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Ispitano je vezanje iona žive i kadmija na prirodnom zeolitu u prisustvu otopina Humistar ® i Fertireg ® koji su dodaci tlu u poljoprivredi. Utvrđen je veći stupanj uklanjanja iona žive i kadmija pri nižim početnim koncentracijama kao i niža količina iona vezana po gramu zeolita. Dodatak otopina Humistar ® i Fertireg ® ne utječe na stupanj uklanjanja žive kao i na količinu vezane žive po gramu zeolita. Utvrđeno je povećanje stupnja uklanjanja kadmija uz dodatak otopina Humistar ® i Fertireg ® i to je povećanje više izraženo uz veće koncentracije organske tvari. Također, količina vezanog kadmija po gramu zeolita raste uz dodatak otopina Humistar ® i Fertireg ® te se može zaključiti da organska tvar pozitivno utječe na remedijaciju tla onečišćenog kadmijem, dok na remedijaciju tla onečišćenog živom nema utjecaja pri ispitanim koncentracijama. The binding of mercury and cadmium ions on natural zeolite has been examined in the presence of Humistar ® and Fertireg ® solutions, which are soil additives in agriculture. A higher degree of removal of mercury and cadmium ions at lower initial concentrations was determined, as well as a lower amount of bound ions per gram of zeolite. The addition of Humistar ® and Fertireg ® solutions does not affect the efficiency of mercury removal as well as the amount of bound mercury per gram of zeolite. An increase in removal efficiency of cadmium is observed with the addition of Humistar ® and Fertireg ® solutions, and this increase is more pronounced with higher concentrations of organic matter. Also, the amount of bound cadmium per gram of zeolite increases with the addition of Humistar ® and Fertireg ® solutions, and it can be concluded that organic matter has a positive effect on the remediation of cadmium soil contaminated, while remediation of mercury soil contaminated has no effect at the examined concentrations.

Ispitana je mogućnost primjene prirodnog zeolita klinoptilolita kao punila u propusnim reaktivnim barijerama (PRB) za zaštitu podzemnih voda od onečišćenja teškim metalima. Za simuliranje dinamičkih uvjeta u podzemlju provedeni su eksperimenti u koloni na nepomičnom sloju prirodnog zeolita klinoptilolita propuštanjem binarne vodene otopine kadmija i cinka od vrha prema dnu kolone pri protocima od 1, 2, 3 i 4 mL/min. Iz dobivenih eksperimentalnih rezultata izračunati su koeficijent raspodjele (K d ) i koeficijent zadržavanja (R d ), kako bi se procijenio potencijal zeolita za sorpciju i zadržavanje kadmija i cinka u barijeri. Također su izračunati hidrodinamički koeficijent disperzije (D L ) i hidrodinamički disperzijski koeficijent zadržavanja (D LR ) u svrhu procjene utjecaja hidrodinamičke disperzije na širenje onečišćenja u podzemnoj vodi i zaobilaženje postavljenje barijere. Za sve ispitane protoke dobivene su veće vrijednosti K d i R d za kadmij nego za cink što upućuje na bolju raspodjelu i zadržavanje kadmija u sloju zeolita. Razlog tome je njegov manji hidratizirani ionski radijus u odnosu na cink, što mu omogućuje bolju pokretljivost, a time i vezanje na slobodna aktivna mjesta na zeolitu. Povećanjem protoka manja je razlika između K d i R d za kadmij i cink jer je uslijed kraćeg vremena kontakta kompeticijski efekt između kadmija i cinka manje izražen. Vrijednosti D L i D LR za oba iona rastu porastom protoka, povećavajući njihovo širenje u poroznom mediju uslijed hidrodinamičke disperzije, što u konačnici može dovesti do zaobilaženja postavljene barijere. Najbolja raspodjela i zadržavanje iona u zeolitnoj barijeri uz njihovo minimalno širenje postignuta je za najmanji protok otopine od 1 mL/min (0,01277 m/min) koji je od svih ispitanih protoka najbliži prosječnom protoku podzemne vode (≈ 0,00003 m/min). Dobiveni rezultati ukazuju na mogućnost primjene prirodnog zeolita klinoptilolita kao punila u propusnim reaktivnim barijerama u svrhu zaštite podzemnih voda od onečišćenja teškim metalima. The possible application of natural zeolite clinoptilolite as filler in permeable reactive barriers (PRBs) for protection of groundwater from contamination by heavy metals were investigated. For simulation of underground dynamic conditions for the column experiments on the fixed natural zeolite layer were performed by passing the binary aqueous solution of cadmium and zinc through the column by down-flow mode at flow rates of 1, 2, 3 and 4 mL/min. From the obtained column results the distribution coefficient (K d ) and retardation coefficients (R d ) were calculated in order to estimate the zeolite potential in sorption and retardation of cadmium and zinc in the barrier. The hydrodynamic dispersion coefficient (D L ) and hydrodynamic dispersion retardation coefficient (D LR ) were calculated as well in order to estimate the impact of the hydrodynamic dispersion on the contaminant plume and possible bypassing of the barrier. For all flow rates tested, the highest values of K d and R d were obtained for cadmium compared to zinc, pointing on better distribution and retardation od cadmium in zeolite layer. The reason for that is smaller hydrated ionic radius of cadmium than zinc, making it more mobile, and thus easier to bind on free active zeolite sites. With increasing in flow rate the difference between the K d and R d of cadmium and zinc is lower due to the shorter contact time at which to competition effect is less pronounced. The D L and D LR values for both ions increase with increasing in flow rate, thus increasing their spreading in the porous media caused by hydrodynamic dispersion, which at the end leads to bypassing of the barrier. The best distribution and immobilization of the ions inside the zeolite barrier, alongside their minimum spreading is achieved for the lowest flow rate of 1 mL/min (0.01277 m/min) which, among all tested flow rates, is the closest to the average flow of the groundwater (≈ 0.000003 m/min). The obtained results pointing on possible application of the natural zeolite clinoptilolite as filler in permeable reactive barriers for protection of groundwater from heavy metals pollution.

Glukozinolati su sekundarni metaboliti koji se sintetiziraju iz aminokiselina. Identificirani su u preko 16 biljnih porodica, a najznačajnija je porodica Brassicaceae u koju se ubraja biljka Lepidium sativum L. Glukozinolati su kemijski i biološki neaktivni spojevi te im je zajedničko da su po kemijskoj strukturi β- tioglukozidni-N-hidroksisulfati s varijabilnim bočnim lancem. Kres salata (Lepidium sativum L.) je jednogodišnja kultura koja sadrži mnoge ljekovite tvari, ali je u ljudskoj prehrani slabo rasprostranjena. Navodi se da je kres salata dobar hiperakumulator teških metala. Biljke nemaju potrebu za kadmijem i uglavnom ne podnose koncentracije veće od 1 ppm, no navedena biljka može akumulirati kadmij u tkivima i tolerirati koncentraciju do 100 ppm. U ovom radu opisan je uzgoj biljke Lepidium sativum L. koji je zalijevan s otopinama kadmija različitih koncentracija od 1 do 50 ppm. Razvoj klica praćen je tijekom 7 dana i jedino pri koncentraciji od 50 ppm došlo je do propadanja biljke. Izolacija glukozinolata se vršila ekstrakcijom uz pomoć 70%-tnog metanola uz desulfataciju, dok se analiza vršila vezanom tehnikom UHPLC-DAD-MS/MS. Identificirani su sljedeći glukozinolati: glukotropeolin koji se nalazi u svim uzorcima i 4-metoksiglukobrasicin koji nije pronađen jedino u sjemenu. Glukotropeolin spada u skupinu arilalifatskih, dok 4-metoksiglukobrasicin pripada skupinu heterocikličnih (indolnih) glukozinolata. Sadržaj glukozinolata, s obzirom na to da su se uzorci zalijevali otopinama kadmija različitih koncentracija, nije se značajno mijenjao. U radu je također opisana priprema biljnog materijala za analizu atomskom apsorpcijskom spektroskopijom. Prije početka analiziranja potrebno je napraviti krivulju umjeravanja, zato što se preko nje iščitavaju koncentracije kadmija u biljnom materijalnu. Na temelju dobivenih rezultata izvodi se zaključak da li se biljka Lepidium sativum L. može koristiti kao hiperakumulator kadmija. Glucosinolates are secondary metabolites that are synthesized from amino acids. They were found in over 16 plant families, the most important being the Brassicaceae family, which includes the plant Lepidium sativum L. Glucosinolates are chemically and biologically inactive compounds and have in common that they are chemically β-thioglucoside-N-hydroxysulfates with a variable side chain. The Lepidium sativum L. plant is an annual crop that contains many medicinal substances, but is poorly used in the human diet. Cress salad is known to be a good hyperaccumulator of heavy metals. Plants do not need cadmium and generally do not tolerate concentrations higher than 1 ppm, but this plant can accumulate cadmium in tissues and tolerate concentrations up to 100 ppm. This thesis describes the cultivation of the plant Lepidium sativum L., which was watered with cadmium solutions of different concentrations from 1 to 50 ppm. Sprouts development was monitored for 7 days and only at a concentration of 50 ppm did the plant decay. Isolation of glucosinolate was performed by extraction with 70% methanol with desulfation, while the analysis was performed using UHPLC-DAD- MS/MS. The following glucosinolates were identified: glucotropeolin was found in all samples and 4- methoxyglucobrasicin which was not found only in seeds. Glucotropeolin belongs to the group of arylaliphatic, while 4-methoxyglucobrasicin belongs to the group of heterocyclic (indole) glucosinolates. The glucosinolate content, since the samples were watered with cadmium solutions of different concentrations, did not change significantly. The thesis also describes the preparation of plant material for analysis by atomic absorption spectroscopy. Before starting the analysis, it is necessary to make a calibration curve because the cadmium concentrations in the plant material are read through it. Based on the obtained results, it was concluded that the plant Lepidium sativum L. can be used as a hyperaccumulator of cadmium.

Ispitano je uklanjanje kadmijevih i cinkovih iona na nepomičnom sloju prirodnog zeolita iz vodene otopine (Cd+Zn) koncentracijskog omjera Cd/Zn od 0,13 i 0,14, pri protocima od 1 i 2 mL/min. Prirodni zeolit klinoptilolit pokazao je dobru učinkovitost u uklanjanju Cd i Zn iona iz binarnog sustava pri ispitanim eksperimentalnim uvjetima. Dobiveni rezultati uspoređeni su s binarnim sustavom (Pb+Zn) za iste eksperimentalne uvjete. Utvrđen je efekt istiskivanja iona Zn iz strukture zeolita ionima Cd i Pb iz početne otopine. Zn je prekoračio svoju početnu koncentraciju za 1,2 puta u prisutnosti Cd te čak 2,3 puta u prisutnosti Pb. Efekt istiskivanja u sustavu (Pb+Zn) može se pripisati puno manjem hidratiziranom radijusu iona Pb u odnosu na ion Zn, a time i njegovu većem afinitetu. Istiskivanje u sustavu (Cd+Zn) bilo je iznenađujuće zbog vrlo sličnih fizikalno-kemijskih svojstava tih dvaju iona. Pri Cd/Zn = 0,14 te Pb/Zn = 0,19 i protoku od 1 mL/min u oba sustava utvrđeno je bolje vezanje iona Zn u odnosu na ione Cd i Pb, unatoč njegovu slabijem afinitetu. Tor ukazuje da je moguće preferencijalno vezanje iona Cd i Pb kontrolirati početnom koncentracijom iona Zn u binarnom sustavu. Ukupni koeficijent prijenosa tvari veći je za (Cd+Zn) nego za (Pb+Zn) sustav zbog manje izražene kompeticije i migracije iona, a time i manjeg otpora. Najsporiji stupanj je difuzija kroz film te ona kontrolira ukupnu brzinu procesa. The removal of cadmium and zinc ions onto fixed zeolite bed from (Cd+Zn) aqueous solution for the Cd/Zn concentration ratios of 0.13 and 0.14, and for the flow rates of 1 and 2 mL/min has been investigated. The natural zeolite clinoptilolite showed good efficiency in Cd and Zn removal from binary system, for examined experimental conditions. The obtained results have been compared with the (Pb+Zn) binary system for the same experimental conditions. The displacement of Zn ions from the zeolite structure by the Cd and Pb ions from the initial solution has been determined. The Zn exceeded its initial concentration up to 1.2 times in the presence of Cd, and up to 2.3 times in the presence of Pb. The displacement effect in the (Pb+Zn) system can be attributed to the much smaller hydrated radius of Pb ion, compared to the Zn ion, and thus to its higher affinity. The displacement in the (Cd+Zn) system was quite surprising due to very similar physicochemical properties of these two ions. In both systems, for Cd/Zn = 0.14 and Pb/Zn = 0.19 for flow rate of 1 mL/min, the better binding of Zn compared to Cd and Pb has been obtained despite its lower affinity. This is of great importance because it indicates that it's possible to control preferencial binding of Cd and Pb ions by the initial Zn ion concentration in binary systems. The overall mass transfer coefficient shows higher values for the (Cd+Zn) system compared to the (Pb+Zn) system, due to the reduced competition, ions migration and thus the lower resistance. The diffusion through the film is the slowest step responsible for the overall process rate.

U ovom završnom radu su određivane koncentracije teških metala, olova i kadmija, u realnim uzorcima meda i šećera. Na elektrodi od staklastog ugljika (GC) kronamperometrijski je formiran film hidroksiapatita (HAp) te su pomoću voltametrijskih metoda (ciklička voltametrija, pravokutnovaln a voltametrija) ispitane njegove osobine te primjena za određivanje koncentracije teških metala (olova i kadmija). Prilikom mjerenja korištene su tri elektrode: radna elektroda (GC elektroda), referentna elektroda (Ag/AgCl) i prouelektroda (platinska žica). Hidroksiapatit posjeduje veliku poroznost te sposobnost prihvaćanja drugih iona kao supstituenata. Nanošenjem ovog filma, elektrodi je povećavana osjetljivost te granica detekcije do jako niskih koncentracija teških metala. Izmjerena i određena koncentracija u šećeru za Pb iznosila je 823,7 μg/kg, dok je koncentracija izmjerena za Cd iznosila 860,0 μg/kg. Izmjerena i određena koncentracija u medu za Pb iznosila je 4410,0 μg/kg, dok je koncentracija izmjerena za Cd iznosila 387,4 μg/kg. Određene koncentracije za olovo i kadmij u oba realna uzorka premašuju vrijednosti koje su propisane Pravilnikom kao dozvoljene koncentracije tih teških metala u medu i šećeru. In this bachelor thesis, concentrations of heavy metals (Pb and Cd) are determined in real samples of sugar and honey. Hydroxyapatite (HAp) film was chronoamprometrically formed on the glassy carbon (GC) electrode and voltammetric methods (cyclic voltammetry, square wave voltammetry) were used for testing its properties and for determination of the concentrations of heavy metals (Pb and Cd). Three electrodes were used during the measurement: working electrode (GC electrode), reference electrode (Ag/AgCl) and counterelectrode (platinum wire). Hydroxyapatite has great porosity and ability to accept other ions as substituens. The presence of HAp increased the sensitivity and capacit y of GC electrode for the determination of heavy metals accurately at very low level. The concetration that we determined in sugar for the Pb is 823,7 μg/kg, while the concentration that we determined in sugar for the Cd is 860,0 μg/kg. The concentration that we determined in honey for the Pb is 4410,0 μg/kg, while the concentration that we determined in honey for the Cd is 387,4 μg/kg. The resulting concentrations of lead and cadmium in both real samples exceed the values prescribed by the Ordinance as permissible concentrations of these heavy metals in honey and sugar.

Ispitan je proces uklanjanja kadmija i cinka postupkom u koloni iz binarne ekvimolarne vodene otopine ukupne početne koncentracije c o (Cd+Zn) ≈ 1 mmol/L pri protocima od Q = 1, 2 i 3 mL/min. Provedena su tri radna ciklusa i tri ciklusa regeneracije na istom uzorku zeolita visine sloja od 8 cm. Iz eksperimentalnih rezultata nacrtane su krivulje proboja i krivulje regeneracije, izračunati su karakteristični parametri te je utvrđena učinkovitost procesa. Povećanjem protoka otopine proboj i iscrpljenje se pojavljuju ranije, smanjuje se kapacitet zeolita i efikasnost kolone. Prirast ukupne količine (Cd+Zn) iona vezanih na zeolitu linearno raste od početka eksperimenta nakon čega se počinje smanjivati (točka infleksije) što ukazuje na promjenu mehanizma koji kontrolira ukupnu brzinu procesa. Primjenom Advekcijsko-disperzijsko-reakcijskog modela (ADR) izračunat je koeficijent aksijalne disperzije, D L , pomoću kojega je izračunat koeficijent prijenosa tvari, k f kroz difuzijski granični sloj čestice zeolita. Utvrđeno je da je utjecaj aksijalne disperzije izraženiji za veće protoke otopine kroz sloj jer otopina zaobilazi dio čestica u zeolitnom sloju zbog nedovoljnog kontakta između otopine i zeolita. Najveća vrijednost k f utvrđena je u točki proboja, a zatim opada prema točki iscrpljenja uslijed povećanja debljine difuzijskog graničnog sloja. Do područja infleksije brzinu procesa kontrolira prijenos tvari konvekcijom u tekućoj fazi, a nakon infleksije prijenos tvari difuzijom kroz česticu. Povećanjem protoka može se obraditi veći volumen otopine u kraćem vremenu, međutim protok postaje ograničavajući faktor jer uslijed njegova povećanja dolazi do pojave aksijalne disperzije koja dovodi do smanjenja efikasnosti kolone. Removal of cadmium and zinc from equimolar binary aqueous solution of total initial concentration of c o (Cd+Zn) ≈ 1 mmol/L has been investigated using the column process at the flow rates of Q = 1, 2 and 3 mL/min. Three service and three regeneration cycles were performed on the same zeolite bed with height of 8 cm. The experimental results are shown by breakthrough and regeneration curves, and the characteristic parameters have been calculated as well as removal efficiency. By increasing in flow rate, the breakthrough and exhaustion points occured earlier, while zeolite capacity and column efficiency decreased. The quantity of (Cd+Zn) ions increases linearly from the beginning of the experiment, after that decrease (inflection point) indicating a change in mechanism which controls the overall process rate. The Advection-Dispersion-Reaction (ADR) model was applied for calculation of the axial dispersion coefficient, D L from which the mass transfer coefficient, k f , through the diffusion boundary layer has been calculated. The impact of axial dispersion is more pronounced for higher flow rates because of the solution bypassing some of the zeolite particles due to insufficient contact between the solution and the zeolite layer. The highest value of k f is observed in the breakthrough point, and then decreases to the exhaustion point due to increase in thickness of diffusion boundary layer. Up to inflection, the mass transfer by convection through the liquid phase controls the overall procces rate, and after that the mass transfer by diffusion through the boundary layer of the zeolite particle. By increasing in flow rate a larger volume of the solution can be treated in a shorter time, but the flow of the solution becomes a limiting factor because with its increase, an axial dispersion occurs which consequently results in a reduction of column efficiency.

U ovom radu je analizirana primjena „low cost“ sorbenata kao materijala za permeabilnu reaktivnu barijeru (PRB) za uklanjanje kadmija iz oneĉišćene vode primjenom šarţnog postupka. Analiziran je proces zasićivanja prirodnog zeolita, kemijski modificiranog zeolita, apatita, koncentriranog apatita, kaolina i bentonita sa kadmijevim ionima kao i proces desorpcije zasićenih uzoraka u otopinama ultraĉiste vode razliĉitih poĉetnih pH vrijednosti. Rezultati pokazuju najveću sposobnost vezanja iona kadmija na kemijski modificirani zeolit i bentonit. MeĊutim, zbog desorpcije kadmijevih iona na bentonitu pri pH vrijednosti 6,07, kemijski modificirani zeolit se odabire kao potencijalni materijal za uklanjanje kadmija u permeabilnoj reaktivnoj barijeri. In this paper, the use of “low cost'' sorbents as the material for permeable reactive barrier (PRB) for the removal of cadmium from contaminated water by applying the batch process has been analysed. The process of saturation of natural zeolite, chemically modified zeolite, apatite, concentrated apatite, kaolinite and bentonite with cadmium ions has been analysed as well as the process of desorption of saturated samples in ultra pure water solution with different initial pH values. The results have indicated the highest ability to bind cadmium ions show chemically modified zeolite and bentonite. However, due to desorption of cadmium ions from bentonite at 6.07 pH value, chemically modified zeolite is selected as a potential material for the removal of cadmium ions in permeable reactive barrier.

Ispitano je uklanjanje Cd i Zn iona postupkom u koloni iz binarne vodene otopine ukupne početne koncentracije c o (Cd+Zn) ≈ 1 mmol/L, a koncentracijskog omjera kadmija i cinka Cd/Zn = 1,93. Radni ciklus proveden je propuštanjem otopine s vrha prema dnu kolone kroz nepomičan sloj zeolita visine H = 8 cm pri stalnom protoku od Q = 1 mL/min. Tijek radnog ciklusa pratio se određivanjem koncentracije Cd i Zn iona te pH vrijednosti u efluentu. Nakon radnog ciklusa provedena je regeneracija sloja zeolita otopinom NaNO 3 c = 176,5 mmol/L, uz iste radne uvjete. Rezultati su prikazani krivuljama proboja i krivuljama regeneracije, iz kojih su određene točka proboja, točka iscrpljenja, završetak regeneracije te su izračunati karakteristični parametri: kapacitet u točki proboja, kapacitet u točki iscrpljenja, efikasnost kolone te stupanj regeneracije. Proboj je postignut nakon ≈ 44 h pri čemu je obrađeno ≈ 2,7 L binarne otopine, a do točke proboja Cd i Zn ioni vezali su se istovremeno. Iscrpljenje je postignuto nakon ≈ 65 h do kada je obrađeno ≈ 3,9 L binarne otopine. Koncentracija Cd u efluentu neznatno prelazi njegovu koncentraciju u influentu, dok je koncentracija Zn znatno veća od one u influentu, što ukazuje na efekt istiskivanja već vezanih Zn iona iz strukture zeolita ionima Cd iz otopine. Ovo nije očekivano budući da Cd i Zn ioni imaju slična fizikalna svojstva kao hidratizirani ionski radijus, elektronegativnost i energiju hidratacije. Razlog istiskivanja može se pripisati većoj koncentraciji Cd iona u početnoj otopini, u odnosu na koncentraciju Zn iona, što znači da se promjenom koncentracije iona u influentu može utjecati na količinu vezanih iona u radnom ciklusu. Prema rezultatima ciklusa regeneracije veća je količina eluiranih Cd nego Zn iona, što potrđuje da se u strukturi zeolita vezalo više Cd. Potpuna regeneracija sloja zeolita završena je već nakon ≈ 5 h pri čemu je utrošeno svega 0,31 L otopine NaNO 3 . Visoki stupanj regeneracije α R ukazuje na uspješno provedenu regeneraciju čime je omogućeno ponovno korištenje istog sloja zeolita u novom radnog ciklusu, što je od izuzetne važnosti za primjenu u praksi. The removal of Cd and Zn ions by column method from binary aqueous solution with total initial concentration c o (Cd+Zn) ≈ 1 mmol/L, and with concentration ratio Cd/Zn = 1.93 has been investigated. Service cycle has been performed by passing the feeding solution from the top to the bottom of the column through the fixed zeolite bed of height H = 8 cm at a constant flow rate of Q = 1 mL/min. After service cycle, the regeneration of zeolite bed has been performed at the same experimental conditions with NaNO 3 solution of c = 176.5 mmol/L. The progress of the service and regeneration cycles was tracked by measuring the Cd and Zn concentrations and pH values in the effluents. The results are shown by breakthrough and regeneration curves from which the breakthrough and exhaustion points and the end of regeneration have been determined, as well as the characteristic parameters have been calculated: breakthrough and exhaustion capacities, removal efficiency, and the degree of regeneration. The breakthrough has been obtained after ≈ 44 h when ≈ 2.7 L of binary solution has been treated, and until breakthrough the Cd and Zn ions bound simultaneously. The exhaustion has been achieved after ≈ 65 h when ≈ 3.9 L of binary solution has been treated. The concentration of Cd in the effluent slightly exceeds its influent concentration, while Zn concentration is considerably higher than its influent concentration. This indicates the displacement of already bound Zn in zeolite structure by Cd from the feeding solution. This behaviour has not been expected since Cd and Zn ions have similar physical properties such as hydrated ionic radius, electronegativity and energy of hydration. The reason of displacement can be attributed to the higher inlet Cd concentration, compared to Zn. This means that changing the inlet concentration can affect the amount of bound ions in the service cycle. According to the results of the regeneration cycle the amount of eluted Cd is greater compared to Zn, which confirms that the zeolite structure bound more Cd. The regeneration of zeolite layer has been completed after ≈ 5 h wherein only 0.31 L of NaNO 3 solution was spent. The high degree of regeneration α R indicates a successfully performed regeneration. This enables for reuse the same zeolite layer in a new service cycle, which is extremely important for practical application.

U ovom radu, analizirana je primjena modificiranog zeolita kao materijala za permeabilnu reaktivnu barijeru (PRB) za uklanjanje kadmija i bakra iz onečišćenih voda primjenom šaržnog postupka. Uspoređene su količine vezanog bakra i kadmija na modificiranom zeolitu te izračunati koeficijenti raspodjele (K d ) i koeficijenti zadržavanja (R d ) metalnih iona na zeolitu. Također su uspoređene količine zadržavanja metalnih iona na zeolitu nakon desorpcije zasićenog zeolita u ultračistoj vodi različitih početnih pH vrijednosti te pH vrijednosti suspenzija tijekom desorpcije. Rezultati pokazuju da modificirani zeolit može biti upotrijebljen kao materijal za PRB u području pH = 4-9 jer ima veliku sposobnost vezanja i zadržavanja iona bakra i kadmija te puferska svojstva u suspenziji. In this paper, application of modified zeolite as a material for permeable reactive barrier (PRB) for copper and cadmium removal from polluted water was evaluated using batch mode. Amounts of copper and cadmium removal on modified zeolite were compared and the distribution and retardation coefficients (K d and R d ) were calculated. In addition, amounts of metal retaining by zeolite after desorption of metal-saturated zeolite in ultrapure water of different initial pH values were compared as well as pH values of suspensions during desorption test. Results showed that modified zeolite could be used as material for PRB in pH range 4-9 since it efficiently retained metal ions and showed buffering abilities in suspensions.

Provedena je kemijska modifikacija prirodnog zeolita (PZ) porijeklom iz Vranjske Banje s vodenom otopinom Fe(NO3)3 u acetatnom puferu pri pH=3,6 te s otopinom NaOH i NaNO3. Dobiveni Fe(III)-modificirani zeolit (FeZ) pokazao je 3-4 puta veći kapacitet vezivanja cinka i kadmija u odnosu na prirodni. Modifikacijom nije došlo do promjena u strukturi i mineraloškom sastavu, a povećao se volumen pora i količina natrijevih iona kao rezultat ionske izmjene i neutralizacije negativnog naboja nastalog tijekom modifikacije. Upravo povećana količina natrijevih iona povećava kapacitet FeZ prema ionima cinka i kadmija. Ispitan je utjecaj pH i koncentracije otopine metalnih iona, veličine čestica i mase zeolita izražene preko S/L omjera (engl. soli/ liquid), te vremena kontakta zeolit-otopina na vezivanje cinka i kadmija na PZ i FeZ. Ravnotežni rezultati za različite koncentracije otopina cinka i kadmija i dvije veličine čestica PZ i FeZ su testirani prema izotermnim modelima: Langmuir, Freundlich, Temkin, Dubinin-Radeuskevich, Sips, Toth i Hill. Dimenzijskom analizom dobile su se vrijednosti ravnotežnih parametara koji su neovisni o S/L omjeru i početnim koncentracijama. Kinetički rezultati su testirani prema reakcijskim (Lagergren-ov model pseudo prvog reda i Ho-ov model pseudo drugog reda) i difuzijskim kinetičkim modelima (Dvostruko-eksponencijalni, Weber-Morris, Bangham, Vermeulenova aproksimacija i Model difuzije kroz laminarni film). Ustanovljeno je da je difuzija kroz česticu najsporiji stupanj koji odreñuje brzinu procesa. Iz izračunatih parametara modela dobivene su modelne krivulje ovisnosti količine vezanog metalnog iona po gramu zeolita o vremenu. Dvostruko-eksponencijalni model i model prema Vermeulen-ovoj aproksimaciji pokazali su slaganje u cijelom ispitivanom vremenskom intervalu te su odabrani za predviñanje količine vezanja cinka i kadmija za proizvoljno odabranu početnu koncentraciju. Ispitivanjem desorpcije cinka i kadmija iz zasićenih uzoraka modificiranih zeolita u ultračistoj vodi različitih početnih pH, utvrñeno je da ne dolazi do desorpcije cinka i kadmija, dok je desorpcija značajna u otopinama NaCl, NaNO3 i KCl. Tijekom četiri uzastopna ciklusa zasićivanja i regeneracije iste mase FeZ nije došlo do smanjenja kapaciteta što ukazuje na izvrsna sorpcijsko-regeneracijska svojstva FeZ. Chemical modification of natural zeolite (NZ) originated from the Vranjska Banja deposit has been performed with the aqueous solution of Fe(NO3)3 at pH=3.6 and with NaOH and NaNO3 solutions. Fe(III)-modified zeolite (FeZ) has shown 3-4 times higher capacity towards cadmium and zinc compare to the natural zeolite. The modification did not cause changes in the structure and mineralogical composition, but it increased the pore volume and the amount of sodium as a result of ion exchange and neutralization of the negative charge created during the modification. The increased sodium content is responsible for the higher removal capacity of FeZ toward zinc and cadmium. The effect of pH and concentration of the metal ions solution, the particle size and the mass of zeolite expressed by S/L ratio (solid/liquid), and the contact time of zeolite-solution, on zinc and cadmium removal on NZ and FeZ have been investigated. Equilibrium results for different concentrations of Zn and Cd and two particle sizes of NZ and FeZ have been tested according to the isothermal models: Langmuir, Freundlich, Temkin, Sips, Toth, DubininRadeuskevich and Hill. The dimensional analysis has been applied and equilibrium parameters which are independent of S/L ratio and the initial concentrations have been obtained. Kinetic results were tested according to the reaction kinetic model (Lagergren's pseudo-first-order and Ho's pseudo-second-order) and diffusion kinetic models (Doubleexponential, Weber-Morris, Bangham, Vermeulen's approximation and diffusion through the laminar film). It has been found that the diffusion through the particle is the rate limiting step of process. The model curves for metal ions uptake per gram of zeolite vs. time were obtained from the calculated parameters of the models. It has been found that the Double-exponential model and Vermeulen's approximation fit throughout the whole examinated time interval. Hence, these models have been selected for predicting the quantity of zinc and cadmium uptake at chosen time and at chosen initial concentration. The investigation of desorption of zinc and cadmium from saturated modified zeolites in ultrapure water of different initial pH has shown that saturated zeolites do not release zinc and cadmium, while they are released in NaCl, KCl and NaNO3 solutions. During four consecutive cycles of saturation and regeneration of the same FeZ mass the capacity remained unchanged, indicating excellent sorption-regeneration properties of FeZ.