ritnms
Not a member yet
1551 research outputs found
Sort by
Limestone of 'Međeđe': Nikšić as filler in various industries
No full textU ovom radu su prikazani rezultati ispitivanja mogućnosti primene krečnjaka iz ležišta Međeđe-Nikšić u različitim granama industrije. Prilikom ispitivanja krečnjaka određena je vlaga, hemijski sastav, granulometrijski sastav, nasipna masa, specifična zapreminska masa, stepen beline, upijanje ulja i vode, granulometrijski sastav mikronizovanih uzoraka i specifična površina. Sva ispitivanja su obavljena na 8 uzoraka uzetih iz različitih delova ležišta a u radu su prikazane srednje vrednosti dobijenih rezultata. Na osnovu fizičko-hemijskih karakteristika može se konstatovati da krečnjak iz ovog ležišta ima visok sadržaj CaO i CaCO3 od 99,01%, relativno nizak sadržaj MgO od 0,32%, nizak sadržaj SiO2 od 0,26%, alkalija i R2O3, kao i nizak sadržaj teških metala, što je veoma povoljno za primenu krečnjak. Sa ovim fizičko-hemijskim karakteristikama, ispitivani krečnjak se može koristiti u sledećim granama industrije: boja i lakova, papira, guma i PVC, livarstvo i livnička industrija, industrija šećera, metalurgija, proizvodnja stakla, proizvodnja stočne hrane i proizvodnja mineralnih đubriva. Ozbiljna mana krečnjaka iz ležišta Međeđe je nizak stepen beline, koji ne prelazi 89,6%, što onemogućava njegovu upotrebu u farmaceutskoj i hemijskoj industriji, dok relativno visok sadržaj K2O, Fe i Mn sprečava njegovu primenu za kalcifikaciju kiselih zemljišta.This paper presents the results of testing the possibility of using limestone from the "Međeđe" - Nikšić deposit in different industries. During the examination, the coarse moisture, chemical composition, granulometric composition, bulk and particle density, degree of whiteness, oil and water absorption, granulometric composition of micronized samples and specific surface area were determined. All tests were performed on 8 samples taken from different parts of the deposit and the mean values of the obtained results are presented here. Based on the physico-chemical characteristics, it can be stated that this limestone has a high content of CaO and CaCO3 of 99.01%, as well as a relatively low content of MgO of 0.32% and a low content of SiO2 of 0.26% and alkali and R2O3, with also low content of heavy metals, which is very favorable for limestone. With these physico-chemical properties, this limestone can be used in the following industries: paints and varnishes, paper, rubber and PVC, foundry and foundry industry, sugar industry, metallurgical purposes, glass production, animal feed production and mineral fertilizer production. A serious defect of "Međeđa" limestone is the low degree of whiteness, which does not exceed 89.6%, which prevents its use in the pharmaceutical and chemical industries, while the relatively high content of K2O, Fe and Mn prevents its use in calcification of acid soils
Transformations of mechanochemical activated Na2CO3
No full textDuring mechanical activation, energy of treated material is increase to a higher level. This can lead to chemical transformation of the activated material. This is the point where we can talk about mechanochemical transformations that have occurred as a result of mechanical activation. The subject of this paper is to monitor mass changes of material after different degrees of activation. One of the substances which is often used in the processes of mechanochemical synthesis is sodium carbonate. The mass changes occurring during the treatment were detected and measured by various methods, depending on the processing environment. The mass increase was attributed to chemisorption of moisture and carbon-dioxide present in air, as a consequence of the sodium carbonate activation. The methods we used were calcimetric chemical analysis. According to obtained results, it was found that activated sodium carbonate is mass-transformed into sodium bicarbonate, whereby these changes are functionally dependent on activation time and the processing atmosphere
Graphene-loaded bioactive hydroxyapatite coatings on titanium substrate - fundamental in vitro investigations
No full textPreliminary genetic model of zeolitic tuff deposits in the tertiary basins of Serbia
No full textDeposits of zeolite tuffs, rich in minerals of the heylandite-clinoptilolite series, in Serbia are
spatially and genetically related to volcanogenic-sedimentary series of sedimentary basins and
were formed as a product of devitrification of volcanic glass. Zeolite minerals in sedimentary
rocks of Neogene age are found in association with volcanic and volcaniclastic rocks. The
lacustrine or marine environment had a great influence on the diagenesis of sediments and the
formation of clinoptilolite at the expense of volcanic glass. In this paper, a preliminary model of
the formation of zeolite deposits in the Tertiary basins of Serbia is presented, through the
processing of all elements of the genetic model
Use of agricultural waste as raw materials for obtaining glass and glass-ceramics: A review
No full textGlobal trends are moving towards a circular economy to replace the deeply grounded one linear economics and waste management. Circular economy implies and the protection of human rights through sustainable development, global security natural resources, combating climate change, energy security, insurance sufficient amounts of food, reducing inequalities, preservation of health and a cleaner environment and the rights of future generations to resources, etc. The policy of procurement of raw materials in the circular economy is focused on the use of secondary raw materials. A big challenge for modern production is to use different types of waste to obtain new products without the use of raw materials. This kind of production requires new knowledge, adaptation of existing technologies or new technologies, new jobs, etc. Large amounts of vegetative residues are produced annually by agriculture. Agricultural waste is very often incinerated or disposed of on land and is still not used. Most of the agricultural waste ashes consist of silicon dioxide along with other oxides which may vary according to region and atmosphere of the local conditions. This paper gives an overview of the possibilities of using agricultural waste for obtaining glass and glass ceramics. Previous research has shown that various types of glass and glass-ceramics can be successfully obtained from agricultural waste, which can be used in construction, medicine, various composites, etc
Hydrothermal carbonization of grape pomace-form waste to potential biofuel
No full textBackground: Over the years, the mass utilization of fossil fuels causes numerous harmful effects on the
environment. Therefore, great attention is paid to the implementation of technologies that would enable
the production of biofuels from renewable sources. Hydrothermal carbonization (HTC) is recognized as
one of the highly efficient and promising technologies for the production of value-added materials from
wet and waste biomass.
Objective: The main goal of this study is the valorization of waste grape pomace (GP) using HTC
technology. Emphasis will be placed on the examination of the influence of process temperature on the
selected structural and fuel characteristics of the obtained solids (hydrochars).
Methods: For the preparation of hydrochars 10g of GP and 150 mL of ultrapure water were carbonized
using laboratory autoclave (Carl Roth, Model II). Carbonization was carried out at 180, 200, 220, 240
and 260 °C within 1 h. Obtained hydrochars (H180, H200, H220, H240 and H260) were separated from
process water, rinsed and dried to constant weight. Elemental content of solid` (C, H, N, S) was performed
using Vario EL III; C, H, N, S/O Elemental Analyzer, while O contents and HHV were calculated.
Results: Obtained results showed that carbonization temperature significantly influences the structural
characteristics of produced hydrochars. The C content was increased from 48.9% (GP), up to 69.9%
(H260) with the temperature increase, while the content of other elements was decreased. Observed
changes in elemental composition are caused by dehydration and decarboxylation of biomass during the
HTC process. Additionally, the HHV of GP was 21.64 MJ/kg, while it was increased upon carbonization
up to 26.78 MJ/kg (H260).
Conclusion: Preliminary results of this study determined that implementation of HTC technology
improves fuel characteristics of GP and may represent a suitable route for the utilization of waste
biomass
Advanced oxidation processes for treatment of industrial wastewater
No full textDue to the increased pollution of waters, the general interest is to put this issue in the foreground, as one of the biggest problems of modern society. Following that, there is a need for the development of various technologies for their purification, as well as their constant improvement from the point of cost-efficiency of the process. Because of that, various techniques called ‘’advanced oxidation processes’’ are applied to remove pollutants from wastewater. They differ in the mode of action and application in specific cases of water pollution (i.e., the origin and type of treated wastewater). The following techniques are most commonly used: ozonation, ultrasound (US), UV radiation, and different combinations of them: ozonation with US, UV radiation with various catalysts, ozone with hydroxide-peroxide, etc. Before the advanced processes, the application of standard wastewater treatments (such as coagulation, flocculation, sedimentation, and filtration) was performed to optimize the applied treatment, as well as to assess the increase the overall efficiency of so-called ‘’coupled technologies’’. In this study, the wastewater samples originating from the armor industry were treated firstly by coagulation, and then with a combination of ozone and US. The purification efficiency was analyzed by reducing the concentration of heavy metals (Pb2+, Cd2+) using atomic absorption spectroscopy (AAS). The concentration of organic pollutants was followed by the values of chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). The removal degree of metals were over 70%, and organic compounds were 95%). Based on the obtained results, combining the conventional and advanced wastewater treatment, the optimal purification solution was determined
Deposition of goethite and ferrihydrite onto expanded vermiculite surface: chemical properties and potential application
No full textCurrent demand on adsorbent materials is in constant growth, hence scientific society is in ceaseless
research subjecting cheap and optimal adsorbent. Abundant raw materials which may be utilized as
adsorbent of cation species are mica minerals, and vermiculite as one of them is widely examined.
Since wastewater may contain anion or/ and non-ionic pollutants it is needed to functionalize
adsorbent so it may attract those species as well. Goethite and ferrihydrite are potential candidates
for such modification since they: have large specific surface area (SSA), possess hydroxide group
and they are not toxic to the environment. Goethite/ expanded vermiculite (Goe/EV) and ferrihydrite/
expanded vermiculite (Fer/EV) are successfully prepared and those composites have showed better
adsorption related chemical properties than expanded vermiculite (EV) itself. Utilizing BET
methodology, it is determined that Fer/EV possess five-time larger SSA than EV, while Goe/EV is
two times larger. Measuring cation exchange capacity (CEC) it is determined that modified samples
have only ~10% smaller values of CEC. Summary, both composites have shown higher affinity
toward cationic dye, malachite green and also showed their adsorbent potential toward anionic dye,
tartrazine. Thanks to facile preparation of such materials and its cost, it may be concluded that they
are prospective choice as adsorbents, in first order of heavy metals and dyes
Scientific expert validation of Pb-Zn slag from topionica Veles (Northern Macedonia), based on physico-chemical and mineralogical tests of slag samples from the landfil
No full textPb-Zn slag from “Topionica”-Veles- North Macedonia, belongs to potentially valuable technogenic raw materials. There are over 2,000,000 tons of this material at the landfill near Topionica-Veles. In ITNMS, a detailed physic-chemical characterization was performed on this sample of Pb-Zn slag. These tests were the basis for the validation of this raw material and they determined the parameters that are needed as a basis for further technological tests
Karakterizacija uzorka Holovim efektom i Van der Pauovom metodom
No full textU radu je izvršeno posmatranje električnih karakteristika uzorka primenom sistema za merenje Holovog efekta (Hall Effect Measurement System), oznake HMS-3000, firme Ecopia. Nakon izvršenog merenja uz pomoć sistema za merenje Holovog efekta na ispitivanom uzorku, podaci su automatski izračunati. Podaci koje smo dobili nakon merenja su: površinska koncentracija nosilaca, pokretljivost, specifična otpornost, provodljivost, Holov koeficijent, magnetna otpornost (pojava promene otpornosti kada se uzorak izloži magnetnom polju), alpha (horizontalni/vertilkalni odnos otpornosti), itd. Pozitivne vrednosti Holovog koeficijenta ukazuju da je ispitivani materijal p-tipa. Sprovedeno istraživanje uzorka Bi2Te2.8Se0.2 je obogatilo skup podataka relevantnih za dalja istraživanja