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Dvostepena termohemijska modifikacija otpadne biomase kao pravac dobijanja visokoefikasnih adsorbenasa
No full textGlavni cilj ove studije jeste priprema Fe/Mg-modifikovane hidročađi komine grožđa i ispitivanje uticaja dvostepenog termohemijskog tretmana na efikasnost uklanjanja jona cinka. Preliminarni adsorpcioni test je ukazao na višestruko poboljšanje kapaciteta sorpcije nakon modifikacije. Detaljniji uvid u adsorpcioni proces je ispitan kroz uticaj vremena kontakta i kinetičku studiju. Dobijeni rezultati su pokazali da uklanjanje jona cinka primenom Fe/Mg-hidročađi sledi kinetički model pseudo-drugog reda. Ovaj model pretpostavlja hemijsku interakciju između jona metala i funcionalnih grupa na površini hidročađi kao glavni mehanizam vezivanja. Sumiranjem zaključaka se može istaći da Fe/Mg-hidročađ pokazuje efikasno adsorpciono ponašanje i može se razmatrati kao nova opcija valorizacije agro-otpada
Innovative Technology for Recycling Polyethylene Terephthalate: Climate Changes, Approaches, Solutions
No full textWorldwide pollution induces a negative impact on the complete environment. Modern societies are becoming
more involved in developing and implementing climate change adaptation policies as a result of
the enormous hazards that climate change poses to human safety worldwide. One of the biggest problems
that highly affects climate change is plastic pollution. Also, the utilization of a linear economy prevents the
opportunity of solving mentioned problem. Hence, a major component of the strategy for tackling plastic
pollution and trying to decrease global weather changes is an implementation of a circular economy. Plastic
has to be reduced, reused, and recycled since its widespread consumption has put environmental protection
at risk. PET, also known as polyethylene terephthalate, is a prominent polymer material used for
the production of packaging, particularly plastic bottles. The majority of PET-based products are made
using raw materials supplied from fossil fuels. However, methods based on biobased materials and recycling-
modified products for obtaining novel products from waste PET have fewer greenhouse gas (GHG)
emissions than the traditional method. Therefore, the subject of this paper is the innovative technology for
the fabrication of materials by PET recycling. Obtained monomer units - glycolysates were acquired by PET
depolymerization by inducing greener solutions. The resulting glycolysate was structurally modified with
maleic anhydride and finally with 2-octanol to obtain a novel plasticizer. The physicochemical characterization
of the obtained plasticizer, performed by infrared spectroscopy with Fourier transform (FTIR) and
NMR spectroscopy, confirmed structural modifications. The mechanical characteristics of the final product
were tested after the plasticizers had been combined with bitumen at a range from 1 to 10 wt.% concentration.
In addition, other PET recycling techniques will be presented and discussed. By comparing them,
it will be determined which technique is most suitable for recycling with the smallest carbon footprint. The
second purpose of the research is to evaluate and contrast the financial and ecological implications of recycling
PET in comparison to other types of waste and renewable energy sources
Diatomic earth: Structure and modification
No full textOne of the most interesting secondary raw materials within the Kolubara Basin is diatomaceous earth or diatomite, with reserves of 308.670 t in fields B and C. Chemical and mineralogical tests were performed on diatomaceous earth samples. The results of these tests are presented in this paper. Diatomite is a soft sedimentary rock formed by the deposition of cell walls (frustulae) of single-celled algae-diatoms at the bottom of sea and lake basen. Diatom frustules consist of two parts that lie on top of each other and represent a highly porous skeleton of amorphous hydrated silica. Diatom frustule size ranges from 1 μm to 1 mm, usually 10-200 μm.The specific area (SBET (m2/g)) is 47.6. The SEM/EDS, BET and FTIR methods were used for characterization. Based on the presented results, diatomaceous earth can be used in the pharmaceutical, ceramic and food industries
From waste cellulose to effective biomembranes: Wastewater purification
No full textPollution of water with toxic substances is increased. Therefore, innovative solutions
for their treatment are essential. This paper represents results from an adsorption study where
novel synthesized biobased membranes were applied in the removal of dye metanil yellow
from wastewater solution. Batch adsorption tests were applied, where the different
operational impacts including contact time, initial pollutant concentration, temperature, etc.
were varied. Fabricated membranes were based on waste cellulose tobacco boxes modified
by amino acid lysine with an aim to increase sorption capacity toward azo dye. Structural
properties were examined by FE-SEM and ATR-FTIR techniques. The activities of materials
prior to and after modification were compared. It was found that the modified material
achieved a better sorption capacity. The resulting adsorption capacity for the improved
membrane was 65 mg/l compared to 51 mg/l, at 45°C, for the base cellulose membrane. The
kinetics of the process follows a pseudo second-order curve. The best agreement of the
correlation factor R2 was shown with the Freundlich isotherm. The obtained results show the
success of the modification with a good sorption capacity of the material towards the target
pollutant. Overall, it can be concluded that the modified membranes lay a good foundation
for potential application in industrial dye wastewater treatment systems
Single-step, electrophoretically deposited Hydroxyapatite/Poly(Vinyl Alcohol)/Chitosan/Gentamicin coating for biomedical applications
No full textBiocomposite hydroxyapatite/poly(vinyl alcohol)/chitosan/gentamicincoatings were fabricated on titanium by an electrophoretic deposition process (EPD) from an aqueous suspension using the constant voltage method. Characterization of the deposited coatings was performed by scanning electron micros-copy with field emission (FE–SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffrac-tion (XRD) after immersion in simulated body fluid (SBF) at 37°C. The concentration of the released gentamicin was determined using high-performance liquid chromatography (HPLC) coupled with a mass spectrometer (MS). The release profile confirmed an initial “burst-release effect”with ~ 30% of the gen-tamicin released in the first 48 h, which could be of assistance in the prevention of biofilm formation. An-tibacterial activity was proven by the agar diffusion method on Staphylococcus aureusTL and Escherich-ia coliATCC 25922 bacterial strains. Cytotoxicity was tested by the dye exclusion test (DET) on MRC-5 and L929 fibroblast cell lines, with both coatings expressing nontoxicity. The results showed the high ap-plicability potential of a poly(vinyl alcohol)-based biocomposite coating for medical purposes
Search for the source rocks in the Turija oil field region (SE Pannonian Basin, Serbia)
No full textIn the last two decades, the Turija oil field (Serbia) has attracted attention through oil discoveries in new wells. A total of 119 wells have been drilled in this field, of which 72 are active in oil production. The source rocks of the Turija oil are still unknown. In this study, potential lower Miocene (Ottnangian-Karpatian) to upper Miocene (Pannonian) source rocks from some boreholes near the Turija oil field were investigated to determine the origin, depositional environment, hydrocarbon potential and maturity of organic matter (OM). The Rock-Eval method, biomarker and carbon isotope analyses were used.
The majority of the lower Miocene samples contain kerogen Type II. Distributions of n-alkanes and regular C27-C29 αα(R) steranes indicate a mixed aquatic-terrestrial origin of OM in samples from the two studied boreholes TUS 2 and TUI 1. This is further supported by the Gammacerane Index (GI=10 × gammacerane/ (gammacerane+C30 αβ hopane)) ranged from 0.89 to 1.05 and the Oleanane Index (OI=10 × oleanane/(oleanane+C30 αβ hopane)), which varied between 0.40 and 0.55. The slight negative δ13C slope with an increased n-alkane chain length was observed for oils from fluvio-deltaic and freshwater transitional environments (Murray et al., 1994), while the relative flat δ13C profile of n-alkanes between C24 and C30 implies marine incursion. The ratios of pristane to phytane (Pr/Ph) and C35 αβ/C34 αβ hopane indicate transitional to oxic depositional environment.
The majority of the middle Miocene (Badenian) samples contains kerogen Type II and II/III, with few exceptions with kerogen Type I or III. The distributions of the n-alkanes with a maximum at C17 or C27 and the distributions of C27-C29 αα(R) steranes in samples from the borehole TU 2 indicate a mixed aquatic-terrestrial origin. The GI is slightly lower (≈ 0.8), while the OI (0.5-0.6) shows similar values to the lower Miocene samples. The slight negative δ13C slope with increasing n-alkane carbon number suggests a marine influenced deltaic environment, consistent with Hydrogen Index (HI) ranging from 163 to 300 mg hydrocarbons (HC)/g TOC. The Pr/Ph and the C35 αβ/C34 αβ hopane ratio imply deposition of OM under oxic conditions. Samples from the borehole TUS 2 have similar biomarker characteristics with samples from the borehole TU 2, with a somewhat greater impact of aquatic OM, in accordance with higher HI (294-429 mg HC/g TOC). However, δ13C profiles of n-alkanes indicate difference between TUS 2 and TU 2 samples. The 13C depletion of n-alkanes in TUS 2 samples may be indicative for reduced salinity and/or enhanced microbial activity. Samples from the borehole TU 4 showed different biomarker patterns, compared to the other Badenian samples. They are characterized by n-alkane maxima at C23 and C21, apparent prevalence of C28 homologues in the distribution of C27-C29 αα(R) steranes, high GI > 2.6 and lower OI (≤ 0.25). Furthermore, the δ13C profile of n-alkanes is quite different from the other samples, showing significant 13C depletion and V-shape. Similar V-shaped patterns, associated with elevated C28 steranes were observed in samples from the lower Oligocene Tard Clay Formation (Hungary; Körmös et al., 2021). The results obtained suggest a predominance of aquatic OM (phytoplankton) with a significant bacterial contribution and some influence of land plant vegetation, consistent with an HI in range 339-440 mg HC/g TOC. The samples from borehole TUS 7 are also significantly different from the other Badenian rocks. They are characterized by a notable prevalence of short chain n-alkanes with a maximum at C18, Carbon Preference Index (CPI < 0.9), relatively high amount of squalane in the TIC of saturated fraction, Pr/Ph < 0.7, GI in the range of 0.85 to 2.88, and dominance of C35 over C34 αβ hopane. This indicates a notable prevalence of aquatic OM, low terrigenous input (OI ≤ 0.25), and deposition under reducing conditions. These results coincide with high HI values (524-646 mg HC/g TOC) and a flat δ13C profile of n-alkanes from C18 to C24.
The upper Miocene (Pannonian) samples from all studied boreholes have similar biomarker compositions. They are characterized by the predominance of short chain n-alkanes with a maximum at C17, uniform or C28 enhanced distributions of C27-C29 αα(R) steranes, high GI (> 2), OI 1, implying the predominance of aquatic OM deposited under reducing conditions. The results are consistent with high and relatively uniform HI values (415-666 mg HC/g TOC). The V-shape of δ13C profile of n-alkanes can be attributed to bacterial activity.
The majority of studied samples show a good oil generation potential (TOC > 1%, (S1+S2) > 5 mg HC/g rock; HI > 300 mg HC/g TOC; S2/S3 >10). The measured vitrinite reflectance, Rock-Eval Tmax, and hopane, sterane and phenanthrene maturity ratios indicate that the OM of the Pannonian and Badenian samples from borehole TUS 7 is immature; the OM of the Badenian samples from boreholes TUS 2 and TU 4 and OM of the lower Miocene samples from borehole TUI 1 is at a very early stage of oil window maturity; while the lower Miocene samples from borehole TUS 2 and the Badenian samples from borehole TU 2 reached peak oil window maturity. The large heterogeneity (facies and maturity) of the Badenian samples is consistent with remarkable environmental changes caused by the uplift of the Alps and Carpathians in the middle to late Badenian
The Nanomaterials Fractal CharacterizationFractals and Bioforensic Science
No full textNanotechnology and nanomaterials are beginning to have an impact on the bioforensic science, regarding handling of evidence at crime scenes, its analysis in the laboratory and its presentation in the courtroom. Many different nanomaterials are used for processing of the samples, as DNA, gun powder residues, body fluids etc. Nevertheless, nanopowders, especially luminescent, are the most important for the fingerprinting method. The application of each nanomaterial in the forensic examination depends on its structure and properties, which can successfully be determined by applying fractal nature analysis, as an excellent method for micro and nanomaterials characterization. In our research we successfully synthesized photoluminescent Bi, Y and Ag zeoliteLTA topology nanopowders, which could be used for taking fingerprints from different materials, and therefore, they should be well characterized by fractal analysis. This article aims to highlight some of the major advances in forensic science brought about by nanomaterials fractal characterization, but is not exhaustive of the subject matter
Mg/Fe-pyro-hydro char derived from corn cob as effective adsorbent of lead removal from aqueous solutions
No full textThe corn cob was investigated as available agrowaste material for the production of potential efficient material for heavy
metals removal. The hydrothermal carbonization (HTC) technology is one of the appropriate methods for biomass
transformation into high-value carbonaceous products than can be utilized as adsorbents. In this study, modified pyrohydrochar
derived from corn cob (MCC) was effectively prepared by modification with Mg-Fe solution and pyrolysis.
This material was used for Pb ions removal from aqueous solutions. The effect of solution pH, contact time and initial Pb
concentration were examined in batch system. The achieved results revealed that the most effective Pb adsorption take
place at pH 5. The experimental results were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models.
The best data fit was achieved with the Sips isotherm model with maximum adsorption capacity for Pb removal of 214.9
mg/g. Additionally, the experimentally results from kinetic study were fitted by pseudo-first and pseudo-second order
models. According to kinetic parameters, the Pb removal using MCC follows pseudo-second order model, which assumes
that chemical interaction between Pb ions and functional groups on the MCC surface was involved in metal adsorption.
According to data from this investigation and in comparisons to other adsorbents can be concluded that investigated
material can be used as potential suitable adsorbent of Pb from aqueous solutions
The adsorption of arsenic(v) ions from aqueous solutions by composite of natural polymer and metal oxide
No full textThe presence of arsenic in drinking water above the permissible limits is one of the current problems facing modern
engineers in the field of separations and it has not yet been satisfactorily resolved, because the permissible concentrations
of arsenic in drinking water are constantly reduced by the World Health Organization (WHO). Among the various
processes for arsenic removal, adsorption has a special place as one of the most efficient and cheap process. Many natural
and artificial materials are tested for adsorption processes, and adsorption on metal powders is particularly interesting
because they represent adsorbents with fast kinetics and relatively high adsorption capacities. However, the application
of powder adsorbents is difficult due to their separation from the mixture after adsorption. In order to solve that problem,
metal powders may be immobilized into particles obtained by gelling natural polymers. In this way, it is easier to separate
the adsorbent from the mixture, however this must be achieved without losing the adsorption capacity and rate compared
to pure metal powders.
In this study, the use of metal oxide (iron oxide nanoparticles) immobilized within the alginate gel showed good potential
for arsenic (V) ions removal. The obtained results showed that arsenic adsorption by obtained composite has fast kinetic,
following pseudo-second-order model, and that it is conducted in several steps, according to the Weber-Morris model. It
was suggested that external diffusion is the dominant mechanism at the beginning of the arsenic adsorption, followed by
intraparticle diffusion. The obtained results confirmed that gelling with alginate did not significantly affect the adsorption
process, that is, it does not interfere with the adsorption capacity of metal oxides, which is a very important factor. Arsenic
(V) removal was successfully performed using the investigated composite
Engineered Biochar Made from Waste Plum Stones as Efficient Sorbent in Phosphate Removal
No full textThe concerns over the environmental and economic issues of the phosphates as eutrophication agents are continiously rising, due to their toxic
effects on the whole environment. The greatest risk arises from entering phosphates into water streams as the runoff from agricultural lands and
those from sewage water. Among the conventional methods used for phosphate removal, adsorption technology appeared as the most promising
one, due to its simplicity and economical feasibility. Another advantage of this technique is the possibility of sorbent regeneration with low amounts
of by-products, and possible reuse of regenerated sorbate in different applications, including agriculture. Amongst many sorbents widely used,
modified activated carbon (AC) is mostly used, but the application of modified AC raises costs of AC production/application. In the sense of this,
the search for cheaper sorbents with higher phosphate removal capacity is still needed. Biochar (BC) is a cost-effective and environmental friendly
stable solid material rich in carbon, resistant to decomposition and mineralization [1]. Although BC and AC are made from similar raw materials, BC
is usually produced at lower temperatures, resulting in a price of BC that is app. 1/6 of the price of the commercial AC [2]. In the last decade, BC is
receiving great attention as a promising sorbent for different pollutants from water streams, but the use of BC also supports the reduction of
greenhouse gases and its application into soils enhance the soil fertility. Many recent studies with unmodified BCs [3] have shown lower phosphate
removal ability, indicating negative surface charge as one of the factors influencing lower removal of negatively charged ions over a wide pH range.
In order to increase BCs sorption capacity toward phosphates, the introduction of some cationic species is often required. In this paper, synthesis
of MgO-biochar from waste lignocellulosic biomass was applied, in order to create highly porous nanocomposite material with efficient phosphate
removal. For this purpose, feedstock used to make the MgO-biochar nanocomposites were plum stones (PmS) obtained from the local factory,
where they have been disposed as a waste. After receiving, feedstock was air dried and milled into 0.1-0.5 mm particles. MgCl2·6H2O was used to
prepare a solution to pre-treat the PmS feedstock according to the procedure described in [4]. After immersing procedure, the oven dried mixture
was heated at 10 °C/min up to 500 °C under Ar flow for 1,5 h. For the purpose of sorbent characterisation, pHpzc, XRD, TG-DTG and FTIR analysis
were performed. The existence of Mg nanoparticles shifts the pHPZC from 6.7 to highly alkaline value of 10.7 which facilitates the electrostatic
interactions between the negatively charged PO43- ions and PmS-M-B. The diffraction peaks identified as MgO revealed that MgO particles were
highly crystalline, and uniformly deposited across the entire PmS-M-B surface. TGA analyses revealed four stage degradation, where the peaks for
the PmS-M-B shifted to the higer temperatures compared to the unmodified biochar (PmS-B) and higher residual mass after final combustion stage.
FTIR spectra have showed most band differences in the 1800–600 cm−1 range. The characterised MgO-biochar nanocomposite produced from
pyrolysis (PmS-M-B) was further used in sorption experiments. A stock phosphate solution was prepared using KH2PO4 and diluted to the required
concentrations. The adsorption isotherm of phosphate on the PmS-M-B was determined using the batch sorption technique by mixing 0.1 g of the
biochar sample with 50 mL of phosphate solutions of different concentrations ranging from 10 to 500 mg/L. The reaction vessels were shaken (150
rpm, 25 °C) and after the desired contact times (from 5 min to 24 h), the samples were filtered, phosphate concentrations in the liquid phase samples
were determined using MD 610 colorimeter (Lovibond, Germany), and the amount of PO43- adsorbed onto PmS-M-B was calculated. Data obtained
through the isothermal experiments were fitted using three commonly applied isotherms: Langmuir, Freundlich and Sips. Isotherm equilibrium
modelling revealed that the Sips isotherm provided the best model fit with maximum sorption capacity of 181.46 mg/g. This sorption capacity is
much higher than the most of the others reported in literature [5, 6] .A possible sorption mechanism of PO43 removal might be assigned to
electrostatic attraction and hydrogen bonding, Obtained results demonstrated that engineered MgO-biochar derived from waste PmS can be used
as a promising green material for removing phosphates from contaminated waters, providing opportunities in developing low-cost and highly
efficient material to resolve eutrophication issue. In the same time, environmental benefits might be multiple: decreasing environmental hazards by
reducing waste landfills, and also using exhausted sorbate in soil remediation and as a slow release fertilizer, confirming advantages of the biochars
amongst the other available adsorbents