution time of betaine. When a WAC-resin is in hydrogen form, the retention time of betaine is the longest and betaine elutes as the last component of vi-nasse from the chromatographic column. If the feed solution contains salts and its pH is not acidic enough to keep the resin undissociated, the ionic form of the hydrogen form resin starts to alter. Vinasse contains salts and its pH is around 5, it also contains weak acids. To keep the metal ion content (Na/H ratio) of the resin low enough to ensure successful separation of betaine, acid has to be added to either eluent (water) or vinasse. The aim of the present work was to examine by laboratory experiments which option requires less acid. Also the retention mechanism of betaine was investigated by measuring retention volumes of acetic acid and choline in different Na/H ratios of the resin. It was found that the resulting ionic form of the resin is the same regardless of whether the regeneration acid is added to the eluent or the feed solution (vinasse). Be-sides the salt concentration and the pH of vinasse, also the concentration of weak acids in the feed affects the resulting ionic form of the resin. The more buffering capacity vinasse has, the more acid is required to keep the ionic form of the resin desired. Vinasse was found to be quite strong buffer solution, which means relatively high amounts of acid are required to prevent the Na/H ratio from increasing too much. It is known that the retention volume of betaine decreases significantly, when the Na/H ratio increases. This is assumed to occur, because the amount of hydrogen bonds between the carboxylic groups of betaine and the resin decreases. Same behavior was not found with acetic acid. Choline has the same molecular structure as betaine, but instead of carboxylic group it has hydroxide group. The retention volume of choline increased as the Na/H ratio of the resin increased, because of the ion exchange reaction between choline cation and dissociated carboxylic group of the resin. Since the retention behavior of choline on the resin is opposite to the behavior of be-taine, the strong affinity of betaine towards hydrogen form WAC-resin has to be based on its carboxylic group. It is probable that the quaternary ammonium groups also affect the behavior of the carboxylic groups of betaine, causing them to form hydrogen bonds with the carboxylic groups of the resin.

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.

Ion-exchange resins as stationary phase in reactive chromatography

Dynamic behavior of bothisothermal and non-isothermal single-column chromatographic reactors with an ion-exchange resin as the stationary phase was investigated. The reactor performance was interpreted by using results obtained when studying the effect of the resin properties on the equilibrium and kinetic phenomena occurring simultaneously in the reactor. Mathematical models were derived for each phenomenon and combined to simulate the chromatographic reactor. The phenomena studied includes phase equilibria in multicomponent liquid mixture¿ion-exchange resin systems, chemicalequilibrium in the presence of a resin catalyst, diffusion of liquids in gel-type and macroporous resins, and chemical reaction kinetics. Above all, attention was paid to the swelling behavior of the resins and how it affects the kinetic phenomena. Several poly(styrene-co-divinylbenzene) resins with different cross-link densities and internal porosities were used. Esterification of acetic acid with ethanol to produce ethyl acetate and water was used as a model reaction system. Choosing an ion-exchange resin with a low cross-link density is beneficial inthe case of the present reaction system: the amount of ethyl acetate as well the ethyl acetate to water mole ratio in the effluent stream increase with decreasing cross-link density. The enhanced performance of the reactor is mainly attributed to increasing reaction rate, which in turn originates from the phase equilibrium behavior of the system. Also mass transfer considerations favor the use ofresins with low cross-link density. The diffusion coefficients of liquids in the gel-type ion-exchange resins were found to fall rapidly when the extent of swelling became low. Glass transition of the polymer was not found to significantlyretard the diffusion in sulfonated PS¿DVB ion-exchange resins. It was also shown that non-isothermal operation of a chromatographic reactor could be used to significantly enhance the reactor performance. In the case of the exothermic modelreaction system and a near-adiabatic column, a positive thermal wave (higher temperature than in the initial state) was found to travel together with the reactive front. This further increased the conversion of the reactants. Diffusion-induced volume changes of the ion-exchange resins were studied in a flow-through cell. It was shown that describing the swelling and shrinking kinetics of the particles calls for a mass transfer model that explicitly includes the limited expansibility of the polymer network. A good description of the process was obtained by combining the generalized Maxwell-Stefan approach and an activity model that was derived from the thermodynamics of polymer solutions and gels. The swelling pressure in the resin phase was evaluated by using a non-Gaussian expression forthe polymer chain length distribution. Dimensional changes of the resin particles necessitate the use of non-standard mathematical tools for dynamic simulations. A transformed coordinate system, where the mass of the polymer was used as a spatial variable, was applied when simulating the chromatographic reactor columns as well as the swelling and shrinking kinetics of the resin particles. Shrinking of the particles in a column leads to formation of dead volume on top of the resin bed. In ordinary Eulerian coordinates, this results in a moving discontinuity that in turn causes numerical difficulties in the solution of the PDE system. The motion of the discontinuity was eliminated by spanning two calculation grids in the column that overlapped at the top of the resin bed. The reactive and non-reactive phase equilibrium data were correlated with a model derived from thethermodynamics of polymer solution and gels. The thermodynamic approach used inthis work is best suited at high degrees of swelling because the polymer matrixmay be in the glassy state when the extent of swelling is low.

Synteesikaasun liukoisuus ja aineensiirto fermentointiliuokseen

Työssä tutkittiin synteesikaasun komponenttien: hiilimonoksidin, vedyn ja hiilidioksidin liukoisuutta ja aineensiirtonopeutta fermentointiliuokseen. Kirjallisuusosassa käsitellään kaasujen liukoisuuksiin ja kaasu-nesteaineensiirtoon vaikuttavia tekijöitä ja esitellään korrelaatioita, jotka on kehitetty volumetrisen aineensiirtokertoimen ennustamiseen sekoitetussa fermentorissa. Kirjallisuus-osassa esitetään myös synteesikaasun komponenttien liukoisuudet veteen, etanoliin ja etikkahappoon 37 ºC lämpötilassa ja esitellään Flowbat-simulointiohjelman MHV2-mallin käyttöä kaasu-neste tasapainojen mallin-nuksessa. Työn kokeellisessa osassa tutkittiin synteesikaasun komponenttien liukoisuuksia veteen ja kasvatusalustaan sekä kehitettiin mittausmenetelmä kaasu-neste tasapainojen mittaukseen. Tasapainomittauksissa tutkittiin etanolin ja etikkahapon konsentraatioiden vaikutusta synteesikaasun liukoisuuteen. Lisäksi mallinnettiin kaasu-neste tasapainoja monikomponenttisysteemeissä MHV2-mallin avulla. Kokeellisen osan aineensiirtomittauksissa tutkittiin sekoitusnopeuden ja kaasun volumetrisen syöttönopeuden vaikutusta hiilimonoksidin ja vedyn volumetriseen aineensiirtokertoimeen kLa kahden litran tilavuuksisessa laboratoriofermentorissa. Mittaustulosten perusteella kasvatusalustan komponentit vaikuttavat merkittävästi hiilidioksidin liukoisuuteen. Lisäys etanolin ja etikkahapon konsentraatioissa parantaa hiilimonoksidin liukoisuutta kasvatusalustaan. Kaasun volumetrinen syöttönopeus ja sekoitusnopeus vaikuttavat voimakkaasti volumetrisen aineensiirtokertoimen arvoon. Tutkitussa systeemissä korkein teoreettinen solutiheys, joka voitiin saavuttaa suurimmalla hiilimonoksidin aineensiirto-nopeudella, oli 3 g/L. Tämä on kaksinkertainen verrattuna aiemmissa VTT:n kokeissa saavutettuihin solutiheyksiin.

Regeneroidun selluloosapinnan modifiointi kestämään mikro-organismien toimintaa

Työn tavoitteena oli kehittää mikro-organismeja kestävä suoli eli makkarankuori. Työ suoritettiin modifioimalla regeneroitua selluloosaa. Modifiointiliuoksena käytettiin etikkahapon ja etikkahappoanhydridin seosta, johon lisättiin rikkihappoa katalyytiksi. Työssä etsittiin parasta yhdistelmää, joka koostui modifiointiradannopeudesta, modifiointiliuoskoostumuksesta ja erilaisista modifiointimenetelmistä. Kirjallisuusosassa käsiteltiin yleisesti asetaattikalvoja, niiden valmistusta ja ominaisuuksia. Lisäksi perehdyttiin entsyymin ominaisuuksiin ja toimintaan yleisesti. Entsyymeistä yksi otettiin lähempään tarkasteluun. Kokeissa regeneroitua selluloosaa modifioitiin liuoksessa, jonka koostumusta muunneltiin. Kokeissa oli kolme erilaista modifiointimenetelmää, joissa käytettiin neljää modifiointiliuoskoostumusta ja kolmea modifiointinopeutta. Mittauksissa tutkittiin modifioinnin vaikutusta suoliin verrattuna normaaleihin suoliin. Suolille tehtiin sekä mekaanisia että kemiallisia testejä. Kemiallisista testeistä tärkein oli testi, jossa modifioitu suoli altistettiin mikro-organismille. Tulosten perusteella valittiin paras menetelmä. Työssä havaittiin yhden menetelmän olevan muita paljon parempi. Tällä menetelmällä suoritettiin toistokokeita, jotka varmistivat jo saatuja tuloksia. Liuoskoostumusten välillä ei ollut suuria eroja, mutta kuitenkin niistä yksi osoittautui parhaimmaksi. Nopeutta oli vaikeampi määrittää, mutta siitäkin saatiin määritettyä tietty haarukka, jossa reaktio oli tehokkain.

Gas-phase photocatalytic oxidation of volatile organic compounds

Substances emitted into the atmosphere by human activities in urban and industrial areas cause environmental problems such as air quality degradation, respiratory diseases, climate change, global warming, and stratospheric ozone depletion. Volatile organic compounds (VOCs) are major air pollutants, emitted largely by industry, transportation and households. Many VOCs are toxic, and some are considered to be carcinogenic, mutagenic, or teratogenic. A wide spectrum of VOCs is readily oxidized photocatalytically. Photocatalytic oxidation (PCO) over titanium dioxide may present a potential alternative to air treatment strategies currently in use, such as adsorption and thermal treatment, due to its advantageous activity under ambient conditions, although higher but still mild temperatures may also be applied. The objective of the present research was to disclose routes of chemical reactions, estimate the kinetics and the sensitivity of gas-phase PCO to reaction conditions in respect of air pollutants containing heteroatoms in their molecules. Deactivation of the photocatalyst and restoration of its activity was also taken under consideration to assess the practical possibility of the application of PCO to the treatment of air polluted with VOCs. UV-irradiated titanium dioxide was selected as a photocatalyst for its chemical inertness, non-toxic character and low cost. In the present work Degussa P25 TiO2 photocatalyst was mostly used. In transient studies platinized TiO2 was also studied. The experimental research into PCO of following VOCs was undertaken: - methyl tert-butyl ether (MTBE) as the basic oxygenated motor fuel additive and, thus, a major non-biodegradable pollutant of groundwater; - tert-butyl alcohol (TBA) as the primary product of MTBE hydrolysis and PCO; - ethyl mercaptan (ethanethiol) as one of the reduced sulphur pungent air pollutants in the pulp-and-paper industry; - methylamine (MA) and dimethylamine (DMA) as the amino compounds often emitted by various industries. The PCO of VOCs was studied using a continuous-flow mode. The PCO of MTBE and TBA was also studied by transient mode, in which carbon dioxide, water, and acetone were identified as the main gas-phase products. The volatile products of thermal catalytic oxidation (TCO) of MTBE included 2-methyl-1-propene (2-MP), carbon monoxide, carbon dioxide and water; TBA decomposed to 2-MP and water. Continuous PCO of 4 TBA proceeded faster in humid air than dry air. MTBE oxidation, however, was less sensitive to humidity. The TiO2 catalyst was stable during continuous PCO of MTBE and TBA above 373 K, but gradually lost activity below 373 K; the catalyst could be regenerated by UV irradiation in the absence of gas-phase VOCs. Sulphur dioxide, carbon monoxide, carbon dioxide and water were identified as ultimate products of PCO of ethanethiol. Acetic acid was identified as a photocatalytic oxidation by-product. The limits of ethanethiol concentration and temperature, at which the reactor performance was stable for indefinite time, were established. The apparent reaction kinetics appeared to be independent of the reaction temperature within the studied limits, 373 to 453 K. The catalyst was completely and irreversibly deactivated with ethanethiol TCO. Volatile PCO products of MA included ammonia, nitrogen dioxide, nitrous oxide, carbon dioxide and water. Formamide was observed among DMA PCO products together with others similar to the ones of MA. TCO for both substances resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide and water. No deactivation of the photocatalyst during the multiple long-run experiments was observed at the concentrations and temperatures used in the study. PCO of MA was also studied in the aqueous phase. Maximum efficiency was achieved in an alkaline media, where MA exhibited high fugitivity. Two mechanisms of aqueous PCO – decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite - lead ultimately to carbon dioxide, water, ammonia and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. This finding helped in better understanding of the gasphase PCO pathways. The PCO kinetic data for VOCs fitted well to the monomolecular Langmuir- Hinshelwood (L-H) model, whereas TCO kinetic behaviour matched the first order process for volatile amines and the L-H model for others. It should be noted that both LH and the first order equations were only the data fit, not the real description of the reaction kinetics. The dependence of the kinetic constants on temperature was established in the form of an Arrhenius equation.

Biohajoavat kompleksinmuodostajat mekaanisen massan peroksidivalkaisussa

Mekaanisen massan peroksidivalkaisussa on perinteisesti käytetty kahta kompleksinmuodostajaa, jotka ovat dietyleenitriamiinipentaetikkahappo (DTPA) ja etyleenidiamiinipentaetikkahappo (EDTA). Kompleksinmuodostajat saavat aikaan hyvän kelatointituloksen muodostamalla valkaisulle haitallisten metalli-ionien kanssa kompleksin ja estäen näin metalli-ionien valkaisutulosta huonontavan vaikutuksen. Perinteiset kompleksinmuodostajat DTPA ja EDTA eivät kuitenkaan ole biohajoavia ja niiden epäillään irrottavan metalleja vesistöjen sedimenteistä. Työssä selvitettiin kolmen eri biohajoavan kompleksinmuodostajan valkaisuteho verrattuna perinteisiin kompleksinmuodostajiin. Laboratoriossa suoritetut pesukokeet osoittivat, että mikään biohajoava kompleksinmuodostaja ei saavuttanut samaa pesutehoa kuin perinteiset kompleksinmuodostajat. Valkaisukokeet kuitenkin osoittivat, että biohajoava kompleksinmuodostaja ISA pääsi hyvin lähelle perinteisten kompleksinmuodostajien valkaisutuloksia suoritettaessa valkaisu siten, että massa esipestään kompleksinmuodostajalla ja sen jälkeen valkaistaan vakiokemikaaliannoksella alkalina ollessa natriumhydroksidi. Kaksi muuta biohajoavaa kompleksinmuodostajaa, ISA+EDDS ja HAS, eivät saavuttaneet samaa tasoa. HAS toimi kyllä stabilaattorina, muttei pystynyt nostamaan massan vaaleutta.

Water circulations for effective bleaching of high-brightness mechanical pulps

The amount of water available is usually restricted, which leads to a situation where a complete understanding of the process, including water circulations and the influence of water components, is essential. The main aim of this thesis was to clarify the possibilities for the efficient use of residual peroxide by means of water circulation rearrangements. Rearranging water circulations and the reduction of water usage may cause new problems, such as metal induced peroxide decomposition that needs to be addressed. This thesis introduces theoretical methods of water circulations to combine two variables; effective utilization of residual peroxide and avoiding manganese in the alkaline peroxide bleaching stage. Results are mainly based on laboratory and mill site experiments concerning the utilization of residual peroxide. A simulation model (BALAS) was used to evaluate the manganese contents and residual peroxide doses. It was shown that with optimum recirculation of residual peroxide the brightness can be improved or chemical costs can be decreased. From the scientific perspective, it was also very important to discover that recycled peroxide was more effective pre-bleaching agent compared to fresh peroxide. This can be due to the organic acids i.e. per acetic acid in wash press filtrate that have been formed in alkaline bleaching stage. Even short retention time was adequate and the activation of residual peroxide using sodium hydroxide was not necessary. There are several possibilities for using residual peroxide in practice regarding bleaching. A typical modern mechanical pulping process line consist of defibering, screening, a disc filter, a bleach press, high consistency (HC) peroxide bleaching and a wash press. Furthermore there usually is not a particular medium consistency (MC) pre-bleaching stage that includes additional thickening equipment. The most advisable way to utilize residual peroxide in this kind of process is to recycle the wash press filtrate to the dilution of disc filter pulp (low MC pre-bleaching stage). An arrangement such as this would be beneficial in terms of the reduced convection of manganese to the alkaline bleaching stage. Manganese originates from wood material and will be removed to the water phase already in the early stages of the process. Recycling residual peroxide prior to the disc filter is not recommended because of low consistencies. Regarding water circulations, the novel point of view is that, it would be beneficial to divide water circulations into two sections and the critical location for the division is the disc filter. Both of these two sections have their own priority. Section one before the disc filter: manganese removal. Section two after the disc filter: brightening of pulp. This division can be carried out if the disc filter pulp is diluted only by wash press filtrate before the MC storage tower. The situation is even better if there is an additional press after the disc filter, which will improve the consistency of the pulp. This has a significant effect on the peroxide concentration in the MC pre-bleaching stage. In terms of manganese content, it is essential to avoid the use of disc filter filtrate in the bleach press and wash press showers. An additional cut-off press would also be beneficial for manganese removal. As a combination of higher initial brightness and lower manganese content, the typical brightness increase varies between approximately 0.5 and 1% ISO units after the alkaline peroxide bleaching stage. This improvement does not seem to be remarkable, but as it is generally known, the final brightness unit is the most expensive and difficult to achieve. The estimation of cost savings is not unambiguous. For example in GW/TMP mill case 0.6% ISO units higher final brightness gave 10% savings in the costs of bleaching chemicals. With an hypothetical 200 000 ton annual production, this means that the mill could save in the costs of bleaching chemicals more than 400 000 euros per year. In general, it can be said that there were no differences between the behavior of different types of processes (GW, PGW, TMP and BCTMP). The enhancement of recycling gave a similar response in all cases. However, we have to remember that the utilization of residual peroxide in older mills depends a great deal on the process equipment, the amount of water available and existing pipeline connections. In summary, it can be said that processes are individual and the same solutions cannot be applied to all cases.

Lämpötilan vaikutus kalvojen likaantumiseen erityisesti adsorptiolla

Työssä tutkittiin lämpötilan vaikutusta kalvon likaantumiseen mustalipeällä ja puuperäisellä hydrolysaatilla lämpötiloissa 20, 45 ja 70 °C:tta. Työn tavoitteena oli löytää lämpötila, jossa tutkimuksessa käytetyt puuperäiset liuokset likasivat kalvoja mahdollisimman vähän. Tutkimuksessa käytettiin Alfa Lavalin UFX5-ultrasuodatuskalvoa sekä Microdyn-Nadirin ultrasuodatuskalvoa UP010 ja nanosuodatuskalvoa NP010. Ennen puuperäisten liuosten adsorboimista kalvoihin säilöntäaineet poistettiin kalvoista sekä kalvojen toiminta stabiloitiin esikäsittelemällä kalvot. Esikäsittelyssä kalvoja pestiin alkalisella pesuaineella, puristettiin 8 bar:n paineessa sekä huuhdeltiin vedellä ja etikkahapolla. Esikäsitellyt kalvot karakterisoitiin mittaamalla malliaineliuoksen vuo ja malliaineiden retentiot suodattamalla polyetyleeniglykoliliuosta kolmikennosuodattimella paineissa 2, 4 ja 6 bar. Tämän jälkeen kalvot altistettiin lämpötiloissa 20, 45 ja 70 °C:tta mustalipeälle ja hydrolysaatille. Altistuksen jälkeen karakterisointi tehtiin uudelleen, jotta vuoarvoja ja retentioita vertaamalla voitiin arvioida altistuksen aikana tapahtunutta kalvojen likaantumista. Adsorboituneen lian puhdistusta kalvoista tutkittiin pesemällä kalvoja alkalisella pesuliuoksella 20 °C:ssa tehdyn altistuksen jälkeen. Mustalipeälle altistettujen kalvojen likaantuminen oli vähäisintä kokeissa, joissa lämpötila oli 20 °C. Alfa Lavalin UFX5-kalvolla 70 °C:ssa tehdyssä kokeessa kalvon likaantuminen oli myös erittäin vähäistä, sillä permeabiliteetti pieneni mustalipeäaltistuksen seurauksena alle 5 %. Hydrolysaatille altistetut kalvot likaantuivat adsorptiolla vähiten Alfa Laval UFX5-kalvoilla 20 °C:ssa tehdyissä kokeissa ja 45 °C:ssa Microdyn-Nadir NP010-kalvoilla tehdyissä kokeissa. Kokeiden perusteella tutkituista vaihtoehdoista korkein tutkimuksessa käytetty lämpötila 70 °C ja Alfa Lavalin UFX5-kalvo soveltuvatkin parhaiten mustalipeän kalvosuodatukseen adsorptiivisen likaantumisen kannalta.

Lignoselluloosapohjaisten väkevähappohydrolysaattien jatkuvatoiminen kromatografinen fraktiointi

Työssä tutkittiin lignoselluloosapohjaisten väkevähappohydrolysaattien (monosakkaridit, rikki- ja etikkahppo) jatkuvatoimista kromatografista fraktiointia käyttäen Japan Organo SMB -prosessia. Adsorbenttinä toimi happomuotoinen (H+) vahva kationinvaihtohartsi. Panostoimista fraktiointia käytettiin vertailukohtana. Jatkuvatoimisen prosessin optimoinnilla saavutettiin monosakkaridien suurimmaksi tuottavuudeksi 283 mol/(m3 h) (panosprosessille 145 mol/(m3 h). JO-prosessilla saavutettiin korkeat rikki- ja etikkahapon saannot: 97,3 % ja 93,5 %. Monosakkaridisaanto jäi hieman alhaisemmaksi (61,7 %) johtuen monosakkaridi- ja rikkihappo-profiilien hankalasta erottamisesta. Ulostulo virtojen puhtaudet olivat korkeat: 89 % monosakkarideille, 89 % rikkihapolle ja 100 % etikkahapolle.

Extraction of polymeric galactoglucomannans from spruce wood by pressurized hot water

The major type of non-cellulosic polysaccharides (hemicelluloses) in softwoods, the partly acetylated galactoglucomannans (GGMs), which comprise about 15% of spruce wood, have attracted growing interest because of their potential to become high-value products with applications in many areas. The main objective of this work was to explore the possibilities to extract galactoglucomannans in native, polymeric form in high yield from spruce wood with pressurised hot-water, and to obtain a deeper understanding of the process chemistry involved. Spruce (Picea abies) chips and ground wood particles were extracted using an accelerated solvent extractor (ASE) in the temperature range 160 – 180°C. Detailed chemical analyses were done on both the water extracts and the wood residues. As much as 80 – 90% of the GGMs in spruce wood, i.e. about 13% based on the original wood, could be extracted from ground spruce wood with pure water at 170 – 180°C with an extraction time of 60 min. GGMs comprised about 75% of the extracted carbohydrates and about 60% of the total dissolved solids. Other substances in the water extracts were xylans, arabinogalactans, pectins, lignin and acetic acid. The yields from chips were only about 60% of that from ground wood. Both the GGMs and other non-cellulosic polysaccharides were extensively hydrolysed at severe extraction conditions when pH dropped to the level of 3.5. Addition of sodium bicarbonate increased the yields of polymeric GGMs at low additions, 2.5 – 5 mM, where the end pH remained around 3.9. However, at higher addition levels the yields decreased, mainly because the acetyl groups in GGMs were split off, leading to a low solubility of GGMs. Extraction with buffered water in the pH range 3.8 – 4.4 gave similar yields as with plain water, but gave a higher yield of polymeric GGMs. Moreover, at these pH levels the hydrolysis of acetyl groups in GGMs was significantly inhibited. It was concluded that hot-water extraction of polymeric GGMs in good yields (up to 8% of wood) demands appropriate control of pH, in a narrow range about 4. These results were supported by a study of hydrolysis of GGM at constant pH in the range of 3.8 – 4.2 where a kinetic model for degradation of GGM was developed. The influence of wood particle size on hot-water extraction was studied with particles in the range of 0.1 – 2 mm. The smallest particles (< 0.1 mm) gave 20 – 40% higher total yield than the coarsest particles (1.25 – 2 mm). The difference was greatest at short extraction times. The results indicated that extraction of GGMs and other polysaccharides is limited mainly by the mass transfer in the fibre wall, and for coarse wood particles also in the wood matrix. Spruce sapwood, heartwood and thermomechnical pulp were also compared, but only small differences in yields and composition of extracts were found. Two methods for isolation and purification of polymeric GGMs, i.e. membrane filtration and precipitation in ethanol-water, were compared. Filtration through a series of membranes with different pore sizes separated GGMs of different molar masses, from polymers to oligomers. Polysaccharides with molar mass higher than 4 kDa were precipitated in ethanol-water. GGMs comprised about 80% of the precipitated polysaccharides. Other polysaccharides were mainly arabinoglucuronoxylans and pectins. The ethanol-precipitated GGMs were by 13C NMR spectroscopy verified to be very similar to GGMs extracted from spruce wood in low yield at a much lower temperature, 90°C. The obtained large body of experimental data could be utilised for further kinetic and economic calculations to optimise technical hot-water extractionof softwoods.

Biomassahydrolysaattien puhdistus uutolla

Lignoselluloosasta koostuvasta biomassasta valmistetaan hydrolysoimalla sokereita, jotka jatkojalostetaan fermentoimalla bioetanoliksi. Bioetanolia käytetään fossiilisten polttoaineiden korvaajana esimerkiksi ajoneuvoissa. Bioetanolin valmistuksessa pyritään mahdollisimman hyvään saantoon, jotta sen valmistus olisi taloudellisesti kannattavaa. Hydrolyysin aikana syntyy sokerien lisäksi orgaanisia happoja, furaanin johdannaisia sekä fenolisia yhdisteitä. Yleisimpiä syntyviä yhdisteitä ovat muun muassa etikkahappo, furfuraali ja hydroksimetyylifurfuraali. Nämä yhdisteet haittaavat sokerien fermentointiprosessia ja pienentävät etanolin saantoa. Fermentointiprosessia haittaavien yhdisteiden poistoon hydrolysaattiliuoksesta voidaan käyttää esimerkiksi haihdutusta, membraanierotusta, adsorptiota, saostusta, sekä uuttoa. Tämän työn tarkoituksena oli tutkia leikkaussekoittimen soveltuvuutta biomassahydrolysaatin epäpuhtauksien erotukseen. Lisäksi kirjallisuusosassa on esitetty hydrolysointiprosessissa syntyviä haitta-aineita ja niiden erotusmenetelmiä.

Chromatographic recovery of chemicals from acidic biomass hydrolysates

Lignocellulosic biomasses (e.g., wood and straws) are a potential renewable source for the production of a wide variety of chemicals that could be used to replace those currently produced by petrochemical industry. This would lead to lower greenhouse gas emissions and waste amounts, and to economical savings. There are many possible pathways available for the manufacturing of chemicals from lignocellulosic biomasses. One option is to hydrolyze the cellulose and hemicelluloses of these biomasses into monosaccharides using concentrated sulfuric acid as catalyst. This process is an efficient method for producing monosaccharides which are valuable platforn chemicals. Also other valuable products are formed in the hydrolysis. Unfortunately, the concentrated acid hydrolysis has been deemed unfeasible mainly due to high chemical consumption resulting from the need to remove sulfuric acid from the obtained hydrolysates prior to the downstream processing of the monosaccharides. Traditionally, this has been done by neutralization with lime. This, however, results in high chemical consumption. In addition, the by-products formed in the hydrolysis are not removed and may, thus, hinder the monosaccharide processing. In order to improve the feasibility of the concentrated acid hydrolysis, the chemical consumption should be decreased by recycling of sulfuric acid without neutralization. Furthermore, the monosaccharides and the other products formed in the hydrolysis should be recovered selectively for efficient downstream processing. The selective recovery of the hydrolysis by-products would have additional economical benefits on the process due to their high value. In this work, the use of chromatographic fractionation for the recycling of sulfuric acid and the selective recovery of the main components from the hydrolysates formed in the concentrated acid hydrolysis was investigated. Chromatographic fractionation based on the electrolyte exclusion with gel type strong acid cation exchange resins in acid (H+) form as a stationary phase was studied. A systematic experimental and model-based study regarding the separation task at hand was conducted. The phenomena affecting the separation were determined and their effects elucidated. Mathematical models that take accurately into account these phenomena were derived and used in the simulation of the fractionation process. The main components of the concentrated acid hydrolysates (sulfuric acid, monosaccharides, and acetic acid) were included into this model. Performance of the fractionation process was investigated experimentally and by simulations. Use of different process options was also studied. Sulfuric acid was found to have a significant co-operative effect on the sorption of the other components. This brings about interesting and beneficial effects in the column operations. It is especially beneficial for the separation of sulfuric acid and the monosaccharides. Two different approaches for the modelling of the sorption equilibria were investigated in this work: a simple empirical approach and a thermodynamically consistent approach (the Adsorbed Solution theory). Accurate modelling of the phenomena observed in this work was found to be possible using the simple empirical models. The use of the Adsorbed Solution theory is complicated by the nature of the theory and the complexity of the studied system. In addition to the sorption models, a dynamic column model that takes into account the volume changes of the gel type resins as changing resin bed porosity was also derived. Using the chromatography, all the main components of the hydrolysates can be recovered selectively, and the sulfuric acid consumption of the hydrolysis process can be lowered considerably. Investigation of the performance of the chromatographic fractionation showed that the highest separation efficiency in this separation task is obtained with a gel type resin with a high crosslinking degree (8 wt. %); especially when the hydrolysates contain high amounts of acetic acid. In addition, the concentrated acid hydrolysis should be done with as low sulfuric acid concentration as possible to obtain good separation performance. The column loading and flow rate also have large effects on the performance. In this work, it was demonstrated that when recycling of the fractions obtained in the chromatographic fractionation are recycled to preceding unit operations these unit operations should included in the performance evaluation of the fractionation. When this was done, the separation performance and the feasibility of the concentrated acid hydrolysis process were found to improve considerably. Use of multi-column chromatographic fractionation processes, the Japan Organo process and the Multi-Column Recycling Chromatography process, was also investigated. In the studied case, neither of these processes could compete with the single-column batch process in the productivity. However, due to internal recycling steps, the Multi-Column Recycling Chromatography was found to be superior to the batch process when the product yield and the eluent consumption were taken into account.

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.