Sorption of lead, cadmium and zinc ions from aqueous solutions onto natural and modified zeolite

Sorpcija se koristi za uklanjanje zagađujućih materija iz vode, zahvaljujući efikasnosti i ekonomičnosti, posebno ako se koriste jeftini sorbenti i ukoliko je moguća njihova višestepena regeneracija. Zeoliti zauzimaju značajno mesto među sorbentima za uklanjanje neorganskih jona iz prirodnih i otpadnih voda. Da bi se sorpcioni kapacitet prirodnih zeolita za jone metala povećao i proces sorpcije unapredio, poslednjih godina se proučavaju različiti postupci modifikovanja zeolita. Jedan od efikasnih postupaka modifikacije je nanošenje na površinu zeolita gvožđe(III)-oksihidroksida, koji su takođe aktivni sorbenti i igraju značajnu ulogu u imobilizaciji jona u prirodi. U ovoj doktorskoj disertaciji je proučavana sorpcija jona olova, kadmijuma i cinka iz jednokomponentnih i višekomponentnih rastvora u dejonizovanoj i komunalnoj otpadnoj vodi, na prirodnom zeolitu i zeolitu koji je modifikovan gvožđe(III)-oksihidroksidima. Cilj disertacije je bio objašnjenje razlike u mehanizmima sorpcije i sorpcionim kapacitetima prirodnog i modifikovanog zeolita. Karakterizacija prirodnog i modifikovanog zeolita pokazala je da nije došlo do narušavanja strukture zeolita i da se modifikacija odigrala na površini, obrazovanjem klastera amorfnog gvožđe(III)-oksihidroksida. Adsorpcijom azota na temperaturi tečnog azota utvrđeno je da je modifikacija uzrokovala značajno povećanje specifične površine i zapremine mezopora, kao i zatvaranje mikropora. Specifična površina oba zeolita je određena i na osnovu adsorpcionih izotermi za n-heksan, benzen, hloroform i tetrahidrofuran primenom inverzne gasne hromatografije u uslovima konačne prekrivenosti na temperaturi od 240 °C. Niže vrednosti specifične površine dobijene inverznom gasnom hromatografijom za modifikovani zeolit u odnosu na vrednost dobijenu na osnovu adsorpcije azota ukazuju na prisustvo mezopora manjih dimenzija, manjih nego u slučaju prirodnog zeolita, koje su dostupne molekulima azota, a nisu molekulima n-heksana, benzena, hloroforma i tetrahidrofurana, koji su većih dimenzija u odnosu na N2...Sorption is used to remove pollutants from water, thanks to its efficiency and cost effectiveness, especially if cheap sorbents are used and if there is a possibility for their multistage regeneration. Zeolites occupy an important place among the sorbents for removal of inorganic ions from natural and waste waters. In order to increase the sorption capacity of natural zeolites for metal ions, and to improve the sorption process, various methods for modifying zeolites have been studied in recent years. One of the most effective methods is a modification of the surface of the zeolite with iron(III)–oxyhydroxides, which are also active sorbents and play a important role in the immobilization of ions in nature. This doctoral thesis investigates sorption of lead, cadmium and zinc ions from multicomponent solutions in deionized and municipal waste water, onto natural zeolite and zeolite modified with iron(III)-oxyhydroxides. The goal of the thesis was the explanation of differences in the sorption mechanisms and sorption capacity of natural and modified zeolites. Characterization of natural and modified zeolites showed that no damage to the zeolite structure was done and that the modification occurred on the surface, forming clusters of amorphous iron(III)-oxyhydroxides. Nitrogen adsorption at liquid nitrogen temperature determined that the modification caused a significant increase in specific surface area and volume of mesopores and micropores closing. The specific surface area of natural and modified zeolite was also determined based on the adsorption isotherms of n-hexane, benzene, chloroform and tetrahydrofuran by inverse gas chromatography at finite concentration condition at a temperature of 240 °C. Lower values of specific surface area obtained by inverse gas chromatography for the modified zeolite, compared to the value obtained by nitrogen adsorption, indicate the presence of mesopores with smaller dimensions, smaller than in the case of natural zeolite. These pores are available for nitrogen molecule, and they are not available for the molecules of n-hexane, benzene, chloroform and tetrahydrofuran, which are large in size in comparison to N..

Susceptibility to antifungal agents of Candida spp. from blood and feces collected in Novi Sad in 3-year period (2008-2010)

Candidemia is an important emerging nosocomial infection in patients with risk factors. Candida species from nonsterile sites can give insight into the characteristics of strains that may cause invasive disease. The aim of this study was to evaluate antifungal susceptibility of Candida blood and fecal isolates in Novi Sad, Vojvodina. During a 3-year period (2008 to 2010), 424 isolates of Candida spp. were collected, 30 bloodstream isolates and 394 strains from fecal samples. In vitro susceptibility of these isolates to five antifungal agents was established using commercial ATB FUNGUS 3 (Bio-Mérieux). Predominant species was Candida albicans (6 isolates from blood and 269 from feces). Resistance to one or more antifungal agents was less common in Candida albicans (3.63%) than in other species (24.83%). Resistance to itraconazole was the most commonly found in both groups of isolates, 9.64% strains from feces and 20% from blood samples. Twelve isolates were multiply resistant, usually to fluconazole, itraconazole, and voriconazole. Resistance to amphotericine B was extremely rare. Although resistance to antimycotics of Candida spp. is rare at present, continued surveillance of antifungal susceptibility is necessary in order to monitor trends, and to choose the right empiric therapy

Economic victimisation of women in the labour market

The paper first emphasises the fact that the equality of all citizens is clearly declared as part of the value system of modern states. International organisations, such as the United Nations and Council of Europe, began to promote combating abuse of and violence against women as a goal-oriented behaviour during the last decade of the twentieth century. Relevant studies in the field have endeavoured to explain the concept of economic victimisation of women in the labor market by drawing attention to the fact that it can be seen as a result of persistent domestic violence. They have focused on poverty, homelessness and social assistance for women who are in the labor market. The results of these studies show that unemployment at the time of social crisis does not only initiate the commission of property and other crimes but also deviant behaviours. According to the economic theory, the economic model of crime makes individuals choose between crime and legal work, depending on the characteristics, rewards and the price of either of them. This is important in those periods when individuals can only get odd, rather insecure and poorly-paid jobs. The theory states that the higher the level of the economy deterioration in terms of reducing number of jobs or even lower payments, the higher the crime rate. Job loss, inability to find new employment in the profession, inadequate remuneration all contribute to creating a situation which defines a new quality of family relationships. A newlybuilt attitude, which has become part of the cultural milieu of the new generation, the wish to illegally reach wealth in an easier, faster and more effective way will be much harder to eradicate. The Strategy to combat violence against women, the importance of training of women and the range of options contribute to the improving of their status and enable access to material goods and resources. The authors of this paper refer to certain macro-economic mechanisms that countries can implement to reduce the victimisation of women in the labor market and improve their economic situation, such as measures of gender budgeting, developing social entrepreneurship, subsidies and social cooperatives

Definition the technology method of apatite flotation concentration from the phosphate deposit 'Lisina'

This paper presents the importance of phosphate in the world, and the problems that arise in the process of preparing the low-grade phosphate ore for obtaining the phosphate concentrate using the flotation concentration. The apatite concentrates are obtained using the selective flotation from the silicate and oxide minerals while defining the process of selective flotation of apatite from carbonate deposits is the major problem worldwide. The experimental part of this paper presents the results of laboratory flotation tests of phosphate ore from the surface part of the location 'Panjevica' of the deposit 'Lisina'. The results have enabled definition of the flotation process in continuous conditions of work

Investigation the calcite hydrophobisation of different grain sizes

This paper presents the investigations of possibility of calcite hydrophobisation. Two samples of calcite of different size classes from the site 'Dobar kamen', Arandjelovac, Serbia, were used in the experimental work. Modifying the surface of calcite was carried out by stearic acid with 'dry' method. Concentrations of stearic acid in the modifying method were as follows: 0.3, 0.5, 0.8, 0.9, 1, 2, 2.5, 3 and 4%. The results showed that a complete hydrophobicity (I0=99.9%) of calcite sample with the medium diameter (d50) 10.87 μm was achieved at concentration of stearic acid of 0.8%, while for the sample with the mean grain diameter (d50) of 29.14 μm, it was achieved at concentration of stearic acid of 3%. These results were confirmed by the microscopic analysis

The process of obtaining quartz sand size fraction -0.4 + 0.05 mm for use in water glass production

The paper presents the process of quartz sand processing from the „Bijela Stijena“-Skočić deposit in the plant „Kesogradnja d.o.o.“ at Kozluk near Zvornik, Republic of Srpska. Bearing in mind the fact that this quartz sand is used for water glass production in the company „Birač“ - Zvornik or „Alumina“ Zvornik, it was necessary to meet the quality requirements prescribed by that industrial production. Thus, the required size was -0.4+0.05 mm and the Fe2O3 content was maximum of 0.04%. Based on the laboratory tests, a technological scheme for the quartz raw material valorization was conceived in the separation of the company „Kesogradnja d.o.o.“. The obtained results showed that quartz sand for water glass size fraction -0.4+0.05 mm could be obtained in the plant. Also, by introducing a magnetic concentration after washing and grading, the Fe2O3 content was reduced from 0.131% as it is in the initial sample to 0.038% which meets the required conditions from the water glass producers

Reactions of calcite in water in the presence of stearic acid

In the suspension of water and calcite, with pH 10.14, on the border of calcite / water was formed a double electric layer. Its structure, or hydrophilic properties of minerals, depended on the concentration of potential determination ions, Ca2+ i 2 CO3 , pH of the environment, and the adsorption of water molecules and ions (and molecules), formed in a suspension of calcite as a result of its solubility in alkaline media. The structure of such a way formed electrical double layer, influenced on interaction of minerals with stearic acid as a surface of active substance. In the presence of stearic acid, the pH value of slurry decreased to 8.72 due to the dissociation of stearic acid in alkaline medium and reaction of neutralization. As the result of dissociation, in the suspension, besides the un-dissociated acid molecules, there were also stearine ions CH3(CH2)16COO-, (St-), which have reacted with the surface of minerals, transforming it from hydrophilic to hydrophobic

Application of lime in the polyvinyl chloride industry

This paper presents the importance of limestone in a variety of industries with a special focus on the use of limestone as filler in the industry of polyvinyl chloride (PVC). Of Out of all fillers, used in the industry of PVC processing, calcium carbonate type of fillers are 80%. Fillers are used in order to improve various mechanical properties of polymer such as tensile and breaking properties, density, bending strength, hardness, thermal stability, viscosity and more. Latest trends of industrial development and demands of the processing industry for high quality carbonate fillers influenced the implementation process of surface modification limestone and calcite, which is the main constituent of fine micronized limestone in order to enhance its performance

Reconstructing and counting genomic fragments through tagmentation-based haploid phasing

Single-cell sequencing provides a new level of granularity in studying the heterogeneous nature of cancer cells. For some cancers, this heterogeneity is the result of copy number changes of genes within the cellular genomes. The ability to accurately determine such copy number changes is critical in tracing and understanding tumorigenesis. Current single-cell genome sequencing methodologies infer copy numbers based on statistical approaches followed by rounding decimal numbers to integer values. Such methodologies are sample dependent, have varying calling sensitivities which heavily depend on the sample’s ploidy and are sensitive to noise in sequencing data. In this paper we have demonstrated the concept of integer-counting by using a novel bioinformatic algorithm built on our library construction chemistry in order to detect the discrete nature of the genome.Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4686

Besplatna pravna pomoć – pružanje u uslovima terenskog rada

Pravo na pristup pravdi je jedan od aspekata kompleksnog prava na pravično suđenje. Ono je sadržano kao obaveza države u brojnim međunarodnim dokumentima: Univerzalna deklaracija o lјudskim pravima, Međunarodni pakt o građanskim i političkim pravima, Evropska konvencija za zaštitu lјudskih prava i osnovnih sloboda i brojne druge preporuke Saveta Evrope. Kako je Republika Srbija članica Saveta Evrope, ona je obavezna da sledi preporuke ove organizacije, te na tome i počiva njena obaveza da zakonom uredi i operacionalizuje pružanje pravne pomoći, uklјučujući i besplatnu pravnu pomoć. Jedan od načina pružanja besplatne pravne pomoći su tzv. pravne klinike, koje se organizuju na pravnim fakultetima. Pravni fakultet u Nišu je bio pionir u organizovanju posebnog sistema rada studenata, koji su radom sa „živim“ klijentima, pružali besplatnu pravnu pomoć. Mobilna pravna klinika je specifična, jer se njena suština otelotvoruje u tome da dolazi do transfera pravne pomoći u kućne uslove živih klijenata. U radu su predstavlјeni preduslovi za uspešno funkcionisanje Mobilne pravne klinike