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Aparat za uklanjanje dlaka sa gubarevih (Lymantria dispar) jaja
No full textAparat za uklanjanje dlaka sa gubarevih (Lymantria
dispar) jaja upotrebom aparata za uklanjanje
dlaka sa gubarevih (Lymantria dispar) jaja. Aparat se
sastoji iz više delova od čega najmanje sadrži: jednu
cilindričnu cev (1.1) sa navojima sa obe strane i blagim
suženjem, zatvarač (1.2) sa navojem i otvorom sa jedne
strane i otvorom koji je uži od poklopca, namenjen
priključku usisne cevi usisnog aparata bilo koje vrste, sa
druge strane, zatvarač (1.3)sa navojem i mehanizmom
za uklanjanje dlaka sa druge strane cilindrične cevi (1.1),
aparat sa elektro
motorom koji obezbeđuje rotaciju osovine (3.3)
a na koju se priključuje
jedan odvojivi cilindrični umetak (1.4) sa mrežicom
Possibility of using limestone from Vučića Brijeg-Ulcinj deposit as a filler in various industry branches
No full textThis paper presents results of investigations of the possibility of us-ing “Vučića Brijeg”-Ulcinj limestone (Republic Montenegro) as filler in vari-ous industry branches. Micronization methods, granulometric composition, oil and water absorption and degree of whiteness were investigated, and chemical and thermal analyses (DT/TG) were performed. Physico-chemical properties of this limestone classify it among high quality car-bonate raw materials with high CaCO3 content of 97.87%, as well as MgO con-tent of 1.04% (2,18% content of MgCO3 ) and low silicate content (SiO2 0.40%). Its quality satisfies requirements of standards on using of calcium carbonate as filler in industry of paints and coatings; paper industry; rubber and PVC industry; glass industry; production of mineral fertilizers; foundry industry; sugar industry and metallurgy. Due to the low degree of whiteness (81.65%) „Vučića Brijeg” limestone cannot be used in pharmaceutical and cosmetics industry. Due to rela- tively high content of heavy metals, Pb (55 ppm), Cu (10 ppm), Ni (23ppm) and Cd (5 ppm), “Vučića Brijeg”-Ulcinj limestone cannot be used, in production of cattle feed and for neutralization of acidic soils
Current conditions and future perspectives of grasslands in Serbia
No full textNatural grasslands and pastures occupy 5.96% of the country territory. According to
European Space Agency, changes in land cover from 2000–2015 indicate decrease in total
grassland area of 1765 km2 (30.03%), emphasizing dominant conversion of grasslands to
forests. Ongoing depopulation trend, rural to urban migrations, and decrease in livestock
population are some of main factors impacting grasslands. This trend favors further
naturalization of pastures striving to increase the areas under natural grasslands. Such
conversion will contribute to overall change in biodiversity richness, especially in areas with
saline soils and high mountain regions with increased level of endemic species.
Grasslands play important role in overall sustainability, but their importance it is not
properly addressed. Environmental experts should recognize drivers of grasslands degradation
and propose appropriate conservation and restoration measures. The priority should be
avoidance of grassland degradation that requires good assessment of their current conditions
and monitoring of plant, soil, climate conditions and land use activities. Further measures are
deduced to sustainable land management practices and smooth human interventions, whereas
the aftermost adopted measures should be related to restoration. Grasslands should have more
emphasized role in our society and LDN principles should be applied for their preservation
Uklanjanje fosfata sorbentom na bazi biočađi koštice šljive impregnisane magnezijumom
No full textФосфати представљају озбиљну претњу за екосистем, због еутрофикационих својстава и токсичног дејства на живе организме. Утврђено је да највећи ризик представљају фосфати који су доспели у водотокове отицањем са пољопривредног земљишта и из канализационих вода. Међу методама које се користе за уклањање фосфата из воде, адсорпциона технологија се показала као најефикаснија, а биочађ као најефикаснији адсорбенат. У овом раду, биочађ добијена спором пиролизом отпадне биомасе (коштице шљива) је модификована у циљу повећања адсорпционог капацитета и затим тестирана као сорбент за уклањање фосфата. Прелиминарни резултати показују да ова врста сорбента има сорпциони потенцијал за ефикасно уклањање фосфата
Immobilized Bentonite In Alginate Matrix – Efficient Sorbent Of Brilliant Green
No full textThe environmental pollution by dyes has become an important concern due to the harmful effects
on human health and entire ecosystem. In this study, bentonite immobilized in calcium-alginate (ImB)
was studied as a sorbent for the Brilliant Green (BG) removal from aqueous solutions. The prepared
composite sorbent was characterized by pHpzc, SEM and EDX. The sorption kinetic was best fitted by the
pseudo-second-order model and simultaneously followed the film diffusion and intra-particle diffusion
model during the sorption. This study proved that ImB might be an efficient sorbent for removing dyes
from aqueous solutions
From waste to eco materials – the application of sour cherry stone sorbents in heavy metal removal
No full textSerious environmental problem worldwide are effluent waters from many industries, such
as mining, refining ores, pesticide, batteries, paper industries, etc., containing toxic
components, mostly heavy metals, which are not treated properly in many cases. These
pollutants pose serious threat to environment and human health because of their toxicity,
persistence and bioaccumulation tendency. There are plenty of conventional methods for
heavy metal removal, but in most cases, they are too expensive for removing low, but still
toxic present concentrations, with high operational cost/energy demand, or they create large
quantities of toxic sludge which request further processing. The application of low cost,
mostly waste materials as a heavy metal sorbent are a potential alternative to the existing
conventional technologies for the removal/recovery of metal ions from aqueous solutions.
The major advantages of sorption by renewable biomass over conventional treatment
methods include low cost and abundance of biomaterials, high efficiency with minimum
sorbent treatments, minimization of sludge generation and feasible regeneration with
possibility of metal recovery. At the same time, application of renewable waste materials
contributes to carbon sequestering and climate change mitigations, avoiding land usage and
negative impact of landfilled material onto environment. The revalorization of this kind of
sorbents also contributes to resource conservation and circular economy in its broadest
sense. In this research, lignocellulosic waste material from food industry (sour cherry
stones) has been applied as a sorbent for treatment of polluted water with various heavy
metals. The sour cherry stones are widespread, locally available waste with considerable
potential for sorbents development. This lignocellulosic material was grinded into particle
size of approximately 0.5 mm, marked as CSP, and investigated for removal of heavy metal
content in contaminated water containing highly toxic metals: Cd2+, Cu2+, Ni2+, Zn2+, and
Pb2+. Sorption experiments were performed in an isothermal batch system with stirring
under specified operational conditions, avoiding metal precipitation. The removal
efficiency of investigated metals reduced in order Pb2+ > Cd2+ > Cu2+ > Zn2+ > Ni2+ using
CSP as a sorbent. The CSP characterisation included: contact pH (pHsus), point of zero
charge (pHpzc), Scanning Electron Microscopy (SEM) and energy-dispersive X-ray
spectroscopy (EDX). Structural characterization of the CSP surface was performed using
Fourier transform infrared spectroscopy (FTIR), which disclosed the presence of specific
functional groups (hydroxyl, carbonyl and carboxyl) responsible for the removal of heavy
metals ions. The obtained results suggest that the application of the raw CSP is an
economic and environment feasible strategy for removing heavy metals from water polluted
streams
Improvement of combustible characteristics of Paulownia leaves via hydrothermal carbonization
No full textThe Paulownia leaves (PL) was used for the first time as feedstock for the potential production of novel carbon-rich materials applying hydrothermal carbonization (HTC) technology. The HTC is one of the suitable methods for converting biomass into high-value carbonaceous products that could replace existing fossil fuels or be used for some other application. In this study, hydrochars of PL were obtained at five different temperatures (180, 200, 220, 240, and 260 degrees C), and the influence of temperature on hydrochar structures was analyzed. Physicochemical composition, structural, and combustion properties were estimated for hydrochar efficient characterization. The results showed that tested hydrochars had lower moisture, volatiles, oxygen, and sulfur content compared to PL biomass. Also, the HTC process increases carbon content and created high-energy C-C bond structures in hydrochars which improved fuel ratio (FR), energy density (ED), higher heat value (HHV), and lower heating value (LHV). However, hydrochar mass yields were significantly low, which affected the lower heating value (EY). The spectroscopic and thermal analysis confirmed the formation of new aromatic structures in hydrochars and enhancement of their thermal stability and combustion ability, respectively. Before hydrochar practice, in order to enhance their mass yields, it is necessary to further analyze the influence of the HTC parameters or hydrothermal co-carbonization with other biomass should be taken into concern. The results showed that HTC could be an efficient method to improve the combustion properties of PL biomass
Modifikacija površine titanijum-dioksida srebro(i)-oksidom kao katalizatora za fotokatalitičku degradaciju fungicida
No full textPollution of water presents one of the biggest problems of modern society. Pesticide
production, usage and release, as well as their persistence in the environment, have
detrimental effects on the aquatic and non-target species. Therefore, it is necessary to apply
treatment techniques in order to prevent these negative consequences. The processes used
so far do not have the necessary efficiency to optimally solve this problem. Hence, plenty
of advanced oxidation processes (AOPs) has been developed, among which photocatalysis
has stood out. Thus, photocatalytic degradation of fungicide thiophanate-methyl by using
recently synthesized catalyst Ag2O/TiO2 was considered. The effect of the various
parameters, such as catalyst amount, fungicide concentration, and also the distance of the
lamp from the photocatalytic reactor was studied. The obtained photocatalyst was examined
using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy
(SEM), as well as Diffuse reflectance spectroscopy (DRS). Photocatalytic assays
employing Ag2O/TiO2 catalyst with the concentration of 0.065 g/l yielded the best results.
The degradation rate constant was measured as 0,040 min-1 by observing values of
absorbances from the UV spectrophotometer Shimadzu 1800. Under the optimal
conditions, the complete disappearance of 10 mg/l of fungicide occurred within 2 h by
using Ag2O/TiO2. However, the limitation of the applied process is reflected in the volume
of wastewater that can be treated, while making it economically viable. Obtained results
show that synthesized catalysts pose a great ability to effectively decompose thiophanatemethyl
under UV light
Stress state analysis of propane butane gas spherical storage tanks
No full textThe paper presents the design of a spherical tank using a
combination of analytical procedure with FEM analysis
and experimental testing in order to minimize design time
and verify the design strength. The analytical procedure for
calculating the tank strength in the initial stages of the design
process is briefly presented. Based on analytical results, the
tank is designed and by created FEM model. FEM analysis
is used to identify areas of high stress concentration. FEM
results show that the equivalent value of stress at the points
of spherical tank support exceeds the values of yield stress,
but not significantly and in a very small area, so the overall
design is deemed worthy. Experimental measurements verify
FEM results that show it is not necessary to reinforce the
spherical tank at the points of support. After 8 months, exper-
iments are repeated giving the same results as the original
measurements, thus justifying the decision not to reinforce
tank supports.U radu je prikazano projektovanje sfernog rezervoara kombinacijom analitičke procedure sa MKE analizom i eksperimentalnim ispitivanjem, kako bi se minimiziralo vreme projektovanja i proverila nosivost. Ukratko je prika-zan analitički postupak za proračun čvrstoće rezervoara u početnim fazama procesa projektovanja. Na osnovu anali-tičkih rezultata rezervoar je dimenzionisan uz kreiranje MKE modela. MKE analiza se koristi za identifikaciju oblasti sa velikom koncentracijom napona. Rezultati MKE pokazuju da ekvivalentna vrednost napona na tačkama oslonca sfernog rezervoara premašuje napon tečenja, ali ovo prekoračenje nije značajno, na veoma maloj površini, pa je celokupno projektovanje ocenjeno kao korektno. Eksperimentalna mere-nja potvrđuju MKE rezultate da nije potrebno ojačati sferni rezervoar na tačkama oslonca. Posle 8 meseci eksperimenti su ponovljeni dajući iste rezultate kao i originalna merenja, čime se pravda odluka da se ne pojačaju nosači rezervoara