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Surface modified natural zeolites (SMNZs) as nanocomposite versatile materials for health and environment
No full textThe present research deals with the evaluation of a clinoptilolite-rich rock, occurring in the Nizny Hrabovec deposit (Slovakia), for high-value technological applications based on sorption and in vitro release of nonsteroidal anti-inflammatory drugs (i.e., ibuprofen sodium salt). This georesource was surface modified (SMNZ) using four cationic surfactants. Results demonstrate that ibuprofen sorption is very fast and SMZNs can sorb up to (similar to)26 mg/g of drug as a function of the type of counterion and morphology of surfactant, as well as the hydrophobicity and molecular structure of the drug. Maximum sorption capacities observed for all SMNZs are fully comparable to other adsorbent carriers usually used for removal of contaminants in wastewaters. Sorption of ibuprofen is controlled by a dual mechanism: external anionic exchange and partition into the hydrophobic portion of the patchy bilayer. A prompt drug release in simulated intestinal fluid (SIF) was also observed, making this natural material also suitable to provide rapid soothing effects in potential pharmacological applications. Comparing the results of this study with other recent investigations, a good technological performance of clinoptilolite-rich rock can be inferred despite the relatively low zeolite content ((similar to)56 wt.%)
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 an alternative and energy-efficient renewable fuels. The carbon, fixed carbon, sulphur 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. Higher yields of carbon and fixed carbon observed in hydrochars indicated that intensive carbonization of biomass occurred. On the contrary, sulphur 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 vapours and pollutant emission during combustion, while decreased sulphur content preventing generation and emission of harmful sulphur oxides, SOx, compared to the parent biomass. The present study showed that hydrothermal carbonization mproved fuel qualities and potential of grape pomace hydrochars among different reaction temperatures
In situ synthesis of potassium tungstophosphate supported on BEA zeolite and perspective application for pesticide removal
No full textPotassium tungstophosphate is supported on BEA zeolite by in situ synthesis for glyphosate removal. Spectroscopic measurements identified hydrogen bonding as a primal interaction of potassium salt and BEA zeolite. Composites are evaluated for glyphosate herbicide removal and adsorption process is analyzed using two isotherm models. Obtained adsorption capacities for all prepared composites lay between 45.2 and 92.2 mg of glyphosate per gram of investigated composite. Suspension acidity revealed that glyphosate is adsorbed mainly in the zwitter-ion form at the composite surface while the amount of potassium salt in the composites is crucial for the adsorption application. Exceptional adsorption behavior is postulated to come from a high degree of homogeneity among surface active sites which is confirmed by different experimental methods. Temperature programmed desorption of glyphosate coupled with mass spectrometer detected one broad, high-temperature peak which represents overlapped desorption processes from active sights of similar strength. Introduction of potassium tungstophosphate affects active sites present in BEA zeolite for glyphosate desorption and significantly increases the amount of adsorbed pesticide in comparison to BEA zeolite. Supporting of potassium tungstophosphate on BEA zeolite via in situ synthesis procedure enables the formation of highly efficient adsorbents and revealed their perspective environmental application
Oxidation roasting of pentlandite samples at elevated temperatures
No full textIt is known that virtually all of the nickel in nickel sulfide ores occurs in the
mineral pentlandite [(Ni,Fe)9S8]. Therefore, pentlandite is the most common and
abundant ore for extraction of nickel, accounting for over 60% of nickel world
production [1, 2].
The pyrometallurgical extraction of nickel from its sulfide ores is very similar
to the copper extraction process from copper sulfide concentrates. In essence, iron
and sulfur are eliminated by selective oxidation and fluxing. In fact, the oxidation of
pentlandite is the most important chemical process in the pyrometallurgical route
[3].
Because of all mentioned, the characterization of the structural properties of
six pentlandite samples was carried out in this paper. The samples of pentlandite
were roasted in air atmosphere for 30min, in five different temperatures: 400, 500,
600, 700 and 800 °C. Investigation of structural properties and obtained oxidation
products was performed using X-ray diffraction (XRD), scanning electron microscopy
(SEM) and energy dispersive spectrometry (EDS)
Removal of hexavalent chromium Cr(VI) from aqueous solutions using cellulose-magnetite membrane CelMag-M
No full textThe industries of leather-tanning, mining and textile dyeing, generate large amounts of
chromium-containing wastewater. Hexavalent Cr(VI) is highly poisonous and extremely
mobile in the surface-water and groundwater in a broad pH range and therefore it has
been identified as a potentially carcinogenic substance. The aim of the presented work
was to develop cellulose-based membrane functionalized with magnetite, which could
be used as an efficient adsorbent for the removal of hexavalent chromium Cr(VI) ions
from aqueous solutions. Cellulose-based filter (CF) was functionalized with magnetite
in three-step process. In the first and second step CF surface was modified using
an ethanolic solution of (3-aminopropyl)triethoxysilane (APTES), and
diethylenetriaminepentaacetic acid dianhydride, respectively. The introduction of amino
and carboxylic groups provided successful precipitation of magnetite in the third step.
The obtained cellulose-magnetite membrane (CelMag-M) was characterized by FTIR
and SEM analysis. Adsorption of Cr(VI) onto CelMag-M was studied using batchadsorption
test. Under optimum pH conditions, the maximum experimental adsorption
capacity of CelMag-M for Cr(VI) was found to be 111.2 mg g–1. The adsorption process
was endothermic, the equilibrium adsorption data could be best fitted to the Langmuir
adsorption isotherm model and kinetics was in agreement with the pseudo-second-order
rate equation
Quartz sand processing methods for the application in water glass production
No full textTo use quartz sand for water glass production, processing of raw quartz
sand is necessary. The objectives of processing are: achieving the required
granulometric composition, increasing the content of SiO2 and reducing the content
of impurities that lower its quality. The most frequently used method is the attrition
cleaning in combination with gravity and magnetic concentration. In order to
eliminate quartz sand impurities to a greater extent, it is approached to different
methods of preparing mineral raw materials, which depends of the content and
type of impurities as well as on the way they appear (as individual grains, surface
coatings on quartz grains or as a form of intergrowth with quartz). The size
reduction processes are used when it comes to sandstone or large-grained sand,
whereby the size decreases up to 0.6 mm. Besides that, washing, attrition
scrubbing, grading and also gravity, flotation, and magnetic concentration are
used. Desliming, washing, and grading procedures are used almost always
because there is clay present in the quartz raw material as impurities. The
scrubbing procedure in attrition machines is used when the quartz surface is
kaolinized and limonitised. The flotation concentration is used when in raw material
beside the quartz, there is mica and feldspar, with preceding washing and grading
procedures to eliminate the clay component. That is so-called „reverse“ flotation
consisting of flotating mica and feldspar is applied, and the pure quartz remains in
the pulp. The magnetic separation process is used when in quartz raw material are
also magnetic impurities type Fe2O3 as carriers of total iron. Efficacy of the removal
of iron is expressed as a rate of reduction of Fe2O3. In the company „Kesogradnja
d.o.o.“ at Kozluk, near Zvornik (Republic of Srpska) from quartz sand deposit
„Bijela Stijena Skočić“, quartz sand for the production of water glass was obtained
by the procedures of washing, grinding, sizing and magnetic separation
Activities in order to reduce gas emission with effect of greenhouse
No full textZaštita životne sredine je izuzetno važana u svim zemljama i u direktnoj je vezi 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 ljudske
aktivnosti, ali paralelno sa tim stvara se mogućnost veće degradacije životne sredine. Zbog toga je
važno analizirati negativan uticaj svih primenjenih tehničko-tehnoloških procesa kao i elemente
kontrolisanog korišćenje prirodnih resursa i energije, kako bi se na vreme usvojila strategija i
definisale aktivnosti u cilju sprovođenja adekvatnih mera zaštite životne sredine. Jedan od od velikih
problema u zaštiti životne sredine je pojava emisije gasova sa efektom staklene bašte. Svetske
organizacije koje se bave zaštitom životne sredine pružaju veliki podsticaj za razvoj i stvaranje boljih,
inovativnijih održivih rešenja u građevinarstvu. Tako je jedan od prioriteta proizvođača cementa
pronalaženje novih načina za daljim smanjenjem potrošnje energije i emisije CO2 koja je najveća u
fazi proizvodnje klinkera (proizvod procesa pečenja cementa prilikom spravljanja portland cementa).
Tako neprekidno nastaju nova rešenja koja smanjuju količinu klinkera dok u isto vreme potenciraju
upotrebu alternativnih materijala. Materijali koji mogu zameniti upotrebu cementa (supplementary
cementitious materials- SCM), kao i mešavine cementa nude prednosti u boljim karakteristikama i
održivosti za one koji grade i one koji koriste građevine svih vrsta. Prednosti su, ne samo u
dugotrajnijem betonu boljeg kvaliteta, već i u manjoj potrošnji energije i emisije gasova sa efektom
staklene bašte
Adsorption of alachlor and pentachlorbenzene on biochar and hydrochar originating from Miscanthus giganteus and sugar beet shreds
No full textIn this work we studied the adsorption of two structurally different organic compounds (pentachlorobenzene and alachlor) on biochar
and hydrochar obtained during different thermal carbonization processes. As biomass we used energy cropMiscanthus×giganteus and
sugar beet shreds. Both types of hydrochar were obtained at three different HTC temperatures (180, 200 and 220ºC), while the biochar
was obtained during a slow pyrolysis process at 400ºC.
Characterization of the investigated adsorbents included multi-point BET specific surface area (SSA), pore volume and elemental
analysis. The multi-point BET (Brunauer-Emmett-Teller) SSA and pore volume of the adsorbents was determined by nitrogen
adsorption at 77 K using an AutosorbiQ Surface Area Analyzer (Quantochrome Instruments, USA). Elemental analysis (C, H, N, and
S) was conducted using a Vario EL III CHNS Analyzer. The SSA for all investigated adsorbents ranged from 3.87 to 260 m2/g. Both
of the biochars had a significantly higher SSA than the hydrochar. The mesopore contents of the biochars were expressed as BJH total pore volume (cm3/g),and for the biochars obtained from sugar
beet shreds and Miscanthus were 0.016 and 0.023 cm3/g, respectively. The obtained mesopore volumes were lower compared to the
hydrochars, which shows that the porosity of the material decreased during pyrolysis at higher temperatures. The biochars originating
from sugar beet shreds and Miscanthushad micropore volumes of 0.086 and 0.1042 cm3/g, respectively. All the investigated
hydrochars originating from Miscanthushad higher pore volumes (micro- meso and total pore volume) than those obtained for
hydrochars of sugar beet shreds. Additionally, it can be noticed that the volume of micro- meso- and total pore volume for all the
investigated hydrochars increases with increasing temperature from 180°C to 220°C.
The results of the elemental analysis show that the H/C atomic ratiodecreases with increasing temperature of the HTC processto
values close to 1, indicating an increase in the aromatic structure as the temperature of the process increases. In addition, (N+O)/C
ratio, expressed as the polarity index, decreases as the temperature of the process rises, which indicates the formation of less polar
structures with increasing temperature. In order to investigate the adsorption characteristics of the adsorbents, experiments were performed in conventional batch adsorption
experiments. The background solution was 0.01 M CaCl2 in doubly distilled water with 100 mg/l NaN3 as a biocide.The amount of
adsorbent in each experiment corresponded to a sample/solution ratio that resulted in 20-80% uptake of the given organic compounds.
The procedure was as follows: flasks containing premeasured adsorbent and background solution and a certain volume of methanol
organic compoundstock solution was spiked and equilibrated at room temperature by continuous shaking for 72 h. Samples of clear
supernatant were then removed for gas-chromatographic determination of the organic compound equilibrium concentrations.
All adsorption isotherms well fitted the Freundlich model. The nonlinearity of all the isotherms ranged from 0.450 to 0.986, except for
alachlor on sugar beet shreds hydrochar at200ºC, where the value of n was 1.180. Adsorption coefficients (KF) were in the range
0.053 to 243 (μg/g)/(μg/l)n for both compounds and all adsorbents. However, direct comparison of adsorption affinities could not be
made because of their different units as a result of the nonlinearity of the adsorption isotherms. Therefore, distribution coefficients
(Kd) were calculated for three equilibrium concentrations (Ce = 0.01SW, 0.1SW and 0.5SW). Generally, in the case of both compounds,
theKd values increased in the range: hydrochar of sugar beet shreds<hydrochar of Miscanthus<biochars of sugar beet shreds and
Miscanthus. The highest adsorption affinities were obtained for biochars for both investigated compounds. The reason for the higher
adsorption affinity for both compounds on the investigated biochars may be due to higher specific surface areas.It is known that slow
pyrolysis produces biocharswith higher specific surface area, as well as a higher content of aromatic structures in relation to the
hydrochar produced by hydrothermal conversion process, which can affect the formation of additional adsorption sites on the surface
as well as increase the hydrophobicity of the adsorbent To support this fact, the logKd values obtained for the adsorbents were correlated with the atomic H/C ratios, whereby a positive trend
was observed between the aromaticity and the affinity for adsorption in the case of both investigated compound. Generally,
adsorption affinity increased with increasing aromatic structure in the adsorbents. In addition, it can be noticed that changes in logKd
with the change in the atomic H/C ratio were particularly pronounced at the low equilibrium concentrations, indicating the importance
of specific interactions such as π-π interactions in the overall adsorption mechanism. Based on the obtained results, it can be concluded that the adsorption efficiency is significantly dependent on the physico-chemical
characteristics of the investigated adsorbents, which arestrongly affected by the process and conditions during adsorbents synthesis. In
addition,both investigated adsorbents could be used for the purpose of remediationof water or sediment polluted with organic
compounds
Causes and Consequences of Inadequate Biological Reclamation of Mine Lands: Case Study Bor, Serbia
No full textSeveral decades after termination of dumping at the mine waste sites in Bor area
biological reclamation process has been only sporadically implemented, with very
limited success. Overburden dumps and tailings nowadays present the source of
contamination for surrounding environment by spreading the particles enriched with
metals into the pedosphere, biosphere, atmosphere, and hydrosphere. Wind and water
erosion, as well as the chemical leaching of wastes are the main vectors of pollution.
This paper presents case study of inadequate biological reclamation process in one of
the largest copper mine basins in Europe, aiming to summarize the causes and
consequences of such a case
Comparison of extraction agents for metal determination in sediments from artificial lakes and rivers in Serbia
No full textThe purpose of this paper was to investigate the effectiveness of three different extraction agents for the extraction of 25 elements from sediment samples collected from 4 artificial lakes and 12 rivers in Serbia (33 samples in total). The extraction efficiency of the agents was evaluated by its ability to extract the highest quantity of the elements. For that purpose, three acids (1M HCl, 2M HNO3 and 0.43M CH3COOH) have been used. Inductively coupled plasma atomic emission spectrometry (ICP-OES) was used for quantitative determination of following elements: Al, As, B, Ba, Be, Bi, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Na, Pb, Sb, Se, Sr, V, and Zn. The extraction with 1M HCl has shown the best results for the majority of investigated elements (especially Sr, Mn and Ca). Antimony (Sb) was detected only after extraction with 0.43M CH3COOOH, while selenium (Se) could not be detected when 2M HNO3 was applied as extraction agents. The present study could be very useful for choosing a suitable method for specific elements and also can be helpful in the evaluation of the contaminants in freshwater sediments in Serbia. This might contribute to environmental risk assessment of the present elements