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Grape pomace hydrochars as potential adsorbents of Cd(II) and Al(III) from aqueous solutions
No full textRecently, there is a growing interest in the utilization of waste biomass to curb its potential negative impact on the environment, which includes CO2 emission and various types of soil pollution. Simultaneously, the development of thermochemical technolo gies for conversion of waste biomass into valuable materials becomes very attractive. Hydrothermal carbonization is proposed as a promising and highly effective technology in this field.
In this paper, grape pomace was hydrothermally carbonized at 220 and 240°C to explore the potential application of derived hydrochars (HC-220 and HC-240, respectively) for removal of Cd(II) and Al(III) from aqueous solutions. Obtained preliminary results showed that adsorption capacities achieved using the HC-220 were 65.25 mg/g for Cd(II) and 17.13 mg/g for Al(III). On the other hand, the HC-240 showed smaller capacities for both examined materials (24.25 mg/g for Cd(II) and 9.0 for Al(II)). Differences in the structural properties of hydrochars produced at different carboniza- tion temperatures could be a reason for this observation. Literature data states that higher temperature causes the formation of energy-dense coal-like hydrochars with dominant aromatic structure. Therefore, material obtained at 240°C had less functional
group on its surface and more aromatic structure compared to the HC-220, and thus
less electron donating sites for metal ions adsorption.
Results from this paper suggest that the grape pomace could be a promising precursor for the production of low-cost hydrochars for adsorption of Cd(II) and Al(III) from wastewaters. Besides, results can be further used for the optimization of the HTC
process parameters to find the most adequate reuse of the waste grape pomace
Izmene Tehnološkog Postupka Flotacijske Koncentracije Pb-Zn Rude "Rudnika –Grot A.D." (Blagodat)- Kriva Feja (Vranje)
No full textU ovom radu prikazani su rezulati rada Rudnika-Grot. Pre svega su prikazani stanje, tehnologija I način rada na rudi olova i cinka koja se eksploatisala i prerađivala u prethodnom periodu. Prikazano je osnovno eksploataciono polje Rudnika Blagodat do 2018., geološke karakteristike ležišta, mineralni sastva i ostale fizičko-hemijske osobine rude. Osim toga u radu je prikazana tehnološka inovacija iz 2017. kojom je izmenjena šema tehnološkog postupka u pogonu za flotiranje olovo- cinkane rude Rudnika Grot. U okviru ovoga dati su svi tehnološki parametri, tehničko-tehnološki efekti izvedene inovacije, kao i postignute uštede u postupku flotiranja u pogonu
Apricot shells biosorbent for Cu(II) ions: determination of optimal alkaline treatment conditions
No full textThe apricot stones (KK) were investigated as biosorbent of copper ions from aqueous
solution. The rigidity of lignocellulosic compact molecular arrangement, induce the necessity of its
modification. The aim of this paper was to establish optimal parameters of KK modification in order
to improve low-cost biosorbent with improved biosorption characteristics. The modification
parameters were: initial NaOH concentration, contact time and biomass/base solution ratio. After
sets of experiments, the optimal modification parameters for copper removal were found to be:
initial concentration of modification agent 1.0 mol/L NaOH, solid/liquid ratio 1:20 and 180 minute
of contact time.
The results show that modified apricot shells doubled the binding affinity toward copper ions, and
could be used as an efficient low-cost biosorbent, promoting more sustainable production and to
stop waste disposal at landfill sites
Zeolite-group minerals in phonolite-hosted deposits of the Kaiserstuhl Volcanic Complex, Germany
No full textSubvolcanic phonolite intrusions of the Kaiserstuhl Volcanic Complex (Germany) show variable degrees of alteration. Their secondary mineralogy has been characterized by petrographic textural observations, bulk-rock powder X-ray diffraction, thermogravimetry, differential thermal analysis, and electron probe microanalysis. The alteration assemblage is dominated by various zeolites that occur in fissures, vugs, and as replacement products of primary phases within the phonolite matrix. Phonolites in the eastern Kaiserstuhl were emplaced into a sedimentary sequence and are characterized by high zeolite contents (Endhalden: 48 wt%, Fohberg: 45 wt%) with the temporal sequence: +/- thomsonite-Ca +/- mesolite - gonnardite - natrolite - analcime. In the western Kaiserstuhl zeolite contents are lower (Kirchberg: 26 wt% or less) and the crystallization sequence is: +/- thomsonite-Ca - gonnardite - natrolite - chabazite-Ca. Pseudomorphic replacement textures and barite inclusions in secondary aggregates suggest that zeolites grew at the expense of a sulfate-bearing sodalite-group mineral, i.e., hauyne. Fresh grains of sodalite-hauyne are only found at Kirchberg, whereas the pervasive alteration at Fohberg and Endhalden transformed feldspathoid minerals completely to zeolites. Zeolites formed in a continuously cooling hydrothermal regime after emplacement and solidification of phonolitic magmas. The common paragenetic sequence corresponds to a decrease in the Ca/Na ratio, as well as an increase in the Si/Al ratio with time. The shift from Ca-Na-to pure Na-zeolites is an expression of closed-system behavior in a water-rich environment at Fohberg and Endhalden, which both intruded an Oligocene pre-volcanic sedimentary unit. The late crystallization of K-bearing chabazite-Ca points to a progressively more open hydrothermal system in the Kirchberg phonolite, which was emplaced in a subaerial volcanic succession and was influenced by K-enriched fluid from leucite-bearing country rock. Therefore, the geological setting and nature of emplacement are important factors that control the degree of zeolitization of intrusive feldspathoid minerals-bearing rocks and whether a zeolite occurrence can be used as mineral deposit
Effects of mechanical-activation and TiO2 addition on the behavior of two-step sintered steatite ceramics
No full textSteatite, as ceramic with composition predominantly resting on magnesium silicate, was produced from economic resources - talc, aluminosilicate clays, and either BaCO3 or feldspar as flux. Titanium dioxide was a doping agent. Four steatite mixtures were mechanically activated in a planetary ball mill for 30, 45 or 60 min, prior to the thermal treatment. Two-step sintering with initial phase set at 1350 degrees C and holding period conducted at 1250 degrees C was applied to initiate diffusion and prevent grain growth. Thereby, a high density ceramic material with low-porous submicron structure was acquired. The effects of TiO2 addition on densification, microstructure, and dielectric characteristics of steatites were monitored. The thermal stability of green mixtures was tested by differential thermal and thermogravimetric analyses. Changes in crystallinity and mineral phase composition were observed by the X-ray diffraction technique. Microstructural visualization with spatial arrangements of individual chemical elements on surface of the sintered ceramics was acquired by scanning electron microscopy accompanied with EDS mapping. In order to test the possibility of employment of the obtained steatites in insulation materials, electrical measurements were conducted by recording variations of the dielectric constant and loss tangent as a function of alternations in the mix-design and the mechanical activation period
Eksploatacija prirodnih resursa u funkciji održivog razvoja
No full textPrirodni resursi su ograničeni i njihova nekontrolisana eksploatacija može imati
negativne posledice na životnu sredinu. Zbog toga je neophodno pronaći načine za njihovo održivo
korišćenje. Održivi razvoj je okvir za oblikovanje politika i strategija kontinualnog državnog i
socijalnog napretka, bez štete za okolinu i prirodne izvore bitne za ljudske delatnosti u budućnosti.
Jedan od modela kojim se reguliše održivo korišćenje je niz strategija i zakonskih regulativa koje
uređuju oblast eksploatacije prirodnih resursa i energije. Osnovni cilj je osigurati održivo
korišćenje prirodnih izvora kako na nacionalnom tako i na međunarodnom, globalnom, nivou.
Održivo korišćenje prirodnih resursa je u direktnoj vezi sa zaštitom životne sredine. Takođe,
očuvanje radne i životne sredine je povezano sa stepenom ekonomskog razvoja i nivoa edukacije
stanovništa o značaju zdrave životne sredine i načinu njenog očuvanja. Ubrzani tehnološki razvoj
dovodi do poboljšanja kvaliteta života u svim sferama ljudskih aktivnosti, ali paralelno sa tim
stvara se mogućnost veće degradacije životne sredine. Zbog toga je neophodno da se u okviru
ciljeva razvojne politike društva uvrste i pravilni kriterijumi koji će doprinositi održivom razvoju.
Samo na taj način doprinosimo očuvanju životne sredine i eliminisanju svih akcidentnih situacija
koje ugrožavaju ravnotežu prirodnih ekosistema
The Crystallization of Glass Samples from the System P2O5-CaO-SrO-Na2O-TiO2
No full textIn this paper crystallization of glass 42P2O5·40CaO·5SrO·10Na2O·3TiO2 (mol %) was studied. The glass was prepared by the standard melt-quenching method. The experiments were performed under non-isothermal conditions using the XRD and DTA methods. It was determined that the surface and volume crystallization mechanism act simultaneously in bulk glass samples. The sintered calcium phosphate glass-ceramic which contains bioactive β-Ca3(PO4)2 and β-Ca2P2O7 phases was prepared. From the experimental data an activation energy of crystal growth is calculated Ea=126.61±2.39 KJ / mol
Characterization of different bioactive phosphate glasses
No full textDue to their potential bioactive properties, different types of phosphate based glasses have been considered for bone tissue engineering and drug delivery applications. In this experiment, four different compositions of glasses (42P2O5·40CaO·5SrO·10Na2O·3TiO2 , 46P2O5·40CaO·SrO·10Na2O·3TiO2 , 42P2O5·40CaO·5La2O3·10Na2O·3TiO2 , and 46P2O5·40CaO·La2O3·10Na2O·3TiO2 (mol%)) were obtained by standard melt-quenching method. The crystallization and sintering behavior of glasses have been studied by using DTA, HSM and XRD methods. For all of the glass compositions the sintered phosphate glass-ceramic samples contained certain bioactive phases (α-Ca3(PO4)2, β-Ca3(PO4)2, β-Ca2P2O7,β-CaP2O6). Based on the glass properties, the use of these glasses in obtaining the bioactive glass scaffolds with a suitable interconnected porous structure is achievable. Bioactive scaffolds have potential to aid the bone regeneration process by giving cell a temporary template to grow into, provoking bone cell activity. Also, glasses with stable uniform porous structure and high surface area can be used as porous carriers for controlled drug delivery
Fuel potential and properties of grape pomace hydrochar
No full textIncreasing fossil fuel depletion that leads to air pollution and global warming have become
serious environmental problem. For this reason, a numerous of alternative biofuels have been
developed and investigated as potential energy sources to substitute them. One of promising
and highly effective technology for conversion of wet and waste biomass into multi-functional
materials is a hydrothermal carbonization. In this study grape pomace was hydrothermally
carbonized at different temperatures (180, 200 and 220 °C). Produced hydrochars were
characterized in order to investigate its potential application as alternative and energy-efficient
renewable fuels. The carbon, fixed carbon, sulfur and volatile matter contents were determined
in all hydrochar samples. Obtained results showed that temperatures play significant role on the
structural characteristics of produced materials. As expected, the carbon content and fixed
carbon content in hydrochars were increased with temperature increasing (Table 1). Higher
yields of carbon and fixed carbon observed in hydrochars indicated that intensive carbonization
of biomass occurred. On the contrary, sulfur and volatile matter content were decreased.
Observed reduction may be a result of dehydration and decarboxylation of grape pomace during
hydrothermal treatment. These reductions are highly beneficial and improve the efficiency of
solids’ direct combustion. Decreased volatile matter content can potentially reduce the release
of inorganic vapors and pollutant emission during combustion, while decreased sulfur content
preventing generation and emission of harmful sulfur oxides, SOx, compared to the parent
biomass. The present study showed that hydrothermal carbonization improved fuel qualities
and potential of grape pomace hydrochars among different reaction temperatures
Prečišćavanja otpadnih voda primenom ozonizacije
No full textUsled razvoja industrije i rastom populacije tokom poslednjih godina javljaju se
problemi u vezi sa otpadnim vodama iz proizvodnje koje je neophodno rešavati na ekološki i
ekonomičan način. Sve otpadne vode iz postrojenja bez obzira kako su nastale sadrže štetne
materije koje mogu da imaju i određen stepen toksičnih primesa, moraju se prečistiti ako njihov
kvalitet ne odgovara zakonskim okvirima. Svrha tretmana otpadnih voda je uklanjanje štetnih
materija čime se postiže smanjnje stepena njene zagađenosti, a istovremeno se ostvaruje i određen
ekonomski i ekološki efekat, stoga je u ovom radu izvršeno prečišćavanje otpadne vode postupkom
taloženja upotrebom kalcijum-oksida u cilju uklanjanja koloidnih materija i teških metala. Većina
zagađujućih materija su organskog porekla i njihovo ukljanjanje vršiće se primenom naprednih
oksidacionih procesa korišćenjem ozona i ozona u kombinaciji sa ultrazvukom u cilju postizanja
kvaliteta vode koji odgovara zakonskoj regulativi. Proces prečišćavanja će se optimizovati u
odnosu na tehnološki postupak, koncentraciju, vreme tretmana i količinu primenjenog oksidacionog
sredstva. Stepen zagađenosti vode organskim jedinjenjima će se određivati na osnovu merenja
HPK, BPK i koncentracije teških metala (olovo, gvožđe, hrom, bakar, cink, aluminijum).Due to the development of industry and population growth during the in recent years,
there are problems with wastewater from production that needs to be addressed in an
environmentally and economical way. All wastewaters from industry, no matter how they are
created, contain harmful substances that may have some degree of toxicity, must be treated if their
quality does not meet the legal requirements. The purpose of wastewater treatment is to remove
harmful substances, thereby reducing its pollution level, and at the same time, it also has a certain
economic and environmental effect. Therefore, wastewater treatment was carried out in this work by precipitation using calcium oxide to remove colloidal substances and heavy metals. Most
pollutants are of organic origin and their removal will be carried in this work out using advanced
oxidation processes using ozone, and ozone in combination with ultrasound to achieve water
quality that complies with the law. The purification process will be optimized with respect to,
method, time and amount of oxidizing agent applied. The degree of pollution of water by organic
compounds will be determined on the basis of measurements of HPK, BOD and the concentration of
heavy metals (lead, ferrum, chromium, copper, zinc, aluminum)