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pH influence on iron corrosion in acidic perchloric solutions : bachelor thesis
No full textCilj ovog rada je bio ispitati utjecaj pH na koroziju željeza u perkloratnim otopinama ionske jakosti 0,5 i 0,1 mol/L. Istraživanje je provedeno uz praćenje promjene potencijala otvorenog strujnog kruga s vremenom, elektrokemijskom impedancijskom spektroskopijom na potencijalu otvorenog strujnog kruga i potenciodinamičkom polarizacijom sa sporom promjenom potencijala (0,5 mV/s) u području potencijala ±0,120 V u odnosu na potencijal otvorenog strujnog kruga. Povećanjem pH uz istu ionsku jakost dolazi do smanjenja korozije željeza u otopinama ionske jakosti 0,5 mol / L i u otopinama ionske jakosti 0.1 mol/L. Pri istim pH struje korozije su veće u otopinama ionske jakosti 0,5 mol/L nego u otopinama ionske jakosti 0,1 mol/L. Smanjenjem pH vrijednosti rezultati ovih metoda pokazuju međusobno veće odstupanje koje je posebice značajno u otopinama ionske jakosti 0,5 mol/L. Za ispitivane otopine obje ionske pri pH 0,3; 1 i 2 rezultati ukazuju da je korozija pod aktivacijskom kontrolom, dok je pri pH 3 korozija kontrolirana katodnom difuzijskom strujom.In this study, the effect of pH on iron corrosion in perchlorate solutions with ionic strengths of 0.5 and 0.1 mol/L was investigated. This study was carried out by electrochemical techniques (open circuit potential measurement, potentiodynamic polarisation measurement and electrochemical impedance spectroscopy). In both solutions with an ionic strength of 0.1 mol/L and 0.5 mol/L, raising the pH while maintaining the same ionic strength results in a decrease in iron corrosion. In solutions with an ionic strength of 0.5 mol/L compared to those with an ionic strength of 0.1 mol/L, corrosion currents are higher at the same pH value. The results of these measurements deviate from one another more when the pH value is lowered, which is particularly notable in solutions with an ionic strength of 0.5 mol/L. The results show that corrosion is under activation control for the examined solutions of both ionic solutions at pH 0.3, 1, and 2, however at pH 3, corrosion is controlled by the cathodic diffusion current
ACTIVATION OF ALUMINUM WITH GALLIUM : diploma thesis
No full textU ovom radu je mjerenjem vremenske promjene potencijala otvorenog strujnog kruga, primjenom polarizacijskih metoda (potenciodinamčke polarizacije i galvanostatske pulsne metode (uz paralelno mjerenje volumena vodika)) te elektrokemijske impedancijske spektroskopije ispitano ponašanje Al i Al-Ga legura (s 0.01, 0.05 0.10 i 0.20 % Ga) u NaCl otopini. Legiranjem aluminija malim količinama Ga (do 0.20 %) uklanjaju se njegovi osnovni nedostaci pri primjeni u Al-zrak baterijama, odnosno: • potencijal otvorenog strujnog kruga se značajno pomiče u negativni smjer, • smanjuje se spontana korozija na potencijalu otvorenog strujnog kruga, • sužava se pasivno područje potencijala, • smanjuje se polarizacija elektrode, • smanjuje se negativni diferencijalni efekt, • povećava se anodna učinkovitost. Legura s 0.10 % Ga ima najbolje karakteristike za izradu anoda u Al-zrak baterijama sa slanima elektrolitom.In this work, the behavior of Al and Al-Ga alloys (with 0.01, 0.05, 0.10, and 0.20 % Ga) in NaCl solution is studied. Alloying Al with small amounts of Ga (up to 0.20 %) eliminates its basic drawbacks when used in Al-air batteries, namely: • the potential of the open circuit moves significantly in the negative direction, • the spontaneous corrosion at the open circuit is reduced, • the range of the passive potential narrows, • the polarization of the electrodes decreases • the negative differential effect is reduced • the efficiency of the anode increases. The alloy with 0.10 % Ga has the best properties for the production of anodes in Al-air batteries with saline electrolyte
Analysis of the biowaste composting process in the C-EcoForHome composter under anaerobic conditions : bachelor thesis
No full textUpravljanje otpadom predstavlja glavni izazov u ustanovama gdje se generira velika količina otpada čije nepravilno zbrinjavanje može dovesti do ekoloških problema. Kompostiranje je način zbrinjavanja biološkog otpada uz prisustvo mikroorganizama. Može se provoditi aerobno (uz prisustvo kisika) i anaerobno (bez prisustva kisika). Metode kompostiranja su ekološki prihvatljive jer dovode do oporavka resursa. U ovome radu je praćen proces kompostiranja biootpada u C-EcoForHome komposteru. Prikupljeni biootpad je sadržavao sirove ostatke voća i povrća, a prikupljen je u trima ustanovama: Kliper, Obrtnička škola Split i Udruzi Škmer. Praćena su fizička i kemijska svojstva komposta: visina kompostne hrpe, temperatura, pH-vrijednost, električna vodljivost, udjeli vlage, suhe tvari, hlapljive tvari, ugljika, dušika te C/N omjer.Waste management represents the main challenge in institutions where a large amount of waste is generated, the improper disposal of which can lead to environmental problems. Composting is a method of disposal of biological waste with the presence of microorganisms. It can be carried out aerobically (with the presence of oxygen) and anaerobically (without the presence of oxygen). Composting methods are environmentally friendly because they lead to the recovery of resources. In this work, the biowaste composting process in the C-EcoForHome composter is monitored. The collected biowaste contained raw remains of fruits and vegetables, and it was collected in three institutions: Kliper, Trade School Split and Škmer Association. The physical and chemical properties of the compost were monitored: height of the compost pile, temperature, pH value, electrical conductivity, moisture content, dry matter, volatile matter, carbon content, nitrogen content and C/N ratio
Comparison of sorption of copper ions on two types of cat litter : master thesis
No full textU ovom diplomskom radu ispitivana je ravnoteža sorpcije bakrovih iona iz otopina bakrovog(II) klorida različitih početnih koncentracija na dvije vrste mačjeg pijeska (prirodni i sintetski bentonit) u šaržnom reaktoru pri stalnoj temperaturi od 300 K, brzini miješanja od 200 okr min-1 te trajanju eksperimenta od 72 h. Ravnotežna količina sorbiranih bakrovih iona na prirodnom bentonitu raste s povećanjem ravnotežne koncentracije iona teškog metala u otopini i postiže svoju maksimalnu vrijednost pri najvišoj odabranoj koncentraciji otopine teškog metala od 29,135 mmol dm-3 koja iznosi 1,053 mmol g-1. Porast početnih koncentracija otopine bakrovih iona ne utječe značajno na ravnotežnu koncentraciju sorbiranih bakrovih iona na sintetskom bentonitu koja na samom početku raste, a potom se značajno ne mijenja daljnjim porastom ravnotežne koncentracije iona teškog metala u otopini, a koja se također postiže pri najvišoj odabranoj koncentraciji otopine teškog metala te iznosi 0,549 mmol g-1. Uspješnost uklanjanja bakrovih iona na obje vrste mačjeg pijeska neprestano opada porastom početne koncentracije bakrovih iona u otopini što se može pripisati zasićenju dostupnih mjesta za sorpciju. Učinak sorpcije bakrovih iona gotovo je dvostruko veći primjenom prirodnog bentonita. Dobiveni eksperimentalni podatci testirani su Langmuirovim, Freundlichovim, Tothovim, Redlich-Petersonovim te Sipsovim modelom. S obzirom na vrijednosti kriterija procjene može se zaključiti kako Freundlichova izoterma najbolje opisuje sorpciju bakrovih iona na prirodnom bentonitu. Niža vrijednost parametra koji opisuje heterogenost površine sugerira jaču interakciju između prirodnog bentonita i bakrovih iona. Sorpcija bakrovih iona na sintetskom bentonitu je nabolje opisana Langmuirovim modelom čime se sugerira jednoslojna sorpcija na sintetskom bentonitu podrazumijevajući kako sva površinska mjesta imaju jednak afinitet prema sorbatu te da se na njima može sorbirati samo jedan atom neovisno o popunjenosti susjednih mjesta.In this diploma thesis, the equilibrium of copper ion sorption from copper (II) chloride solutions of different initial concentrations on two types of cat litter (natural and synthetic bentonite) was examined in a batch reactor at a constant temperature of 300 K, a stirring speed of 200 rpm and an experiment duration of 72 h. The equilibrium amount of sorbed copper ions on natural bentonite increases with the increase of the equilibrium concentration of heavy metal ions in the solution and reaches its maximum value at the highest selected concentration of the heavy metal solution of 29.135 mmol dm-3 with the value of 1.053 mmol g-1. The increase in the initial concentration of the copper ion solution does not significantly affect the equilibrium concentration of sorbed copper ions on the synthetic bentonite, which increases at the very beginning, and then does not significantly change with a further increase in the equilibrium concentration of heavy metal ions in the solution, and is also achieved at the highest selected concentration of the heavy metal solution, with the value of 0.549 mmol g-1. The removal efficiency of copper ions on both types of cat litter continuously decreases with the increase of the initial concentration of copper ions in the solution, which can be attributed to the saturation of the available sites for sorption. The effect of sorption of copper ions is twice as high with the use of natural bentonite. The obtained experimental data were tested with the Langmuir, Freundlich, Toth, Redlich-Peterson and Sips models. Considering the values of the assessment criteria, it can be concluded that the Freundlich isotherm best describes the sorption of copper ions on natural bentonite. A lower value of the parameter describing the surface heterogeneity suggests a stronger interaction between natural bentonite and copper ions. Sorption of copper ions on synthetic bentonite is best described by the Langmuir model, which suggests monolayer sorption on synthetic bentonite, implying that all surface sites have the same affinity for sorbate and that only one atom can be sorbed on them, regardless of the occupancy of neighboring sites
Sunset Yellow colour removal from aqueous solution by electrocoagulation : diploma thesis
No full textPromatrana je učinkovitost uklanjanja boje Sunset Yellow (SY) iz vodene otopine procesom elektrokoagulacije (EK) pri različitim gustoćama struje (0.004, 0.008, 0.016 i 0.024 A/cm 2 ), početnim pH (3.2, 5.5, 7.0) te brzinama vrtnje miješala (100, 200 i 300 okr/min). Tijekom EK procesa, uočene su promjene pH, temperature, električne provodnosti te koncentracije SY boje. Općenito gledajući, učinkovitost uklanjanja SY boje je izuzetno dobra te kod svih eksperimentalnih uvjeta raste i postiže određenu maksimalnu vrijednost. Gustoća struje od 0.024 A/cm 2 , početna pH od 3.2 te brzina vrtnje miješala od 200 okr/min pokazali su se kao optimalni uvjeti u postupku uklanjanja SY boje. Tijekom EK procesa dolazi do potrošnje anodnog, ali i katodnog materijala. Potrošnja anoda je znatno veća od potrošnje katoda, a ta razlika se naročito povećava s porastom gustoće struje. Porastom brzine miješanja smanjuje se brzina otapanja katoda. Izgled anoda nakon EK procesa ukazuje na dominantni utjecaj dvaju oblika korozije: opće (pri nižim strujama, pH vrijednostima i brzinama miješanja) i interkristalne korozije (pri višim strujama). S druge strane, katode kod svih eksperimentalnih uvjeta korodiraju interkristalno.The efficiency of Sunset Yellow (SY) dye removal from aqueous solution by electrocoagulation (EC) was observed at different current densities (0.004, 0.008, 0.016, and 0.024 A/cm 2 ), initial pH (3.2, 5.5, 7.0), and stirring speeds (100, 200, and 300 rpm). Changes in pH, temperature, electrical conductivity, and SY dye concentration were observed during the EC process. In general, the efficiency of SY dye removal is very good and increases under all experimental conditions, reaching a certain maximum value. The current density of 0.024 A/cm 2 , the initial pH of 3.2, and the stirring speed of 200 rpm were found to be optimal conditions for the process of SY dye removal. During the EC process, anodic and cathodic material is consumed. The anodic consumption is significantly higher than the cathodic consumption, and this difference increases especially with increasing current density. As the mixing rate increases, the dissolution rate of the cathode decreases. The appearance of the anodes after the EC process indicates the dominant influence of two forms of corrosion: general corrosion (at lower currents, pH values, and mixing rates) and intergranular corrosion (at higher currents). On the other hand, the cathodes corrode intercrystalline under all experimental conditions
Temperature impact on copper sorption on NaX zeolite : bachelor thesis
No full textU radu je ispitan utjecaj temperature na kinetiku sorpcije bakra na zeolitu NaX. Eksperimenti su provedeni korištenjem turbinskog miješala s ravnim lopaticama u staklenom šaržnom reaktoru nestandardne konfiguracije (D/d T = 0,57, C/H = 0,10) s razbijalima virova standardnih dimenzija (R V = d T /10). Dobiveni eksperimentalni podatci analizirani su Blanchardovim i Weber–Morrisovim kinetičkim modelima. Rezultati kinetičke analize pokazali su da brzina ispitivane reakcije sorpcije bakra na zeolitu NaX raste s porastom temperature; reakcija je drugog reda, a sam proces sorpcije bakra na zeolitu NaX pri svim ispitivanim temperaturama odvija se u kinetičkom području.The temperature effect on the sorption kinetics of copper on NaX zeolite was investigated. The experiments were conducted using a flat blade turbine impeller in a glass batch reactor of nonstandard configuration (D/d T = 0.57, C/H = 0.10) with standard size baffles (R V = d T /10). The obtained experimental data were analyzed by Blanchard and Weber–Morris kinetic models. The results of kinetic analysis showed that the rate of copper sorption reaction on NaX zeolite surface increases with temperature increase, that the reaction is second order, and the process of copper sorption on NaX zeolite at all temperatures takes place in the kinetic domain
Preparation and characterization of natural zeolite clinoptilolite coated with iron sulfide species - determination of the selectivity of the prepared sample towards Hg(II) in relation to other divalent heavy metal cations : diploma thesis
No full textPrirodni zeolit klinoptilolit obložen željezo sulfidnim specijama (FeS) dobiven je dvostupanjskom kemijskom modifikacijom prirodnog zeolita (PZ) klinoptilolita s Fe(NO 3 ) 3 ·9H 2 O i Na 2 S·9H 2 O. Svrha modifikacije zeolita bila je poboljšati sorpciju Hg(II). Klasična kemijska analiza, kisela i bazična svojstva određena Bohemovom metodom, kemijsko ponašanje pri različitim pH o vrijednostima, zeta potencijal pri različitim pH o vrijednostima, specifična površina, rendgenska difrakcijska analiza praškastog uzorka (XRPD), pretražna elektronska mikroskopija s energijsko disperzivnom rendgenskom spektroskopijom (SEM-EDS), infracrvena spektroskopija s Fourierovom transformacijom (FTIR) kao i termogravimetrijska analiza (TG-DTG) korišteni su za detaljnu komparativnu mineralošku i fizikalno-kemijsku karakterizaciju PZ i FeSZ. Rezultati su pokazali da je površina FeSZ uspješno obložena željezo sulfidnim specijama u obliku FeS i CaS. Novoformirane faze na površini FeSZ uzrokovale su povećanje bazičnosti i ukupnog negativnog naboja površine te blago smanjenje kristaliničnosti. Modificirani uzorak, FeSZ pokazao je iznimnu selektivnost prema Hg(II) u odnosu na ostale dvovalentne katione teških metala. Utvrđen je redoslijed selektivnosti: Hg > Pb > Cd > Cu > Zn > Ni > Co > Mn. Na temelju rezultata, modificirani uzorak se čini izvrsnim izborom za sanaciju lokacija onečišćenih živom.Natural zeolite clinoptilolite coated with iron sulfide species (FeS) was obtained by two-step chemical modification of natural zeolite clinoptilolite (PZ) with Fe(NO 3 ) 3 ·9H 2 O and Na 2 S·9H 2 O. The purpose of the zeolite modification was to improve the sorption of Hg(II). Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pH o values, zeta potential, cation-exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of PZ and FeSZ. The results showed that the FeSZ surface was successfully coated with iron sulfide species in the form of FeS and CaS. Newly formed phases on the FeSZ surface caused an increase in basicity and total negative surface charge and a slight decrease in crystallinity. The modified sample, FeSZ, showed exceptional selectivity towards Hg(II) in relation to other divalent heavy metalcations. The order of selectivity was determined: Hg > Pb > Cd > Cu > Zn > Ni > Co > Mn. Based on the results, the modified sample appears to be an excellent choice for the remediation of mercury-contaminated sites
Kinetic analyisis of copper ions sorption on zeolite NaX in a batch reactor under different hydrodynamic conditions : doctoral thesis
No full textSažetak Zeoliti su mikroporozni kristalni alumosilikati koji su svojom primjenom kao katalizatori i sorbensi promijenili petrokemijsku i kemijsku industriju. Katalitička svojstva zeolita mogu se prilagoditi „umetanjem” iona teških metala u zeolit, a jedna od metoda koja se može koristiti za pripremu katalizatora je sorpcija. Sorpcija na zeolitima koristi se i za uklanjanje metala iz kontaminiranih voda. Ako se proces sorpcije vodi u kotlastom (šaržnom) reaktoru njegova učinkovitost ovisi o različitim procesnim parametrima, uključujući i parametre miješanja, a čiji utjecaj na samu sorpciju još uvijek nije dovoljno istražen. Hidrodinamički uvjeti u određenom sustavu posljedica su geometrijskih karakteristika reaktora i korištenog miješala te brzine vrtnje miješala. Stoga je u ovom radu ispitan utjecaj hidrodinamičkih uvjeta u reaktoru na učinkovitost i kinetiku sorpcije bakrovih iona na sintetskom zeolitu NaX u otvorenom šaržnom reaktoru s razbijalima virova. Miješanje se provodilo upotrebom triju različitih tipova miješala: aksijalnog propelerskog miješala, radijalno-aksijalnog turbinskog miješala s ravnim lopaticama nagnutim pod kutom (PBT) i radijalnog turbinskog miješala s ravnim lopaticama (SBT). Za sve tipove miješala sagledan je utjecaj tipa miješala te masene koncentracije zeolita NaX u otopini na kritičnu brzinu vrtnje miješala za postizanje stanja potpune suspenzije, N JS , kao i na kinetiku i na učinkovitost sorpcije bakrovih iona na zeolitu NaX. Pri najnižoj ispitivanoj masenoj koncentraciji suspenzije zeolita NaX u otopini, za sve tipove miješala, ispitan je utjecaj brzine vrtnje miješala, N/N JS , na provedbu ispitivanog procesa. Za PBT tip miješala je ispitan i utjecaj pozicije i promjera miješala na kinetiku i na učinkovitost ispitivanog procesa pri najnižoj ispitivanoj masenoj koncentraciji zeolita NaX u otopini. Procjena kinetičkih parametara provedena je nelinearnom i linearnom regresijskom analizom za tri kinetička modela: Ritchiejev model, Miješani kinetički model adsorpcije kontrolirane površinskom reakcijom i difuzijom (Miješani model) te Weber-Morrisov model. Kinetičkom analizom dobivenih eksperimentalnih podataka odabranim kinetičkim modelima utvrđeno je koji kinetički model najprikladnije opisuje kinetiku sorpcije bakrovih iona na zeolitu NaX te su izračunati kinetički parametri. Budući da je sorpcija heterogeni proces određen je i najsporiji korak procesa za ispitivane uvjete. Analizom eksperimentalnih kinetičkih podataka utvrđeno je da sorpciju bakrovih iona na zeolitu NaX najpotpunije opisuje Ritchiejev model. Međutim, pri brzinama vrtnje propelerskog i SBT miješala N/N JS od 0,60 i 0,80, Miješani model se bolje slaže s eksperimentalnim kinetičkim podatcima, sugerirajući da je reakcija drugog reda ograničena difuzijom. Da bi se dobio potpuniji uvid u hidrodinamička zbivanja u ispitivanom sustavu, uporabom programskog paketa ANSYS Fluent v17.2 simulirani su tokovi fluida. S obzirom na kinetiku i količinu sorbiranih bakrovih iona predložena je najpovoljnija geometrija reaktora.Abstract Zeolites are microporous crystalline aluminosilicates that have transformed the petrochemical and chemical industries through their use as catalysts and sorbents. The catalytic properties of zeolites can be altered by introducing heavy metal ions into the zeolite, and one of the methods used to prepare catalysts is sorption. Sorption on zeolites can also be used to remove metals from contaminated water. If the sorption process is carried out in a batch reactor, its efficiency depends on various process parameters, including the mixing parameters, the influence of which on sorption itself has not been sufficiently studied. The hydrodynamic conditions in a given system result from the geometrical characteristics of the reactor and the impeller used, as well as from the impeller rotation speed. For this reason, the influence of hydrodynamic conditions on the efficiency and kinetics of copper ions sorption on synthetic zeolite NaX in an uncovered batch reactor with baffles was studied in this work. Mixing was performed using three different impeller types: an axial propeller impeller, a radial-axial pitched blade turbine impeller (PBT), and a radial straight blade turbine impeller (SBT). For all impeller types, the effect of impeller type and zeolite NaX mass concentration in a solution on the critical impeller speed required to achieve a state of complete suspension, N JS , was investigated. The effect of impeller type on the kinetics of copper ions sorption on zeolite NaX and removal efficiency was studied. At the lowest mass concentration of NaX zeolite in the solution investigated, the effect of the impeller rotation speed, N/N JS , on the performance of the studied process was also investigated for all impeller types. For the PBT impeller, the effect of the impellers' position and its diameter on the kinetics of the copper ion sorption process on zeolite NaX and the removal efficiency at the lowest mass concentration of NaX zeolite in the solution investigated, were studied too. Kinetic parameter estimation was performed using nonlinear and linear regression analysis for three kinetic models: Ritchie’s model, Mixed kinetic model of adsorption controlled by surface reaction and diffusion (Mixed model), and Weber-Morris model. By kinetic analysis of the obtained experimental data using the selected kinetic models, a kinetic model that describes the kinetics of sorption of copper ions onto zeolite NaX, and the kinetic parameters were calculated. Since sorption is a heterogeneous process, the slowest step of the process was defined for the conditions studied. By analysing the experimental kinetic data, it was found that the sorption of copper ions onto zeolite NaX is well described by the Ritchie’s model. However, at impeller speeds of N/N JS 0.60 and 0.80, the Mixed model agrees better with the experimental kinetic data, suggesting that the second order reaction is suppressed by diffusion. To obtain a more complete insight into the hydrodynamic processes in the studied system, the fluid flows were simulated using the ANSYS Fluent v17.2 software package. Taking into account the obtained results, i.e. the kinetics and the amount of sorbed copper ions, the most favourable reactor geometry was proposed
Modeling and optimization of mercury removal on natural and Fe(III)-modified zeolite : graduate thesis
No full textU ovom radu provedena je sorpcija Hg(II) na prirodnom (PZ) i Fe(III)-modificiranom zeolitu (FeZ) pri različitim početnim koncentracijama s ciljem dizajniranja jednostupanjskog i dvostupanjskog istosmjernog sorpcijskog šaržnog reaktora. Pri optimalnim sorpcijskim uvjetima (omjer kruto/tekuće = 10 g/L, pH o = 2 i t = 24 h) ustanovljen je dvostruko veći sorpcijski kapacitet FeZ prema Hg(II) u odnosu na polazni materijal, PZ (0,538 mmol/g vs. 0282 mmol/g). Na temelju primijenjena tri izotermna modela, Langmuirov, Freundlichov i Temkinov, utvrđeno je da eksperimentalni rezultati slijede Langmuirov model. Zbog toga je potonji primijenjen u optimizaciji mase u jednostupanjskim i dvostupanjskim istosmjernim sorpcijskim šaržnim reaktorima uz uvjet učinkovitosti uklanjanja od 99,9 %. Optimalne minimalne mase FeZ u jednostupanjskom i dvostupanjskom reaktoru bile su za 3,7 puta manje u odnosu na potrebne mase PZ za postizanje iste učinkovitosti uklanjanja (99,9 %). S druge strane, ukupna potrebna masa PZ u jednostupanjskom reaktoru bila je 15 puta veća nego u dvostupanjskom reaktoru, dok je u slučaju FeZ taj odnos bio 13 puta. Zaključno, utvrđena značajno manja potrošnja FeZ u odnosu na PZ, doprinosi ekonomičnijoj izvedbi procesa, a posebice kad se primjenjuje dvostupanjski istosmjerni šaržni reaktor. Stoga, dvostupanjski šaržni reaktor mogao bi se primijeniti za ex-situ remedijaciju živom onečišćenog okoliša, posebice korištenjem FeZ.In this paper, the sorption of Hg(II) on natural (PZ) and Fe(III)-modified zeolite (FeZ) was carried out at different initial concentrations with the aim of designing single- and two-stage cross-current sorption batch reactors. Under optimal sorption conditions (solid/liquid ratio = 10 g/L, pH o = 2 and t = 24 h), a twice higher sorption capacity of FeZ towards Hg(II) was established compared to the starting material, PZ (0.538 mmol/g vs. 0.282 mmol/g). Based on the applied three adsorption isotherm models, Langmuir, Freundlich and Temkin, it was determined that the experimental results follow the Langmuir model. Therefore, the latter was applied in mass optimization in single-stage and two-stage cross-current sorption batch reactors with the condition of a removal efficiency of 99.9%. The optimal minimum masses of FeZ in the single-stage and two-stage reactor were 3.7 times less compared to the required masses of PZ to achieve the same removal efficiency (99.9 %). On the other hand, the total required mass of PZ in the single-stage reactor was 15 times higher than in the two-stage reactor, while in the case of FeZ this ratio was 13 times. In conclusion, the significant savings in FeZ consumption compared to PZ were established, contributing to a more economical process performance, especially when a two-stage cross-current batch reactor is used. Consequently, a two-stage batch reactor could be applied for ex-situ remediation of mercury-contaminated environments, especially using FeZ
Comparison of biowaste composting in small decentalized composting devices : diploma thesis
No full textDecentralizirani uređaji za kompostiranje su danas prepoznati kao ključ za rješavanje problema zbrinjavanja biorazgradivog otpada u urbanim područjima te predstavljaju korak ka postizanju održivosti preradom manjih količina otpada na izvoru njegovog nastanka. U ovom radu je uspoređen proces kompostiranja biootpada u tri decentralizirana kompostera: „C-EcoForHome komposteru“ uz dodatak inokulanta s anaerobnim mikroorganizmima i dva „Organko“ kompostera uz dodatak inokulanta s aerobnim te bez dodatka mikroorganizama. Tijekom procesa kompostiranja uzorkovana je kompostna masa i nastala procjedna voda te su ispitani fizikalno-kemijski pokazatelji. Nakon procesa kompostiranja, dobiveni predkomposti su podvrgnuti dozrijevanju u dvije vrste tla, a nastala procjedna voda je obrađena hibridnim postupkom elektrokoagulacije uz dodatak sintetskog zeolita NaX. Temeljem dobivenih rezultata izvedeni su zaključci o procesu kompostiranja biootpada u malim decentraliziranim. uređajima.Decentralized composting devices are recognized as the key to solving the problem of biodegradable waste disposal in urban areas, and represent a step towards achieving sustainability by processing smaller amounts of waste at the source. This paper compares the biowaste composting process in three decentralized composters: “C-EcoForHome” composter with the addition of inoculant with anaerobic microorganisms and two “Organko” composters with the addition of inoculant with aerobic and without the addition of microorganisms. During the composting process, the compost mass and the resulting compost leachate were sampled, and the physical and chemical indicators were analyzed. After the composting process, the obtained precomposts were subjected to maturation in two types of soil, while the resulting leachate was treated by a hybrid electrocoagulation process with the addition of synthetic zeolite NaX. Based on the obtained results, conclusions were drawn about the biowaste composting process in small decentralized devices