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Physical and chemical modification of lignocellulosic waste biomass-tool for improving sorption capacity
No full textThe main constituents of ligno-cellulosic (LC) biomass are lignin, celluloses and hemicelluloses, complex polymers with many functional groups, which can be modified with the purpose to improve the sorption properties of the starting material. This paper presents several physical and chemical modifications applied to LC biomass of peach stones (Prunus persica L.), abundant waste from food industry. These stones were firstly mechanically activated in two mill types, and then by different chemicals. Sorption experiments were performed in batch reaction system with stirring. Cu(II) sorption kinetic was tested through three reaction kinetic models: pseudo-first order, pseudo-second order and Elovich equation. FT-IR analyses of chemically modified samples is also presented and discussed
Food sterilization by ionizing radiation
No full textIn addition to the usual methods for food preservation, the use of radiation is
increasingly widespread. The beginnings of radiation use date from the end
of the 19th century, but more intensive application is noticed only after the
Second World War [1]. Most of the research was carried out to determine
the stability and food safety.
Compared to the thermal sterilization, the radiation technique was
developed later, and found less or limited application in the conservation of
foods [2]. It should be noted that electromagnetic radiation is used not only
for the destruction of microorganisms, but also for:
destruction of insects,
culinary food processing (microwave ovens),
slowing down certain biochemical activities (preventing
germination)
improving certain technological parameters of some foods
(improving the rehydration of dried fruits and vegetables).
The radiation of a short wavelength (approximately 30 nm) is characterized
by high energy, so it has a pronounced mutagenic and lethal effect. This
radiation acts in two ways, either directly with nucleic acids or by forming
the very reactive radicals that can react easily with various organic
compounds, making them unavailable to microorganisms. Free radicals are
ionized molecules - most commonly water molecules.
Besides electromagnetic radiation (X - rays, gamma rays and cosmic rays),
alpha and beta - (corpuscular) radiation can also perform ionization of
molecules. By using ionizing radiation, only a small part of the energy is
transformed into heat. Compared to thermal sterilization, this amounts to
less than 2%, i.e. the temperature of the food does not rise more than 2 ° C,
which is why this treatment is called cold sterilization
Synthesis and characterization of luminescent fluorapatite nanorods for labelling of Saccharomyces cerevisiae cells
No full textIn this study, the preparation and characterization of luminescent
fluorapatite (FAP) nanoparticles (50 and 80 nm rod-size), and their use for
labeling of Saccharomyces cerevisae cells were investigated. Fluorapatite
nanoparticles were obtained by neutralization method. X-ray diffraction
(XRD), scanning electron microscopy (SEM) and photoluminescence (PL)
methods have confirmed a rod-like material of nanometer size with
broadband emission within 380-600 nm under UVA light excitation.
Fluorescence microscopy showed that fluorapatite nano-fluorophors
successfully labeled S. cerevisiae cells, by attaching the proteins on the cell
wall. Obtained luminescent fluorapatite nanorods could be used as a probe
for visualization and detection of yeast cells
Compound spinel as a masking pigment obtained by mechanochemical treatment
No full textMechanochemical and thermal treatment of metal oxides (Chromium, Cobalt, Zinc,
Titanium, Magnesium, and Aluminum oxides) results in the formation of compound spinel with
a formula Co0.51Zn0.29Mg0.41Cr1.24Al0.24Ti0.31O4 - used as masking pigment. Such treatment of
metallic oxides initiates a complex series of transformation using mechanical energy disturbing
the arrangement of the crystal and molecular structure, as chemical and thermodynamic balance.
With optical and scanning electron microscopy with EDX analysis. X-ray and chemical analysis
of the resulting spinel - the quality, structure, grain size and color of the obtained spinel were
determined. Also, the reaction surfaces, the resulting phase transformations, and the degree of
formed dislocations and defects in the crystal lattice of the obtained spinel were determined. By
the obtained results, the optimal conditions of the mechanochemical process have been designed,
which involve the design the vibration mill (geometry, ceramic balls, and other), grinding time,
the temperature in the mill, and rpm of the mill
Emerging contaminants and surface modified natural zeolites as a new promising environmental challenge
No full textIntroduction
The emerging contaminants (ECs) are chemicals that can have negative ecological and health effects but they are still unregulated by legal frameworks (E.J.Tiedeken et al., 2017). Monitoring survey of ECs in waters (surface waters, wastewater treatment plants (WWTPs) effluents, underground water) in several European countries evidenced different concentrations (ng/l to μg/l) of pharmaceuticals, personal care products, plasticizers, flame retardants, surfactants, steroid hormones, pesticides, etc (Loos et al., 2013, and references therein). Although these concentrations are not considered high, the possible issue could be the accumulation of ECs (for example, hormones) that can show biological activity even in small doses (Liu et al., 2013). Many studies have been conducted in order to investigate these issues.
Experimental Methods
The results acquired from WWTPs effluents have shown that the conventional treatment procedures of the wastewater are not always effective in the removal of the ECs (Bolong et al., 2009). At neutral pH, pharmaceuticals (clofibric acid, diclofenac, hormones, ibuprofen, etc.) usually appear as ions in a water phase, and cannot be removed by the activated sludge (Urase and Kikuta, 2005). Non-steroidal anti-inflammatory drug (NSAID) diclofenac was found to be very persistent and hard to remove (Płuciennik, 2014). In order to remove persistent ECs, it is necessary to apply an additional treatment such as ozonation, UV irradiation, adsorption on the activated carbon, etc. or their combination (E.J.Tiedeken et al., 2017). Moreover, these treatments are expensive, most of the WWTPs cannot easily implement them and, last but not least, they are not obligated by law regulation to remove ECs. In order to solve these issues, it is necessary to explore achievable and low-cost methods for water treatment. For this purpose, the adsorption has been considered as the very promising mechanism and different adsorbents can be potentially studied (activated carbon and zeolites) due to their very high specific surface area and their attitude to exchange ions (Li et al., 2011). Moreover, the use of surface modified natural zeolites (SMNZs) instead of other adsorbents could be preferred due to abundance, worldwide availability, low cost of the natural zeolites, and because these adsorbents are considered as eco-friendly materials for water treatment (Delkash et al., 2015).
Results and Discussion
SMNZs were used for adsorption of inorganic anions (de Gennaro et al. 2014) and organic molecules from BTEX group (Bowman, 2003), humic acid (Li et al. 2011), mycotoxins (Daković et al. 2005), etc. Also, it has been shown that SMNZs have the ability to adsorb pharmaceutical NSAIDs such as ibuprofen (IBU) (Krajišnik et al., 2010) and diclofenac sodium (DS) (de Gennaro et al., 2015). Natural zeolites (clinoptilolite, phillipsite, and chabazite) from different geographical areas were characterized and their ability to be functionalized with different cationic surfactants (hexadecyltrimethylammonium bromide/chloride, benzalkonium chloride, and cetylpyridinium chloride) has been verified (Cappelletti et al., 2017). A new approach for fast functionalization has also been proposed (de Gennaro et al., 2016). The adsorption of anionic DS on a clinoptilolite-rich rock modified with cetylpiridimum chloride has been conducted and kinetic models of adsorption were suggested. It has been shown that 40.3 and 65.0 mg of DS can be adsorbed per g of SMNZ (de Gennaro et al., 2015). Surface modified phillipsite-rich tuff from the Campania region (southern Italy) was examined for adsorption of IBU by loading and release kinetics tests. Depending on the stabilizing anions, Cl- and Br-, loading amounts were 26.8 and 28.1 mg/g, respectively (Mercurio et al., 2018). The possible pharmaceutical application of SMNZs for the adsorption of the two NSAIDs (IBU and DS) has been confirmed. Whereas for the application of the SMNZs as adsorbents of ECs it is necessary to define the following:
1- To determine affinity for each of the ECs towards SMNZs.
2- A detailed characterization and leaching test to prevent potential toxicity of SMNZs.
3- To consider a real medium (a wastewater from a WWTP).
4- To set up the best experimental conditions for a most effective adsorption of the ECs.
5- To select a novel cationic eco-friendly surfactant not harmful to the aquatic organisms
A review of the Pb-Zn-Cu-Ag-Bi-W polymetallic ore from the Rudnik orefield, Central Serbia
No full textThe Rudnik orefield is one of the well-known skarn-replacement and high-temperature
hydrothermal Pb-Zn-Cu-Ag-Bi-W polymetallic sulfide deposits, and is a part of the Šumadija Metallogenic
District, Serbia. It comprises ore bodies grouped into several major ore zones. The pseudostratified and plate-
like ore bodies have relatively high content of valuable metals. The average content varies in wide ranges: Pb
(0.94–5.66 wt%), Zn (0.49–4.49 wt%), Cu (0.08–2.18 wt%), Ag (50–297 ppm), Bi (~100–150 ppm), and Cd
(~100–150 ppm). Generally, a complex mineral association has been determined. Iron sulfides, arsenopyrite,
chalcopyrite, sphalerite, galena and sulfosalts are abundant minerals in the ore. Carrier minerals of Bi and Ag
are Bi-sulfosalts, such as galenobismutite, cosalite, Ag-bearing aschamalmite, vikingite, schirmerite and gus-
tavite. Copper, Ag and Pb-Sb sulfosalts have been found only locally. Complex Ni-minerals (sulfides,
arsenides and sulfoarsenidеs) with Fe, Co and Ag were formed under to the influence of present serpentine
rocks and their yield of Ni, Co and Cr in the hydrothermal ore-bearing solutions. Significant scheelite mine-
ralizations have been found in the Nova Jama, Gušavi Potok and Azna ore zones. The presence of Bi-sulfo-
salts and argentopentlandite suggests formation temperatures higher than 350, and lower than 445°C, respecti-
vely. Therefore, the mineralization was formed in the temperature range 350 to 400°C. The continuity of py-
rite, pyrrhotite and siderite colloform bands in relic aggregates shows frequent changes of
f
S
2
and
f
O
2
in hy-
drothermal solutions. Isotopic composition of sulfur also confirms that the source of the ore-bearing fluids
was magmatic. In addition, the enrichment of Bi and Ag indicates a magmatic origin. The appearance of Bi-
minerals represents a significant genetic indicator for detection of increased Ag concentrations within the ore
mineralizations. Typical gangue minerals are quartz, silicates, carbonates, oxides and different oxy-hydroxi-
des. Special attention is given to the paragenetic relationships and the genetic significance of mineral associ-
ations as indicators of ore-forming conditions
Dobijanje koncentrata K/Pb i K/Zn tržišnog kvaliteta postupkom gravitacijske koncentracije bogate rude sa povećanim sadržajem metaličnih minerala iz “Pb-Zn” Rudnika Grot
No full textKrajem 2016. godine utvrđeno je u ležištu „Rudnika -Grot“ postojanje oko 100t bogate rude (sa visokim sadržajem metala Pb+Zn oko 90%, Tabela 4). Ruda ovakvog tipa nije mogla biti tretirana flotacijom - konvecionalnim postupkom pripreme i koncentracije za koji je postrojenje projektovano. Na reprezentativnom uzorku bogate Pb-Zn rude „Grot“ sa povišenim sadržajem metala, potrebno je bilo ispitati mogućnost odvajanja minerale Pb i Zn u komercijalne proizvode. Nakon ovih ispitivanja predstavnici „Rudnika-Grot“ su uzorkovali novi reprezentativni uzorak u odnosu na celokupnu masu rude koji je bio mase m=500kg, na kome su obavljena tehnološka ispitivanja koja su predmet ovog tehničko-tehnološkog rešenja. Ovaj uzorak je obeležen kao „Grot 2-1“
Lignocelulozna biomasa: obnovljivi i efikasan adsorbent organskih polutanata
No full textZagađenje životne sredine organskim polutantima predstavlja jedan od značajnijih ekoloških problema. Mnoge industrije kao što su tekstilna, papirna, proizvodnja plastike i dr, u svojim procesima koriste različite vrste organskih boja i samim tim kontaminiraju životnu sredinu ovim polutantima. Upotreba jeftinih biosorbenata predstavlja alternativnu metodu u odnosu na konvencialne adsorbente za uklanjanje metilen plavog (MB) iz vodenih rastvora. Prednost upotrebe ovih materijala su: dobre adsorpcione karakteristike, efikasnost, laka dostupnost i niska cena. Upravo zbog toga ovaj rad obuhvata literaturni pregled korišćenih lignocelulznih materijala za adsorpciju MB, sa posebnim osvrtom na njihove karakteristike kao i mehanizme biosorpcije
New insights on surface modified natural clinoptilolite-rich carrier for sorption and in vitro release of ibuprofen sodium salt
No full textIntroduction
Ion-exchange capacity represents a very important property of natural zeolites and has been widely investigated for environmental remediation and drug delivery (Mercurio et al., 2018 and references therein). Thanks to this property, zeolite can be surface modified via adsorption of long-chain cationic surfactants, providing an organo-mineral composite known as Surface Modified Natural Zeolite (SMNZ) able to sorb specific molecules by anion-exchange and partition mechanisms (Farías et al., 2010; Mercurio et al., 2018).
This study aims to test the technological performance of a surface modified clinoptilolite-rich rock in the loading and in vitro release of ibuprofen sodium salt (IBU), in order to evaluate its possible use in high-value technological applications based on the sorption of non-steroidal anti-inflammatory drugs (NSAIDs).
Experimental Methods
A clinoptilolite-rich rock (CLI) from an economic deposit of zeolite located in the East-Slovakia basin (Nižný Hrabovec) has been surface modified using four cationic surfactants, namely cetylpyridinium chloride (CC), benzalkonium chloride (BC), hexadecyltrimethylammonium chloride (HC) and bromide (HB). Briefly, CLI (clinoptilolite content ~55.7 wt%) was added to a surfactant solution with an initial concentration equivalent to 200% of the external cation exchange capacity (ECEC) of starting material (~0.119 mEq/g). The so formed SMNZs (labelled CLI_CC, CLI_BC, CLI_HC and CLI_HB) were used to carry out IBU equilibrium sorption isotherms and loading/release kinetic tests according to Mercurio et al. (2018). Experimental points were fitted using several mathematical models, which non-linear fitting parameters and applicability were evaluated by considering determination coefficient (R2) and Bayesian Information Criterion (BIC). Further details about mineralogical and technological characterization of starting material, SMNZs preparation and mathematical modeling of sorption/release profiles are reported in Cappelletti et al. (2017), de Gennaro et al. (2016) and Mercurio et al. (2018), respectively.
Results and Discussion
Table 1 reports the preliminary results of equilibrium sorption tests indicating that the best-fit for isotherms was attained implementing Langmuir and Toth mathematical models, as already observed for other zeolite carriers (Mercurio et al., 2018). Goodness-of-fit (GOF) indicates that R2 values are quite similar for the two mathematical models used for the fitting of experimental data in samples CLI_CC and CLI_BC, although a preference for the Langmuir model can be observed. On the contrary, BIC values of Toth model decrease in both SMNZs, as well as in sample CLI_HC. It means that Toth equation could be considered as the best-fitting model, since BIC provides a better discrimination between a two-parameters model (i.e., Langmuir) and a three-parameters one (i.e., Toth), especially in non-linear regressions. These results can be generally explained taking into account that chlorinated surfactants form onto the surface of the zeolite a patchy bilayer, where sorption of NSAIDs is controlled by a dual mechanism: a) external anionic exchange and b) partition into the hydrophobic portion of the micelle. In fact, the best-fit in equilibrium sorption isotherms of CLI_HB was provided by Langmuir equation. In this case, as well known in literature (de Gennaro et al., 2014), the presence of bromide counterion tend to form a complete bilayer micelle promoting the adsorption mechanism, properly described by a simple Langmuir equation. It is worth to note that the values of IBU sorbed by CLI_HB represent a prediction of the amounts of ibuprofen that could be sorbed by SMNZ at the equilibrium (asymptotic plateau), and could be not appreciated from a graphical point of view.
Loading kinetic runs (Fig. 1a), modelled with a pseudo-second order equation, highlight a very fast loading process, where most of the IBU is sorbed by SMNZs within half an hour. Furthermore, maximum sorption capacities found in loading kinetic runs (16.9 mg/g for CLI_CC, 15.0 mg/g for CLI_BC, 22.5 mg/g for CLI_HC and 25.9 mg/g for CLI_HB) generally fit the experimental points of isotherms.
Lastly, drug release occurred quite completely within the first hour and dissolution profiles (Fig. 1b) were fitted by a first-order equation according to literature (Mercurio et al., 2018).Implications
The examined starting material represents an important georesource in the economy of Slovakia, since it was already used in several technological applications as, for example, water cleanup processes. This study sheds new light on NSAIDs sorption mechanisms from clinoptilolite, encouraging further practical uses of this geomaterial both in pharmaceutical sector and environmental remediation (Płuciennik-Koropczuk, 2014)
Antibacterial activity and biocompatibility of novel composite hydroxyapatite/chitosan/gentamicin coating
No full textNovel composite coating based on hydroxyapatite, chitosan and gentamicin
(HAP/CS/Gent) was successfully obtained by single-step electrophoretic deposition
process from aqueous suspension. In order to investigate the potential application of
composite HAP/CS/Gent coating, biological properties were examined. The
antibacterial activity of composite coating was tested using an agar diffusion method
and test in suspension against two bacteria strains- Staphylococcus aureus and
Escherichia coli. Biocompatibility was evaluated by cytotoxicity testing, towards MRC-
5 and L929 cell lines using MTT and DET tests. The ability of biomineralization was
tested by ALP assay towards MRC-5 and L929 cell lines as model cells. Excellent
antibacterial properties were observed for HAP/CS/Gent coating, especially in case of
S. aureus. DET and MTT assays indicated low cytotoxicity against MRC-5 and L929
tested cell lines, indicating good biocompatibility. High ALP level in the cell extract
implicates the good bioactivity of HAP/CS/Gent coating. Due to the compatibility of
the cells, MRC-5 cell line responded better in ALP assay.
Due to good antibacterial and anti-biofilm efficacy, good biocompatibility and ability to
promote biomineralization, composite HAP/CS/Gent coating can be can be considered
for future medical application as hard tissue implant