Annealing study and thermal investigation on bismuth sulfide thin films prepared by chemical bath deposition in basic medium

This is a post-peer-review, pre-copyedit version of an article published in Applied Physics A 124.2 (2018): 166. The final authenticated version is available online at: http://doi.org/10.1007/s00339-018-1584-7Bismuth sulfide thin films were prepared by chemical bath deposition using thiourea as sulfide ion source in basic medium. First, the effects of both the deposition parameters on films growth as well as the annealing effect under argon and sulfur atmosphere on as-deposited thin films were studied. The parameters were found to be influential using the Doehlert matrix experimental design methodology. Ranges for a maximum surface mass of films (3 mg cm-2) were determined. A well crystallized major phase of bismuth sulfide with stoichiometric composition was achieved at 190°C for 3 hours. The prepared thin films were characterized using Grazing Incidence X-ray diffraction (GIXRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). Second, the band gap energy value was found to be 1.5 eV. Finally, the thermal properties have been studied for the first time by means of the electropyroelectric (EPE) technique. Indeed, the thermal conductivity varied in the range of 1.20 - 0.60 W m-1 K-1 while the thermal diffusivity values increased in terms of the annealing effect ranging from 1.8 to 3.5 10-7 m2s-1This work was financially supported by the Tunisian Ministry of Higher Education and Scientific Research and by the WINCOST (ENE2016-80788-C5-2-R) project funded by the Spanish Ministry of Economy and Competitivenes

Pectins – occurrence, chemical constitution and physicochemical properties

Pectins are important polysaccharide structure constituents of plant middle lamellae and primary cell walls ensuring their water retention performance and the pH stability [1, 11]. Due to the high gelling, stabilising and thickening properties they are widely used in the food and pharmaceutical industry [3, 9]. Commercial pectin substances are extracted from the waste material, especially citrus peels (from orange, grapefruit, lemon and lime fruit), apple pomace and sugar beet pulp. The high concentration of pectins is found also in other fruits and vegetables, mainly soy hull, mango peels and sunflower heads [3, 11, 12, 14]. The properties of pectins result mainly from their chemical structure. The pectin backbone is primarily composed of homogalacturonan (Fig. 1), which is a linear polymer consisting of α-1→4-linked d-galacturonic acid units, partially methylesterified or O-acetylated [3, 9]. Other structural elements of pectins are rhamnogalacturonan type I (Fig. 2) and type II (Fig. 3), xylogalacturonan (Fig. 5), arabinan (Fig. 6), arabinogalactan type I (Fig. 7) and type II (Fig. 8) [3, 5, 8]. The gelling property of pectins depends on the degree of methyl esterification of their carboxyl groups (DE). According to this parameter there are high ester pectins (DE > 50) and low ester pectins (DE < 50). The high ester pectins form gels in the presence of high sugar concentrations exceeding 55% and pH lower than 3.5, while in the case of low ester pectins the gelation process occurs even at low concentrations of sugar but the presence of divalent ions is required (e.g. calcium) [18, 21]. The aim of this study was a review of the available literature regarding the sources of pectins, their types, chemical structure and physicochemical properties

Whole Wheat Stillage as an Attractive Feedstock for Ethanol 2nd Generation Biofuel – Effect of Pretreatment on Chemical Composition

W pracy zbadano przebieg kwasowej hydrolizy surowego pszenicznego wywaru gorzelniczego prowadzonej w temperaturze 121°C, określono wpływ zastosowanych parametrów hydrolizy (czas reakcji (15 i 30 min.) i stężenie kwasu (1, 3 i 5%)) i uzyskany skład chemiczny frakcji produktów. Po hydrolizie dokonano próby detoksykacji tj. usunięcia z wywaru poddanego hydrolizie furfurali tj. substancji inhibujących przebieg fermentacji etanolowej. Przy 30 min. hydrolizy wpływ użytego do hydrolizy stężenia H2SO4 na uzyskany wynik detoksykacji był niewielki. Z kolei przy czasie sterylizacji wynoszącym 15 min., użycie H2SO4o różnych stężeniach miało wpływ na przebieg detoksykacji. W przypadku FA najkorzystniejszy wynik uzyskano stosując 1% H2SO4, natomiast dla HMF – 5% H2SO4, przy czym stopień detoksykacji FA osiągnął 96%, a HMF 88%. Usuwanie FA i HMF z frakcji poddanych kwasowej hydrolizie niekorzystnie wpływało na zawartość monosacharydów. Wyjątek stanowiły eksperymenty, w których do hydrolizy surowego wywaru pszenicznego użyto 1% H2SO4, a czas reakcji wynosił 30 min.The influence of the acidic hydrolysis (reaction time (15 and 30 min.) and acid concentration (1, 3 and 5% H2SO4)) conducted at 121°C on chemical composition of the raw wheat stillage fractions has been studied. After hydrolysis, an attempt was made to detoxify, i.e. to remove substances (mainly furfurals) that inhibit the course of ethanol fermentation. At 30 min. the effect of H2SO4 concentration on the obtained detoxification results was small. In turn, with 15 min., the use of H2SO4with different concentrations had an effect on detoxification. In the case of furfural (FA), the most favorable result was obtained using 1% H2SO4, while for hydroxymethyl-furfural (HMF) – 5% H2SO4, the degree of FA detoxification reached 96% and HMF 88%. Removal of FA and HMF from the acidic hydrolysis fractions adversely affected the content of monosaccharides. The exception were the experiments in which 1% H2SO4and the reaction time 30 min. was used to hydrolyze the raw wheat stillage

Innovative Techniques and Alternative Solvents for Green Extraction of Proteins from Pulses and Oleaginous Meals as Industrial Sources for Food and Feed

International audienceConsidering the global population growth driven by emerging countries and the increase in nutritional needs of populations, the valorization of protein fractions of plant resources, particularly oilseed crops, appears to be a major issue to answer the demand. Oilseeds are indeed rich in both oil and protein. Historically, oil being the main compound valued, the current crushing process is optimized to maximize its extraction and the proteins remain in the cake (valued in animal feed). The conditions applied during the process and, in particular, during the step of desolventization of the cake after the extraction of the oil with hexane, cause degradation of the proteins. The valorization of these proteins uses traditional extraction methods as well as innovative techniques in order to preserve the nutritional and functional quality of proteins. This chapter gives a picture of current knowledge on extraction techniques, procedures, and solvents for proteins from pulses and oleaginous meals. The modern innovative and intensified extraction techniques, alternative solvents, and original procedures (ultrasound, microwaves, bio-based solvents, mechanical extraction, enzyme-assisted extraction, natural deep eutectic solvents, pulsed electric fields) are summarized in terms of their principles, processes, applications, benefits, and disadvantages