Teofil Jesionowski

Zinc Oxide—From Synthesis to Application: A Review

Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide.

Enzyme immobilization by adsorption: a review

Endowed with unparalleled high catalytic activity and selectivity, enzymes offer enormous potential as catalysts in practical applications. These applications, however, are seriously hampered by enzymes’ low thermal and chemical stabilities. One way to improve these stabilities is the enzyme immobilization. Among various tested methods of this process that make use of different enzyme-carrier interactions, immobilization by adsorption on solid carriers has appeared most common. According to these findings, in this review we present a comparative analysis of the literature reports on the recent trends in the immobilization of the enzymes by adsorption. This thorough study was prepared in order to provide a deeper understanding of the process. Both carriers, carrier modifiers and procedures developed for effective adsorption of the enzymes are discussed. The review may thus be helpful in choosing the right adsorption scheme for a given enzyme to achieve the improvement of its stability and activity for a specific application.

Influence of silane coupling agents on surface properties of precipitated silicas

Silicas of highly dispersion degree were obtained. This process includes formation of silica particles and their aggregation. The ethylene glycol solution was used in precipitation process, resulting in a partial blocking of the silica surface hydroxyl groups (silanol groups) and, thus, in a decreased hydrophilicity of silica. Studies on the surface modification of silicas using silane coupling agents are described. The best modifiers were selected, which inducted a change of the silica surface from hydrophilic to hydrophobic. Basic physicochemical analyses of the obtained silicas were performed. The methods of evaluating the degree of surface modification of the silica were presented. Near infrared spectroscopy (NIR) was used to determine the degree of condensation of the silica surface silanol groups. The degree of hydrophobization of silica surface was determined by a calorimetric method. Moreover, studies on morphology and microstructure using transmission electron microscopy (TEM) were performed. Size distribution of primary particles and aggregates and agglomerates structures were determined by ZetaPlus instrument using dynamic light scattering (DLS) method.

Preparation of the hydrophilic/hydrophobic silica particles

Abstract Silicas of high dispersion degree were obtained. The process included formation of silica particles and their aggregation. Glycerin solution was used in precipitation process, resulting in a partial blocking of the silica surface hydroxyl groups (silanol groups) and, thus, in a decreased hydrophilicity of silica. Studies on the surface modification of silicas using silane coupling agents are described. The best modifiers were selected, which induced a change of the silica surface from the hydrophilic to the hydrophobic one. Basic physicochemical analyses of the obtained silicas were performed. Near infrared spectroscopy (NIR) was used to determine the degree of condensation of silica surface silanol groups. The degree of hydrophobization of silica surface was determined by a calorimetric method. Moreover, zeta potential, size distribution of primary particles, aggregates and agglomerates structures were determined by ZetaPlus instrument using electrophorectic (ELS) and dynamic (DLS) light scattering techniques.

Modification of Chitin with Kraft Lignin and Development of New Biosorbents for Removal of Cadmium(II) and Nickel(II) Ions

Novel, functional materials based on chitin of marine origin and lignin were prepared. The synthesized materials were subjected to physicochemical, dispersive-morphological and electrokinetic analysis. The results confirm the effectiveness of the proposed method of synthesis of functional chitin/lignin materials. Mechanism of chitin modification by lignin is based on formation of hydrogen bonds between chitin and lignin. Additionally, the chitin/lignin materials were studied from the perspective of waste water treatment. The synthetic method presented in this work shows an attractive and facile route for producing low-cost chitin/lignin biosorbents with high efficiency of nickel and cadmium adsorption (88.0% and 98.4%, respectively). The discovery of this facile method of synthesis of functional chitin/lignin materials will also have a significant impact on the problematic issue of the utilization of chitinous waste from the seafood industry, as well as lignin by-products from the pulp and paper industry.

Adsorption of dyes on a silica surface

Abstract Adsorption of several organic dyes was examined on a modified silica surface. For this purpose, EG-Silica was applied, precipitated from sodium metasilicate solution using carbon dioxide in presence of ethylene glycol. In order to promote their interaction with dyes, the silica surface was modified using silane coupling agents with the amino functional group. Technique of conducting the adsorption process was discussed. Studies on morphology and microstructure were performed employing scanning electron microscopy (SEM). Particle size distribution was also examined using the technique of dynamic light scattering. The SEM micrographs and particle size distributions showed that highly uniform pigments can be obtained employing EG-Silica as a core. Studies on elution of dyes from the silica surface demonstrated that, in general, stable pigments were obtained.

Physicochemical and electrokinetic properties of silica/lignin biocomposites

A new method of synthesis of novel composites obtained from silica and Kraft lignin has been proposed. Silica used in the study was obtained by three methods (hydrolysis and condensation of tetraethoxysilane, precipitation in a nonpolar and polar medium with the use of sodium silicate). To extend the possible range of applications, the silica was preliminary modified with N-2-(aminoethyl)-3-aminopropyltrimethoxsysilane, and finally it was modified with Kraft lignin earlier oxidised with sodium periodate (lignin bonded to SiO2 by covalent interactions). The products physicochemical and electrokinetic properties were thoroughly analysed. The dispersive properties and surface morphology were evaluated on the basis of particle size distributions and SEM images. The stability of dispersion in inorganic-organic systems were characterised on the basis of the zeta potential, whose value also permitted concluding on the interactions between colloidal molecules dispersed in water solutions. The products were subjected to elemental analysis to get percentage contents of N, C, H, S elements and were also characterised by XPS and FT-IR spectroscopy. Results of the study are of practical importance in prospective applications of SiO2/lignin biocomposites.

Isolation and identification of chitin in three-dimensional skeleton of Aplysina fistularis marine sponge

The recent discovery of chitin within skeletons of numerous marine and freshwater sponges (Porifera) stimulates further experiments to identify this structural aminopolysaccharide in new species of these aquatical animals. Aplysina fistularis (Verongida: Demospongiae: Porifera) is well known to produce biologically active bromotyrosines. Here, we present a detailed study of the structural and physico-chemical properties of the three-dimensional skeletal scaffolds of this sponge. Calcofluor white staining, Raman and IR spectroscopy, ESI-MS as well as chitinase digestion test were applied in order to unequivocally prove the first discovery of α-chitin in skeleton of A. fistularis.

Influence of aminosilane surface modification and dyes adsorption on zeta potential of spherical silica particles formed in emulsion system

Abstract Studies were performed on the synthesis of spherical silica in an emulsion system. The obtained silica was subjected to surface modification using N-2-(aminoethyl)-3-aminopropyltrimethoxysilane in order to increase adsorptive properties of the silica surface. On surfaces of the unmodified silica material and the aminosilane-functionalised silica C.I. Reactive Blue 19 and C.I. Acid Red 18 were adsorbed. The obtained silica and its derivatives were subjected to physicochemical evaluation: particle size and polydispersity were examined, specific surface area (BET) was determined, surface composition was defined using elemental analysis. The principal aim of the studies was to define electrokinetic (zeta) potential and determination of its alterations as a function of pH in all types of the tested silica colloids. For the purpose the technique of electrophoretic light scattering (ELS) was applied. Effect of ionic strength on stability of tested colloids was also examined. The tested aminosilane was found to exert critical influence on values of zeta potential and, thus, on values of isoelectric point (i.e.p.). The modified silicas reached peak stability within the pH range of 2–4 manifesting zeta potential within the range of (−20) to (−45) mV.

Microstructure and structural transition in microemulsions stabilized by aldonamide-type surfactants.

Significant efforts were undertaken to characterize the microstructure and structural properties of water-in-oil (w/o), oil-in-water (o/w), and bicontinuous (bc) microemulsions composed of N-alkyl-N-methylgluconamides (n-alkyl = n-C(12)H(25), n-C(14)H(29), n-C(16)H(33)) and n-alcohols (ethanol, n-propanol, n-butanol) or iso-alcohols (iso-propanol, iso-butanol) as cosurfactants, as well as iso-octane and water. The internal structure of so created four-component system was elucidated by means of an analysis of isotropic area magnitudes in phase diagrams and conductivity measurements. Dynamic light scattering (DLS) measurements provided the microemulsion size and polydispersity. Polarity and viscosity of microemulsion microenvironment were acquired by means of electron paramagnetic resonance (EPR), UV-vis absorption spectroscopy (in the case of w/o droplets), and steady-state fluorescence (SSF) (in the case of o/w droplets). The results show that both the surfactant and the cosurfactant types affect the shape and extent of microemulsions. The size of droplets depends strongly on the type of examined microemulsion and the type of cosurfactant (linear or brunched) but is almost independent of the length of the surfactant alkyl chain. The size of microemulsion droplets ranges from 8.1 to 22.6 nm and from 3.7 to 14.3 nm respectively, for o/w and o/w microemulsions, making them good candidates for both template-based reactions and household components solubilizing media.