Aqueous extraction of anions from coal and fly ash followed by ion-chromatographic determination

Three different techniques were applied for the aqueous extraction of anions from coal and fly ash: rotary mixer-and ultrasonic-assisted extraction with different duration time, and microwave-assisted extraction at different temperatures. Validation showed that the ion-chromatographic method was suitable for the analysis of anions in coal and fly ash extracts. The variations in the amounts of anions using different extraction times during rotary-assisted extraction were minimal for all investigated anions. The efficiency of ultrasound-assisted extraction of anions from coal depended on the sonication time and was highest at 30 min. The ultrasound-assisted extraction was less efficient for the extraction of anions from fly ash than rotary-assisted extraction. Increase of temperature in the microwave-assisted extraction had a positive effect on the amounts of all anions extracted from coal and sulphate from fly ash, while the amounts of fluoride and chloride in fly ash extracts decreased. The microwave-assisted extraction of coal at 150 degrees C was compared with standard ASTM methods, and results were in good agreement only for chloride. Changes in the pH value and conductivity during ultrasound-assisted extraction were measured in order to explain changes on the surface of coal particles in contact with water and different processes that occur under environmental conditions

Comparison of sequential and single extraction in order to estimate the environmental impact of metals from fly ash

The aim of this paper is to simulate leaching of metals from fly ash in different environmental conditions using ultrasound and microwave-assisted extraction techniques. Single-agent extraction and sequential extraction procedures were used to determine the levels of different metals leaching. The concentration of metals (Al, Fe, Mn, Cd, Co, Cr, Ni, Pb, Cu, As and Be) in fly ash extracts were measured by inductively coupled plasma-atomic emission spectrometry. Single-agent extractions of metals were conducted at sonication times of 10, 20, 30, 40 and 50 min. Single-agent extraction with deionized water was also performed by exposing samples to microwave radiation at temperature of 50 degrees C. The sequential extraction was conducted according to the BCR procedure which was modified and applied to study the partitioning of metals in coal fly ash. The microwave-assisted sequential extraction was performed at different extraction temperatures: 50, 100 and 150 degrees C. The partitioning of metals between the individual fractions was investigated and discussed. The efficiency of the extraction process for each step was examined. In addition, the results of the microwave-assisted sequential extraction are compared to the results obtained by standard ASTM method. The mobility of most elements contained in the fly ash is markedly pH sensitive

Seasonal variations of concentrations of inorganic anions in atmospheric aerosols

8. Simpozijum "Hemija i zaštita životne sredine" sa međunarodnim učešćem : Knjiga izvoda ; 30. maj - 1. jun 2018; Kruševac, Srbija8th Symposium Chemistry and Environmental Protection with international participation : Book of Abstracts ; 30th May - 1st June 2018 ; Kruševac, Serbi

Improved electrochemical epoxidation of cholesterol and avarol dimethyl ether

Electrochemical epoxidation of cholesterol and avarol dimethyl ether with bromide as heteromediator was performed, and its mechanism discussed. The influence of the solvent, the mediator concentration, and different electrolytic techniques on yield of the products was examined. Under optimal conditions, the yield of the cholesterol epoxides (5α,6α and 5β, 6β) was 88%, and of the corresponding epoxides of the avarol dimethyl ether 72%

Improved electrochemical epoxidation of cholesterol and avarol dimethyl ether

Electrochemical epoxidation of cholesterol and avarol dimethyl ether with bromide as heteromediator was performed, and its mechanism discussed. The influence of the solvent, the mediator concentration, and different electrolytic techniques on yield of the products was examined. Under optimal conditions, the yield of the cholesterol epoxides (5α,6α and 5β, 6β) was 88%, and of the corresponding epoxides of the avarol dimethyl ether 72%

Investigation of different extraction procedures for the determination of major and trace elements in coal by ICP-AES and ion chromatography

This paper presents the extraction of major and trace elements from a coal sample, in deionized water, by using three different extraction techniques. Rotary mixing and ultrasonic extraction were examined for different extraction times, while the microwave-assisted extraction was performed at different temperatures. Metal concentrations (Na, K, Ca, Mg, Al, Fe, Mn, Be, Cd, Co, Cr, Hg, As, Ni, Se, Sb and Pb) in solution were determined employing inductively coupled plasma atomic emission spectrometry; whereas the results obtained for Na, K, Ca and Mg were compared employing ion chromatography. Comparing the rotary-and ultrasonic-assisted extractions, it was shown that the former technique was more efficient for the determination of Fe, Na and Pb, whereas the latter one proved more efficient for the determination of Co and Cr ions. Microwave-assisted extraction was shown to be the most efficient method for all the tested elements in coal. In addition, sequential extraction of the elements was realized using microwave digestion. The results of the sequential extraction experiments indicated associations of investigated elements with a mineral phase and organic matrix. Sequential extraction provided information on possible leaching of As, Cd, Co, Cr, Ni, Pb, Fe and Mn under environmental conditions

Ispitivanje adsorpcije fenola na makroporoznim polimernim adsorbensima

This work reports results on phenol adsorption from aqueous solution by porous copolymers based on glycidyl methacrylate: two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), were synthetized by suspension copolymerisation with ethylene glycol dimethacrylate. In addition, the two copolymer samples were functionalized with ethylene diamine. The amounts of adsorbed phenol were presented in the form of adsorptions isotherms, which were interpreted using Langmuir, Freundlich and Sips' equations. The first was found to express high level of agreement with experimental data. Phenol adsorption indicate the homogeneous distribution of active sites present on the investigated polymers. It was found that adsorption of phenol on copolymers is fast and depends on the presence of amino groups and on the pore size. From the obtained results, it was possible to distinguish macroporous polymer as a material which possesses the capacity for adsorption of phenol comparable to that of activated carbon.Ovaj rad se bavi proučavanjem adsorpcije fenola iz vodenih rastvora na kopolimerima različitih poroznih karakteristika i polarnosti. Korišćeni adsorbensi se baziraju na glicidil metakrilatu: dva uzorka makroporoznog poli(glicidil metakrilat-co-etilen glikol dimethakrilat) su sintetisani suspenzionom kopolimerizacijom sa etilen glikol dimetakrilatom. Dodatno, dva kopolimera su funkcionalizovani sa etilen diaminom. Količina adsorbovanog fenola je predstavljena u vidu adsorpcionih izotermi, koje su interpretirane korišćenjem Langmuir-ove, Freundlich-ove i Sips-ove jednačine: prva od ovih daje visok nivo slaganja sa eksperimentalnim podacima. Adsorpcija fenola ukazuje na homogenu raspodelu aktivnih mesta prisutnih u ispitivanim polimernim sistemima. Rezultati dobijeni u ovom istraživanju pokazuju da adsorpcija fenola na ispitivanim kopolimerima zavisi od prisustva amino grupa i od veličine pora. Adsorpcija fenola iz vodenih rastvora je brza u slučaju svih korišćenih adsorbenasa. Na osnovu dobivenih rezultata, može se zaključiti da su makroporozni polimeri materijali čije je adsorpcioni kapacitet za fenol uporediv sa onim koji ima aktivni ugalj

Određivanje katjona i metala u pivu i sirovinama za proizvodnju piva metodama jonske hromatografije (IC) i atomske apsorpcione spektrofotometrije (AAS)

In order to control the quality of beer and raw materials for beer production, methods as ion chromatography (IC) and atomic absorption spectrophotometry (AAS) were applied. Water was analyzed as a raw material for beer production (urban, technological and demineralized water). Measurements of pH values indicated the increased pH values in the sample of tehnological water, but it had no impact on wort hopping, since the tested samples of wort, young beer and final product had a pH value in the expected range. Analyzing the content of anions and cations in the examinated water samples, it is shown that the concentration of these examinated anions (Cl- , NO3-, SO42- and PO43-) and cations (NH4+, Na+, K+, Ca2+, Mg2+), as and microelements (Fe, Cu i Zn) are within the limits prescribed by the Regulations on hygienic safety of drinking water and the Regulations of quality and other requirements for beer. Investigating contents of anions in samples of wort and beer (young beer and final product) showed that the contents of SO42- and NO3- ions were within recommended limits and the concentration of Cl- ions was above 150 mg/dm3, which may have an impact on sensory characteristics of beer, while changes in the content of PO43- ions were insignificant. Since AAS method is a standard method for analyzing content of alkaline and alkaline earth metals, the results obtained by this method in beer samples are taken as a referent results and according to them an analyse was performed and results obtained by IC method were compared. Results of the determination of Na, Ca and Mg in examinated water samples have shown variations, but both methods have shown the increased content of Na in demineralized water. The contents of alkaline and alkaline earth metals in wort and beer (young beer and final product) have shown that the results obtained by these two methods were in agreement.U cilju kontrole kvaliteta piva i sirovina za proizvodnju piva u Beogradskoj industriji piva (BIP) primenjene su metode jonske hromatografije (IC) i atomske apsorpcione spektrofotometrije (AAS). Od sirovina za proizvodnju piva analizirana je voda (gradska, tehnološka i demineralizovana). Merenja pH vrednosti ukazala su na povećanu pH vrednost u uzorku tehnološke vode, ali to nije imalo uticaj na ukomljavanje slada pošto su ispitivani uzorci sladovine, kao i uzorci mladog piva i gotovog proizvoda imali pH vrednost u očekivanom opsegu. Analiza sadržaja anjona i katjona u ispitivanim uzorcima vode, pokazala je da je koncentracija ispitivanih anjona (Cl-, NO3 -, SO4 2- i PO4 3-) i katjona (NH4 +, Na+, K+, Ca2+, Mg2+), kao i mikroelemenata (Fe, Cu i Zn) u granicama propisanim Pravilnikom o higijenskoj ispravnosti vode za piće i Pravilnikom o kvalitetu i drugim zahtevima za pivo. Ispitivanje sadržaja anjona u uzorcima sladovine i piva (mladog i gotovog proizvoda) pokazalo je da je sadržaj SO4 2-- i NO3 --jona bio u preporučenim granicama, koncentracija Cl-- jona bila je iznad 150 mg/dm3, što može imati uticaj na senzorne karakteristike piva, dok je promena sadržaja PO4 3--jona bila neznatna. Pošto je AAS standardna metoda za analizu sadržaja alkalnih i zemnoalkalnih metala, rezultati dobijeni ovom metodom u uzorcima piva uzeti su kao referentni i prema njima je izvršena analiza i upoređivanje rezultata dobijenih metodom IC. Rezultati određivanja Na, Ca i Mg u ispitivanim uzorcima vode, pokazala su odstupanja, ali su obe metode ukazale na povećan sadržaj natrijuma u demineralizovanoj vodi. Sadržaj alkalnih i zemnoalkalnih metala u uzorcima sladovine i piva (mladog i gotovog proizvoda) ukazao je da su rezultati dobijeni ovim dvema metodama bili u saglasnosti

Arsenic removal from aqueous solutions by sorption onto zirconium- and titanium-modified sorbents

Arsenic reduction in drinking water can include treatment by adsorption, switching to alternative water sources, or blending with water that has a lower arsenic concentration. Commercial sorbents MTM, Greensand and BIRM (Clack Corporation) were modified with zirconium and titanium after activation. The modifications were performed with titanium tetrachloride and zirconium tetrachloride. The modified sorbents were dried at different temperatures. The sorption of arsenate and arsenite dissolved in drinking water (200μg L-1) onto the sorbents were tested using a batch procedure. After removal of the sorbent, the concentration of arsenic was determined by HG-AAS. Zirconium-modified BIRM showed the best performance for the removal of both arsenite and arsenate. Modification of the greensand did not affect arsenic sorption ability. Zirconium-modified BIRM diminished the concentration of total As to below 5 μg L-1

Primena klasičnih i instrumentalnih metoda analize u kontroli kvaliteta piva

In order to control the quality of beer and raw materials for production of beer in Belgrade Beer Industry (BIP), water is analyzed (city, technological and demineralized water). Measurements of pH values indicated the increased pH values in the sample of technological water, which had no impact on wort hopping, since the tested samples of wort, young beer and final product had a pH value within the expected range. After processing city water, a sample of technological water was found with increased carbonate hardness, which is caused by the increased content of sodium hydrogen carbonate. Analysing the titration alkalinity, titration acidity and buffering power, it was found that the alkalinity was decreasing which is in accordance with the determination of pH values of wort and beer samples (young beer and final product). Analyzing the content of anions and cations in the examined water samples, it has been shown that the concentration of these examinated anions (Cl-, NO3-, SO42- and PO43-) and cations (NH4+, Na+, K+, Ca2+, Mg2+) are within the limits prescribed by the Regulations on hygienic safety of drinking water, and thus by the Regulations of quality and other requirements for beer. The contents of anions in wort and beer samples (young beer and final product) were determined by ion chromatography method. The contents of sulphate and nitrate ions were within the recommended limits. The concentration of chloride ions was above 150 mg/dm3, which may have an impact on the sensory properties of beer, while changes in the content of phosphate ions were insignificant.U cilju kontrole kvaliteta piva i sirovina za proizvodnju piva u Beogradskoj industriji piva (BIP) analizirana je voda (gradska, tehnološka i demineralizovana). Merenja pH vrednosti ukazala su na povećanu vrednost pH u uzorku tehnološke vode, ali to nije imalo uticaja na ukomljavanje slada pošto su ispitivani uzorci sladovine, kao i uzorci mladog piva i gotovog proizvoda imali vrednost pH u očekivanom opsegu. Obradom gradske vode dobio se uzorak tehnološke vode sa povećanom karbonatnom tvrdoćom, koja je prouzrokovana povećanim sadržajem natrijum-hidrogenkarbonata. Analizom titracionog alkaliteta, titracionog aciditeta, i moći puferovanja, utvrđeno je da se alkalitet smanjuje što je u saglasnosti i sa određivanjem pH vrednosti uzoraka sladovine i piva (mladog i gotovog proizvoda). Analiza sadržaja anjona i katjona u ispitivanim uzorcima vode, pokazala je da je koncentracija ispitivanih anjona (Cl-, NO3-, SO42- i PO43-) i katjona (NH4+, Na+, K+, Ca2+, Mg2+) u granicama propisanim Pravilnikom o higijenskoj ispravnosti vode za piće, a time i sa Pravilnikom o kvalitetu i drugim zahtevima za pivo. Sadržaj anjona u uzorcima sladovine i piva (mladog i gotovog proizvoda) određen je metodom jonske hromatografije. Sadržaj sulfat- i nitrat-jona je bio u preporučenim granicama. Koncentracija hlorid-jona je bila iznad 150 mg/dm3, što može imati uticaja na senzorne karakteristike piva, dok je promena sadržaja fosfat-jona bila neznatna