Chemical characterization of inks for inkjet decoration of ceramic tiles

The inkjet decoration of ceramic tiles has become the most widespread decoration technology in this field. It is also a technology in constant evolution, in order to obtain: better color performances, inks with improved stability and rheological properties, lower production costs, etc. Inks formulation is one of the most critical point because polluting emissions during firing, rheological parameters, jettability and stability of inks depend on inks formulation itself. This study focuses on the characterization of inks now in commerce, to understand their thermal behavior, chemical composition, polluting emissions during firing and rheological properties. We performed TG-DTA analysis, FTIR spectrometry, X-Ray fluorescence, and we are testing GC-MS and HPLC methodologies, on both inks and dispersing agents. First data from TG-DTA seem to underline different thermal behaviors between different dispersing agents. By cross-checking these data with FTIR results, we divided our samples in 5 groups, depending on dispersing agents class: paraffin oil, esters, paraffin oil added with esters, tripropylene glycol n-butyl ether (TpnB), water added with paraffin oil. From X-ray fluorescence on liquid inks and by comparison with literature [3,4], we recognized the chemical composition of coloring phases of inks. Our study is now focusing on testing GC-MS and HPLC methodologies to characterize polluting emissions, collected by firing a selected quantity of samples in a tubular kiln that simulates industrial processes. The following step will be the cross-check of data coming from TG-DTA, rheological characterization, that will be carried out by ISTEC-CNR in Faenza (Bologna), and chromatographies. The final phase of this project will focus on a possible re-formulation of inks, to reach even better properties and decrease potential polluting emissions during firing processes

VOCs monitoring of new materials for ceramic tiles decoration: GC–MS analysis of emissions from common vehicles and inkjet inks during firing in laboratory

Abstract The decoration of ceramic tiles "ink-jet revolution" has brought significant advantages to tiles manufacturing, but the explosive diffusion, until 4–5 years ago, of this technique has not been accomplished by an adequate scientific research. Among all the features that have to be studied yet, one of the most important is the influence of the new generation inks on the total emission at ceramic chimneys. In this paper, we present a first characterization of emissions from a set of commercial inks and vehicles: they were collected by propter firing of samples in an electric kiln and analyzed by GC–MS. This study is part of a larger research project, which includes the chemical characterization and the evaluation of thermal behavior of inks and vehicles by TG-DTA and other techniques. The obtained results permit to divide common vehicles into 3 classes, depending on their thermal behavior and emissions pattern. Inks, most of which present an ester based formulation, sometimes mixed with glycols or paraffins, follow the behavior of their single components. The most common formulation leads to the presence in the emission pattern of evaporation products (2-ethylhexyl esters of lauric, myristic, decanoic and octanoic acids) and decomposition products (mainly aldehydes and 2-ethyl-1-hexanol)

Hydrogen production from aluminum reaction with NaOH/H2O solution: Experiments and insight into reaction kinetics

Hydrogen as a clean energy carrier is a promising candidate for a shift from fossil fuels to renewable sources. Since hydrogen shall be separated from other elements, various chemical processes may be exploited to this end, including the reaction between aluminum and alkaline solutions. The chemical kinetics of the reaction between aluminum and NaOH/water solution was investigated experimentally in a setup relying on the Dietrich-Frühling method. The parametric analysis encompassed aluminum surface area available for interaction, NaOH concentration and operating temperature, including subzero conditions. Hydrogen production aligned with that predicted through stoichiometric calculations. Moreover, it was demonstrated that reaction rate increases with temperature, concentration and specific surface area of the aluminum samples, also showing how an increase in one of those parameters counterbalances the effect by decreasing another. Finally, activation energy was calculated for the involved reaction as equal to about 50 kJ mol−1, together with Arrhenius coefficient (20526 s−1)

Study of Black Core, ceramic tile’s defect, by a multi technique approach

The traditional ceramic industrial production, for most of its applications, i.e. Ceramic Tiles, Heavy Clay Products, Tableware and Sanitaryware, is often affected by the formation, during the firing process, of a dark color core, normally named “Black Core”, that can represent an aesthetical and technological problem. The true nature of this defect was never clearly stated, but it is known to be due to the presence of chromophores, like Iron, and organic or reducing materials, combined with a lack of permeability of the unfired body. A novel, mullti-approach study was made by XRD, XRF, SEM-EDS, FTIR and Mossbauer Spectroscopy, and by micro Raman spectroscopy and mapping, with the aim to clarify the morphology, the composition and the Iron oxidation state of this inner layer. Possible solutions were suggested, by the addition to the recipe of proper additives

Development of a redox polymer based on poly(2-hydroxyethyl methacrylate)for disposable amperometric sensors

Membranes based on poly(2-hydroxyethyl methacrylate), chemically modified with ferrocene functionalities, are proposed as novel coatings for the development of disposable amperometric sensors. They are mass-produced on an inert support through an UV photo-induced polymerization, forming self-standing films that can be transferred on an electrode surface. Thanks to the characteristic of the functionalized methacrylate matrix to rapidly and reversibly swell by incorporation of large amounts of water, the ferrocene moieties are in intimate contact with the electrolytic solution. They can activate effective electrocatalytic processes that can be exploited in the field of amperometric sensing. The performance of the methacrylate coating with respect to the determination of hydroquinone benchmark analyte has been tested both in a static solution and in a flux cell

Rootlets, a malting by-product with great potential

Barley rootlets are the most abundant by-product from the malting industry. Due to the inherent association of the malting industry with brewing and distilling industries, it is also considered a by-product of these industries. Barley rootlets are produced during the germination step of malting. These rootlets are a valuable source of nutrition, with protein and fibre holding a large proportion of their composition. Barley rootlets are generally pelletised and used as animal fodder; however, their usage may not be limited to this. Efforts have been made to utilise barley rootlets as food ingredients, sources of enzymes, antioxidants, raw materials in fermentations, and in biochar production. Conversion of this by-product into other/new applications would reduce waste production from their industry origin and reduce some of the impending environmental concerns associated with by-product production. The current review focuses on providing information on the formation, production, and processing of barley rootlets, while also highlighting the composition, quality, and potential applications of barley rootlets

Fast firing of heavy clay products in roller kilns

Analytic aspects of the consequencies of fast firing on the composition and structure of ceramic tile

Modern decoration technologies for tiles: new products, new additives, new problems

This lecture wants to emphasise the main evolution in the latest years of the decoration techniques for ceramic tiles, particularly referring to the necessity that was risen on the evolution of the liquid part of the inks : vehicles, binders, fixatives, additives etc