EDTA- and DTPA-functionalized silica gel and chitosan adsorbents for the removal of heavy metals from aqueous solutions

Adsorbents functionalized with chelating agents are effective in removal of heavy metals from aqueous solutions. Important properties of such adsorbents are high binding affinity as well as regenerability. In this study, aminopolycarboxylic acid, EDTA and DTPA, were immobilized on the surface of silica gel, chitosan, and their hybrid materials to achieve chelating adsorbents for heavy metals such as Co(II), Ni(II), Cd(II), and Pb(II). New knowledge about the adsorption properties of EDTA- and DTPA-functionalizedadsorbents was obtained. Experimental work showed the effectiveness, regenerability, and stability of the studied adsorbents. Both advantages and disadvantages of the adsorbents were evaluated. For example, the EDTA-functionalized chitosan-silica hybrid materials combined the benefits of the silica gel and chitosan while at the same time diminishing their observed drawbacks. Modeling of adsorption kinetics and isotherms is an important step in design process. Therefore, several kinetic and isotherm models were introduced and applied in this work. Important aspects such as effect of error function, data range, initial guess values, and linearization were discussed and investigated. The selection of the most suitable model was conducted by comparing the experimental and simulated data as well as evaluating the correspondence between the theory behind the model and properties of the adsorbent. In addition, modeling of two-component data was conducted using various extended isotherms. Modeling results for both one- and twocomponent systems supported each other. Finally, application testing of EDTA- and DTPA-functionalized adsorbents was conducted. The most important result was the applicability of DTPA-functionalized silica gel and chitosan in the capturing of Co(II) from its aqueous EDTA-chelate. Moreover, these adsorbents were efficient in various solution matrices. In addition, separation of Ni(II) from Co(II) and Ni(II) and Pb(II) from Co(II) and Cd(II) was observed in two- and multimetal systems. Lastly, prior to their analysis, EDTA- and DTPA-functionalized silica gels were successfully used to preconcentrate metal ions from both pure and salty waters

Alikriittisen veden käyttö kromatografisessa erotuksessa

Alikriittisellä vedellä tarkoitetaan paineistettua vettä, joka on kriittisen lämpötilansa (374 °C) alapuolella nestemäisessä tilassa. Veden tiheys pienenee lämpötilan kasvaessa Veden liuotinominaisuuksia voidaan säädellä lämpötilan avulla. Veden pintajännitys, viskositeetti, tiheys ja polaarisuus pienenevät lämpötilan kasvaessa, ja alikriittisen veden aineominaisuudet muuttuvat lähemmäksi orgaanista liuotinta. Alikriittisen veden dielektrisyysvakion aleneminen johtuu pääasiassa lämpötilan vaikutuksesta ja vain vähän paineen vaikutuksesta. Alikriittistä vettä on käytetty liuottimena uutossa, mutta nyt myös alikriittinen kromatografia on kehittymässä oleva erotusmenetelmä. Työn kokeellisessa osassa kehitettiin kromatografinen laitteisto alikriittiselle vedelle, jolla tutkittiin sokerialkoholien ja sokerien kromatografista erotusta alikriittisen veden avulla. Lisäksi tutkittiin sokerialkoholien, sokereiden ja stationäärifaasien termistä kestävyyttä. Tutkittavina komponentteina olivat sorbitoli, mannitoli, ksylitoli, arabinoosi, mannoosi, ksyloosi, maltoosi ja ramnoosi. Stationäärifaaseina käytettiin makrohuokoista funktionalisoimatonta polystyreenidivinyylibentseenikopolymeeriä, sekä vahvoja ja heikkoja divinyylibentseenillä ristisilloitettuja kationinvaihtohartseja, jotka olivat joko Na+- tai Ca2+-ionimuodoissa. Veden lämpötilan nostaminen vaikuttaa sekä kromatografisen stationäärifaasin tilavuusmuutoksiin että näytekomponenttien ominaisuuksiin. Vahvoilla kationinvaihtimilla havaittiin termisten tilavuusmuutosten riippuvan ionimuodosta: Na+-muotoiset hartsit turpoavat ja Ca2+-muotoiset kutistuvat lämpötilan noustessa. Heikot kationinvaihtimet kutistuvat molemmissa ionimuodoissa, mutta Ca2+-muoto kutistuu Na+-muotoa voimakkaammin. Näytekomponenteista sokerialkoholien havaittiin kestävän paremmin korkeita lämpötiloja kuin sokerien. Sokerialkoholeista kestävimmäksi havaittiin ksylitoli ja sokereista ramnoosi. Tutkittavien komponenttien piikkien havaittiin kapenevan, häntimisen vähenevän, ja piikkien eluoituvan aikaisemmin riippuen käytettävästä stationäärifaasista. Ca2+-muotoisen vahvan kationinvaihtimen kompleksinmuodostuskyky heikkeni lämpötilan kasvaessa. Näytekomponenttien erotus ei kuitenkaan parantunut lämpötilan noustessa tutkituilla stationäärifaaseilla.

Design and production of protein nanostructures for biomolecular detection

Particulate nanostructures are increasingly used for analytical purposes. Such particles are often generated by chemical synthesis from non-renewable raw materials. Generation of uniform nanoscale particles is challenging and particle surfaces must be modified to make the particles biocompatible and water-soluble. Usually nanoparticles are functionalized with binding molecules (e.g., antibodies or their fragments) and a label substance (if needed). Overall, producing nanoparticles for use in bioaffinity assays is a multistep process requiring several manufacturing and purification steps. This study describes a biological method of generating functionalized protein-based nanoparticles with specific binding activity on the particle surface and label activity inside the particles. Traditional chemical bioconjugation of the particle and specific binding molecules is replaced with genetic fusion of the binding molecule gene and particle backbone gene. The entity of the particle shell and binding moieties are synthesized from generic raw materials by bacteria, and fermentation is combined with a simple purification method based on inclusion bodies. The label activity is introduced during the purification. The process results in particles that are ready-to-use as reagents in bioaffinity. Apoferritin was used as particle body and the system was demonstrated using three different binding moieties: a small protein, a peptide and a single chain Fv antibody fragment that represents a complex protein including disulfide bridge.If needed, Eu3+ was used as label substance. The results showed that production system resulted in pure protein preparations, and the particles were of homogeneous size when visualized with transmission electron microscopy. Passively introduced label was stably associated with the particles, and binding molecules genetically fused to the particle specifically bound target molecules. Functionality of the particles in bioaffinity assays were successfully demonstrated with two types of assays; as labels and in particle-enhanced agglutination assay. This biological production procedure features many advantages that make the process especially suited for applications that have frequent and recurring requirements for homogeneous functional particles. The production process of ready, functional and watersoluble particles follows principles of “green chemistry”, is upscalable, fast and cost-effective.

Adsorptive removal of harmful organic compound from aqueous solutions

Adsorption is one of the most commonly used methods in water treatment processes. It is attractive due to it easy operation and the availability of a wide variety of commercial adsorbents. This doctoral thesis focuses on investigating and explaining the influence of external phase conditions (temperature, pH, ionic strength, acidity, presence of cosolutes) on adsorption phenomena. In order to cover a wide range of factors and phenomena, case studies were chosen from various fields where adsorption is applied. These include the adsorptive removal of surface active agents (used in cleaning chemicals, for example) from aqueous effluents, the removal of hormones (estradiol) from drinking water, and the adsorption of antibiotics onto silica. The latter can beused to predict the diffusion of antibiotics in the aquatic system if they are released into the environment. Also the adsorption of living cells on functionalized polymers to purify infected water streams was studied. In addition to these examples, the adsorptive separation of harmful compounds from internal water streams within a chemical process was investigated. The model system was removal of fermentation inhibitors from lignocelluloses hydrolyzates. The detoxification of the fermentation broth is an important step in the manufacture of bioethanol from wood, but has not been studied previously in connection with concentrated acid hydrolyzates. New knowledge on adsorption phenomena was generated for all of the applications investigated. In most cases, the results could be explained by combining classical theories for individual phenomena. As an example, it was demonstrated how liquid phase aggregation could explain abnormal-looking adsorption equilibrium data. In addition to the fundamental phenomena, also process performance was of interest. This aspect is often neglected in adsorption studies. It was demonstrated that adsorbents should not be selected for a target application based on their adsorption properties only, but regeneration of the spent adsorbent must be considered. It was found that using a suitable amount of organic co-solvent in the regeneration can significantly improve the productivity of the process.

Lethal weapons : novel approaches for receptor-targeted cancer cell elimination

The currently used forms of cancer therapy are associated with drug resistance and toxicity to healthy tissues. Thus, more efficient methods are needed for cancer-specific induction of growth arrest and programmed cell death, also known as apoptosis. Therapeutic forms of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) are investigated in clinical trials due to the capability of TRAIL to trigger apoptosis specifically in cancer cells by activation of cell surface death receptors. Many tumors, however, have acquired resistance to TRAIL-induced apoptosis and sensitizing drugs for combinatorial treatments are, therefore, in high demand. This study demonstrates that lignans, natural polyphenols enriched in seeds and cereal, have a remarkable sensitizing effect on TRAIL-induced cell death at non-toxic lignan concentrations. In TRAIL-resistant and androgen-dependent prostate cancer cells we observe that lignans repress receptor tyrosine kinase (RTK) activity and downregulate cell survival signaling via the Akt pathway, which leads to increased TRAIL sensitivity. A structure-activity relationship analysis reveals that the γ-butyrolactone ring of the dibenzylbutyrolactone lignans is essential for the rapidly reversible TRAIL-sensitizing activity of these compounds. Furthermore, the lignan nortrachelogenin (NTG) is identified as the most efficient of the 27 tested lignans and norlignans in sensitization of androgen-deprived prostate cancer cells to TRAIL-induced apoptosis. While this combinatorial anticancer approach may leave normal cells unharmed, several efficient cancer drugs are too toxic, insoluble or unstable to be used in systemic therapy. To enable use of such drugs and to protect normal cells from cytotoxic effects, cancer-targeted drug delivery vehicles of nanometer scale have recently been generated. The newly developed nanoparticle system that we tested in vitro for cancer cell targeting combines the efficient drug-loading capacity of mesoporous silica to the versatile particle surface functionalization of hyperbranched poly(ethylene imine), PEI. The mesoporous hybrid silica nanoparticles (MSNs) were functionalized with folic acid to promote targeted internalization by folate receptor overexpressing cancer cells. The presented results demonstrate that the developed carrier system can be employed in vitro for cancer selective delivery of adsorbed or covalently conjugated molecules and furthermore, for selective induction of apoptotic cell death in folate receptor expressing cancer cells. The tested carrier system displays potential for simultaneous delivery of several anticancer agents specifically to cancer cells also in vivo.

Synthesis, characterization and chemical sensor application of conducting polymers

Polymeric materials that conduct electricity are highly interesting for fundamental studies and beneficial for modern applications in e.g. solar cells, organic field effect transistors (OFETs) as well as in chemical and bio‐sensing. Therefore, it is important to characterize this class of materials with a wide variety of methods. This work summarizes the use of electrochemistry also in combination with spectroscopic methods in synthesis and characterization of electrically conducting polymers and other π‐conjugated systems. The materials studied in this work are intended for organic electronic devices and chemical sensors. Additionally, an important part of the presented work, concerns rational approaches to the development of water‐based inks containing conducting particles. Electrochemical synthesis and electroactivity of conducting polymers can be greatly enhanced in room temperature ionic liquids (RTILs) in comparison to conventional electrolytes. Therefore, poly(para‐phyenylene) (PPP) was electrochemically synthesized in the two representative RTILs: bmimPF6 and bmiTf2N (imidazolium and pyrrolidinium‐based salts, respectively). It was found that the electrochemical synthesis of PPP was significantly enhanced in bmimPF6. Additionally, the results from doping studies of PPP films indicate improved electroactivity in bmimPF6 during oxidation (p‐doping) and in bmiTf2N in the case of reduction (n‐doping). These findings were supported by in situ infrared spectroscopy studies. Conducting poly(benzimidazobenzophenanthroline) (BBL) is a material which can provide relatively high field‐effect mobility of charge carriers in OFET devices. The main disadvantage of this n‐type semiconductor is its limited processability. Therefore in this work BBL was functionalized with poly(ethylene oxide) PEO, varying the length of side chains enabling water dispersions of the studied polymer. It was found that functionalization did not distract the electrochemical activity of the BBL backbone while the processability was improved significantly in comparison to conventional BBL. Another objective was to study highly processable poly(3,4‐ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) water‐based inks for controlled patterning scaled‐down to nearly a nanodomain with the intention to fabricate various chemical sensors. Developed PEDOT:PSS inks greatly improved printing of nanoarrays and with further modification with quaternary ammonium cations enabled fabrication of PEDOT:PSS‐based chemical sensors for lead (II) ions with enhanced adhesion and stability in aqueous environments. This opens new possibilities for development of PEDOT:PSS films that can be used in bio‐related applications. Polycyclic aromatic hydrocarbons (PAHs) are a broad group of π‐conjugated materials consisting of aromatic rings in the range from naphthalene to even hundred rings in one molecule. The research on this type of materials is intriguing, due to their interesting optical properties and resemblance of graphene. The objective was to use electrochemical synthesis to yield relatively large PAHs and fabricate electroactive films that could be used as template material in chemical sensors. Spectroscopic, electrochemical and electrical investigations evidence formation of highly stable films with fast redox response, consisting of molecules with 40 to 60 carbon atoms. Additionally, this approach in synthesis, starting from relatively small PAH molecules was successfully used in chemical sensor for lead (II).

Printed platforms for paper-based analytical applications

Paper-based analytical technologies enable quantitative and rapid analysis of analytes from various application areas including healthcare, environmental monitoring and food safety. Because paper is a planar, flexible and light weight substrate, the devices can be transported and disposed easily. Diagnostic devices are especially valuable in resourcelimited environments where diagnosis as well as monitoring of therapy can be made even without electricity by using e.g. colorimetric assays. On the other hand, platforms including printed electrodes can be coupled with hand-held readers. They enable electrochemical detection with improved reliability, sensitivity and selectivity compared with colorimetric assays. In this thesis, different roll-to-roll compatible printing technologies were utilized for the fabrication of low-cost paper-based sensor platforms. The platforms intended for colorimetric assays and microfluidics were fabricated by patterning the paper substrates with hydrophobic vinyl substituted polydimethylsiloxane (PDMS) -based ink. Depending on the barrier properties of the substrate, the ink either penetrates into the paper structure creating e.g. microfluidic channel structures or remains on the surface creating a 2D analog of a microplate. The printed PDMS can be cured by a roll-ro-roll compatible infrared (IR) sintering method. The performance of these platforms was studied by printing glucose oxidase-based ink on the PDMS-free reaction areas. The subsequent application of the glucose analyte changed the colour of the white reaction area to purple with the colour density and intensity depending on the concentration of the glucose solution. Printed electrochemical cell platforms were fabricated on paper substrates with appropriate barrier properties by inkjet-printing metal nanoparticle based inks and by IR sintering them into conducting electrodes. Printed PDMS arrays were used for directing the liquid analyte onto the predetermined spots on the electrodes. Various electrochemical measurements were carried out both with the bare electrodes and electrodes functionalized with e.g. self assembled monolayers. Electrochemical glucose sensor was selected as a proof-of-concept device to demonstrate the potential of the printed electronic platforms.

New [18F]Tracers for Alzheimer's Disease Imaging. Labeling Synthesis And Biological Testing

Alzheimer’s disease (AD) is the most common form of dementia. Characteristic changes in an AD brain are the formation of β-amyloid protein (Aβ) plaques and neurofibrillary tangles, though other alterations in the brain have also been connected to AD. No cure is available for AD and it is one of the leading causes of death among the elderly in developed countries. Liposomes are biocompatible and biodegradable spherical phospholipid bilayer vesicles that can enclose various compounds. Several functional groups can be attached on the surface of liposomes in order to achieve long-circulating target-specific liposomes. Liposomes can be utilized as drug carriers and vehicles for imaging agents. Positron emission tomography (PET) is a non-invasive imaging method to study biological processes in living organisms. In this study using nucleophilic 18F-labeling synthesis, various synthesis approaches and leaving groups for novel PET imaging tracers have been developed to target AD pathology in the brain. The tracers were the thioflavin derivative [18F]flutemetamol, curcumin derivative [18F]treg-curcumin, and functionalized [18F]nanoliposomes, which all target Aβ in the AD brain. These tracers were evaluated using transgenic AD mouse models. In addition, 18F-labeling synthesis was developed for a tracer targeting the S1P3 receptor. The chosen 18F-fluorination strategy had an effect on the radiochemical yield and specific activity of the tracers. [18F]Treg-curcumin and functionalized [18F]nanoliposomes had low uptake in AD mouse brain, whereas [18F]flutemetamol exhibited the appropriate properties for preclinical Aβ-imaging. All of these tracers can be utilized in studies of the pathology and treatment of AD and related diseases.

Magnetic properties of defective graphene

In this thesis, the influence of the functionalization of graphene and graphite on their magnetic properties was investigated. The functionalization was performed by covalent attaching of a phenyl groups with three different radicals (4-bromoaniline, 4-chloroaniline and 4-nitroaniline). Magnetic properties were measured by SQUID magnetometer. Both pristine graphite and graphene showed strong diamagnetic behavior. For good quality graphite, diamagnetism was found to be temperature-dependent. All samples demonstrated noticeable paramagnetic contribution below 50 K. According to fitting experimental results with Brillouin function and Curie law, it was shown that paramagnetism is provided by small clusters of spins (superparamagnetic behavior). Moreover, the clusters size and spin concentrations were calculated. For the samples functionalized with nitroaniline the antiferromagnetic transition around 120 K was observed. To explain this behavior, a simple model was proposed. Additional analysis of the graphene quality, structure and composition of the samples was carried out by HRTEM, EDS mapping, Raman spectroscopy and X-ray diffraction techniques.

Bio and chemocatalysis for stereo and regioselective one-pot reaction applications

The development of cost efficient, selective and sustainable chemical processes for production of chiral building blocks is of great importance in synthetic and industrial organic chemistry. One way to reach these objectives is to carry out several reactions steps in one vessel at one time. Furthermore, when this kind of one-pot multi step reactions are catalyzed by heterogeneous chemo- and bio-catalysts, which can be separated from the reaction products by filtration, practical access to chiral small molecules for further utilization can be obtained. The initial reactions studied in this thesis are the two step dynamic kinetic resolution of rac-2-hydroxy-1-indanone and the regioselective hydrogenation of 1,2-indanedione. These reactions are then combined in a new heterogeneously catalyzed one-pot reaction sequence enabling simple recovery of the catalysts by filtration, facilitating simple reaction product isolation. Conclusively, the readily available 1,2-indanedione is by the presented one-pot sequence, utilizing heterogeneous enzyme and transition metal based catalysts, transferred with high regio- and stereoselectivity to a useful chiral vicinal hydroxyl ketone structure. Additional and complementary investigation of homogeneous half-sandwich ruthenium complexes for catalyzing the epimerization of chiral secondary alcohols of five natural products containing additional non-functionalized stereocenters was conducted. In principle, this kind of epimerization reactions of single stereocenters could be utilized for converting inexpensive starting materials, containing other stereogenic centers, into diastereomeric mixtures from which more valuable compounds can be isolated by traditional isolation techniques.

Characterization of amine-based CO2 adsorbent for Direct Air Capture

Direct air capture technologies extract CO2 from air at a concentration of as low as 400ppm. The captured CO2 can be used for the production of synthetic methane or liquid fuels. In the literature survey of this thesis, results related to direct air capture by using solid sorbents are presented and critically discussed. In the experimental part, a proprietary amine functionalized resin is characterized for direct air capture. Structural comparison is also made to a commercial resin of similar type. Based on the literature survey, the most important parameters in direct air capture process are low adsorption and desorption temperatures, good cyclic stability in dry and humid conditions, high CO2 outlet purity and a high working capacity. Primary amine functionalized solid sorbents are found to often have good qualities for direct air capture, but overall process performance is rarely studied exhaustively. Based on FTIR spectra, both resin adsorbents are found to be consisted of polystyrene functionalized with primary amine, and capture CO2 by forming carbamate. The commercial resin is more porous, has a slightly higher particle size and contains fewer impurities. Important physical parameters are gained of the proprietary resin, such as internal porosity and median particle size. The resin’s amine group is found to endure thermal treatment reasonably well. CO2 adsorption capacity gained by thermal gravimetry from 400ppm CO2 is highest at 25oC, and is found to be reasonable compared to values presented in literature. Thus, the resin is stated to exhibit promising qualities for direct air capture.

Synthesis and characterization of nanoperforated metal oxide thin films

For advanced devices in the application fields of data storage, solar cell and biosensing, one of the major challenges to achieve high efficiency is the fabrication of nanopatterned metal oxide surfaces. Such surfaces often require both precise structure at the nanometer scale and controllable patterned structure at the macro scale. Nowadays, the dominating candidates to fabricate nanopatterned surfaces are the lithographic technique and block-copolymer masks, most of which are unfortunately costly and inefficient. An alternative bottom-up approach, which involves organic/inorganic self-assembly and dip-coating deposition, has been studied intensively in recent years and has proven to be an effective technique for the fabrication of nanoperforated metal oxide thin films. The overall objective of this work was to optimize the synthesis conditions of nanoperforated TiO2 (NP-TiO2) thin films, especially to be compatible with mixed metal oxide systems. Another goal was to develop fabrication and processing of NP-TiO2 thin films towards largescale production and seek new applications for solar cells and biosensing. Besides the traditional dip-coating and drop-casting methods, inkjet printing was used to prepare thin films of metal oxides, with the advantage of depositing the ink onto target areas, further enabling cost-effective fabrication of micro-patterned nanoperforated metal oxide thin films. The films were characterized by water contact angle determination, Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Grazing Incidence XRay Diffraction. In this study, well-ordered zinc titanate nanoperforated thin films with different Zn/Ti ratios were produced successfully with zinc precursor content up to 50 mol%, and the dominating phase was Zn2Ti3O8. NP-TiO2 structures were also obtained by a cost-efficient means, namely inkjet printing, at both ambient temperature and 60 °C. To further explore new biosensing applications of nanoperforated oxide thin films, inkjet printing was used for the fabrication of both continuous and patterned polymeric films onto NP-TiO2 and perfluorinated phosphate functionalized NP-TiO2 substrates, respectively. The NP-TiO2 films can be also functionalized with a fluoroalkylsilane, resulting in hydrophobic surfaces on both titania and silica. The surface energy contrast in the nanoperforations can be tuned by irradiating the films with UV light, which provides ideal model systems for wettability studies.

Viologen based electroactive polymers and composites for durable electrochromic systems

Electrochromism, the phenomenon of reversible color change induced by a small electric charge, forms the basis for operation of several devices including mirrors, displays and smart windows. Although, the history of electrochromism dates back to the 19th century, only the last quarter of the 20th century has its considerable scientific and technological impact. The commercial applications of electrochromics (ECs) are rather limited, besides top selling EC anti-glare mirrors by Gentex Corporation and airplane windows by Boeing, which made a huge commercial success and exposed the potential of EC materials for future glass industry. It is evident from their patents that viologens (salts of 4,4ʹ-bipyridilium) were the major active EC component for most of these marketed devices, signifying the motivation of this thesis focusing on EC viologens. Among the family of electrochromes, viologens have been utilized in electrochromic devices (ECDs) for a while, due to its intensely colored radical cation formation induced by applying a small cathodic potential. Viologens can be synthesized as oligomer or in the polymeric form or as functionality to conjugated polymers. In this thesis, polyviologens (PVs) were synthesized starting from cyanopyridinium (CNP) based monomer precursors. Reductive coupling of cross-connected cyano groups yields viologen and polyviologen under successive electropolymerization using for example the cyclic voltammetry (CV) technique. For further development, a polyviologen-graphene composite system was fabricated, focusing at the stability of the PV electrochrome without sacrificing its excellent EC properties. High electrical conductivity, high surface area offered by graphene sheets together with its non-covalent interactions and synergism with PV significantly improved the electrochrome durability in the composite matrix. The work thereby continued in developing a CNP functionalized thiophene derivative and its copolymer for possible utilization of viologen in the copolymer blend. Furthermore, the viologen functionalized thiophene derivative was synthesized and electropolymerized in order to explore enhancement in the EC contrast and overall EC performance. The findings suggest that such electroactive viologen/polyviologen systems and their nanostructured composite films as well as viologen functionalized conjugated polymers, can be potentially applied as an active EC material in future ECDs aiming at durable device performances.

Metal oxides prepared through the nanocasting approach-mechanistic study, surface interactions and applications in separation

Mesoporous metal oxides are nowadays widely used in various technological applications, for instance in catalysis, biomolecular separations and drug delivery. A popular technique used to synthesize mesoporous metal oxides is the nanocasting process. Mesoporous metal oxide replicas are obtained from the impregnation of a porous template with a metal oxide precursor followed by thermal treatment and removal of the template by etching in NaOH or HF solutions. In a similar manner to the traditional casting wherein the product inherits the features of the mold, the metal oxide replicas are supposed to have an inverse structure of the starting porous template. This is however not the case, as broken or deformed particles and other structural defects have all been experienced during nanocasting experiments. Although the nanocasting technique is widely used, not all the processing steps are well understood. Questions over the fidelity of replication and morphology control are yet to be adequately answered. This work therefore attempts to answer some of these questions by elucidating the nanocasting process, pin pointing the crucial steps involved and how to harness this knowledge in making wholesome replicas which are a true replication of the starting templates. The rich surface chemistry of mesoporous metal oxides is an important reason why they are widely used in applications such as catalysis, biomolecular separation, etc. At times the surface is modified or functionalized with organic species for stability or for a particular application. In this work, nanocast metal oxides (TiO2, ZrO2 and SnO2) and SiO2 were modified with amino-containing molecules using four different approaches, namely (a) covalent bonding of 3-aminopropyltriethoxysilane (APTES), (b) adsorption of 2-aminoethyl dihydrogen phosphate (AEDP), (c) surface polymerization of aziridine and (d) adsorption of poly(ethylenimine) (PEI) through electrostatic interactions. Afterwards, the hydrolytic stability of each functionalization was investigated at pH 2 and 10 by zeta potential measurements. The modifications were successful except for the AEDP approach which was unable to produce efficient amino-modification on any of the metal oxides used. The APTES, aziridine and PEI amino-modifications were fairly stable at pH 10 for all the metal oxides tested while only AZ and PEI modified-SnO2 were stable at pH 2 after 40 h. Furthermore, the functionalized metal oxides (SiO2, Mn2O3, ZrO2 and SnO2) were packed into columns for capillary liquid chromatography (CLC) and capillary electrochromatography (CEC). Among the functionalized metal oxides, aziridinefunctionalized SiO2, (SiO2-AZ) showed good chemical stability, and was the most useful packing material in both CLC and CEC. Lastly, nanocast metal oxides were synthesized for phosphopeptide enrichment which is a technique used to enrich phosphorylated proteins in biological samples prior to mass spectrometry analysis. By using the nanocasting technique to prepare the metal oxides, the surface area was controlled within a range of 42-75 m2/g thereby enabling an objective comparison of the metal oxides. The binding characteristics of these metal oxides were compared by using samples with different levels of complexity such as synthetic peptides and cell lysates. The results show that nanocast TiO2, ZrO2, Fe2O3 and In2O3 have comparable binding characteristics. Furthermore, In2O3 which is a novel material in phosphopeptide enrichment applications performed comparably with standard TiO2 which is the benchmark for such phosphopeptide enrichment procedures. The performance of the metal oxides was explained by ranking the metal oxides according to their isoelectric points and acidity. Overall, the clarification of the nanocasting process provided in this work will aid the synthesis of metal oxides with true fidelity of replication. Also, the different applications of the metal oxides based on their surface interactions and binding characteristics show the versatility of metal oxide materials. Some of these results can form the basis from which further applications and protocols can be developed.

New biomass derived carbon catalysts for biomass valorization

Due to diminishing petroleum reserves, unsteady market situation and the environmental concerns associated with utilization of fossil resources, the utilization of renewables for production of energy and chemicals (biorefining) has gained considerable attention. Biomass is the only sustainable source of organic compounds that has been proposed as petroleum equivalent for the production of fuels, chemicals and materials. In fact, it would not be wrong to say that the only viable answer to sustainably convene our future energy and material requirements remain with a bio-based economy with biomass based industries and products. This has prompted biomass valorization (biorefining) to become an important area of industrial research. While many disciplines of science are involved in the realization of this effort, catalysis and knowledge of chemical technology are considered to be particularly important to eventually render this dream to come true. Traditionally, the catalyst research for biomass conversion has been focused primarily on commercially available catalysts like zeolites, silica and various metals (Pt, Pd, Au, Ni) supported on zeolites, silica etc. Nevertheless, the main drawbacks of these catalysts are coupled with high material cost, low activity, limited reusability etc. – all facts that render them less attractive in industrial scale applications (poor activity for the price). Thus, there is a particular need to develop active, robust and cost efficient catalytic systems capable of converting complex biomass molecules. Saccharification, esterification, transesterification and acetylation are important chemical processes in the valorization chain of biomasses (and several biomass components) for production of platform chemicals, transportation fuels, food additives and materials. In the current work, various novel acidic carbons were synthesized from wastes generated from biodiesel and allied industries, and employed as catalysts in the aforementioned reactions. The structure and surface properties of the novel materials were investigated by XRD, XPS, elemental analysis, SEM, TEM, TPD and N2-physisorption techniques. The agro-industrial waste derived sulfonic acid functionalized novel carbons exhibit excellent catalytic activity in the aforementioned reactions and easily outperformed liquid H2SO4 and conventional solid acids (zeolites, ion-exchange resins etc). The experimental results indicated strong influence of catalyst pore-structure (pore size, pore-volume), concentration of –SO3H groups and surface properties in terms of the activity and selectivity of these catalysts. Here, a large pore catalyst with high –SO3H density exhibited the highest esterification and transesterification activity, and was successfully employed in biodiesel production from fatty acids and low grade acidic oils. Also, a catalyst decay model was proposed upon biodiesel production and could explain that the catalyst loses its activity mainly due to active site blocking by adsorption of impurities and by-products. The large pore sulfonated catalyst also exhibited good catalytic performance in the selective synthesis of triacetin via acetylation of glycerol with acetic anhydride and out-performed the best zeolite H-Y with respect to reusability. It also demonstrated equally good activity in acetylation of cellulose to soluble cellulose acetates, with the possibility to control cellulose acetate yield and quality (degree of substitution, DS) by a simple adjustment of reaction time and acetic anhydride concentration. In contrast, the small pore and highly functionalized catalysts obtained by hydrothermal method and from protein rich waste (Jatropha de-oiled waste cake, DOWC), were active and selective in the esterification of glycerol with fatty acids to monoglycerides and saccharification of cellulosic materials, respectively. The operational stability and reusability of the catalyst was found to depend on the stability of –SO3H function (leaching) as well as active site blocking due to adsorption of impurities during the reaction. Thus, our results corroborate the potential of DOWC derived sulfated mesoporous active carbons as efficient integrated solid acid catalysts for valorization of biomass to platform chemicals, biofuel, bio-additive, surfactants and celluloseesters.