Abstract The production of liquid transportation fuels such as bioethanol and more recently also biobutanol from renewable resources has received considerable attention. In the production of bio-based alcohols, the separation steps are expensive as the mixtures to be separated are dilute. As an energy-efficient separation technology, pervaporation is considered to be a potential process in biofuel purification. One of the main constraints in the commercialization of pervaporation has been low membrane fluxes, and the consequent high costs due to the high membrane area needed. In order to obtain high fluxes, the membranes should be as thin as possible. In this thesis, the performance of ultra-thin zeolite membranes in pervaporation was investigated. Binary ethanol/water and n-butanol/water mixtures were studied using both hydrophobic and hydrophilic zeolite membranes for alcohol concentration, as well as dehydration. The development of pervaporation membranes and processes has been mainly empirical. Process modeling, however, is an indispensable tool in process design. In this work, the pervaporation performance of the studied membranes was evaluated on the basis of experimental results in combination with mathematical modeling. Due to the low film thickness of the studied membranes, the fluxes were generally higher than reported earlier. Nevertheless, the evaluation in this work showed that the pervaporation performance of the ultra-thin membranes decreased due to flux limitation by membrane support. In this work, pervaporation was modeled by applying both a semi-empirical and a detailed Maxwell-Stefan based mass transfer model. The latter model considers explicitly both adsorption and diffusion, i.e. the phenomena involved in separation by pervaporation. The description of the support behavior was included in the models. Maxwell-Stefan formalism was applied in unary pervaporation for the determination of diffusivities in zeolite membranes. The models performed well within the range of experimental data. Additionally, a practical modeling approach was developed in this work to predict the temperature dependency of adsorption on zeolites. The developed approach can be utilized, e.g., in pervaporation modeling. Thus, this thesis provides knowledge of using ultra-thin zeolite membranes in the pervaporation of alcohol/water mixtures, and offers tools for pervaporation modeling. / Tiivistelmä Kiinnostus uusiutuvista raaka-aineista valmistettavia liikennepolttoaineita, kuten bioetanolia ja -butanolia, kohtaan lisääntyy koko ajan. Biopohjaisten alkoholien tuotannossa etenkin erotusvaiheet ovat kalliita, koska erotettavat liuokset ovat laimeita. Pervaporaatio on energiatehokas kalvoerotusmenetelmä ja sen vuoksi potentiaalinen osaprosessi biopolttoaineiden tuotantoon. Pervaporaation kaupallistamisen merkittävimpiä rajoitteita ovat olleet alhaiset ainevuot, jotka johtavat suureen kalvopinta-alan tarpeeseen ja näin ollen korkeisiin kustannuksiin. Korkean ainevuon saavuttamiseksi kalvojen tulisi olla mahdollisimman ohuita. Tässä väitöstyössä tutkittiin hyvin ohuiden zeoliittimembraanien suorituskykyä pervaporaatiossa. Kohteena olivat binääriset etanoli/vesi- ja n-butanoli/vesiseokset, joista väkevöitiin alkoholeja tai poistettiin vettä hydrofobisia ja hydrofiilisiä zeoliittimembraaneja käyttäen. Pervaporaatiossa käytettävien kalvojen ja pervaporaatiota hyödyntävien prosessien kehitystyö on ollut pääasiassa kokeellista. Prosessimallinnus on kuitenkin tärkeä työkalu prosessisuunnittelussa. Tässä työssä membraanien suorituskykyä pervaporaatiossa arvioitiin sekä kokeellisesti että mallinnuksen keinoin. Käytettyjen kalvojen ohuuden ansiosta tässä työssä saavutetut ainevuot olivat yleisesti ottaen korkeampia kuin aiemmin raportoiduilla membraaneilla. Ohuilla kalvoilla tukimateriaalin aiheuttama aineensiirron vastus oli kuitenkin merkittävä, alentaen membraanien suorituskykyä. Tässä työssä pervaporaatiota mallinnettiin käyttäen sekä puoliempiiristä että yksityiskohtaisempaa Maxwell-Stefan -pohjaista mallia. Jälkimmäisessä mallissa adsorptio ja diffuusio, eli ilmiöt joihin erotus pervaporaatiossa perustuu, otetaan eksplisiittisesti huomioon. Myös tukimateriaalin vaikutukset huomioitiin käytetyissä malleissa. Maxwell-Stefan -mallinnusta käytettiin puhtaiden komponenttien pervaporaatiossa zeoliittimembraanin diffuusiokertoimien määrittämiseksi. Käytettyjen mallien suorituskyky kokeellisella alueella oli hyvä. Tässä työssä kehitettiin lisäksi helppokäyttöinen menetelmä aineiden adsorptiokäyttäytymisen ennustamiseen zeoliiteissa eri lämpötiloissa. Kehitettyä menetelmää voidaan hyödyntää esimerkiksi pervaporaation mallinnuksessa. Kokonaisuudessaan väitöstyöstä saadaan tietoa ultraohuiden membraanien käytöstä pervaporaatiossa sekä työkaluja pervaporaation mallinnukseen.

No description available.

Several commercially available reverse osmosis (RO) membranes were characterized with aqueous solutions of ammonium sulfate, potassium triphosphate, and mixtures of these two salts at different feed concentrations, compositions and pressures. The objective of this study was to investigate the rejection of these solutes, in particular the ammonium ion (NH4+), by different RO membranes. The aqueous solutions were assumed to come from an anaerobic digester via a process, currently under investigation by CHFour Biogas Inc., to maintain low concentrations of ammonia in the digester in order to maximize the biogas production. The ammonium ions present in the liquid produced from the process are then concentrated using membrane separation. The concentrated ammonium solution would be a valuable fertilizer that could be used by agriculture. The membranes were characterized with three models: the solution-diffusion model, the Kedem-Katchalsky model, also known as the irreversible thermodynamics model, and the Donnan Steric Pore Model (DSPM). The solution-diffusion and irreversible thermodynamics models were found to be inadequate for proper membrane characterization and the use of the DSPM model yielded membrane properties in good agreement with those found in already existing literature. The pore radius of investigated membranes ranged from 0.39 to 0.51 nm. The effect of pH on membrane surface charge was also studied, with the conclusion that increases in pH led to increasingly negative surface charges. This affected the transport of individual ions through the membrane due to preferential passage of the counter-ions. The effects of applied pressure on the stoichiometric nature of salt rejections were also studied. The minimal observed rejection from the range of experiments carried out using ammonium sulfate was 93%Non-stoichiometric rejections of ions were also observed in the experiments with single and multiple solutes. Furthermore, the rejection of ammonium ions in the presence of other ions (K+, SO42-, PO43-) increased as feed concentration increased, which was a result of the synergistic effects of feed pH and ionic interactions. The minimum NH4+ rejection in the presence of other ions was 95.4%, which suitability using RO membranes for concentration of ammonium from dilute aqueous solutions.

No description available.

Water is an essential and indispensable component is the pulp- and paper production industry.The increase in energy costs, stricter environmental regulations and water resource shortageshave caused a reduction of the water footprint in the industry as well as an increase in waterrecycling and water circuit closure. Reducing water usage requires an understanding of wherecontaminants originate, as well as which streams are critical to the process and how they impactmill operation. The recirculation of water can cause contaminant accumulation; therefore millsemploy technologies for water treatment in the internal water cycles, the so-called ‘kidneys’.Application of membrane technology is one such option which can improve the recycled waterquality and reduce contaminant buildup.The present study was carried out on a lab-scale for the treatment of a tissue mill effluent usingmembrane separation. A combination of pretreatment methods and various membranes werecompared with regards to separation, flux and fouling. The AlfaLaval M20 device was to treatwastewater samples sent from the mill, where the permeate was recirculated to the feed tank.COD and TOC levels are compared with regards to determining the separation efficiency. Thepermeate flux was measured over the two-hour filtration period, as well as flux recovery todetermine fouling levels. Additionally, some economic aspects of the process are discussed.This study suggests the potential application of a combination of flocculation or centrifugationpretreatment, with reverse osmosis membranes for recycling water to replace freshwater intake.The results also indicate the possibility of using ultrafiltration as kidneys to decreasecontamination buildup for further water loop closure.

Organic micropollutants (OMPs) in climate change affected natural environment such as wetlands, and engineered systems have brought serious concerns for water security and public health. These issues have increased the demand for better managing water resources and developing effective technologies for aqueous micropollutants removal. This thesis investigated these subjects through the following five sub-research projects. First, boreal peatland was used as a case study for understanding how peatland fires and droughts impacts peatland resilience. Laboratory results suggested that heating and moisture condition, coupled with peat organic hydrophobic transformations, influence peat soil hydrophobicity and the resultant water-extractable pollutant leaching, which potentially threatens peatland downstream receiving waters such as potable waters by high organic loads. Further, post-fire peat chemistry and their mechanistic relationships to leached pollutants (total organic carbon (TOC), nutrients and phenols) were elucidated through a laboratory leaching study. Increased contaminant loading was observed in post-heated peat leachates, suggesting negative effects to water treatment efficiency and an increase of treatment costs to surface waters as potable water source. Next, peat soils damaged from extreme fires and droughts were upcycled for producing high surface area, value-added porous carbons based on a rapid, facile chemical activation approach. This application had the simultaneous benefit of peatland ecological restoration, protecting downstream communities from heavy run-off, and using the sustainable damaged peats for effective environmental remediation though adsorption. Moreover, a critical review of nano-enabled composite membranes for OMP removal (size-exclusion, adsorption, charge interaction, and photo- and electro-catalysis) and their respective benefits and limitations were discussed. This work brought new perspectives for next-generation nanocomposite membranes for OMP removal. Finally, a novel, hyperbranched polyethylenimine (HPEI) crosslinked iron doped reduced graphene oxide (rGO) nanocomposite membrane was synthesized for process-intensified flow-through separation of phenolic micropollutants. Mechanisms and separation performance to phenolic micropollutant and azo dyes were investigated. / Thesis / Doctor of Philosophy (PhD) / Climate change, industrial manufacture, and population growth have been exacerbating the global water stress. Organic micropollutants (OMPs) are potentially toxic, persistent and can exist even at trace levels, which have been increasingly discovered and identified in natural and built systems. In this research, environmental chemistry of climate-change impacted boreal peatland soils, and their mechanistic relationships to peat soil hydrophobicity, organic substance transformations, micropollutant leaching, and impacts to downstream potable water quality was investigated as a case study. Two different innovative water treatment strategies were developed for restoring peatland resilience and enhancing water resource sustainability including treating peatland phenolic micropollutants. The first approach converted shallow layer wildfire- and drought- damaged peats into value-added porous carbons for adsorption. The second approach synthesized a novel reduced graphene oxide (rGO) nanocomposite membrane for process-intensified flow-through separation. These solutions provide novel insights for source water protection and wastewater treatment in adaption to climate change.

No description available.

No description available.

Adsorption, separation and conversion of CO₂ from industrial processes are among the priorities of the scientific community aimed at mitigating the effects of greenhouse gases on the environment. One of the main focuses is the capture of CO₂ at stationary point sources from fossil fuel emissions using porous crystalline materials. Porous crystalline materials can reduce the energy costs associated with CO₂ capture by offering high adsorption rates, low material regeneration energy penalties and favorable kinetic pathways for CO₂ separation. MOFs consist of polymeric inorganic networks with adjustable chemical functionality and well-defined pores that make them ideal for these applications. The objective of this research was to test the potential for CO₂ capture on Zn-based MOFs by studying their sorption, transport and gas separation properties as adsorbents and continuous membranes. Three Zn-based MOFs with open Zn-metal sites were initially studied. Zn4(pdc)4(DMF)2•3DMF (1) exhibited the best properties for CO₂ capture and was investigated further under realistic CO₂ capture conditions. The MOF exhibited preferential CO₂ adsorption based on a high enthalpy of adsorption and selectivity of CO₂ over N₂ and CH₄. Sorption dynamics of CO₂ indicated fast adsorption and a low activation energy for sorption. Diffusion inside the pores is the rate-limiting step for diffusion, and changes in the process temperature can enhance CO₂ separation. Desorption kinetics indicated that CO₂ has longer residence times and lower activation energies for desorption than N₂ and CH₄. This suggests that the selective adsorption of CO₂ is favored. MOF/Polymer membranes were synthesized via a solvothermal method with structural defects sealed by a polymer coating. This method facilitates the permeation measurements of materials that cannot form uniform-defect-free layers. The membrane permeation of CO₂, CH₄, N₂ and H₂ exhibited a linear relation to the inverse square root of the molecular weight of the permanent gases, indicating that diffusion occurs in the Knudsen regime. Permselectivity was well-predicted by the Knudsen model with no temperature dependence, and transport occurs inside the pores of the membrane. MOF (1) exhibits ideal properties for future applications in CO₂ capture as an adsorbent. / Ph. D.

Los dos baños de cobre más utilizados comercialmente son el baño ácido a base de sulfato y el baño alcalino a base de cianuro. Los baños alcalinos son utilizados principalmente para producir recubrimientos en piezas con geometría compleja y para evitar la deposición galvánica cuando se deposita un metal en un sustrato menos noble. Debido a la toxicidad de los compuestos de cianuro, se han desarrollado baños alternativos usando diferentes agentes complejantes. El punto de partida de la presente investigación es un baño primario sin cianuros para deposición de cobre en sustratos de Zamak desarrollado en el Instituto de Investigaciones Tecnológicas del Estado de Sao Paulo / Brasil. La sustitución de materias primas como el cianuro debe ser económicamente ventajosa y técnicamente viable. De esta manera, la investigación presentada pretendió proponer una alternativa para el tratamiento de residuos líquidos del baño ya mencionado con la finalidad de recuperar de manera simultánea el agua y las materias primas en un sistema cerrado. Se ha estudiado el proceso de separación por membranas de intercambio iónico, la electrodiálisis, usando un sistema en escala de laboratorio y una disolución sintética que simulaba las aguas residuales del baño a base de HEDP. Se ha evaluado la viabilidad del sistema por medio del análisis de los parámetros de operación, como la extracción de iones, la tasa de desmineralización, el porcentaje de concentración, la eficiencia de la intensidad calculada para cada especie y el consumo medio de energía. Debido a que el ácido HEDP es un agente quelante, se ha evaluado el transporte de los quelatos Cu(II) HEDP a través de membranas de intercambio de aniones por medio de métodos electroquímicos. Se han construido curvas cronopotenciométricas y curvas intensidad-potencial para diferentes disoluciones sintéticas que contenían los mismos compuestos que el baño original. Se ha establecido la relación entre la presencia de los quelatos en las disoluciones y los grupos fijos de intercambio de aniones. Por fin, se han realizado las pruebas de deposición usando electrólitos conteniendo los compuestos reciclados y se han evaluado las características de los depósitos obtenidos. Los resultados indicaron que el sistema de electrodiálisis usando membranas de intercambio de aniones con grupos de intercambio de base fuerte ha podido producir disoluciones tratadas y un concentrado conteniendo los iones del baño. Se ha podido añadir el concentrado al baño original para compensar eventuales perdidas del arrastre sin afectar la calidad de los depósitos. Por lo tanto, la aplicación de la electrodiálisis demostró ser una alternativa viable para la recuperación del agua y de las materias primas de la disolución evaluada, reduciendo la generación de residuos líquidos y ahorrando los recursos naturales. / The two most common commercial copper baths are the acid sulfate copper bath and the alkaline cyanide copper bath. Alkaline copper baths are mostly used to coat parts with complex geometry and to avoid galvanic deposition when depositing a metal on a less noble substrate. Because of the toxicity of cyanide compounds, alternative baths have been developed using different complexing agents. The starting point of the present study is a cyanide free strike bath developed for copper plating on Zamak substrates developed by the Institute for Technological Research of the State of São Paulo/ Brazil. The replacement of a raw material such as cyanide must be economically advantageous and technically feasible. Therefore, this study intended to propose an alternative to the treatment of liquid wastes from the mentioned bath, aiming at simultaneous water reclamation and chemicals recovery in a closed system. The electrodialysis membrane separation process was studied, using a laboratory-scale system operating with a synthetic solution simulating the rinsing waters from the HEDP-based bath. The feasibility of the technique was evaluated by analyzing operational parameters such as ion extraction, demineralization rate, concentration rate, current efficiency for each anionic specie and average energy consumption. Because HEDP is a chelating agent, the transport of Cu(II) HEDP chelates through anion exchange membranes was also evaluated by means of electrochemical methods. Chronopotentiometric and current-voltage curves were constructed for different model solutions containing the same compounds as the original bath. A relation between the presence of chelates in the solutions and the fixed ion exchange group could be established. Lastly, deposition tests were performed using electrolytes containing the recycled inputs and the characteristics of the coatings were analyzed. The results showed that an electrodialysis stack using strongly basic anion exchange membranes was suitable to produce treated solutions and a concentrate containing the ions from the bath. The concentrate could be added to the copper bath to compensate eventual drag-out losses without affecting the quality of the coatings. Thus, the application of electrodialysis was shown to be a feasible alternative for recovering water and inputs from the evaluated solution, reducing the wastewater generation and saving natural resources. / Els dos banys de coure més utilitzats comercialment són el bany àcid a base de sulfat i el bany alcalí a base de cianur. Els banys alcalins són utilitzats principalment per a produir recobriments en peces amb geometria complexa i per a evitar la deposició galvànica quan es deposita un metall en un substrat menys noble. A causa de la toxicitat dels compostos de cianur, s'han desenrotllat banys alternatius usant diferents agents complexants. El punt de partida de la present investigació és un bany primari sense cianurs per a deposició de coure en substrats de Zamak desenrotllat en l'Institut d'Investigacions Tecnològiques de l'Estat de Sao Paulo / Brasil. La substitució de matèries primeres com el cianur ha de ser econòmicament avantatjosa i tècnicament viable. D'aquesta manera, la investigació presentada va pretendre proposar una alternativa per al tractament de residus líquids del bany ja mencionat amb la finalitat de recuperar de manera simultània l'aigua i les matèries primeres en un sistema tancat. S'ha estudiat el procés de separació per membranes d'intercanvi iònic, electrodiàlisi, usant un sistema en escala de laboratori i una dissolució sintètica que simulava les aigües residuals del bany a base d'HEDP. S'ha avaluat la viabilitat del sistema per mitjà de l'anàlisi dels paràmetres d'operació, com l'extracció d'ions, la taxa de desmineralització, el percentatge de concentració, l'eficiència de la intensitat calculada per a cada espècie i el consum mitjà d'energia. Pel fet que l'àcid HEDP és un agent quelant, s'ha avaluat el transport dels quelats Cu (II)-HEDP a través de membranes d'intercanvi d'anions per mitjà de mètodes electroquímics. S'han construït corbes cronopotenciomètriques i corbes intensitat-potencial per a diferents dissolucions sintètiques que contenien els mateixos compostos que el bany original. S'ha establit la relació entre la presència dels quelats en les dissolucions i els grups fixos d'intercanvi d'anions. Finalment, s'han realitzat les proves de deposició usant electròlits contenint els compostos reciclats i s'han avaluat les característiques dels depòsits obtinguts. Els resultats van indicar que el sistema d'electrodiàlisi usant membranes d'intercanvi d'anions amb grups d'intercanvi de base forta ha pogut produir dissolucions tractades i un concentrat que conté els ions del bany. S'ha pogut afegir el concentrat al bany original per a compensar eventuals perdudes de l'arrossegament sense afectar la qualitat dels depòsits. Per tant, l'aplicació de l'electrodiàlisi va demostrar ser una alternativa viable per a la recuperació de l'aigua i de les matèries primeres de la dissolució avaluada, reduint la generació de residus líquids i estalviant els recursos naturals. / Scarazzato, T. (2017). Treatment of a cyanide-free copper electroplating solution by electrodialysis: study of ion transport and evaluation of water and inputs recovery [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/98502