Determination of rate and equilibrium adsorption mechanisms for fluoride removal from water on activated carbons with kinetic models and adsorption isotherms

Vode koje sadrže povišene koncentracije fluorida predstavljaju javnozdravstveni problem i prijetnja su za okoliš. Adsorpcija je jedna od najčešće korištenih metoda za uklanjanje fluorida iz vode. Stoga su u ovom radu ispitana adsorpcijska svojstva četiri komercijalna aktivna ugljena te njihovih modificiranih oblika dobivenih oksidacijom s HNO3 i H2O2. Ispitivanje adsorpcijskih svojstava svih adsorbensa obuhvaćalo je utjecaj početne koncentracije fluorida (2 – 40 mg/L), pH vrijednosti (4 – 9), vremena adsorpcije (15 – 360 minuta), koncentracije adsorbensa (2 – 20 g/L) i temperature (25 – 45 ºC). Rezultati istraživanja pokazali su smanjenje udjela adsorbiranih fluorida povećanjem njihove početne koncentracije dok je povećanje temperature pozitivno djelovalo na povećanje udjela uklonjenih fluorida. Najveća količina adsorbiranih fluorida ostvarena je pri pH vrijednostima od 4 do 6. S ciljem određivanja mehanizma adsorpcije primijenjene su Langmuirova, Freundlichova, Temkinova i Dubinin-Radushkevicheva izoterma pri čemu su eksperimentalni podaci pokazali najbolje slaganje s Freundlichovim modelom pri svim temperaturama dok je kinetičkim modelom pseudo-drugog reda najbolje opisana brzina adsorpcije. Povećanje temperature adsorpcije pozitivno je utjecalo na adsorpcijska svojstva aktivnih ugljena pri svim ispitanim parametrima. Iz dobivenih rezultata istraživanja može se zaključiti kako su ispitani komercijalni aktivni ugljeni, a posebice njihovi oksidirani oblici, pogodni za uklanjanje povišenih koncentracija fluorida iz vode.The water containing high fluoride ions could do harm to human and environment and the adsorption process is widely used method for the removal of fluoride. In this study, the applicability of four commercial activated carbons as adsorbents for the removal of excess fluoride from water was investigated. Activated carbons were also modified by liquid-phase oxidation using HNO3 and H2O2. Adsorption experiments were carried out at various initial fluoride concentration (2 – 40 mg/L), pH (4 – 9), time interval (15 – 360 minutes), adsorbent dose (2 – 20 g/L) and temperature (25 – 45ºC). The amount of fluoride adsorbed decreased with increasing initial fluoride concentration but increased with temperature increasing. The optimal pH for the adsorption was from 4 to 6. Adsorption isotherms have been modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and adsorption followed Freundlich isotherm model. From the results of various kinetic models, pseudo-second-order fit well with the fluoride adsorption kinetic conducted at different temperature. Study of temperature effect on fluoride adsorption confirmed the endothermic behavior of the process. As a result of this study, it was concluded that activated carbons and their oxidized forms are efficient adsorbent for the removal of fluoride. The ability of oxidized activated carbon to remove fluoride ions was greater than with non-oxidizing

Determination of rate and equilibrium adsorption mechanisms for fluoride removal from water on activated carbons with kinetic models and adsorption isotherms

Vode koje sadrže povišene koncentracije fluorida predstavljaju javnozdravstveni problem i prijetnja su za okoliš. Adsorpcija je jedna od najčešće korištenih metoda za uklanjanje fluorida iz vode. Stoga su u ovom radu ispitana adsorpcijska svojstva četiri komercijalna aktivna ugljena te njihovih modificiranih oblika dobivenih oksidacijom s HNO3 i H2O2. Ispitivanje adsorpcijskih svojstava svih adsorbensa obuhvaćalo je utjecaj početne koncentracije fluorida (2 – 40 mg/L), pH vrijednosti (4 – 9), vremena adsorpcije (15 – 360 minuta), koncentracije adsorbensa (2 – 20 g/L) i temperature (25 – 45 ºC). Rezultati istraživanja pokazali su smanjenje udjela adsorbiranih fluorida povećanjem njihove početne koncentracije dok je povećanje temperature pozitivno djelovalo na povećanje udjela uklonjenih fluorida. Najveća količina adsorbiranih fluorida ostvarena je pri pH vrijednostima od 4 do 6. S ciljem određivanja mehanizma adsorpcije primijenjene su Langmuirova, Freundlichova, Temkinova i Dubinin-Radushkevicheva izoterma pri čemu su eksperimentalni podaci pokazali najbolje slaganje s Freundlichovim modelom pri svim temperaturama dok je kinetičkim modelom pseudo-drugog reda najbolje opisana brzina adsorpcije. Povećanje temperature adsorpcije pozitivno je utjecalo na adsorpcijska svojstva aktivnih ugljena pri svim ispitanim parametrima. Iz dobivenih rezultata istraživanja može se zaključiti kako su ispitani komercijalni aktivni ugljeni, a posebice njihovi oksidirani oblici, pogodni za uklanjanje povišenih koncentracija fluorida iz vode.The water containing high fluoride ions could do harm to human and environment and the adsorption process is widely used method for the removal of fluoride. In this study, the applicability of four commercial activated carbons as adsorbents for the removal of excess fluoride from water was investigated. Activated carbons were also modified by liquid-phase oxidation using HNO3 and H2O2. Adsorption experiments were carried out at various initial fluoride concentration (2 – 40 mg/L), pH (4 – 9), time interval (15 – 360 minutes), adsorbent dose (2 – 20 g/L) and temperature (25 – 45ºC). The amount of fluoride adsorbed decreased with increasing initial fluoride concentration but increased with temperature increasing. The optimal pH for the adsorption was from 4 to 6. Adsorption isotherms have been modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and adsorption followed Freundlich isotherm model. From the results of various kinetic models, pseudo-second-order fit well with the fluoride adsorption kinetic conducted at different temperature. Study of temperature effect on fluoride adsorption confirmed the endothermic behavior of the process. As a result of this study, it was concluded that activated carbons and their oxidized forms are efficient adsorbent for the removal of fluoride. The ability of oxidized activated carbon to remove fluoride ions was greater than with non-oxidizing

Supplements and Down Syndrome

Down syndrome (DS) is one of the most common genetic disorders associated with a number of difficulties that are visible through the motor and cognitive development. Some theories claim that intake of supplements in very high doses could upgrade the physical and intellectual status of individuals with DS. Numerous papers have been published to support these theories, but at the same time, a great number of papers have warned of the risks of uncontrolled, excessive use of dietary supplements and asked for the proof of such claims by independent scientific studies. In this chapter, we will provide a review of the most commonly used supplements and major findings on this matter. Open access to information about the positive and negative sides of such supplementation is primarily important for guardians of people with DS in order to make the decision whether to use such preparations. It could also be an incentive for scientists to focus on the development of beneficial and safe therapies

The effect of fluoride in drinking water on health

Ovisno o koncentraciji u kojoj se nalaze, fluoridi prisutni u vodi za piće mogu imati pozitivan ili negativan učinak na ljudsko zdravlje. Prema preporuci Svjetske zdravstvene organizacije kao i Pravilnika o parametrima sukladnosti i metodama analize vode za ljudsku potrošnju (NN 125/2013, 141/2013, 128/2015) maksimalno dopuštena koncentracija fluorida u vodi za piće iznosi 1,5 mg/L. Koncentracija fluorida u površinskim i podzemnim vodama ovisi o pH vrijednosti vode, dostupnosti i topljivosti minerala bogatih fluoridima s kojima voda dolazi u doticaj, poroznosti stijena, brzini protjecanja vode i temperaturi. Drugi značajni izvori fluorida su industrije fosfatnih gnojiva koje mogu povisiti prirodnu koncentraciju fluorida u vodi, zatim proizvodnja kemikalija kao što su fluorovodična kiselina, kalcijev i natrijev fluorid te sumporni heksafluorid, proizvodnja opeke, keramike i stakla te korištenje pesticida koji sadržavaju fluoride. Kao posljedica konstantnog unosa u organizam vode koja sadrži koncentracije fluorida veće od maksimalno dopuštene dolazi do nastanka fluoroza koje se manifestiraju na različite načine. Procjenjuje se da je oko 200 milijuna ljudi diljem svijeta zahvaćeno nekim od oblika fluoroze. Cilj ovoda rada je detaljno prikazati utjecaj povišenih koncentracija fluorida u vodi za piće na zdravlje ljudi.Fluoride in drinking water presents a beneficial and a harmful effect on health. According to the World Health Organization and the Croatian legislation on water for human consumption, the maximum permissible concentration of fluoride in drinking water is 1.5 mg/L. The natural concentration of fluoride in water depends on several contributing factors, such as pH, total dissolved solids, porosity and acidity of the soil and rock, flow rate of water and temperature. Due to various ecological factors either natural or anthropologenic, the groundwater is getting polluted because of the deep percolation from intensively cultivated fields, the disposal of hazardous wastes, wastes from industries and sewage disposal. Depending upon the amount and period of ingestion, illnesses of varying degree, like dental fluorosis, skeletal fluorosis and non-skeletal fluorosis could occur. It is estimated that around 200 million people may be affected by fluorosis. The aim of this paper is to present the influence of a high fluoride amount in drinking water on human health

Tobacco production in the Republic of Croatia

Duhanu su se pripisivala mnoga svojstva, od toga da je „sveta biljka“, do toga da nije dobar za konzumaciju. Bez obzira na to, duhan ima tradiciju uzgoja otkako je otkriven Novi svijet. Obično se proizvodnja duhana povezuje s gospodarstvima država. I Republika Hrvatska ima višestoljetnu tradiciju uzgoja duhana. No, slabim subvencioniranjem uzgoja duhana proizvodnja stagnira, odnosno u blagom je padu; dok prirod raste.Tobacco has been attributed to many properties, from being a "sacred plant" to being not good for consumption. Nonetheless, tobacco has a tradition of cultivation as the New World was discovered. Usually, tobacco production is linked to the economies of the states. The Republic of Croatia also has a centuries-old tradition of growing tobacco. However, due to the weakly subsidization of tobacco production, production is stagnant, i.e. it is in a slight decline while the yield grows

MONITORING OF HONEY CONSUMPTION IN THE AREA OF THE CITY NAŠICE WITH REFERENCE TO THE HEALTH EFFECTS OF HONEY CONSUMPTION

There is a wide range of bee products on the market. The most famous and most accepted by consumers is honey. In Western European countries, the average consumption of honey per capita ranges from three to eight kilograms, while the average consumption of honey in Croatia is very low, 400 grams per capita. The European Union produces only 52% of honey for its own needs. The aim of the research was to study the availability of honey to potential consumers, honey consumption habits, ways of consuming honey, and knowledge of the properties of honey. A survey was conducted online. Respondents were of different genders and different age groups. The survey consisted of 20 questions, and 130 individuals (46% mean and 54% women) from the city of Našice were interviewed. The obtained data were analysed. After conducting research and processing the results, it can be concluded that honey is a product that is accepted by consumers of different age groups. Respondents believe that propolis has better healing properties than honey, but they rarely consume it. Honey is available and affordable to consumers

Adsorpcija fluorida iz vode na otpadnim materijalima

The occurrence and concentrations of fluoride in surface and groundwater depend on pH, total dissolved solids, alkalinity, hardness, and geochemical composition of aquifers. However, in many countries, elevated fluoride concentration values are the result of fluoride-contaminated wastewater discharges. Because of fluoride pollution and the health problems that it causes, the World Health Organization (WHO) has set a maximum permissible fluoride content in drinking water of 1.5 mg l–1. There are different ways of removing elevated concentrations of fluoride from water, such as coagulation and precipitation, membrane processes, electrochemical treatments, ion-exchange and its modification, but the adsorption process is generally accepted as the cheapest and most effective method for removing fluoride from water. Organic waste is increasing every day, especially in developed countries, and is generated in both industries and households. One of the ways to reduce such waste is the production of adsorbents for water defluorination. Adsorbents, most often prepared as activated carbon, can be obtained from various materials such as egg shells, fruit and vegetable peel, various leaves, stems, trunk bark, grain shells, legume shells, and many others. The aim of this paper is to provide an overview of the latest research on the use of adsorbents obtained from organic waste materials in order to remove elevated concentrations of fluoride from water.Pojavnost i koncentracije fluorida u površinskim i podzemnim vodama ovise o pH, ukupnoj otopljenoj krutoj tvari, alkalnosti, tvrdoći i geokemijskom sastavu vodonosnika, no u mnogim zemljama svijeta povišene vrijednosti koncentracije fluorida rezultat su ispuštanja otpadnih voda onečišćenih fluoridima. Zbog onečišćenja fluoridima i zdravstvenih problema koje ono uzrokuje Svjetska zdravstvena organizacija (WHO) odredila je najveći dopušteni sadržaj fluorida u pitkoj vodi od 1,5 mg l–1. Postoje različiti načini uklanjanja povišenih koncentracija fluorida iz vode, kao što su koagulacija i taloženje, membranski procesi, elektrokemijski tretmani, ionska izmjena i njezina modifikacija, ali je adsorpcijski proces općenito prihvaćen kao najjeftinija i najučinkovitija metoda. Količina organskog otpada svakim je danom sve veća, posebice u razvijenim zemljama, a stvara se kako u industriji tako i u kućanstvima. Jedan od načina smanjenja takvog otpada je proizvodnja adsorbensa za defluorizaciju vode. Adsorbensi, najčešće pripremljeni kao aktivni ugljen, mogu se dobiti od raznih materijala, kao što su ljuske jajeta, kore voća i povrća, razni listovi, stabljike, kora debla, ljuske žitarica, ljuske mahunarki i mnogi drugi. Cilj ovog rada je dati pregled najnovijih istraživanja o uporabi adsorbensa dobivenih iz organskog otpada za uklanjanje povišenih koncentracija fluorida iz vode

Utjecaj prorjeđivanja grozdova na kakvoću mošta kultivara Chardonnay u kutjevačkom vinogorju

Kutjevo wine-hills are located on southern slopes of Papuk and Krndija mountains. The area is the most famous by production of Graševina grapes, but increasing share of other varieties cannot be ignored. Chardonnay is the most widespread variety all over the world, and in Požeško-slavonska county is represented by 5 % of total vineyards area. The aim of this research was to determine the influence of cluster thinning in Kutjevo wine-hills on maturation and must quality of Chardonnay grapes. Research was conducted in 2020 in Podgorje location (Kutjevo wine-hills). Experiment was established by a randomized block schedule in two treatments with three repetitions. Five vines in a row makes one repetition. The following parameters have been determined: sugar content and total acidity in grapes in period of one month before harvest, number of clusters per vine, cluster mass, mass of 100 berries, density, total acidity, volatile acidity, tartaric acid, malic acid, lactic acid, pH, reducing sugars, extract, glucose, fructose, glycerol, alfa amino nitrogen, ammonia nitrogen and potassium. Results have showed that cluster thinning had a significant influence on cluster mass and number of clusters per vine, but majority of chemical parameters were not significantly different between two treatments. Statistically significant difference was only in case of pH, lactic acid and ammonium nitrogenVinogorje Kutjevo smješteno na južnim obroncima Papuka i Krndije najpoznatije je po uzgoju grožđa Graševina, međutim ne smije se zanemariti i sve veća zastupljenost ostalih sorti. Chardonnay je najraširenija vinska sorta u svijetu, a u Požeško-slavonskoj županiji zauzima oko 5 % površine vinogradarskih nasada. Cilj ovog rada bio je odrediti utjecaj prorjeđivanja grozdova u vinogorju Kutjevo na kinetiku dozrijevanja grozdova, te kakvoću mošta kultivara Chardonnay. Istraživanje je provedeno tijekom 2020. godine na lokalitetu Podgorje (vinogorje Kutjevo), a pokus je postavljen po slučajnom bloknom rasporedu u dva tretiranja po tri repeticije. Repeticiju čini pet trsova u nizu. Ispitivani su sljedeći parametri: udio šećera i ukupna kiselost u grožđu u periodu mjesec dana prije berbe, broj grozdova po trsu, prosječna masa grozdova, te masa 100 bobica. U moštu su određeni sljedeći parametri: gustoća, ukupna kiselost, hlapiva kiselost, vinska, jabučna i mliječna kiselina, pH, reducirajući šećeri, ekstrakt, glukoza, fruktoza, glicerol, alfa amino dušik, amonijačni dušik, te kalij. Prorjeđivanje grozdova je statistički značajno utjecalo na broj grozdova, masu grozdova, pH vrijednost, mliječnu kiselinu i amonijačni dušik, dok kod drugih analiziranih parametara nije bilo statistički značajne razlike između pokusnih varijanata

Water for all : Proceedings of the 7th international scientific and professional conference Water for all

The 7th International Scientific and Professional Conference Water for all is organized to honour the World Water Day by the Josip Juraj Strossmayer University of Osijek, European Hygienic Engineering & Design Group (EHEDG), Danube Parks, Croatian Food Agency, Croatian Water, Faculty of Food Technology Osijek, Faculty of Agriculture in Osijek, Faculty of Civil Engineering Osijek, Josip Juraj Strossmayer University of Osijek Department of Biology, Josip Juraj Strossmayer University of Osijek Department of Chemistry, Nature Park “Kopački rit”, Osijek- Baranja County, Public Health Institute of the Osijek- Baranja County and „Vodovod-Osijek“ -water supply company in Osijek. The topic of World Water Day 2017 was "Wastewater" emphasizing the importance and influence of wastewater treatments on global environment. The international scientific and professional conference Water for all is a gathering of scientists and experts in the field of water management, including chemists, biologists, civil and agriculture engineers, with a goal to remind people about the significance of fresh water and to promote an interdisciplinary approach and sustainability for fresh water resource management. The Conference has been held since 2011. About 300 scientists and engineers submitted 95 abstracts to the 7th International Scientific and Professional Conference Water for all, out of which 33 was presented orally and 62 as posters. 47 full papers were accepted by the Scientific Committee. 38 full papers became the part of the this Proceedings while 9 papers were accepted for publication in Croatian Journal of Food Science and Technology and Electronic Journal of the Faculty of Civil Engineering Osijek - e-GFOS

Prehrambeno–tehnološko inženjerstvo : priručnik za vježbe

Priručnik za vježbe iz Prehrambeno-tehnološkog inženjerstv