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New approaches and applications of natural zeolites for boron adsorption from aqueous solutions
No full textExcessive mineral extraction and boric acid production can lead to elevated boron concentrations in wastewater. While boron is an essential micronutrient for humans, excessive exposure and intake can result in adverse health effects. Existing treatment processes for boron contaminated wastewater have various limitations related to effectiveness, production of additional solid waste and high operational costs. This study investigates the use of natural zeolite as a cost-effective, sustainable and environmentally friendly adsorbent for boron removal. Natural zeolites are alumosilicate porous minerals widely used in wastewater treatment applications. To enhance its adsorption properties, natural zeolite was modified using a nickel sulphate solution. In this work, four adsorbents were analyzed: raw natural zeolite, nickel-modified natural zeolite, zeolite/hydroxyapatite and nickel-modified zeolite/hydroxyapatite composite. The zeolite/hydroxyapatite composite was synthesized under hydrothermal conditions at 160 °C for 4 hours at autogenous pressure. Characterization of the adsorbents was performed using X-ray powder diffraction (XRPD), scanning electron microscopy and thermogravimetric analysis. XRPD analysis confirmed clinoptilolite as the dominant mineral phase in the zeolitic tuff and showed that hydrothermal treatment did not affect its crystallinity. The adsorption properties were tested using a synthetic boron solution at pH 9, where boron exists in both B(OH)3 and B(OH)4– forms. The results showed that the presence of nickel primarily on the surface of the adsorbent leads to an increase in boron adsorption, which is a consequence of its ability to form complexes with B(OH)4–. This research confirmed that adsorbents based on metal-saturated natural zeolite are promising adsorbents of boron compounds from wastewater
Aglomeracija materijala za deponije
No full textAglomeracija materijala predstavlja ključni proces u upravljanju otpadom, omogućavajući efikasnije odlaganje i reciklažu otpada. Ovaj rad istražuje primene aglomeracije u tretmanu materijala koji se šalju na deponije, naglašavajući njene prednosti u smanjenju rizika od kontaminacije i olakšavanju transporta. Pored toga, rad se fokusira na specifične primere, kao što su leteći pepeo i FGD mulj, koji ilustruju kako aglomeracija može pretvoriti otpadne materijale u proizvode sa dodatnom vrednošću
Characterization of Biochars from Fruit Stones According to IBI Standard: Toxicant Assessment and Safety for Soil Application
No full textThe increasing global population, coupled with the reduction of arable land, poses significant challenges for agricultural production. The use of commercial fertilizers enhances productivity, but their widespread application can lead to both economic and environmental issues. Biochar, carbon-rich material, is gaining increasing attention as a soil amendment, particularly due to its potential to function as a slow-release fertilizer. The International Biochar Initiative (IBI) emphasizes the importance of thorough biochar characterization prior to its use as a soil amendment, aiming to improve soil fertility and contribute to climate change mitigation. In this study, four types of biochars were produced via slow pyrolysis from fruit processing waste: sour cherry, apricot, plum, and peach stones and were characterized according to the Test Category B of the IBI standard. Test Category B (Toxicant Assessment) includes the germination inhibition test (GIT), and covers two categories of toxicants: (i) those that may be present in the feedstock (metals and polychlorinated biphenyls—PCBs), and (ii) those generated during the thermochemical conversion process (polycyclic aromatic hydrocarbons—PAHs, and dioxins/furans). All biochars passed the GIT, indicating no phytotoxic effects. Furthermore, none of the samples exceeded the IBI limits for PAHs, PCBs, and dioxins/furans. However, biochars derived from sour cherry and apricot stones had elevated levels of lead, 321 and 420 mg/kg, respectively, surpassing the IBI threshold of 121–300 mg/kg. Elevated lead content in these samples may pose environmental and agronomic risks, affecting soil microbial communities and nutrient availability, and potentially entering the food chain. Although the tested biochars pass IGT, the presence of elevated lead concentrations in some samples, emphasizing the importance of thorough testing of biochar prior to their application in soil. Biochar produced from plum and peach stones was found to be non-toxic, making it suitable and safe for application in soil
Hydrothermal Carbonization of Waste Biomass: A Review of Hydrochar Preparation and Environmental Application
No full textThe concept of a bio-based economy has been adopted by many advanced countries around
the world, and thermochemical conversion of waste biomass is recognized as the most effective
approach to achieve this objective. Recent studies indicate that hydrothermal carbonization (HTC)
is a promising method for the conversion of waste biomass towards novel carbonaceous materials
known as hydrochars. This cost-effective and eco-friendly process operates at moderate temperatures
(180–280 ◦C) and uses water as a reaction medium. HTC has been successfully applied to a wide
range of waste materials, including lignocellulose biomass, sewage sludge, algae, and municipal solid
waste, generating desirable carbonaceous products. This review provides an overview of the key
HTC process parameters, as well as the physical and chemical properties of the obtained hydrochar.
It also explores potential applications of produced materials and highlights the modification and
functionalization techniques that can transform these materials into game-changing solutions for a
sustainable future
Innovative hydroxyapatite-based coatings for bone implants: A multifaceted approach
No full textINTRODUCTION: Tissue engineering strives for innovative solutions in addressing challenges associated with
contemporary bone tissue implants. This study focuses on the electrophoretic deposition (EPD) of hydroxyapatite-based
bioceramic composites containing antibacterial agents onto titanium surfaces. Two composite coatings, hydroxyapatite/
chitosan (HAP/CS) and hydroxyapatite/chitosan/gentamicin (HAP/CS/Gent) were developed to combat issues such as
poor adhesion, limited antibacterial potential, limited bioactivity, and potential toxicity of implant materials [1].
EXPERIMENTAL: EPD was performed at constant voltage (5 V, 12 min) on pure Ti plates from aqueous (HAP/CS and
HAP/CS/Gent) suspensions. The uniformity and functionality of the deposited coatings were assessed through
comprehensive physico-chemical characterization using X-ray diffraction (XRD) (Philips PW 1710, Netherlands) and
scanning electron microscopy (SEM, Hitachi S-4700, J) equipped with energy dispersive X-Ray spectroscopy (EDS, X-Max,
Oxford Instruments, UK). Antibacterial activity was evaluated against Staphylococcus aureus TL and Escherichia coli ATCC
25922 by quantitatively monitoring changes in the viable number of bacterial cells in suspension. Cytotoxicity against
MRC-5 and L929 cell lines was investigated using trypan blue dye-exclusion test (DET) and MTT assay for assessing cell
metabolic activity. Statistical significance was determined for antibacterial and cytotoxicity results by one-way analysis
of variance (ANOVA), followed by multiple comparisons post-hoc test.
RESULTS AND DISCUSSION: XRD revealed broadened diffraction maximums corresponding to fine HAP crystallites.
Porous surface with homogeneously distributed spherical HAP agglomerates embedded in wax-like polymers' matrix of
CS was observed for both coatings by SEM. The addition of gentamicin significantly enhanced the antibacterial activity
of the HAP/CS/Gent coating – complete reduction of S. aureus bacterial cells was achieved within 1 h of exposure. MTT
and DET tests indicated low cytotoxicity against MRC-5 and L929 tested cell line for both samples. Slightly decreased
cell percentage viability due to gentamicin presence was observed for HAP/CS/Gent.
CONCLUSIONS: Single-step EPD yielded antibacterial composite coatings with potential for biomedical applications.
HAP/CS/Gent showed successful gentamicin loading, favorable crystalline structure, and strong antibacterial effects.
The presence of fine HAP crystallites yielded a larger surface area, favorable for new bone growth and improved
osseointegration. HAP/CS/Gent exhibited good antibacterial activity against both tested bacteria (especially
pronounced against S. aureus – bactericidal effect), while preserving low cytotoxicity, indicating the high potential for
biomedical applications
Electrochemically synthesized biocomposite poly(vinyl alcohol)/chitosan-based coatings for medical applications
No full textOsteoarticular implants are designed to facilitate
full recovery of lost function and ensure effective
fixation of the implant. However, challenges
may arise, resulting in implant failure, primarily
attributed to infections at the implantation site
and aseptic loosening. Thus, the surface of an
implant must be altered to simultaneously offer
osteoinductive and antibacterial properties.
Synthetic hydroxyapatite (HAP) is frequently
employed to modify metallic implant surfaces
or serve as a bone filler material. To enhance
its biocompatibility, HAP-based polymer composites
were developed. Among most popular
synthetic polymers, poly(vinyl alcohol) (PVA), is
widely used because of its similar structure to
the native extracellular matrix, along with chitosan
(CS), a natural cationic polysaccharide, that
shows biocompatibility, biodegradability and
antimicrobial action, and could act as a carrier
of antibacterial agents. The antibiotic of choice
was Gentamicin (Gent), a water-soluble aminoglycoside,
with very potent antibacterial activity
for the treatment of wide range of infections,
caused by Gram-negative and Gram-positive
bacteria. The original approach of the presented
research is the single-step electrophoretic deposition
(EPD) on Ti plates of thus prepared biocomposite
that would allow for on-site release of the
drug. Obtained hydroxyapatite/chitosan/poly(vinyl
alcohol/gentamicin (HAP/PVA/CS/Gent) biocomposite
coating exhibited strong antibacterial
effect against E. coli and S. aureus. Gentamicin release
study indicated “burst” release in the first 48
h, with ~ 30% of total gentamicin released from
the HAP/PVA/CS/Gent coating which is beneficial
for the blockage of biofilm formation, followed
by slow and steady release in the later period. Cytotoxic
effect of HAP/PVA/CS/Gent coating was
not pronounced in investigated MRC-5 and L929
cell lines. Also, in MRC-5 fibroblast cells, alkaline
phosphatase levels doubled when in contact
with HAP/PVA/CS/Gent, indicating good osteogenic
properties. The overall construct on the
substrate in such a form would be well-advanced
arrangement for future medical device improvement
of skeletal implants
Chemometrically-aided general approach to novel adsorbents studies: Case study on the adsorption of pharmaceuticals by the carbonized Ailanthus altissima leaves
No full textA chemometrically based approach was applied to select the most efficient drug adsorbent among the biochars obtained from the novel feedstock, the leaves of the invasive plant (Ailanthus altissima). The representative target adsorbates (atenolol, paracetamol, ketorolac and tetracycline) were selected on the basis of their physicochemical properties to cover a wide chemical space, which is the usual analytical challenge. Their adsorption was investigated using design of experiments as a comprehensive approach to optimise the performance of the adsorption system, rationalise the procedure and overcome common drawbacks. Among the response surface designs, the central composite design was selected as it allows the identification of important experimental factors (solid-to-liquid ratio, pH, ionic strength) and their interactions, and allows the selection of optimal experimental conditions to maximise adsorption performance. The biochars were prepared by pyrolysis at 500 °C and 800 °C (BC-500 and BC-800) and the ZnCl2-activated biochars were prepared at 650 °C and 800 °C (AcBC-650 and AcBC-800). The FTIR spectra revealed that increasing the pyrolysis temperature without activator decreases the intensity of all bands, while activation preserves functional groups, as evidenced by the spectra of AcBC-650 and AcBC-800. High temperatures during activation promoted the development of an efficient surface area, with the maximum observed for AcBC-800 reaching 347 m2 g−1. AcBC-800 was found to be the most efficient adsorbent with removal efficiencies of 34.1, 51.3, 55.9 and 38.2 % for atenolol, paracetamol, ketorolac and tetracycline, respectively. The models describing the relationship between the removal efficiency of AcBC-800 and the experimental factors studied, showed satisfactory predictive ability (predicted R2 > 0.8) and no significant lack-of-fit was observed. The results obtained, including the mathematical models, the properties of the adsorbates and the adsorbents, clearly indicate that the adsorption mechanisms of activated biochars are mainly based on hydrophobic interactions, pore filling and hydrogen bonding
Correlation between morphology and hardness of electrolytically produced copper thin films
No full textCorrelation between morphology of electrolytically produced copper thin films and their hardness has been considered. The Cu films were electrodeposited by galvanostatic (DC) and by the pulsating current (PC) regimes on cathodes of limiting values of hardness (Cu, brass, and Si(111)) from the basic sulfate electrolytes without and with addition of leveling/brightening additives, without and with various ways of electrolyte stirring (ultrasound and magnetic stirring), and characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Hardness of Cu films was determined by microindentation and by application of composite hardness models (CHMs), such as Cheng–Gao (C–G) and Korsunsky (K), with the aim to eliminate a contribution of cathode hardness in the measured film hardness and to determine the absolute hardness of the Cu films. The fine-grained films obtained from the basic sulfate electrolyte were harder than the smooth film obtained from the electrolyte with additives and that obtained by the PC regime, indicating that the PC produced film represents transitional form between these two types of the films. The obtained values of the absolute film hardness in the 1.135–1.647 GPa range were in line with already published values for the electrolytically produced Cu thin films, clearly indicating on successful implementation of CHMs in determination of the absolute hardness of thin films. Correlation between morphology and hardness of Cu films was discussed by the basic laws of electrocrystallization and phenomena on boundary among grains during microindentation processes
Distribution of microplastics in (sub)urban soils of Serbia and Cd, As, and Pb uptake by Capsella bursa-pastoris (L.) Medik
No full textOmnipresent in terrestrial ecosystems, microplastics (MPs) represent a hazard to soil biota and human health, while their relationship with other environmental contaminants remains poorly acknowledged. This study investigated MPs prevalence in (sub)urban soils of Serbia and its impact on Cd, As, and Pb mobility in the soil-medicinal plant Capsella bursa-pastoris (L.) Medik system. Soil physicochemical parameters (pH, Eh, SOM, and texture) were analyzed alongside the Cd, As, and Pb pseudo-total (aqua regia) and phytoavailable (EDTA) contents. Toxic elements' concentrations in soil fractions and C. bursa-pastoris roots and shoots were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). Pseudo-total Cd, As, and Pb contents in soils ranged from 0.16 to 2.23 μg g−1, 2.00–36.92 μg g−1, and 0.18–65.54 μg g−1, respectively. Using an optimized density separation method with 30% H2O2 and 5% NaClO, we found an average abundance of 489 MPs per kg of soil. ATR-FTIR spectroscopy confirmed the presence of seven polymer types, whereby the main contributors were polystyrene (PS) – 28.57% and cardanol prepolymer (PCP) – 23.81%. The dominant associated pollution sources were road networks and industrial activities. Spearman correlation analysis revealed the interconnection among soil MPs, physicochemical variables, and Cd, As, and Pb mobility. We identified significant positive correlations between MPs' abundance and phytoavailable concentrations of Cd, As, and Pb (ρ = 0.82, 0.95, and 0.63). Moreover, soil MPs strongly positively correlated with Cd contents in roots (ρ = 0.61) and shoots of C. bursa-pastoris (ρ = 0.65). These findings underscore the synergistic effects of MPs and toxic metals in urban environmental pollution, with possible implications for human health. Further research is required to deepen our understanding of the impact of MPs on element mobility in complex plant-soil systems and to elucidate the broader consequences of induced alterations
Meteorite: SEM and structural characterization
No full textThe use of meteorites in the ceramic industry is interesting, because the present metals can
strongly attract magnets. A meteorite is a natural stone or solid object that has passed through the
atmosphere from a region of the solar system.The paper presents the results of the examination of
the presumed meteorite found in the Valjevo district. On the basis of X-ray powder diffraction
analysis, the mineralogical composition was determined, with the most abundant mineral being
olivine and the iron oxides-Wüstite. SEM analysis of the examined sample is also presented in
the paper