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Corrosion behavior of high- and low-chromium steel grinding balls in chloride solution
No full textThe corrosion behaviour of three types of alloys (two low-alloy carbon steel and one stainless iron with ~15 wt.% Cr), in a solution which simulates seawater (3% NaCl solution, pH 8.1) was tested. Tested samples are used to make steel (iron) balls applied in mils for grinding copper and other ore. The corrosion tests were performed using three electrochemical methods, at room temperature in the presence of atmospheric oxygen. The linear polarization resistance (LPR) method, electrochemical impedance spectroscopy (EIS) method, and linear sweep voltammetry (LSV) method were applied. Based on measurements by LPR and EIS methods (as non-destructive methods), the value of polarization resistance (Rp) was determined and the general corrosion rate (vcorr) of the examined samples was calculated. The obtained values of the general corrosion rate can be used to calculate the service life of steel (iron) balls under exploitation conditions (seawater). The appearance of the surface after linear sweep voltammetry (LSV) measurement showed the presence of localized corrosion (pits were formed) of the tested samples, especially stainless iron, and the LSV method is not suitable for the determination of the general corrosion rate of tested samples in seawater. This form of corrosion occurs at high anodic polarizations, during performing LSV measurements
Recognising the role of ruderal species in restoration of degraded lands
No full textRuderal plants are an important component of plant communities that develop on the range of anthropogenically degraded lands. Yet they were highly neglected and not recognised as desirable for restoration purposes. The aim of this study was to analyse the potential for using ruderal species in restoration processes and to identify preliminary criteria for species selection that could be included in ecological restoration of degraded man-made habitats under future conditions of increased human disturbance and climate changes. The desirable characteristics of the species depend primarily on the type of habitat to be restored, with plant height, specific leaf area, rooting depth and seed characteristics being the most important traits. The recognised ecosystem services of the species analysed show that the provisioning and regulating services are well represented, particularly erosion control, pollination, phytoremediation and other soil quality improvements. Most of the dominant and diagnostic ruderal species from the man-made habitats of the north-western Balkan Peninsula are sensitive to climate change and their potential distribution range is expected to decrease at the European scale. Higher certain ecological indicator values, as well as values for disturbance severity, frequency and soil disturbance indices were found for species that are expected to increase their range. Ruderal species are becoming increasingly important for restoration purposes, as the focus shifts to the significance of early successional species. The inclusion of ruderal species in the restoration of degraded sites should be based on criteria such as: non-invasiveness, plant traits favourable for colonisation (height, SLA, seed traits, rooting depth), values of ecological and disturbance indices, provision of ecosystem services, and change of distribution range under changing climate conditions
Bioaktivnost kompozitnih biokeramičkih prevlaka i otpuštanje gentamicina – in vitro ispitivanja
No full textPovršine titanskih implantata se mogu unaprediti primenom biokeramičkih, multifunkcionalnih prevlaka koristeći proces elektroforetskog taloženja (EPD) u cilju sprečavanja korozije, poboljšanja biokompatibilnosti i antibakterijske aktivnosti, kao i unapređenja osteointegracije. Materijali poput hidroksiapatita (HAP), hitozana (CS), poli(vinil-alkohola) (PVA) i antibiotika gentamicina (Gent) su korišćeni u ovom procesu kako bi se razvile poboljšane antibakterijske kompozitne prevlake. Nakon taloženja, prevlake su potapane u simuliranu telesnu tečnost (SBF) na 37 °C, a zatim je izvršena karakterizacija skenirajućom elektronskom mikroskopijom sa emisijom polja (FE-SEM) i rendgenskom difrakcionom analizom (XRD). Bioaktivnost istaloženih prevlaka je pokazana i analizom aktivnosti alkalne fosfataze prema MRC-5 i L929 ćelijskim linijama. Koncentracija otpuštenog gentamicina je određena korišćenjem tečne hromatografije visokih performansi (HPLC) sa masenom detekcijom (MS)
Chemical durability evaluation of sintered fly ash based chemical durability evaluation of sintered fly ash based glass
No full textIn order to preserve the environment, the strategy of economic development in the world is based on
the use of waste as a raw material for obtaining new products. Waste can be used in the same industry
in which it was produced or in other industries. This paper presents an examination of the chemical
durability of glass-ceramics obtained by sintering fly ash glass at characteristic temperatures
(850 and 900°C). The chemical stability of the glass-ceramics was tested in three solvents, distilled
water, HCl (0.01 mol/dm3) and NaOH (0.01 mol/dm3). The results indicate that the chemical
durability of glass sintered at 900°C is slightly lower than glass-ceramic sintered at 850°C. The
higher chemical durability of the glass-ceramic sintered at 850°C can be attributed to the presence of
wollastonite, which was not detected in the glass-ceramic sintered at 900°C. The obtained glassceramics
has a high chemical durability, with mass changes below 1%. FTIR and SEM analysis of the
samples after dissolution revealed that there was no disruption of the structure
Influence of Modification on the Textural Properties of the Natural Zeolite and Its Efficiency for the Heavy Metals Ions Removal from Contaminated Aqueous Solution
No full textThe influence of modification on the textural properties of the natural zeolite (NZ) and its efficiency for the heavy metals ions removal from contaminated aqueous solution was investigated. The mineralogical composition of the NZ showed that the dominant mineral is clinoptilolite. The surface of the NZ was modified combining the methods for pure goethite and iron-coated zeolite preparations. After modification, the cation exchange capacities and the specific surface area increased from 30.2 to 52.5 m2/g, i.e., from 141 to 165 meq/100g, respectively. Adsorption experiments were done for different heavy metals initial concentrations (copper(II) 0.8 - 12.6 Cu2+mmol/dm3 or lead(II) 1.9 – 29.0 Pb2+mmol/dm3), for 24h, at pH 4.2, in batch conditions. Results showed positive influence of modification on the heavy metals ions removal. The results were fitted with Langmuir and Freundlich adsorption models, and the best fits were obtained with Freundlich model (R2 > 0.92)
Human health risk assessment of PTEs in Capsella bursa-pastoris and its extracts
No full textOwing to mild properties, wide availability, and low reported side effects, medicinal herbs have
been traditionally utilized for thousands of years as a folk remedy, while almost 80% of the world
population consumes it as a medical supplement of primary healthcare (WHO). Despite widespread
distribution and a broad spectrum of benefits for human health, Capsella bursa-pastoris L. Medik is
an underexplored medicinal species with a recorded significant accumulation capacity for
potentially toxic elements (PTEs). In the present study, we investigated the abundance and mobility
of PTEs (Ba, Co, Cr, Cu, Fe, Mn, Ni, Sr, and Zn) in the urban soil - C. bursa-pastoris system and
comprehensively evaluated potential posing human health risks. Samples were collected in four
Serbian cities – Belgrade, Bor, Vršac, and Sremska Mitrovica. PTEs concentrations in samples were
determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). The
pseudo-total concentrations in soils surpassed the world mean levels. Cu, Zn, Sr, and Mn were the
most abundant, whereby the calculated Igeo index suggested moderate to heavy soil contamination.
Non-carcinogenic (HI) and carcinogenic risks (CR) associated with the ingestion, dermal, and
inhalation exposure to the examined soils were within the acceptable ranges (HI < 1, CR < 10-6).
Although Sr, Cu, and Ni contents were elevated in the plant tissues (roots - up to 57.04 mg kg-1, 23.36 mg kg-1, and 7.90 mg kg-1, and shoots – up to 60.78 mg kg-1, 20.21 mg kg-1 and 6.26 mg kg1), estimated daily intake (EDI), target hazard quotient (THQ), and lifetime carcinogenic risk (LCR)
demonstrated non-significant health risks by consuming C. bursa-pastoris, as a raw herb or herbal
extracts. This study aimed to underscore the urgency of the PTEs' continual monitoring in soils and
medicinal plants and highlight the importance of conducting comprehensive health risk assessments
in providing safe medicinal plant utilization
Investigation of the possibilities of applying limestone in agriculture and its geological characterization
No full textGeological investigations have shown that a large carbonate series is plased in the atar of the
village of Tršić, east of Loznica. This limestone deposit (Dobrilovići) is rich, and geological tests
have shown that the quality of the limestone is satisfy for applying in agriculture. Also, large
reserves of limestone are placed which enable long-term exploitation. Limestone found its
aplication In agriculture for calcification of acidic agricultural soils with an average pH value of
3.5 to 5. For this purpos, a certain dimensions and chemical composition of limestone is suitable
for uses. Chemical analysis of the sample from this deposit showed the presence of CaCO3 above
80% and CaO above 44.80%. Traces of lead, nickel and chromium were found in the deposit (Pb
3 mg/kg, Ni 7 mg/kg and Cr 21 mg/kg). The pH value of limeston was 8.47, while the loss on
ignition was 39.40%. Based on the obtained results, it was concluded that the mineral and
chemical composition of limestone is suitable for calcification of acidic soils. The granulometric
composition of the sample showed the presence of large classes above 50 mm (68%).
Calcification of acidic soils is carried out with a class of 100% -2 mm. A scheme for the
preparation of trench limestone is given, which includes crushing, grinding and grading
Soil conditioners and amendments are key for soil restoration - Types and methods of production
No full textSoil amendments and conditioners are indeed crucial for maintaining soil health and fertility, especially in the face of a growing global population. These tools help to create an environment where fertilizers can effectively provide essential nutrients to crops. As soils become increasingly depleted worldwide, it is essential to focus on improving soil health through the use of these amendments and conditioners. This will support the production of nutrient-rich crops and also contribute to sustainable agriculture practices that can feed a growing population. This paper, provide an overview of their purpose, how they function, and how soil conditioners are generally obtained
Method of a high temperature thermal induced phase transformation of zeolite in the process of obtaining the different materials of feldspar topology
No full textThe preparation of various aluminosilicate ceramic materials using synthetic zeolites as the precursors has been a topic of great interest during the last three decades. This method of synthesis is often called the thermal-induced transformation
of zeolite (ZTIT) and has the certain advantages over the other conventional methods. This paper presents the comparative results of structural and microstructural tests
the products of high-temperature thermal transformation of zeolite Pb, Mn - LTA topology. After thermal treatment at
temperature between 700º - 1500º C, it is transformed into different feldspar structures. Mn-LTA zeolite at
temperature of 1300 ºC is changed to the structure of Mn-anorthite with paremeters (a=8.109(2) b= 12.824 (3) c=7.067 (4) β=115.89º(3). Pb-LTA zeolite transforms into the Pb-celsian structure at temperature of 1200 ºC (a=8.411(2) b= 13.047 (3) c=7.163 (4) β=115.35º(3). Structural and microstructural parameters were determined by the X-ray powder diffraction method on a polycrystalline sample, using the Fullprof program
Removal of Diesel from Aqueous Solutions by a Combined Adsorption and Microbial Degradation Process
No full textDiesel contamination in water bodies poses a significant environmental challenge due to the toxic effects of its water-soluble fraction (WSF) on aquatic ecosystems and human health. The aim of this work was the design of a new technological procedure for the purification of water contaminated with the WSF of diesel. The procedure is based on the adsorption of organic pollution on an organozeolite, after which the biodegradation of the adsorbed pollutant takes place. The material for obtaining organozeolite was a natural zeolite from the Zlatokop deposit (Vranje, Serbia). The zeolitic surface was modified with hexadecyltrimethylammonium bromide (HDTMA-Br), a cationic quaternary ammonium salt. The adsorption experiments, with initial WSF concentrations of 2.5–25 mg/L, at pH 6 and at 20 °C, were performed in a batch system using organozeolite, and the results showed that more than 90% of the WSF of diesel was removed, reaching equilibrium after 1 h. The maximum adsorbed capacity of organozeolite for the removal of the WSF of diesel fuel from water under the tested conditions was 22.2 mg/g. Equilibrium data were well fitted by a linear isotherm model, while a pseudo-second-order equation well fitted the kinetic data. After adsorption, a 15-day biodegradation experiment was carried out under batch conditions. The results showed that the examined consortium of microorganisms degraded 80% of the adsorbed contaminant. Additional respirometric analyses showed that, in parallel with the degradation of the contaminant, the degradation of the long-chain HDTMA ions at the surface of the organozeolite also occurred. To the best of our knowledge, this is the first study combining adsorption and biodegradation to remove the WSF of diesel from water