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Thermochemical conversion of non-edible fruit waste for dye removal from wastewater
No full textIn this study, slow pyrolysis was employed for the thermochemical conversion of peach stones (PS), lignocellulosic waste (LCW) from food industry, to prepare biochar (PS-B), a new and efficient sorbent for the removal of toxic dye, brilliant green (BG), from aqueous solution. Detailed characteristics of PS and PS-B were analysed using pH suspension, pHPZC, zeta potential, particle size distribution, thermogravimetric method (TG-DTG), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results revealed that material loss during slow pyrolysis not only altered the chemical structure of the samples, but also induced the volume shrinking phenomenon, resulting in production of a rougher, porous structure with decreased crystallinity. Also, five times less total organic carbon (TOC) release was demonstrated by biochar compared to native material. Comparison of experimental results for BG sorption by PS and PS-B showed that sorption capacity increased after pyrolysis and that sorption kinetic was significantly improved. The BG sorption by both sorbents followed the pseudo-second-order reaction kinetic model, with the intraparticle diffusion model within pores controlling the adsorption rate in PS-B. Isotherm equilibrium modelling revealed that the Sips isotherm provided the best model fit with maximum sorption capacity of 82.53 and 101.11 mg/g for PS and PS-B, respectively. A possible sorption mechanism of BG was achieved through pore filling (porous diffusion), hydrogen bonding, electrostatic attraction and π-π interactions. The results demonstrated that biochar derived from peach stones can be used as a promising green material for removing BG from contaminated waters
Cascade luminescence and antibacterial behavior of fluorapatite nanopowder co-doped with Pr3+, NO3- and CO32- ions
No full textIn this study, luminescence and antibacterial behavior of pure fluorapatite (FAp) and praseodymium-nitrate-carbonate co-doped fluorapatite (PrNCFAp) nanopowders were investigated. Uniform nanopowders were synthesized by precipitation reaction followed by centrifugation and systematically characterized by XRD, FTIR, SEM-EDS, TG and PL methods. XRD analysis revealed the formation of hexagonal FAp crystals, and FTIR spectra indicate the presence of nitrate (NO3-) and carbonate (CO32-) species. SEM analyzes confirm agglomerates composed of irregular nanometer-sized spheres. Emission of FAp nanopowder occurred in the violet-blue region of the visible part of the spectrum, with redshift to the blue-green color region when Pr3+, NO(3)(- )and CO32- co-doped in the lattice. Analysis of luminescence spectra by MCR-ALS method extract three fluorophores from the PrNCFAp sample and showed simultaneous existents of emission-reabsorption-emission between dopants in FAp lattice. Antibacterial activity against pathogen Staphylococcus aureus was investigated before and after treatment of nanopowders by UVA radiation of 365 nm. Nanopowders irradiated with UVA compared to non-irradiated reduced Staphylococcus aureus by 84.9% for PrNCFAp and 33.3% for FAp in the first 0.5 h of contact, and 76.1% and 42.9% after 24 h of contact. In addition, the obtained luminescent nanomaterials showed a low degree of hemolytic activity and could potentially be candidates for further research in dentistry
Zeolitski tufovi ležišta Slanci u Beogradskom dunavskom ključu
No full textZeoliti čine grupu prirodnih i sintetičkih neorganskih jedinjenja, koja imaju specifične fizičkohemijske osobine pogodne za industrijsku primenu. Po svom postanku, raznovrsnosti hemijskog sastava, strukturnim karakteristikama i primeni, zeoliti čine specifičnu grupu alumosilikatnih minerala u okviru klase tektosilikata. Klinoptilolit-hejlanditska serija minerala (HEU-tip zeolitske mreže) zbog svojih fizičkohemijskih osobina predstavlja ekonomski najznačajniju grupu prirodnih zeolita. Brojna su polja primene ovih minerala u ekosistemima: kod odstranjivanja organskog sumpora vezanog za ulja; kod prečišćavanja vazduha od gasova SO2, CO2 i azotnih oksida; koriste se za odstranjivanje cezijuma i stroncijuma iz zemljišta zagađenog nuklearnim otpadom, u oblasti poljoprivrede i veterinarstvu; i dr. Zeolitski tuf slanačke serije je predstavljen sivobelim do žućkasto bojenim agregatom, sa prisutnim limonitskim skramama koje zapunjavaju prsline i pukotine. Mineralni sastav zeolitskog tufa je: KVARC, FELDSPATI, LISKUNI, MINERALI ZEOLITA (iz grupe hejlandit /klinoptilolit), LIMONIT-GETIT, VULKANSKO STAKLO, MINERALI GLINA, CIRKON, APATIT, RUTIL. Osnova uzoraka zeolitskog tufa je kristaloklastična do vitroklastična, delimično šupljikava i porozna
Dissolution of polyphosphate glass: Impact of pH on diffusion coefficients of modifying cations at low temperatures
No full textThis paper shows the dissolution behavior of polyphosphate glass in demineralized water and 2% citric acid solution at temperatures: 15, 20, 30, 37 and 50 °C. The influence of the solvent type on the diffusion coefficients of the modifying cations, under static conditions, is also presented. The diffusion coefficients, determined from concentration profiles of the modifying cations, are calculated to be in the range of 0.27 to 350x10-14 m2/h for dissolution in demineralized water, and in the range of 3.6 to 148x10-12 m2/h for the dissolution in 2% citric acid solution. The values of activation energy of cations diffusion in demineralized water are in the range from 68.32 to 105.41 kJ/mol, while for 2% citric acid solution they are in the range from 39.28 to 55.34 kJ/mol
Removal of toxic dye by eco-friendly biochar derived from sour cherry stone
No full textIn this study, the use of low-cost, widely available waste biomass of sour cherry stone (CS) was
used for the production of biochar (CSB), and used as an alternative to the expensive removal
techniques for removing toxic dye Brilliant green (BG) from wastewater. Produced CSB was
characterized using Fourier Transform Infrared spectroscopy with attenuated total reflectance
(FTIR-ATR) and Thermogravimetric method (TG-DTG). FTIR-ATR results indicated the
evolution of aromatic functional groups replacing aliphatic groups of CS. The effects of various
operational parameters (pH, contact time, initial dye concentration, adsorbent dosage and
temperature) were investigated and optimal conditions were determined. According to the results,
optimized parameters were: pH 6, contact time of 120 min, initial dye concentration of 50 mg/L,
adsorbent dosage of 2 g/L, and temperature of 35 ℃. These parameters were used for kinetic and
isothermal investigations. The adsorption of BG was evaluated using two kinetic reaction models
(pseudo-first-order and pseudo-second-order). The results showed that the pseudo-second-order
model fitted better the experimental data, indicating chemisorption involving valence forces
through the exchange of electrons between the dye and CSB. According to the adsorption isotherm
analysis, the Langmuir isotherm model better fits experimental data than the Freundlich and Sips
models. The maximum monolayer adsorption capacity of BG on CSB was found to be 109.25
mg/g. The RL value (0.392) verifies that the BG adsorption on CBS is a feasible process. Using
CS as a raw material for biochar production, the problem of waste disposal, its decomposition and
secondary pollution might be solved. In the same time, this waste materials would gain not only
ecological but also significant economic value. These findings demonstrated that CSB, which is
made from waste biomass, can be used as a promising and affordable adsorbent for removing dyes
from aqueous solution
Predicting the modulus of elasticity of biocompatible titanium alloys using machine learning
No full textTitanium alloys are widely employed in various fields, particularly in biomedical engineering, due to their mechanical and corrosion resistance properties combined with good biocompatibility. The modulus of elasticity is a distinguishing feature of this group of materials compared to others used for similar purposes. A database of approximately 238 titanium alloys free of toxic elements was compiled for this study. The influence of different factors (such as alloy element proportions, density, and specific heat) on the modulus of elasticity was predicted using four methods: support vector machine, XGBoost, Neural Network, and Random Forest. The Random Forest mean absolute error (MAE) of 7.33 GPa, falls within the range of experimentally obtained absolute errors in the literature (up to about 11 GPa). A strong correlation (R2 = 0.72) was observed between experimental and predicted data. Lastly, specific alloying element regions were identified for the modulus of elasticity, which can be used to design new biocompatible titanium alloys in the future
REE extraction from hyperaccumulating plants: challenges and prospects
No full textPhytomining although predominantly in its early stages on the broader scientific scope of investigation has garnered
interest in metals such as Ni, Au, Zn or REE. Rare earth elements (REE) are commonly defined as the 15 lanthanides
with the addition of Sc and Y. Since studies of other hyperaccumulating plant species have been conducted before, similar techniques were tried with REE. With the concentration threshold at 0.1 wt% of the dry biomass there have been identified about 22 plant species that hyperaccumulate REE from five families (Phytolaccaceae. Gleicheniaceae, Blechnaceae, Juglandaceae, Thelypteridaceae). One of the most studied REE hyperaccumulators is Dicranopteris linearis (formerly
known as D.dichotoma), a fern native to China that grows on mine tailings. Generally, the techniques for REE
phytomining can be separated into Pyrometallurgy, Hydrometallurgy, Biometallurgy and Novel approaches. Currently most of the research is still focusing on the optimal utilization of various hiperaccumulators and the enchantment of REE extraction from the soil as well as from the enriched biomass. Since recovery of REEs via phytomining is just in its
infancy further multidisciplinary investigations are needed, especially when it comes to valorization and REE recovery.
This paper presents a quick review for the concept of REE phytomining, current state of research, challenges and
prospects
Preliminary physical-chemical and mineralogical characterization of furnace dust samples, the basis for the selection of samples for research within the project EIT Raw Materials ris-dustrec-ii no 22009
No full textLarge amounts of EAF furnace dust are generated in Europe (1.3Mt), as well as in the world (8,764Mt). Due to the high content of Fe and Zn, whose content often reaches a total of between 50 and 60 wt.%, EAF dust has always been interesting for recycling. So far, the most commonly applied method of processing EAF dust is the pyrometallurgical Waelz kiln process of Zn extraction (85% market share). The paper presents EIT Raw Materials Project: RIS-DustRec-II, which aims to develop innovative technologies for the separation, reprocessing, and beneficial use of all components of EAF and CF furnace dust, to reduce the amount of toxic waste and achieve the zero-waste target in the EU. Preliminary chemical, XRD, and SEM analyses on two samples of EAF and CF furnace dust from Italy were performed and presented
Geological characteristics of the limestone deposit "Dobrilovići" - Loznica and its preparation for use in agriculture
No full textThe paper presents the geological characteristics of the limestone of the "Dobrilovići" deposit and the characterization of the trench sample. The technological scheme of limestone preparation, which is used to obtain suitable sizes for use in agriculture, is presented in the paper. Chemical analysis showed the presence of CaCO3 above 80% and CaO above 44.80%. The content of trace metals is low: Cr 21 mg/kg, Pb 3 mg/kg, and Ni 7 mg/kg. The mean value of the loss of ignition is 39.40%, and the pH is 8.47. Based on the obtained results, it was concluded that the chemical and mineral composition of limestone meets the requirements necessary for the calcification of acidic soils. The results of the determination of the granulometric composition showed the dominant presence of large classes above 50 mm (68%). To obtain a class of 100% -2 mm that meets the requirements for application in the calcification of acidic soils, a technological scheme for the preparation of trench limestone is given, which includes crushing, grinding, and grading