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Impact of different concentrations of alginate in alginate-yeast hydrogel biosorbent
Get PDFDyeing industry wastewater is one of the major environmental problems.Biosorption technology is regarded to be inexpensive and ecologically beneficial. Spent brewery yeastused in this researchis proposed as a promising adsorbent [1] but free cells are unsuitable due to separation problems which leads toimmobilization as an importantpartof the practical applicationof biomass biosorption. Alginate is well known;widely usedand inexpensivematerial and the extrusion technique is theeconomical and ecofriendlyencapsulation technique for immobilization with alginate as a carrier.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Adsorption Efficiency of Cadmium (II) by Different Alkali-Activated Materials
No full textThe objective of this study was to demonstrate the potential utilization of fly ash (FA), wood ash (WA), and metakaolin (MK) in developing new alkali-activated materials (AAMs) for the removal of cadmium ions from waste water. The synthesis of AAMs involved the dissolution of solid precursors, FA, WA, and MK, by a liquid activator (Na2SiO3 and NaOH). In concentrated solutions of the activator, the formation of an aluminosilicate gel structure occurred. DRIFT spectroscopy of the AAMs indicated main vibration bands between 1036 cm−1 and 996 cm−1, corresponding to Si-O-Si/Si-O-Al bands. Shifting vibration bands were seen at 1028 cm−1 to 1021 cm−1, indicating that the Si-O-Si/Si-O-Al bond is elongating, and the bond angle is decreasing. Based on the X-ray diffraction results, alkali-activated samples consist of an amorphous phase and residual mineral phases. The characteristic “hump” of an amorphous phase in the range from 20 to 40° 2θ was observed in FA and in all AWAFA samples. By the XRD patterns of the AAMs obtained by the activation of a solid three-component system, a new crystalline phase, gehlenite, was identified. The efficiency of AAMs in removing cadmium ions from aqueous solutions was tested under various conditions. The highest values of adsorption capacity, 64.76 mg/g (AWAFA6), 67.02 mg/g (AWAFAMK6), and 72.84 mg/g mg/g (AWAMK6), were obtained for materials activated with a 6 M NaOH solution in the alkali activator. The Langmuir adsorption isotherm and pseudo-second kinetic order provided the best fit for all investigated AAMs
Synthesis of new composite materials based on carbon feltpolypyrrole-silver-chloride as rechargeable cathodes for magnesium-based systems
Get PDFPredmet naučnog istraživanja ove disertacije je ispitivanje mogućnosti primene punjivih
pozitivnih elektroda na bazi kompozita polipirola, srebro-hlorida i ugljenične tkanine u sistemima sa
elektrolitom na bazi morske vode i legurom magnezijuma kao negativnom elektrodom ćelije, kao
mogućih izvora električne energije elektronskih i električnih komponenti signalne opreme za
spašavanje i plutajućih bova za monitoring životne sredine.
U prvoj fazi izrade disertacije ispitano je elektrohemijsko ponašanje legure magnezijuma AZ63,
polipirola i srebro-hlorida sintetisanih elektrohemijskim metodama na grafitnoj, odnosno srebrnoj
elektrodi, kao model sistema u cilju ispitivanja elektrohemijskih i električnih karakteristika. U cilju
povećanja vrednosti specifičnih kapaciteta, energije i snage i poboljšanja ciklizacionog ponašanja
polipirol je sintetisan na ugljeničnoj tkanini visoko razvijene površine. Na tako pripremljenu
elektrodu nanet je sloj srebro-hlorida jednostavnom i brzom modifikovanom metodom sukcesivne
jonske adsorpcije i reakcije (od eng: Sucesive Ion Layer Adsorption and Reaction, SILAR) u cilju
povećavanja napona ćelije i specifičnog kapaciteta. Ispitana je i funkcionalizacija ugljenične tkanine
jefitnim komercijalnim rastvorom natrijum-hipohlorita u cilju poboljšanja karakteristika punjive
katode. Elektrodni materijali su okarakterisani klasičnim elektrohemijskim metodama u cilju
određivanja potencijala, odnosno napona punjenja i pražnjenja, specifičnog kapaciteta, energije i
snage, kao i ciklizacione stabilnosti, a takođe i spektroskopskim metodama: FE - SEM, XRD, XPS i
FT-IR.
Na kraju je ispitano ponašanje realne ćelije u simuliranoj morskoj vodi i pokazano je da dati
sistem može omogućiti pražnjenje tokom kratkih režima sa velikim strujama i snagom za slanje
podataka, i kontinualno tokom dužeg vremena pri malim strujama i velikom energijom za napajanje
signalnog svetla ili različitih senzora, pri čemu dolazi do redukcije rastvorenog kiseonika na
pozitivnoj elektrodi.The main subject of this dissertation is to examine the possibility to apply rechargeable positive
electrodes based on a composite of polypyrrole, silver chloride and carbon felt in systems with an
electrolyte based on seawater, and a magnesium alloy as the negative electrode of the cell as a
potential source of electric energy for electronic and electrical components of signal equipment for
rescue and floating buoys for environmental monitoring.
In the first part of the dissertation, the electrochemical behavior of magnesium alloy AZ63,
polypyrrole, and silver chloride synthesized by electrochemical methods on a graphite and silver
electrode, respectively, was examined, as a model system to test electrochemical and electrical
characteristics. To increase the value of specific capacity, energy, and power and improve the
cyclization behavior, polypyrrole was synthesized on a carbon felt with a high surface area. A layer
of silver chloride was applied to the electrode thus prepared by a simple and fast modified method of
successive ion adsorption and reaction (Successive Ion Layer Adsorption and Reaction, SILAR) to
increase the cell voltage and specific capacity. The functionalization of the carbon felt with an
inexpensive commercial solution of sodium hypochlorite was also tested to improve the
characteristics of the rechargeable cathode. Electrode materials were characterized by fundamental
electrochemical methods to determine the potentials, i.e. charge and discharge voltage, specific
capacity, energy, and power, as well as cycling stability. Additionally, spectroscopic methods:
FE - SEM, XRD, XPS, and FT- IR were used.
Finally, the behavior of a real cell in simulated seawater was examined, showing that the given
system can enable discharge in short regimes with high currents and power for sending data, and
continuously for a long time applications with low currents for powering a signal light or various
sensors, whereby a reduction of dissolved oxygen can occur on a positive electrodes
QSRR Modeling of Lipophilicity of New Spirohydantoin Derivatives Determined with Various TLC Systems
No full textA Quantitative structure-retention relationship (QSRR) analysis has been performed on the chromatography parameters of lipophilicity of selected spirohydantoins. Multiple linear regression (MLR) was applied to construct the QSRR models. The chromatographic parameters of lipophilicity were determined by reversed-phase thin-layer chromatography. Chromatographic analyses were performed on C-18 modified silica gel with a two-component mobile phase consisting of water and protic organic solvent (ethanol, n-propanol, i-propanol, or t-butanol) in different ratios. QSRR models were also created for additional four aqueous mobile phases: acetone-water, acetonitrile-water, tetrahydrofuran-water, and 1,4-dioxane-water (results published before). In total, chromatographic lipophilicity parameters obtained for two types of organic solvents were subject of the QSRR. The predictive ability of each model was evaluated using internal and external validation. The best QSRR model for predicting the chromatographic parameter of lipophilicity was obtained for tetrahydrofuran as an organic solvent
Environmental Implications of the Soil-to-Groundwater Migration of Heavy Metals in Mining Area Hotspots
No full textGroundwater contamination was studied at several hotspot sites in the Majdanpek copper mining area (Serbia). These sites include a milling facility, a metallurgical wastewater treatment plant, a heavy vehicle service area, and a waste disposal site. In addition to Cu, high concentrations of As and heavy metals (Cd and Pb) were detected in groundwater and soil at the same sampling points. Mining operations and heavy vehicle transport activities have been identified as the main sources of pollution. The migration of metals from soil to groundwater, expressed as a concentration ratio, were the highest for Co and the lowest for Mn. The environmental implications of groundwater pollution were studied using the heavy metal pollution index (HPI), Nemerov pollution index (NPI), hazard index (HI), and incremental lifetime cancer risk (ILCR). HPI and NPI show the high potential of groundwater to have adverse environmental effects. HPI ranges in the following descending order of metals: Cd > Pb > As > Mn > Ni > Cr > Hg > Cu > Zn. NPI exceeds the threshold of 0.7 in 66.7% of the samples. Potential human exposure to the studied groundwater may cause severe health problems in adults, with HI ranging from 0.61 to 5.45 and ILCR from 1.72 × 10−4 to 1.27 × 10−3. Children were more susceptible to non-carcinogenic risk than adults, with HI ranging from 0.95 to 8.27. However, the results indicated that children were less prone to carcinogenic risks, with ILCR ranging from 5.35 × 10−5 to 3.98 × 10−4. Arsenic is the most contributing element to both risks. This research imposes the need for enhanced groundwater monitoring at hotspots in the mining area and the adoption of remediation plans and measures
Isolation of RuBisCO protein from pumpkin leaves using ultrafiltration: enhanchment of yield and protein characterization
No full textRuBisCO (ribulose-1,5-diphosphate carboxylase/oxygenase), an enzyme crucial for plant photosynthesis, is the most widespread protein in the living world. It is predominantly found in the leaves of plants, which mostly remain unused after harvesting. Despite current efforts, the RuBisCO protein isolated from leaves has not yet found significant application as a supplement in human nutrition, due to the complexity and cost-effectiveness of the production process and the low yield. Two ultrafiltration methods were applied for isolation of RuBisCO protein. Initially, cross-flow ultrafiltration was used, employing a membrane module with a membrane’s pore size 10 kDa.
The second method involved dead-end ultrafiltration with a feed flow under a nitrogen stream at a defined pressure, using a membrane with a pore size of 100 kDa. The obtained ultrafiltration fractions were used for the analysis of soluble protein content and protein yield, reducing sugars and polyphenols. The efficiency of the ultrafiltration process and the protein purity were determined by SDS-PAGE electrophoresis. Also, the obtained protein powders were analyzed for the total and free sulfhydryl group contents and surface hydrophobicity. These protein powders were characterized in terms of their technological and functional properties, including solubility, emulsifying properties, and water/oil binding capacities. The results were then compared with those of protein powder obtained from pumpkin leaves using the most common method, isoelectric precipitation. The different techniques for isolating RuBisCO protein showed certain variations in protein yield as well as in its structural and technological-functional properties. Different isoelectric point values were shown for all three protein powders, including variations in the content of free and total sulfhydryl groups. Furthermore, surface hydrophobicity and oil binding capacity showed lower values for the RuBisCO protein obtained by ultrafiltration methods. The solubility of RuBisCO protein obtained by ultrafiltration methods exceeds 90% at pH > 6, indicating that the protein is highly soluble
HIDROGELOVI NA BAZI POLI(METAKRILNE KISELINE) DOBIJENI EKOLOŠKI PRIHVATLJIVOM METODOM: BUBRENJE I KONTROLISANO OTPUŠTANJE LIDOKAIN HIDROHLORIDA
No full textDesign of efficient drug delivery system which can protect drug, preserve its activity, improve its bioavailability, and release it in control manner still presents quite challenge. Encapsulation of drug during the synthesis of drug delivery system is especially complex part. In our previous research we have developed simple and eco-friendly synthesis of hydrogels based on poly(methacrylic acid) that employing hydrogen peroxide and vitamin C (H2O2/VC) as initiator. Present study investigates if the encapsulation of lidocaine hydrochloride during the synthesis of hydrogel and later its con-trolled release, can be achieved by using this method. Results show that mild synthesis conditions enable efficient encapsulation of lidocaine hydrochloride and synthesis of hydrogels based on poly(methacrylic acid) (PMAAL). Lidocaine hydrochloride is local anesthetic which is used in anesthesia and in antiarrhythmic therapy, and it is usually applied by injection. Its encapsulation and controlled release from the hydrogels present good solution to overcome unpleasantness during its application and to reduce required number of dosages. Obtained PMAAL hydrogels are further char-acterized by employing FTIR and SEM analysis, as well as single compression tests. PMAAL swelling and controlled release of the drug are analyzed in two environments with pH 1 and pH 6.8 simulating pH environments in human stomach and intestines. The results show that around eight times higher amount of lidocaine hydrochloride is released in environment with pH 6.8 due to the pH dependent swelling of the PMAAL hydrogels. The change in crosslinker amount on the PMAAL swelling and drug release are also investigated. The increase in the crosslinker amount lead to the decrease of amount of drug released from the PMAAL hydrogels. This study shows that the method which employing H2O2/VC as initiator can be used for efficient encapsulation of lidocaine hydrochloride. Also, this drug can be released in controlled manner from the PMAAL hydrogels for 24h in environment with pH 6.8, such as human intestines where drug absorption is the highest.Razvoj efikasnog sistema za dostavu lekova koji može da zaštiti lek, sačuva njegovu aktivnost, poboljša njegovu biodostupnost i kontrolisano ga otpušta predstavlja još uvek pravi izazov. Inkapsu-lacija leka tokom sinteze sistema za otpuštanje leka je posebno zahtevan deo. U našem prethodnom radu razvili smo jednostavnu i ekološki prihvatljivu sintezu hidrogelova na bazi poli(metakrilne kise-line) kod koje se kao inicijator koristi sistem vodonik peroksid i vitamin C (H2O2/VC). U sadašnjem istraživanju se ispituje da li se može postići inkapsulacija lidokain hidrohlorida tokom sinteze hidro-gela i kasnije njegovo kontrolisano oslobađanje. Rezultati su pokazali da su blagi uslovi sinteze o-mogućili efikasnu inkapsulaciju lidokain hidrohlorida i sintezu hidrogelova na bazi poli(metakrilne kiseline) (PMAAL). Lidokain hidrohlorid je lokalni anestetik koji se koristi kod anestezije i kod tera-pije aritmije, a najčešće se pacijentima daje injekcijom. Njegovo inkapsuliranje i kontrolisano oslo-bađanje iz hidrogelova predstavljaju dobro rešenje kako bi se sprečile neprijatnosti do kojih dolazi tokom njegove administracije i kako bi se smanjio broj doza potrebnih za terapiju. Karakterizacija dobijenih PMAAL hidrogelova je zatim izvedena primenom FTIR i SEM analize, kao i ispitivanjem otpornosti ovih materijala na kompresiju. Bubrenje PMAAL hidrogelova i kontrolisano oslobađanje leka analizirani su u dve sredine sa pH 1 i pH 6,8, koje su simulirale pH sredine u ljudskom želucu i crevima. Rezultati pokazuju da se oko osam puta veća količina lidokain hidrohlorida oslobađa u sredini sa pH 6,8 zbog pH osetljivog bubrenja PMAAL hidrogelova. Takođe je ispitan uticaj promene količine umreživača na bubrenje PMAAL hidrogelova i otpuštanje leka. Povećanje količine umreži-vača dovodi do smanjenja otpuštene količine. Ovo istraživanje pokazuje da metoda kod koje se koristi H2O2/VC kao inicijator može da se koristi za efikasnu inkapsulaciju lidokain hidrohlorida. Takođe, ovaj lek se može kontrolisano otpuštati iz PMAAL hidrogelova tokom 24 časa u sredini sa pH 6,8, kao što su ljudska creva gde je apsorpcija leka najveća
Sunflower Meal Valorization through Enzyme-Aided Fractionation and the Production of Emerging Prebiotics
No full textRecently, there has been a burgeoning interest in harnessing the potential of biomassand industry byproducts for the development of novel products and materials. In particular, thisstudy explored the efficient valorization of sunflower meal (SFM), an underutilized byproduct ofthe oil extraction industry, usually discarded or used as low-value animal feed through enzymeaidedfractionation, specifically targeting the extraction and conversion of its abundant carbohydratecomponent, xylan, into emerging prebiotic compounds—xylo-oligosaccharides (XOSs)—which arerecognized as promotors of a healthy gut microbiome and overall human wellbeing. An enzymatictreatment using Alcalase® 2.4 L was implemented for facilitating the recovery of a highly purehemicellulosic fraction (92.2% carbohydrates) rich in β-(1→4)-linked xylose residues with arabinoseand glucuronic acid substitutions (DP-xylan). A further enzymatic treatment of this substrate,using ROHALASE® SEP-VISCO under optimized conditions (70 ◦C, pH 6, 0.005% v/v enzymeconcentration), produced 52.3% of XOSs with a polymerization degree (DP) less than 20 after twohours. Further analyses demonstrated that the majority of the obtained product had a DP lessthan 6, predominantly consisting of di- and trisaccharides (XOS2 and XOS3) without the significantgeneration of xylose. These findings highlight the significant potential of SFM for the generation ofvaluable prebiotic compounds in a sustainable manner
Silver Linings: Nanowires in Optoelectronics
No full textFor their ease and cost-effectiveness of wet synthesis and processing i.e. from liquid phase, silver
nanowires have been extensively studied as a transparent electrode alternative to conventional
solutions like indium tin oxide.
Elucidating the solid-state wetting and welding mechanisms that occur during annealing of Ag
nanowires before a layer of Al doped ZnO is deposited, can lead to the enhancement of essential
electrode properties. Microstructural characterization using (S)TEM revealed that solid-state
wetting and subsequent welding occurred only between nanowires whose contact geometry is
characterized by an enormous difference in radii of curvature.
A fully solution-processed AgNW/ZnO film was studied to understand how ZnO coating affects
the electrical stability of nanowires, including the degradation mechanism under high electrical
current densities. The nanocomposite transparent electrode was processed with different numbers
of ZnO coatings to evaluate their impact on optoelectronic properties and electrical stability. The
results showed that nanowires with a triple ZnO coating had the optimal combination of
optoelectronic properties and stability at the highest working voltage
The influence of the chemical structure on the antioxidant activity of acridine-1,8-dione derivatives
No full textAcridine-1,8-dione derivatives are compounds with unique physicochemical and pharmacological properties and wide industrial applications. Thanks to their semiplanar structure and the ability to bind to various biological receptors, analogues of this condensed heterocycle are widely commercially available and as such have found application in the treatment of malaria (quinacrine), bacterial infections (acriflavine and proflavine) and cancer (amsacrine and nitracin) [1]. The influence of the chemical structure on the pharmacological potential of seven disubstituted derivatives of 3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8-dione (Figure 1) was evaluated using the "rule of five", Veber's, Egan's and Goz's empirical criterion, as well as by applying different in silico methods. In order to establish a correlation between the empirically estimated and experimentally determined pharmacological activity of seven disubstituted 3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8-diones, the potential antioxidant activity of the synthesized compounds was evaluated using ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) method and by determining the IC50 values of the most effective compounds