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Application of modified natural zeolite phillipsite for removal of ochratoxin A
No full textOrganozeolites were prepared by modification of the natural zeolite – phillipsite with surfactant - cetylpyridinium chloride (CP) in amounts of 50, 100, 150 and 200% of the external cation exchange capacity (ECEC) of zeolite. Adsorption of mycotoxin - ochratoxin A (OCHRA) was followed at different solid to liquid ratio, different initial mycotoxin concentration and different pH values. Results showed that adsorption of OCHRA increased with increasing of the initial mycotoxin concentration, the amount of each adsorbent in suspension and with increasing amounts of CP in the organozeolites. For all adsorbents, the adsorption of OCHRA was higher at pH 3 than at pH 7. The highest adsorption was achieved with the organozeolite with the highest content of CP (200% of ECEC), 18.4 mg/g at pH 3 and 8.5 mg/g at pH 7
Designing of the shape of zinc particles by variation of electrolysis conditions
No full textZinc-air batteries belong to the group of green and sustainable energy storage systems, and as such, they attract a huge attention of both academic and technological communities. For this system, the alkaline electrolytes of zinc with high concentrations of ZnO and KOH are used. Morphology of zinc electrodeposits is characterized by the scanning electron microscopy (SEM) technique, and it was found that it depended on an overpotential of the electrodeposition with a strong contribution of a length of the electrodeposition time on the final shape. Variety of morphological shapes was observed: irregular and regular grains including those hexagonal shape were predominately formed at the overpotential belonging to the plateau of the limiting diffusion current density. The compact both regular and irregular dendrites were formed at this overpotential with the longer electrodeposition time. The 2D (two-dimensional) and 3D (three-dimensional) dendrites were formed at overpotentials outside the plateau of the limiting diffusion current density, in the zone of the rapid growth of the current density with the increase of the overpotential. In this zone, hydrogen evolution reaction as the second reaction to Zn electrolysis at high overpotentials started to take place. It is manifested by the appearance of craters on the surface of the electrode, which originate from detached hydrogen bubbles. All morpholical forms were explained and discussed applying the basic laws of electrocrystallization
Surfactant-modified bentonites for the removal of nonsteroidal antiinflamatory drug: targeting ibuprofen
No full textNatural bentonites, owing to their hydrophilic surfaces, have limited affinity for the adsorption
of anionic species and/or hydrophobic molecules. To address this limitation, bentonite can be
modified by intercalating cationic surfactants into its interlayer regions through ion exchange
with naturally occurring exchangeable cations. This process results in a transformation of the
surface properties of bentonite from hydrophilic to hydrophobic due to the presence of
surfactants within the interlamellar space. These newly acquired hydrophobic characteristics
offer active sites for the adsorption of hydrophobic organic molecules.
This study aimed to prepare and characterize surfactant modified bentonites, and evaluate
their efficacy in removal of ibuprofen sodium, a widely recognized water contaminant. Natural
bentonite (Šipovo deposit, Bosnia and Herzegovina) was modified using surfactant (quaternary
ammonium salt) under the tradename Arquad®2HT-75, at levels corresponding to 50 and
100 % of the bentonite's cationic exchange capacity. Zeta potential measurement and XRD
analysis confirmed the presence of the surfactant in the prepared composites. Adsorption
experiments demonstrated that the uptake of ibuprofen by the composites was rapid and
increased with higher adsorbent mass, surfactant concentration, and initial pharmaceutical
concentrations. These findings suggest that bentonite modified with surfactant could serve as
an efficient adsorbent for the removal of ibuprofen from contaminated water sources
Structural and microstructural properties of (Sr/Ba)2Al2Si2O8 ceramics phase
No full textThe hexacelsian (BaAl2Si2O8) is an important thermo-stable ceramic material because it has low
thermal expansion and good dielectric properties. In this paper are presented the structural and
microstructure data for diphylloaluminosilicates phases of Sr/Ba-hexacelsian, synthesized from
Sr/Ba ion-exchanged zeolites of LTA and FAU topology. During prolonged heating this phase is
polymorphic transformed to Sr/Ba-celsian feldspar. Synthesis of Sr/Ba hexacelsian and celsian
was observed by X-ray powder diffraction method. The crystal structure and microstructural
parameters were refined using Rietveld method. The crystal morphology of thermal treated
samples was observed by SEM/EDAX analysis
Biochar obtained from waste lignocellulosic biomass as a phosphate adsorbent from water solution
No full textWaste lignocellulosic biomass from the fruit and vegetable processing industry was utilised to produce biochar, a multifunctional material that can be used to bind phosphate from water and then as a fertilizer for soil enrichment. In order to improve the phosphate binding capacity, the biochar obtained by the slow pyrolysis is subjected to physical modification (grinding) and then to chemical modification with metal salts (magnesium, iron and calcium). Phosphate binding was performed in a batch sorption system. The modified biochar with the best sorption capacity was characterized by instrumental techniques (SEM and FTIR)
Oxidation products of arsenopyrite and other sulfides from the ore deposit Sastavci, Serbia
No full textThe dominant sulfide minerals of the Pb-Zn deposit Sastavci are arsenopyrite, galena, and
sphalerite. Oxidation of arsenopyrite can lead to the release of arsenic, a highly toxic environmental
element. Oxidation products of arsenopyrite and other sulfides, present in the ores themselves as well as
on the surfaces of samples, were analyzed by the OL microscopy in reflected light, SEM-EDS, and
XRPD methods. It was established that scorodite and Fe sulfo-arsenates are the main alteration
products of arsenopyrite. The Zn- and Mn-sulfates form crusts and aggregates on the surfaces of some
samples. The conclusion is that the main concentrations of released As are found in scorodite, a
relatively stable mineral in the surface conditions, and to a lesser extent in arsenolite
Prediction of Elastic Modulus, Yield Strength, and Tensile Strength in Biocompatible Titanium Alloys
No full textBiocompatible titanium alloys possess a balanced set of improved mechanical properties and good biocompatibility, making them crucial materials in biomedical engineering. There is an increasing demand for these new alloys with superior properties. Furthermore, there is a need to understand the relationship between parameters and properties, and machine learning is being applied to make the whole process cheaper and more efficient. The aim of this study is to develop accurate machine learning models for predicting mechanical properties: modulus of elasticity, tensile strength, and yield strength, specifically using the Extra Trees Regressor model. Compared to the previous results, an improvement of the elastic modulus prediction model was observed after the inclusion of data on heat treatment parameters and Poisson’s ratio, as seen in the reduced MAE from 7.402 to 7.160 GPa. Models were built to predict the values of tensile strength and yield strength, where iron and tin were shown as most important features respectively, while the correlation coefficients for the test set were 0.893 and 0.868
Application of Non-Edible Food Waste in Waste Water Treatment
No full textDue to the ongoing water crisis and the predicted expansion of water-stressed regions globally, addressing the treatment of large volumes of dyed effluents discharged into receiving waters is crucial. Among these coloured effluents, Brilliant Green (BG), toxic cationic dye, is a common pollutant that poses serious environmental and health risks, even at low concentrations (~ 1 mg/L). Food production/processing generates huge amounts of waste, which application as a new value resource might support the principles of the circular economy through accumulation at landfills prevention and reduction of its negative impact on the environment. Utilizing thermochemical converted waste (biochar) as a sorbent, provides a promising solution for removing BG from wastewater, representing a cheaper alternative to most conventional sorbents. The extensive surface area, porous volume, and variety of biochar functional groups enhance superior sorption properties. In this investigation, biochar was produced from peach stone (PS), which is a waste from the fruit processing industry, through slow pyrolysis at optimized conditions. In order to examine the sorption behavior, two sorbents were used: peach stone biochar (PSB) and modified peach stone biochar (M-PSB). The modification was done using acid treatment (blend of H2SO4 and HNO3, volumetric ratio of 1:1). The biochar before and after modification was analysed by pH suspension (pHsus), Fourier transform infra-red (FTIR-ATR) technique and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX). Kinetic experiments were carried out in a batch system with mixing (200 rpm), using initial dye concentration of 50 mg/L, sorbent dosage of 2 g/L, pH 6, at room temperature for 120 minutes. The results showed that the PSB sample achieved 85.0% of dye removal within 120 min, whereas the M-PSB achieved a maximum decolourization efficiency of 98.9% within 80 minutes of sorption. The accelerated and more efficient sorption of BG on M-PSB is attributed to the alterations observed in the SEM analysis. Acid treatment induces a porous surface morphology characterized by increased roughness and the presence of numerous pores and cracks, enhancing accessibility to active sites and facilitating rapid sorption of BG molecules. The lower pHₛᵤₛ of M-PSB (4.87) compared to PSB (5.76) probably suggests a higher number of carboxyl groups, resulting from acid modification, potentially increasing its affinity for cationic sorbates such as BG. The observed results in sorption efficiency, attributed to the porous surface morphology induced by acid treatment, highlight the potential of biochar as an efficient sorbent for eliminating dye pollution in water resources. The application of biochar, particularly modified, represents a promising and cost-effective solution for the purification of contaminated wastewaters
Correlation Between Morphology and Crystal Structure of Electrolytically Produced Zinc Dendritic Particles
No full textThe correlation between the morphology and crystal structure of zinc dendritic particles produced by electrolysis from the alkaline electrolyte has been established. Morphology and crystal structure of Zn particles electrodeposited by the potentiostatic regime of electrolysis at overpotentials inside (−100 and −160 mV) and outside (−220, −280, and −340 mV) the plateau of the limiting diffusion current density were characterized by scanning electron microscope (SEM) and by X-ray diffraction (XRD), respectively. The particle size distribution (PSD) was performed in order to determine the dependency of the size of dendritic particles on applied electrolysis overpotential. With increasing the overpotential of electrolysis, the shape of particles changed from irregular forms denoted as precursors of dendrites to various forms of dendrites, while the size of the particles simultaneously decreased. All types of Zn dendrites exhibited the strong (002) preferred orientation, while the precursors of dendrites exhibited (101)(002) preferred orientation. The development of strong (002) preferred orientation was explained and discussed by making an analogy with the electrolytic production of lead dendrites from the concentrated nitrate electrolyte. Although zinc and lead belong to different types of crystal lattice (Pb-face-centered cubic type and Zn-hexagonal close-packed type), they have a common characteristic that is manifested by the strong preferred orientation in the crystal plane with the lowest surface energy