Heavy-metal pollution (such as Cd(II)) is regarded as a serious environmental problem, posing a great threat to human beings. In this research, a novel water-dispersible magnetic ...alginate/hydroxyapatite composite with high-efficiency Cd(II) adsorption performance was successfully synthesized by a facile wet-chemical method. The magnetic separation experiment and magnetic property analysis indicate that a magnetic alginate/hydroxyapatite composite can be effectively separated under a magnetic field. The zeta-potential result and dispersity experiment indicate that the lowest zeta-potential is –39.4 mV at pH = 5, and the obtained sample dispersed well in a Cd(II) solution after 120 min. The maximum adsorption capacity of a sample on Cd(II) is 135.3 mg g–1 at pH = 5, and the adsorption of Cd(II) reached equilibrium in 10 min. The adsorption data could be fitted well using the Langmuir model, and the adsorption kinetic follows a pseudo-second-order kinetic model.
Lead blast furnace slag (LBFS) generated during lead smelting is a hazardous solid waste containing potentially toxic elements (Pb, Zn, As, and Cd) with high mobility and solubility. In this study, a ...process for the utilization of LBFS by carbothermic reduction-magnetic separation method is proposed. Leaching toxicity and Tessier sequential extraction experiments were conducted on LBFS and magnetic separation tailings (TS), and the environmental risk was evaluated using the risk assessment coding index and potential ecological risk index. The obtained results showed that the potentially toxic elements in the TS were solidified in the spinel phase or silicate phase. In addition, the XRD, SEM-EDS, and FTIR results showed the formation of PbCa2Si3O9, ZnAl2O4, and Ca3(AsO4)2 phases. The leaching concentrations of Pb, Zn, As, and Cd in TS were much lower than the toxicity characteristic leaching procedure (TCLP) and China standard leaching test (CSLT) limits. The results of Tessier sequential extraction procedure confirmed that the proportions of the stable residual state of the potentially toxic elements in TS were significantly higher than in LBFS. Furthermore, the ecological environmental risk level for the TS decreased significantly compared to that of LBFS.
A new technique with carburization followed by magnetic separation is presented for the preparation of high-grade iron carbide from pyrite cinder to promote the high value-added utilization of pyrite ...cinder. The effects of carburizing temperature, carburizing time and Na2SO4 dosage on carburized pellets were investigated, and the effects of Na2SO4 dosage and grinding fineness on magnetic concentrate were carried out. The optimized process parameters were proposed as follows: carburizing at 650?C for 180 minutes in CO-CO2-H2 gas mixtures, Na2SO4 dosage of 9%, magnetic field intensity of 130 mT, and grinding fineness of 92.25% powder passing 0.025mm. The iron content, total carbon content, total iron and carbon content of magnetic concentrate were 82.62%, 5.60%, and 88.22%, respectively. The recovery rate of iron reached 88.67%. The behaviors and mechanisms of carburization, separation, and Na2SO4, were ascertained with optical microscopy, X-ray powder diffraction (XRD), and scanning electron microscope (SEM).
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U predškolskim ustanovama svake školske godine, susrećemo se sa adaptacijom na jaslice, dece uzrasta do tri godine. I pored pripreme dece, roditelja, primene programa adaptacije i dr., separacione ...teškoće različitog intenziteta koje se ne mogu predvideti manifestuju se u toku adaptacije. Sagledavanjem upisa dece u jaslice kroz prizmu TAV data je mogućnost rane predikcije individualnih razlika adaptacije dece na osnovu kvaliteta veze dete-majka, kao i pružanja odgovora na pitanje transfera AV sa majke na vaspitača; kompenzacije negativnih efekata nesigurne veze sa majkom kroz sigurnu vezu sa vaspitačem; kapaciteta deteta jaslenog uzrasta za formiranje multiplih veza; reorganizacije hijerarhije figura i načina kvalitetne podrške od strane vaspitača i vrtića kao institucije, neophodne za formiranje sigurnih relacija. Dakle, ovim radom se traga za odgovorom na pitanje koje sve mogućnosti pruža adaptacija dece na jaslice u smislu podsticanja psihosocijalnog razvoja deteta iz ugla teorije afektivne vezanosti.
Prijenos organizama u brodskom vodenom balastu i sedimentu jedna je od najvećih prijetnja biorazlikosti mora, ekosustavima i čak ljudskom zdravlju. Balastne su se vode dugo vremena smatrale čistima ...tako da postupci balastiranja i debalastiranja brodova nisu bili tretirani kao potencijalna opasnost. Problem prijenosa organizama u brodskom vodenom balastu moguće je između ostaloga riješiti s pomoću metoda obrade balastnih voda. Primarnim metodama obrade postiže se efikasno odstranjivanje organizama i čestica u prvom stupnju obrade. U ovom radu prikazane su različite primarne metode obrade zasnivane na centrifugalnim i gravitacijskim procesima koje se mogu primijeniti u sustavima za obradu balastnih voda na brodu i u kopnenim postrojenjima.
Magnetska separacija s vrtložnim strujama najčešće se koristi za izdvajanje nemagnetičnih metala (Al, Cu, Zn, Pb) iz krutog otpada, a također i za njihovo međusobno odvajanje. Tračni transporter ...doprema ulazni materijal na bubanj s magnetskim poljem. Promjenjivo magnetsko polje inducira vrtložne struje u vodljivim česticama (česticama metala). Interakcija između ovih struja i magnetskog polja uzrokuje elektrodinamičke sile koje djeluju na vodljive čestice, pa će se njihova putanja razlikovati od putanje nevodljivih čestica. Do separacije dolazi djelovanjem nekoliko sila (elektrodinamičke, gravitacijske i sile trenja). U radu su prikazani rezultati izdvajanja aluminija iz smjese metalnog otpada u magnetskom separatoru s vrtložmim strujama. Testiranje je izvedeno u pogonskim uvjetima. Rezultati pokazuju da je moguće postići iskorištenje korisne komponente od 99 % uz sadržaj aluminija u koncentratu od 89 %.
U ovoj studiji dajemo usporedbu dvije vrste separacije boja iz RGB (V - vizualno) digitalnog zapisa u CMYK bojila s kojima će se izvoditi tisak. Separacije su zasnovane s različitim premisama u ...primjeni, a namjenjene su svaka sa svojim specifičnim zadatkom što daje različite rezultate. Algoritmi koriste svojstva procesnih bojila CMY koje mijenjamo sa karbon crnim bojilom po metodi GCR. U CMYKIR separaciju ulazi dodatna nezavisna monokromatska slika nazvana „Z“. Ta slika sadrži željene vrijednosti za kanal/komponentu K. Sa uspješnom ugradnjom Z slike u K kanal, postignuti ćemo cilj da se ta Z slika manifestira, prepoznaje tek u NIR spektru. Z slika je skrivena od golog oka. U ovom članku objavljujemo model CMYKIR separacije preko regresijskih jednadžbi za primjenu u offsetnom tisku. Za nekoliko izabranih bojila sa testne fotografije, demonstriraju se vrijednosti današnje prakse GCR separacije u pet stupnjeva. Za ista bojila prikazali smo numeričke vrijednosti po CMYKIR modelu za Karbon crno bojilo pokrivenosti od 40%. Usporedili smo postojeće stupnjevite GCR modele s kontinuiranim izborom K vrijednosti u CMYKIR separaciji. Izabrane boje demonstriraju ograničenja i domenu moguće upotrebe CMYKIR separacije.
Razdoblje studiranja podudara se sa završetkom adolescentnog razvoja u kojem mladi rezolucijom procesa druge separacije – individuacije završavaju vlastitu tranziciju iz djetinjstva u odraslu dob. ...Posebnost toga životnog razdoblja određena je formiranjem odrasle osobnosti u kojem posebnu ulogu ima uspješnost suočavanja i ovladavanje iskustvima separacije. U skladu s time u tom razdoblju vrlo nepovoljno značenje imaju separacijska iskustva koja mogu potaknuti pojavu simbiotsko-ovisničkih potreba i s njima povezanih strahova. Nemogućnost suočavanja i ovladavanja tim iskustvima može dovesti do zastoja u razvoju mladih na putu njihova odrastanja, odnosno individualizacije. U prikazu slučaja može se dobiti uvid kako je iskustvo separacije, odnosno prekid emocionalne veze potaknuo regresivne tendencije i pojavu ovisnosti o kocki. U skladu s time prikazan je proces u kojem je ponovno pronalaženje objekta u „prijelaznom prostoru“ psihoterapijske seanse dovelo do ponovnog uspostavljanja narušene narcističke ravnoteže i time do mogućnosti suočavanja i ovladavanja ranim iskustvima gubitka koji su stajali na putu realizacije razvojnih zadataka definiranih procesom druge separacije – individuacije.
The aim of the thesis was the development and application of hybrid sorbents for determination of arsenic species in water and selective removal of arsenic from water. Water soluble arsenic species ...in natural water are inorganic (iAs) species, as arsenite, As(III) and arsenate, As(V). It is important to note that in neutral conditions, As(V) species are completely in ionic forms (H2AsO4 - and HAsO4 2-), while As(III) is in molecular form (H3AsO3 or HAsO2). This fact was the base for the application of anion exchange resin and selective hybrid resins for the separation, determenation and removal of iAs. As a result of anthropogenic pollution in water can be present organic (oAs) species as monomethylarsenic acid, MMAs(V) and dimethylarsenic acid, DMAs(V). Methods developed for iAs species should consider oAs species as interferences for the iAs determinations. In the frame of these tasks, efficiency of three types of resins were investigated: a strong base anion exchange (SBAE) resin and two hybrid (HY) resins, HY-Fe which integrates sorption activity of hydrated iron oxides (HFO) with the anion exchange function and HY-AgCl which integrates effects of chemical reaction with the anion exchange function. Two systems were employed: a batch and a fixed bed flow system. The selective bonding of arsenic species on three types of resins makes possible the development of the procedure for measuring and calculation of all arsenic species in water. In order to determine capacity of resins, the preliminary investigations were performed in batch system and fixed bed flow system. Resin capacities were calculated according to breakthrough points in a fixed bed flow system which is the first step in designing of solid phase extraction (SPE) module for arsenic speciation separation and determination. The investigations performed in the scope were focused on: I) separation of As(III) and As(V) species (in order to determine both arsenic species which are prevailing in natural waters), II) separation of organic arsenic species (in order to determine of DMAs(V) and MMAs(V) in natural waters) and III) collection, preconcentration and removal of all arsenic species. The main achievement of thesis is that three methods for arsenic species determination were developed. First method is a simple method for the separation and determination of iAs species in natural and drinking water which was the main task of the thesis. Procedures for sample preparation, separation of As(III) and As(V) species and preconcentration of the total iAs on fixed bed columns were defined. Two resins: SBAE and HY-Fe were utilized. The governing factors for the ion exchange/sorption of arsenic on resins in a batch and a fixed bed flow system were analyzed and compared. Acidity of the water, which plays an important role in the control of the ionic or molecular forms of arsenic species, was beneficial for the separation; by adjusting the pH values to less than 8.0, the SBAE resin separated As(V) from As(III) in water by retaining As(V) and allowing As(III) to pass through. The sorption activity of the hydrated iron oxides (HFO) particles integrated into the HY-Fe resin was beneficial for bonding of all iAs species over a wide range of pH values from 5.0 to 11.0. The resin capacities in flow system were calculated according to the breakthrough points and pH value of water 7.5. The SBAE resin bound 370 μg/g of As(V) while the HY-Fe resin bound 4150 μg/g of As(III) and 3500 μg/g of As(V). The high capacities and selectivity of the resins were considered as advantageous for the development and application of two procedures, one for the separation and determination of As(III) (with SBAE) and the other for the preconcentration and determination of the total arsenic (with HY-Fe resin). The analytical properties of first method developed for the separation and determination of iAs: the limit of detection, LOD, was 0.24 μg/L, the limit of quantification, LOQ, was 0.80 μg/L and the relative standard deviations, RSD %, for samples with a content of arsenic from 10.0 to 300.0 μg/L ranged from 1.1 to 5.8 %. Second method is a simple and efficient method for separation and determination of inorganic arsenic (iAs) and organic arsenic (oAs) in drinking, natural and wastewater. Three types of resins were used: SBAE, HY-Fe and HY-AgCl were investigated. The quantitative separation of molecular and ionic forms of iAs and oAs was achieved by SBAE and pH adjustment, the molecular form of As(III) that exists in the water at pH < 8.0 was not bonded with SBAE, which was convenient for direct determination of As(III) concentration in the effluent. The HY-Fe resin was convenient for the separation of DMAs(V) from all other arsenic species, which were retained on the HY-Fe resin that has a high sorption capacity for the arsenic species, 9000 μg/g. Efficiency of HY-Fe resin makes possible direct measurements of this specie in the effluent. HY-AgCl resin retained all iAs which was convenient for direct determination of oAs species concentration in the effluent, the relative standard deviation (RSD) was between 1.3-5.6 %. The third method is a simple and efficient method for separation and determination of dimethylarsenate DMAs(V). Two resins, SBAE and HY-Fe were tested. By simple adjusting pH value of water at 7.0, DMAs(V) passed through the HY-Fe column without any changes, while all other arsenic species (inorganic arsenic and monomethylarsenate, MMAs(V)) were quantitatively bonded on HY-Fe resin. The resin capacity was calculated according to the breakthrough points in a fixed bed flow system. At pH 7.0, the HY-Fe resins bonded more than 4150 μg/g of As(III), 3500 μg/g of As(V) and 1500 μg/g of MMAs(V). Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anions commonly found in natural water. DMAs(V) was determined in the effluent by inductively coupled plasma mass spectrometry (ICP-MS). The detection limit was 0.03 μg/L and relative standard deviation (RSD) was between 1.1-7.5 %. For the determination of arsenic in all arsenic species in water two analytical methods were applied: the inductively coupled plasma mass spectrometry (ICP-MS) and hydride generationatomic absorption spectroscopy (GH-AAS). Methods were established through basic analytical procedures (with external standards, certified reference materials and the standard addition method) and by the parallel analysis of some samples using the HG-AAS technique. Verification with certified reference materials proved that the experimental concentrations found for model solutions and real samples were in agreement with the certified values. ICPMS detection limit was 0.2 μg/L and relative standard deviation (RSD) of all arsenic species investigated was between 3.5-5.1 %. The interference effects of anions commonly found in water were found to be negligible. Both methods could be applied routinely for monitoring arsenic levels in various water samples (drinking water, ground water and wastewater).
Cilj izrade ove teze je razvoj i primena hibridnih smola kao sorbenata za određivanje i selektivno uklanjanje arsenovih vrsta u vodi. Arsenove vrste rastvorne i prisutne u prirodnoj vodi su neorganska jedinjenja arsena (iAs), arseniti As(III) i arsenati As(V). Bitno je naglasiti da se u neutralnim uslovima, As(V) nalazi u jonskom obliku (H2AsO4 - and HAsO4 2-), dok se As(III) nalazi u molekularnom obliku (H3AsO3 or HAsO2). Ova činjenica je osnova za primenu anjonskih, jonoizmenjivačkih smola i selektivnih hibridnih smola za razdvajanje i uklanjanje iAs. Kao rezultat antropogenog zagađivanja u vodi mogu da budu prisutne i vrste organskog arsena (oAs) kao što je monometilarsenova, MMAs(V) i dimetilarsenova kiselina, DMAs(V). Svaka metoda koja je razvijena za određivanje iAs mora da razmatra i reši problem prisustva oAs kao smetnji za određivanje iAs vrsta. U okviru postavljenih zadataka ispitana je efikasnost tri tipa smola: jako bazna anjonska smola (SBAE) i dve hibridne (HY), HY-Fe koja integriše sorpcionu aktivnost hidratisanog gvožđe oksida (HFO) sa anjonsko-izmenjivačkom funkcijom i HY-AgCl koja integriše efekte hemijske reakcije sa anjonsko-izmenjivačkom funkcijom. Ispitivanja su vršena u šaržnom i protočnom (s nepokretnim slojem) sistemu. U sklopu istaknutih zadataka i ciljeva, ispitivanja u okviru teze su bila fokusirana na: I) razdvajanje As(III) i As(V) vrsta (u cilju određivanja obe ove vrste čije prisustvo preovlađuje u prirodnim vodama), II) razdvajanje organskog arsena vrsta (u cilju određivanja obe ove DMAs (V) i MMAs (V) u prirodnim vodama) i III) sakupljanje, pretkoncentrisanje i uklanjanje svih arsenovih vrsta u vodi. Najvažniji doprinos ostvaren u izradi ove teze je razvoj tri metode za razdvajanje i određivanje arsenovih vrsta u vodi. Prva metoda predstavlja jednostavnu metodu za razdvajanje i određivanje iAs vrsta u prirodnim vodama i vodi za piće, što je i bio glavni zadatak u tezi. Definisani su postupci za pripremu uzoraka, za razdvajanje As(III) i As(V) vrsta, i za pretkoncentrisanje ukupnog sadržaja neorganskog arsena, iAs u protočnom sistemu, u koloni s nepokretnim slojem sorbenta. Ispitane su dve vrste smole: SBAE i HY-Fe. Definisani su i analizirani svi parametri šaržnog i protočnog sistema koji imaju najveći uticaj na jonsku izmenu i sorpciju arsena. Kiselost vode, koja igra vrlo važnu ulogu i u kontroli i prisustvu jonskih i molekulskih vrsta arsena u vodi, predstavlja važan faktor i za razdvajanju iAs arsena u vodi: podešavanjem pH vrednosti na vrednosti manje od 8,0, ostvaruje se mogućnost razdvajanja As(III) i As(V) vrsta: As(V) vrste se zadržavaju jer se nalaze u jonskom obliku, a As(III) vrste prolaze kroz kolonu bez zadržavanja jer se nalaze u molekulskom obliku. Sorpciona aktivnost čestica hidratisanog gvožđe-oksida (HFO) integrisanih u HY-Fe smolu bila je pogodna za vezivanje svih vrsta arsena u vodi, i to u širokom opsegu pH vrednos
U radu se istražuju razlike u učinkovitosti dokazivanja patogenih bakterija Salmonella Enteritidis, Listeria monocytogenes i Escherichia coli O157:H7 između konvencionalne kultivacije bakterija (ISO ...metoda) i imunomagnetne separacije (IMS metoda) u različitim vrstama mliječnih proizvoda s inicijalnim brojem bakterija. Različiti uzorci mliječnih proizvoda (mliječni puding - vanilija ili čokolada; mješavina jogurta i pudinga; čvrsti, tekući i voćni jogurt, AB kultura - sa ili bez voća; sirni namaz) namjerno su kontaminirani različitim brojem istraživanih bakterija (≈10 i ≈30 živih stanica po mL). Klasični ISO postupak pokazao se jednako adekvatnom metodom za uporabu u svrhu otkrivanja S. Enteritidis i L. monocytogenes u mliječnim proizvodima kao i IMS metoda. Međutim, ISO postupak pokazao se neučinkovitim za dokazivanje E. coli O157:H7 u slučajevima kada je početna kontaminacija bila niska (≈10 živih stanica po mL). U takvim slučajevima IMS metoda nije bila učinkovita niti na fermentiranim mliječnim proizvodima. Nasuprot nefermentiranim mliječnim proizvodima, fermentirani proizvodi još uvijek predstavljaju izazov za razvoj rutinske metode detekcije, osobito za S. Enteritidis, dok je detekcija L. monocytogenes i E. coli O157: H7 poboljšana uvođenjem IMS metode. Najveća razlika u efikasnosti dokazivanja patogenih bakterija u uzorcima mliječnih proizvoda, povezana s niskim početnim brojem bakterija u uzorku, pokazala se pri detekciji E. coli O157:H7. Dok izbor hranjive podloge (neselektivna tekuća hranjiva podloga, nasuprot selektivnoj tekućoj hranjivoj podlozi) ne igra važnu ulogu u primjeni IMS postupka pri otkrivanju S. Enteritidis i L. monocytogenes. U slučajevima dokazivanja E. coli O157:H7, uporaba modificiranog tripton-sojinog bujona s novobiocinom (mTSB + Nb) pokazala se učinkovitijom u usporedbi s uporabom puferirane peptonske vode (PPV). Dobiveni rezultati mogu biti od značaja kao znanstvena osnova za buduće određivanje standardnih metoda vezanih za laboratorijsko otkrivanje važnih patogena u mliječnim proizvodima.
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