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Natural clay extracted from the Central Region of Ghana was used for this study. Energy dispersive X-ray and powder X-ray diffraction analysis showed the composition of the clay to be 67.5% kaolinite and 32.5% muscovite. The samples were successfully modified by H2SO4 and NaOH activation. They were also characterized by scanning electron microscopic and Fourier transformed-infrared spectrophotometric techniques. Batch adsorption studies revealed that the samples are effective adsorbents for the removal of Pb(II) ions from aqueous media. Factors studied include contact time, pH, effect of ionic strength and the mass of adsorbent. Generally, the alkali activated samples had the highest adsorptive capacity followed by the acid activated clay. The kinetics of the adsorption process fitted the pseudo-second order model and the adsorption isotherm conformed to the Langmuir as well as the Freundlich models. All the experiments were carried out at room temperature (303 K).

We demonstrate that predepositing a nanometrically thin nickel film on a dielectric surface is sufficient to transform an amorphous pyrolyzed photoresist film (PPF) into a graphitic film (GRF) enriched with nickel particles. The GRF shows 3 orders of magnitude higher carrier mobility than the amorphous PPF, whereas its electrical conductivity doubles after etching away the nickel remains. The pronounced 2D peak in the Raman spectrum, almost dispersionless absorbance in the spectral range of 750-2000 nm, and the saturable absorption coefficient indicate that GRF possesses a graphene-like band structure. The proposed cost-efficient and scalable synthesis route opens avenues toward fabrication of micron size patterned graphitic structures of any shape directly on a dielectric substrate. Having graphene-like transport and electrical properties at 20 times higher absorbance than the single-layer graphene, GRF is attractive for fabrication of fast modulators for optical radiation, bolometers, and other photonics and optoelectronic devices that require enhanced optical absorption.

The coordination modes of 1-vinylimidazole to platinum and gold were studied. Complexes [PtCl3(Hvinylimidazole)]·H2O (1), [Au(vinylimidazole)2]+[AuBr2]− (2), [Hvinylimidazole]+[AuCl4]− (3), and [Hvinylimidazole]+[AuBr4]− (4) were prepared and structurally characterized. Compound 1 is the first structurally characterized transition metal complex containing a protonated vinylimidazole, which is coordinated through the vinyl group in the side-on position. In compound 2, the neutral ligands coordinate through the imidazole nitrogens to the reduced gold(I) center and the charge balancing counter anion [Au(I)Br2]− has a short Au–Au contact with the cationic part. In 3 and 4, the acidic reaction conditions lead to the protonation of the imidazole nitrogen and an ion pair with tetrahalogenide gold(III) is obtained. The tendency to the different crystallized products is attributed to the combination of the metal and the halogen properties with the reaction conditions. Computational chemistry was used to explain the preference of the vinyl coordination type, as well as in the interpretation of the spectroscopic details and the nature of the intra- and intermolecular interactions present in the solid state.

The addition of zinc oxide (ZnO) to sulfur (S-) vulcanized rubbers is known to accelerate the cross-linking kinetics and to increase the heterogeneity of the cross-link density. However, the spatial distribution of cross-links is hardly known and the mechanism of the activity of ZnO is disputed. We therefore investigated S-vulcanized butadiene-styrene rubber comprising ZnO particles. The samples were fractured and then investigated employing the nano-mechanical mapping mode (NM) of scanning force microscopy (SFM), supported by scanning electron microscopy (SEM). We find that rubber around the ZnO particles exhibits a higher Young's modulus in a shell with a width up to about 200 nm. Furthermore, the extension and retraction curves on these shells exhibit a smaller hysteresis than on the rubber further away from the ZnO particles. We attribute the higher Young's modulus and the smaller hysteresis to a higher cross-link density in rubber surrounding the ZnO particles and we discuss a mechanism of the activity of ZnO in rubbers which can explain this.

Three-dimensionally printed solid but highly porous polyamide-12 (PA12) plate-like filters were used as selective adsorbents for capturing tetrachloroaurate from acidic solutions and leachates to prepare PA12–Au composite catalysts. The polyamide-adsorbed tetrachloroaurate can be readily reduced to gold nanoparticles by using sodium borohydride, ascorbic acid, hydrogen peroxide, UV light, or by heating. All reduction methods led to polyamide-anchored nanoparticles with an even size distribution and high dispersion. The particle sizes were somewhat dependent on the reduction method, but the average diameters were typically about 20 nm. Particle sizes were determined by using a combination of single-particle inductively coupled plasma mass spectrometry, helium ion microscopy, and powder X-ray diffraction. Dispersion of the particles was analyzed by scanning electron microscopy with energy-dispersive spectroscopy. Due to the high adsorption selectivity of polyamide-12 toward tetrachloroaurate, the three-dimensional-printed filters were first used as selective gold scavengers for the acidic leachate of electronicwaste (WEEE). The supported nanoparticles were then generated directly on the filter via a simple reduction step. These objects were used as catalysts for the reduction of 4-nitrophenol to 4-aminophenol. The described method provides a direct route from waste to catalysts. The selective laser sintering method can be used to customize the flow properties of the catalytically active filter object, which allows the optimization of the porous catalytic object to meet the requirements of catalytic processes. peerReviewed

Fire hazard associated to wood and wood-based products is a clear shortcoming of natural building materials and hence the use of fire retardants is mandated by national building codes. In this study, we have synthesized a simple and green fire retardant composite using magnesium hydroxide (Mg(OH)2) with casein protein and tested its performance as self-adhesive coating paste. The thermogravimetric analyses indicated that casein-magnesium composites are able to produce thermally stable insulating magnesium oxide (MgO) that suppresses the fire spread as a result of the synergistic combination of physical and chemical actions—the intumescent action of casein, formation of char and thermally stable MgO, and the simultaneous release of water vapor retained by the casein. The most effective performance was obtained with a sample (coating weight of 1080 g/m2) for which the ignition time of pinewood substrate was increased by 147%, while the smoke production rate and the peak heat release rate were decreased by 53% and 30%, respectively.

The inverse opal films of SiO2 containing metal nanoparticles can have both the localized surface plasmon resonance (LSPR) of metal nanoparticles and the Bragg diffraction of inverse opal crystals of SiO2, which are very useful properties for applications, such as tunable photonic structures, catalysts and sensors. However, effective processes for fabrication of these films from colloidal particles have rarely been reported. In our study, two methods for preparation of inverse opal films of SiO2 with three different crystal sizes and containing gold or silver nanoparticles (NPs) via self-assembly using electrostatic interactions and capillary forces are reported. The Bragg diffraction of inverse opal films of SiO2 in the presence and absence of the template was measured and predicted on the basis of with UV–vis spectroscopy and scanning electron microscopy. The preparation methods used provided good-quality inverse opal SiO2 films containing highly dispersed, plasmonic AuNPs or AgNPs and having both Bragg diffractions and LSPRs.

The avoiding of the hole transport layer (HTL) by an UV/ozone treatment of the indium tin oxide (ITO) electrode was successfully tested on the P3HT:PC61BM and PBDTTT-CF:PC71BM organic solar cells with plasmonic gold nanoparticles and gold nanorods spincoated on ITO, respectively. Reference device on bare UV-ozone treated ITO and the one with HTL were also prepared for comparison. It was found that the UV/ozone treatment of the bare ITO and plasmon-enhanced ITO electrode allowed an effective alignment of the electrode work function with the polymer in the active layer at the saturated values of 5.5 eV and 5.6 eV, respectively. This result is well explained by the integer charge transfer model. The power conversion efficiency (PCE) of the device on bare UV/ozone treated ITO was comparable to that of the conventional device with HTL. Application of two types of 30 nm gold nanoparticles and 40 nm long gold nanorods on ITO before the subsequent UV/ozone treatment improved the PCE by up to 20% and 10%, respectively. These results suggest feasibility of a simple and cost-effective preparation of OSCs.

We propose direct synthesis of ultra-thin graphitic films on a dielectric substrate using sacrificial Ni catalyst layer, which significantly increases the crystallinity of the photoresist pyrolyzed at the temperature of 800 °C and above. A considerable amount of multilayer graphene in the photoresist film pyrolyzed in the presence of the Ni catalyst gives rise to an enhancement of the Raman signal of dye Sudan III molecules deposited on the substrate. We demonstrate comparable enhancement of the Raman signal from Sudan III molecules deposited on the fabricated graphitic substrate and those deposited on graphene, which was conventionally transferred to the silica substrate., published version, peerReviewed

In a controlled assembly of gold nanorods (GNRs) into surface patterns the important factors are surface properties of the GNRs and the substrate as well as the immobilization time. Influence of chemical and physical interactions on assembly of positively charged, hexadecyltrimethylammonium bromide (CTAB) stabilized GNRs on silicon wafer and indium tin oxide (ITO) substrate surfaces were studied. The substrates were silanized with mercaptosilane to provide thiol groups for chemical bonding of nanorods. Effect of pH of the GNR solution was examined in assembly of nanorods using electrostatic and morphologic interactions. By using a higher pH and ITO surface, we have demonstrated that the controlled assembly of the GNRs can be guided with ring and line patterns fabricated by electron beam lithography.

A rhodium complex Rh(acac)(CO)2 microencapsulated into poly(4-vinylpyridine) (P4VP) cross-linked with 2% or 25% divinylbenzene (DVB) was developed as a catalyst for the hydroformylation of 1-hexene. A study was made of the catalytic activity, recyclability, and effect of DVB content of the Rh/P4VP-25% and Rh/P4VP-2% systems. The best yields of hydroformylation products were achieved with the Rh/P4VP-25% as a catalyst. With a high DVB content and regular, spherically shaped particles, Rh/P4VP-25% was an efficient heterogeneous catalyst for the hydroformylation of 1-hexene. The recyclability was good and the 1-hexene conversion high.

Silicon–carbon nanoceramics have been synthesised from hexamethyldisilane (HMDS) by the atmospheric pressure chemical vapour synthesis (APCVS). Direct aerosol phase synthesis enables continuous production of high purity materials in one-stage process. The particle formation is based on the decomposition of the precursor in a high temperature reactor. Reaction of the gas phase species leads to homogeneous nucleation and formation of the nanoparticles with a narrow size distribution (geometric mean diameter range of particle number size distribution 160–200 nm with 1.5–1.6 geometric standard deviation at reaction temperatures 800–1200 °C). A systematic investigation of the influence of the process temperature on the powder characteristics, including the particle size, crystallinity, chemical structure, surface and bulk composition and surface morphology, was carried out. At the reactor temperature of 800 °C, the synthesised nanoparticles were amorphous preceramics containing mostly SiC4, Si–CH2–Si and Si–H units. The composition of the powder turned towards nanocrystalline 3C–SiC (crystal size under 2 nm) when the reaction temperature was increased to 1200 °C. The reaction temperature appeared to be a key parameter controlling the structure and properties of the synthesised powders.

The catalytic activity of the ruthenium carbonyl polymer [Ru(CO) 4 ] n was studied in the hydroformylation of 1-hexene. Compared to the more commonly used ruthenium carbonyl catalyst, Ru 3 (CO) 12 , the linear chain polymer showed higher levels of activity. Although [Ru(CO) 4 ] n itself is only sparingly soluble under catalytic conditions and acts as a heterogeneous catalyst on its own, the effects of supports on catalytic activity were also investigated. A series of potential supports including SiO 2 , Al 2 O 3 , zeolite and multiwalled carbon nanotubes (MWCNT) were explored in order to optimize the catalytic preformance and reusability of the catalyst. The highest activities were obtained with MWCNT supported [Ru(CO) 4 ] n . Unlike any of the conventional oxide supports, the MWCNT improved the total catalytic activity in comparison with the unsupported polymer.

Mesoporous aluminas with average pore sizes of 4.3–7.8 nm were prepared by anodization of an aluminum film (AAO), and by a sol–gel templating method (TPL). In addition to a commercial alumina and sulfated TPL, the aluminas were used as supports for cyclopentadienyl zirconocene dichloride (Cp2ZrCl2) and trimethyl(η5-pentamethylcyclopentadienyl)zirconium (Cp*ZrMe3) and tested in the polymerization of ethylene. The metallocenes supported on the alumina prepared with the templating method and its sulfated modification exhibited polymerization activities of 440 and 350 kgPE/(molZr × h × bar), respectively, comparable to that obtained with silica-supported metallocenes (390 kgPE/(molZr × h × bar)). The acid site distribution of the aluminas was studied with FTIR and temperature programmed desorption (TPD) of pyridine, and also the amount of medium and strong acid sites was determined gravimetrically from the adsorption of pyridine. Relative to the surface area, AAO with the highest amount of acid sites (2.10 μmolpy/m) adsorbed Cp2ZrCl2 and Cp*ZrMe3 the most. Study of the polymers' morphology with a scanning electron microscope revealed polyethylene nanofibers in all the polymer samples, also in those obtained from the reference polymerizations with homogeneous Cp2ZrCl2 and Cp*ZrMe3. This finding suggests that a catalyst support with a tubular pore structure is not a prerequisite for the formation of polymer nanofibers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4002–4012, 2007

Hydrophobic polyolefin (PO) surfaces were prepared by perfluoropolyether (PFPE) blending and nanostructuring. Surface modifications were done by injection molding. Two high-density polyethylenes and polypropylene were melt blended with 2.0 wt.% of PFPE. Both polyethylenes formed blends with PFPE and showed improved hydrophobicity. For nanostructuring, self-ordered nanoporous mold inserts were fabricated by anodizing aluminum in polyprotic acid. Nanostructured samples were prepared with nanoporous anodic aluminum oxide masks from pure polyolefins and from PO/PFPE blends containing 2 wt.% PFPE. Nanostructuring had a marked effect on the contact angle between injection moldable polyolefins and water: well-arranged, high aspect ratio nanostructure was found over the entire surface.

An efficient five-step synthetic route was developed for full N-substitution of chitosan with a quaternary betaine moiety. The developed synthetic procedure can also be controlled to produce chitosan N-betainates having lesser degrees of substitution. 6-O-Triphenylmethylchitosan, which is highly soluble in organic solvents, was used as an intermediate for N-acylation reactions. Intermediate products were characterized by 13 C CP/MAS NMR, FT-IR, and elemental analysis. The water-soluble quaternary chitosan N-betainates were thoroughly characterized by 1H NMR and 13C NMR and by 2D 1H-1H COSY NMR and 13 H- 1 H HSQC NMR. Degrees of substitution were determined from the 1 H NMR spectra. A significant degradation of the polysaccharide backbone during the synthetic procedure was determined by GPC with a light scattering detector.

The target of the research is to examine influence of a polymerization process and monomer ratio on structures and compositions of phases in an emulsion copolymerization of n-butyl acrylate (BA) and methyl methacrylate (MMA). Emulsion copolymerizations are performed using three different BA/MMA weight ratios (60%/40%, 50%/50%, and 40%/60%) and two different processes, statistical batch and seeded emulsion polymerizations. Phase structures, monomer compositions, and morphological stabilities of copolymers are investigated by differential scanning calorimetry, 1H-NMR, and scanning electron microscopy. Gel permeation chromatography is used to follow the changes in the molar mass distribution during syntheses. The gel content and backbiting level of end products are measured by extraction and 13C-NMR, respectively. Copolymerizations give products with a bimodal molar mass distribution and three or two separate phases having different BA/MMA compositions. The morphological stability of particles decreases with the increasing BA fraction in the feed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41467.

The interaction of Co(CO)4 and Co(CO)3 species with silica surface was modeled by a non-local density functional method. The geometries of the cobalt carbonyl complexes interacting with the silica surface via SiCo, SiOCCo and SiOCo bonds were optimised, and the interaction energies were calculated. The results of the adsorbate models and the surface complexes bonded via SiCo bonds were found to be in agreement with previously published theoretical data and with available experimental findings. According to our results, cobalt carbonyl species form strong bonds with silica sites and are plausible surface complexes. Bonding via carbonyl ligand was the weakest type of interaction, while bonding via surface oxygen was the strongest. The interaction energies of charged species were higher than those of the radical species. The bond distances between cobalt and its nearest neighbours decreased when there were fewer carbonyl ligands in the complex. The interaction energies and the bond distances between cobalt and its nearest neighbours correlated with the charge of the central cobalt atom.

The mesoporous high surface area MCM-41 material was synthesized and used as a support material for the preparation of Co/MCM-41 samples. Co2(CO)8 was deposited from the gas phase onto the MCM-41 surface in a fluidized bed reactor. Pure MCM-41 and Co/MCM-41 samples were characterized by various spectroscopic and analytical methods. The MCM-41 mesoporous material showed considerable ability to adsorb Co2(CO)8 from the gas phase. The monolayer coverage after one direct deposition and decarbonylation cycle was ca. 20 wt % of cobalt. The metal loading increased up to 41 wt % using the pulse deposition method. The results of IR spectroscopy indicated that all silanols are accessible to the cobalt carbonyl. According to the N2 adsorption/desorption studies, the surface area and pore size distribution were almost unaffected even in the case of high cobalt loadings. The samples were found to have a good metal dispersion.

Dicobalt octacarbonyl, Co 2 (CO) 8 , was deposited on silica support pretreated at 300°C, 500°C and 600°C, by vapour-phase adsorption at low temperature in a fluidized bed reactor. Adsorption of cobalt carbonyl on the silica surface and decarbonylation during heat treatment were followed by diffuse reflectance IR spectroscopy. The Co 2 (CO) 8 rearranged to Co 4 (CO) 12 and the surface was completely decarbonylated via subcarbonyl species. The decarbonylation of cobalt carbonyl on silica was also studied by temperature programmed reduction. Energy dispersive X-ray fluorescence was used to determine the cobalt content on the silica surface. Pretreatment temperature did not affect the saturation level of the cobalt carbonyl but influenced the hydrogen uptake of the non-decarbonylated samples in hydrogen chemisorption studies. Therefore, in gas phase preparation method the pretreatment temperature of the silica support could prove to be useful in the preparation of catalyst systems. A higher amount of cobalt on the support could be achieved through repetition of the deposition–decarbonylation sequence.

The effect of nanostructured supports on the activity of Rh catalysts was studied by comparing the catalytic performance of nano- and bulk-oxide supported Rh/ZnO, Rh/SiO₂ and Rh/TiO₂ systems in 1-hexene hydroformylation. The highest activity with 100% total conversion and 96% yield of aldehydes was obtained with the Rh/nano-ZnO catalyst. The Rh/nano-ZnO catalyst was found to be more stable and active than the corresponding rhodium catalyst supported on bulk ZnO. The favorable morphology of Rh/nano-ZnO particles led to an increased metal content and an increased number of weak acid sites compared to the bulk ZnO supported catalysts. Both these factors favored the improved catalytic performance. Improvements of catalytic properties were obtained also with the nano-SiO₂ and nano-TiO₂ supports in comparison with the bulk supports. All of the catalysts were characterized by scanning electron microscope (SEM), inductively coupled plasma mass spectrometry (ICP-MS), BET, powder X-ray diffraction (PXRD) and NH3- temperature-programmed desorption (TPD). peerReviewed

Mesoporous high surface area MCM-41 and SBA-15 type silica materials with fibrous morphology were synthesized and used as support materials for the ALCVD (atomic layer chemical vapor deposition) preparation of Co/MCM-41 and Co/SBA-15 catalysts. Co/MCM-41 and Co/SBA-15 catalysts were prepared by deposition of Co 2 (CO) 8 from the gas phase onto the surfaces of preheated support materials in a fluidized bed reactor. For both silica materials, two different kinds of preparation methods, direct deposition and a pulse deposition method, were used. Pure silica supports as well as supported cobalt catalysts were characterized by various spectroscopic (IR) and analytical (X-ray diffraction, Brunauer-Emmett-Teller, elemental analysis) methods. MCM-41 and SBA-15 fibers showed considerable ability to adsorb Co 2 (CO) 8 from the gas phase. For MCM-41 and SBA-15 silicas, cobalt loadings of 13.7 and 12.1 wt % were obtained using the direct deposition method. The cobalt loadings increased to 23.0 and 20.7 wt % for MCM-41 and SBA-15 silicas, respectively, when the pulse deposition method was used. The reduction behavior of silicasupported cobalt catalysts was found to depend on the catalyst preparation method and on the mesoporous structure of the support material. Almost identical reduction properties of SBA-15-supported catalysts prepared by different deposition methods are explained by the structural properties of the mesoporous support and, in particular, by the chemical structure of the inner surfaces and walls of the mesopores. Pulse O 2 /H 2 chemisorption experiments showed catalytically promising redox properties and surface stability of the prepared MCM-41- and SBA-15-supported cobalt catalysts.