Advanced Hybrid Materials Based on Titanium Dioxide for Environmental and Electrochemical Applications

Constant technological progress, as well as the pursuit of “friendly” technologies, leads to intensive work on the development of a new generation of advanced products with strictly defined, unique physicochemical properties dedicated to specific applications. This group of materials includes hybrids based on titanium dioxide and its derivatives, characterised with specific, well-defined physicochemical and structural properties, chiefly determined during their synthesis. Different properties of titania nanoparticles depend on their morphology, crystallite size, and crystalline structure. Nanocrystalline titanium dioxide can be synthesised via different methods, among which chemical precipitation, microemulsion method (inversed micelles), sol-gel process and hydrothermal crystallisation are the most important ones. That is why, a crucial part of the following chapter will be paid to characterisation of synthesis routes used for titanium dioxide and titania-based hybrid production. Furthermore, application of TiO2-based materials, including mixed oxide systems as well as graphene oxide–based hybrids, in electrochemical (electrode material) and environmental (photocatalysis) aspects, will be described in detail

EFFECT OF INORGANIC OXIDES TREATMENT ON THE TITANIUM DIOXIDE SURFACE PROPERTIES

Studies were conducted involving evaluation of titanium white, surface-coated with inorganic oxides. The studies aimed at determining dispersion properties, i.a. particle size distribution and polydispersity index. Moreover, microscopic observation allowed to evaluate surface morphology of the modified TiO 2 particles. Colourimetric data of titanium white was measured and the specific surface area was estimated using BET method. Effect of the surface modification with oxides on electrokinetic properties and zeta potential were appraised. Increased amounts of aluminium oxide and silicon dioxide used for modification of titanium dioxide surface deteriorate uniform character of the sample and results in an increase in diameter of pigment particles. The titanium white pigments belong to mesoporous adsorbents. Value of the isoelectric point (IEP) depends on the amounts of aluminium oxide and silica used for surface processing of titanium white

Preparation and Characterization of Multifunctional Chitin/Lignin Materials

Multifunctional chitin/lignin materials were synthesized. In order to combine mechanical milling of the biopolymers with simultaneous mixing, a centrifugal ball mill was utilized. The resulting materials, differing in terms of the proportions of precursors used, underwent detailed physicochemical and dispersive-morphological analysis. On the basis of FT-IR spectra and results of elemental analysis, the efficiency of the preparation of the materials was determined. The influence of the precursors on the thermal stability of the resulting systems was also evaluated. Zeta potential was determined as a function of pH to describe the electrokinetic stability of aqueous dispersions. This is important for evaluating the utility of the materials and indirectly confirms the effectiveness of the proposed method of synthesis of chitin/lignin products. Measurements were performed to determine basic colorimetric parameters, crucial in the production technology of multiple colored materials. It is expected that chitin/lignin materials will find a wide range of applications (biosorbents, polymer fillers, and electrochemical sensors), as they combine the unique properties of chitin with the specific structural features of lignin to provide a multifunctional material

Influence of Selected Alkoxysilanes on Dispersive Properties and Surface Chemistry of Titanium Dioxide and TiO2–SiO2 Composite Material

The paper reports on characterisation of titanium dioxide and coprecipitated TiO2–SiO2 composite material functionalised with selected alkoxysilanes. Synthetic composite material was obtained by an emulsion method with cyclohexane as the organic phase, titanium sulfate as titanium precursor, and sodium silicate solution as precipitating agent were applied. Structures of titania and composite material samples were studied by the wide angle X-ray scattering method. The chemical composition of TiO2–SiO2 composite material precipitated was evaluated based on the energy dispersive X-ray spectroscopy technique. The functionalised TiO2 and TiO2–SiO2 composite material were thoroughly characterised to determine the yield of functionalisation with silanes. The characterisation included determination of dispersion and morphology of the systems (particle size distribution, scanning electron microscope images), adsorption properties (nitrogen adsorption isotherms), and electrokinetic properties (zeta potential)

Evaluation of the photocatalytic ability of a sol-gel-derived MgO-ZrO2 oxide material

This paper deals with the synthesis and characterization of a novel group of potential photocatalysts, based on sol-gel-derived MgO-ZrO2 oxide material. The material was synthesized in a typical sol-gel system using organic precursors of magnesia and zirconia, ammonia as a promoter of hydrolysis and methanol as a solvent. All materials were thoroughly analyzed, including morphology and particle sizes, chemical composition, identification of characteristic functional groups, porous structure parameters and crystalline structure. The proposed methodology of synthesis resulted in obtaining pure MgO-ZrO2 oxide material with micrometric-sized particles and a relatively high surface area. The samples underwent an additional calcination process which led to the crystalline phase of zirconia being formed. The key element of the study was the evaluation of the effectiveness of decomposition of C.I. Basic Blue 9 dye. It was shown that the calcined materials exhibit both satisfactory adsorption and photocatalytic activity with respect to the decomposition of a selected model organic impurity. Total dye removal varied in the range of 50-70%, and was strongly dependent on process parameters such as quantity of photocatalyst, time of irradiation, and the addition of promoters

Synergistic Degradation of Dye Wastewaters Using Binary or Ternary Oxide Systems with Immobilized Laccase

In recent years, groundwater contamination caused by dyes has become an important problem. They enter into wastewater as a result of the textile, automotive, or cosmetics industries. For this reason, new methods are being sought, which would aid at the removal of dye impurities with high efficiency and also would be relatively cheap. In the presented study synthesized TiO2-ZrO2 (with TiO2:ZrO2 molar ratio of 8:2) and TiO2-ZrO2-SiO2 (with TiO2:ZrO2:SiO2 molar ratio of 8:1:1) oxide materials were used as supports for enzyme immobilization. Effective synthesis of the carriers was confirmed by results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), low-temperature nitrogen sorption and Fourier transform infrared spectroscopy (FTIR). The materials achieve high immobilization efficiency of the laccases from Trametes versicolor (83% and 96% for TiO2-ZrO2-laccase and TiO2-ZrO2-SiO2-laccase, respectively). The effect of selected dye concentrations, pH, temperature, and reusability were also tested. The obtained results showed that after removal of textile dyes, such as Alizarin Red S (ARS), Remazol Brilliant Blue R (RBBR), and Reactive Black 5 (RB5), under optimal process conditions, which were pH 5 and 25 °C, from dye solution of 5 mg/L degradation efficiency reached 100%, 91%, and 77%, respectively, suggesting synergistic mechanism of degradation by simultaneous sorption and catalytic action. Finally, reduction of chemical oxygen demand (COD) of the solution after treatment indicated lower mixture toxicity and effective dye degradation

Immobilization of Titanium(IV) Oxide onto 3D Spongin Scaffolds of Marine Sponge Origin According to Extreme Biomimetics Principles for Removal of C.I. Basic Blue 9

The aim of extreme biomimetics is to design a bridge between extreme biomineralization and bioinspired materials chemistry, where the basic principle is to exploit chemically and thermally stable, renewable biopolymers for the development of the next generation of biologically inspired advanced and functional composite materials. This study reports for the first time the use of proteinaceous spongin-based scaffolds isolated from marine demosponge Hippospongia communis as a three-dimensional (3D) template for the hydrothermal deposition of crystalline titanium dioxide. Scanning electron microscopy (SEM) assisted with energy dispersive X-ray spectroscopy (EDS) mapping, low temperature nitrogen sorption, thermogravimetric (TG) analysis, X-ray diffraction spectroscopy (XRD), and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy are used as characterization techniques. It was found that, after hydrothermal treatment crystalline titania in anatase form is obtained, which forms a coating around spongin microfibers through interaction with negatively charged functional groups of the structural protein as well as via hydrogen bonding. The material was tested as a potential heterogeneous photocatalyst for removal of C.I. Basic Blue 9 dye under UV irradiation. The obtained 3D composite material shows a high efficiency of dye removal through both adsorption and photocatalysis

TiO2-ZnO Binary Oxide Systems: Comprehensive Characterization and Tests of Photocatalytic Activity

A series of TiO2-ZnO binary oxide systems with various molar ratios of TiO2 and ZnO were prepared using a sol-gel method. The influence of the molar ratio and temperature of calcination on the particle sizes, morphology, crystalline structure, surface composition, porous structure parameters, and thermal stability of the final hybrids was investigated. Additionally, to confirm the presence of characteristic surface groups of the material, Fourier transform infrared spectroscopy was applied. It was found that the crystalline structure, porous structure parameters, and thermal stability were determined by the molar ratio of TiO2 to ZnO and the calcination process for the most part. A key element of the study was an evaluation of the photocatalytic activity of the TiO2-ZnO hybrids with respect to the decomposition of C.I. Basic Blue 9, C.I. Basic Red 1, and C.I. Basic Violet 10 dyes. It was found that the TiO2-ZnO material obtained with a molar ratio of TiO2:ZnO = 9:1 and calcined at 600 °C demonstrates high photocatalytic activity in the degradation of the three organic dyes when compared with pristine TiO2. Moreover, an attempt was made to describe equilibrium aspects by applying the Langmuir-Hinsherlwood equation

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