THE EFFECT OF DEMULSIFIER AND DEWATERING AGENT ON SEPARATION OF PHASES FROM OILY WATER

Environmental pollution with crude oil and its derivates has become a growing problem due to their toxic and carcinogenic effects on live organisms. Proper collection and treatment of oily wastewaters is very important for prevention and disabling of harmful effects on the environment. The most important step in the oily wastewater treatment process is separation of oil and aqueous phase. Consequently, it is important to examine the conditions which enable the maximum separation effect and provide satisfactory quality of the aqueous phase before discharge into natural recipients. This paper examines the effects of temperature and addition of demulsifier and dewatering agent on phase separation in oily wastewaters. The best separation rate and the highest quantity of the aqueous phase are achieved with the addition of demulsifier in concentration of 500 mg/l and the dewatering agent in concentration of 500 mg/l at 60 °C. The quality of the aqueous phase after separation shows low values of mineral oils and high COD (Chemical Oxygen Demand) values due to the remaining demulsifier and dewatering agent in aqueous phase. For that reason it is necessary to use additional treatments, such as adsorption on active carbon or biological treatment before discharge into natural waters

Primjene različitih metala kao elektrodnog materijala u obradi kompostne procjedne vode

In this paper, different metallic materials (alloys of Fe, Al, and Zn) were investigated as sacrificial anodes during electrocoagulation (EC) for the treatment of compost leachate. Taguchi’s L9 orthogonal array design was applied to investigate the four controllable factors (different metallic material, initial pH value, stirring speed, and contact time) on decrease of chemical oxygen demand (COD) and electrodes mass loss. COD decrease reached values in the range of 75.72–92.97 %. The Taguchi optimisation results showed that the most effective factor for decrease of COD is the duration of the experiment, while the electrode material was for electrodes mass loss. The zinc electrode showed the lowest potential for use in the EC process for treatment of compost leachate, while the Al and Fe electrodes could be used in an acid or slightly acidic environment. The following decreasing order of energy consumption was recorded: Zn > Al > Fe. The measured values of metal electrode mass loss exceeded the theoretical values calculated using Faraday’s law in EC experiments with Al electrodes, while in experiments with Fe and Zn electrodes, those differences were insignificant.U ovom radu različiti metalni materijali (legure Fe, Al, Zn) ispitivali su se kao žrtvene anode tijekom elektrokoagulacije (EK) za obradu kompostne procjedne vode. Taguchijev L9 ortogonalni niz primijenjen je za ispitivanje četiriju kontroliranih čimbenika (različiti metalni materijali, početne pH vrijednosti, brzine vrtnje miješala i vremena kontakta) na uklanjanje organske tvari izražene preko kemijske potrošnje kisika (KPK) i gubitak mase elektroda. Učinkovitost uklanjanja organske tvari izražene preko KPK-a dosegla je vrijednosti u rasponu od 75,72 do 92,97 %. Rezultati optimizacije Taguchi pokazali su da je najučinkovitiji čimbenik za uklanjanje organske tvari, izražene preko vrijednosti KPK-a, trajanje eksperimenta, dok je gubitak mase elektroda za materijal elektrode. Cinkova elektroda pokazala je najmanji potencijal za uporabu u EK procesu za pročišćavanje kompostne procjedne vode, dok se Al i Fe elektroda mogu upotrebljavati u kiselom ili blago kiselom području. Zabilježen je sljedeći opadajući redoslijed potrošnje energije: Zn > Al > Fe. Izmjerene vrijednosti gubitka mase metalne elektrode premašuju teorijske vrijednosti izračunate Faradayevim zakonom u EK eksperimentima s Al elektrodama, dok su u eksperimentima s Fe i Zn elektrodama te razlike manje

Kinetics and thermodynamics study of copper ions removal by natural clinoptilolite

137-144The process of removal of copper ions by means of clinoptilolite type natural zeolite has been studied as a function of the particle size and temperature. Results indicate that increase in temperature and decrease of particle size improves the removal of copper from aqueous solutions. The parabolic diffusion model is well described process in all examined range of time and it shows that the calculated diffusion coefficient increases with temperature. This increase is more visible at higher particle sizes what assume diffusion through zeolite particle as main mass transfer mechanism. The film diffusion model provides calculation of initial sorption rate (k´) and dimensionless parameter proportional to the diffusion film thickness (xi), in relation of particle size and temperature. Diffusion from the surface of zeolite particles through the micro and macro pores is well described with homogenous diffusion model, where change of the calculated overall rate constant is observed at »60 min of the process. This indicates the change of mass transfer rate through porous zeolite particle. The activation energy (Ea), activation enthalpy (H), activation entropy (S) and free energy of activation (G) have been calculated based on kinetic data. These thermodynamic parameters characterize process as diffusion dependent, weakly endothermic and nonspontaneous, where structural changes in structure of natural zeolite particle are not observed

INFLUENCE OF ZEOLITE PARTICLE SIZE AND INITIAL LEAD CONCENTRATION ON SORPTION KINETIC STUDY BY BATCH EXPERIMENTS

The effect of particle size and initial lead concentration on the kinetics of lead ions uptake onto natural zeolite has been examined by batch experiments. The uptake rate of lead ions increases with decreasing particle size and has no effect on the zeolite removal capacities. Also the removal capacities are not affected by initial lead concentrations. To identify the rate rate-determining step, experimental data have been tested by the Lagergren pseudo-first order, Ho pseudo-second order and Elovich reaction kinetic models, Vermeulen’s, Parabolic and Homogeneous diffusion models. For different lead concentrations and particle sizes the kinetic constants obtained have been changed and have consequently been excluded as relevant for the description of kinetics. Vermeulen´s and Homogeneous diffusion models have shown the best fitting with the experimental data, what confirms that intraparticle diffusion is rate-determining step of uptake process of lead ions onto natural zeolite

COMPARISON OF ELECTROCOAGULATION COUPLED WITH SYNTHETIC ZEOLITE, ULTRASOUND AND TWO STEPS ELECTROCOAGULATION

Due to the very complex composition of leachate wastewater, combining two or more physical, chemical, or biological processes, carried out simultaneously or sequentially, is highly needed in order to obtain effluent suitable for further discharge into sewage. In this paper, electrocoagulation coupled with synthetic zeolite (EC-NaX), electrocoagulation coupled with ultrasound (EC-US), and two steps electrocoagulation (EC-1st and EC-2nd) were tested for compost leachate treatment, with very high initial organic loading and acidic pH. The comparison of each process was done in regard to the following parameters: pH, electrical conductivity and temperature change, removal percentage of chemical oxygen demand (COD), turbidity, total solids change, settling ability, and electrode consumption. Results highlight the EC-NaX as the best option for the treatment of compost leachate, due to the highest removal percentage of COD (51.91%), satisfactory removal percentage of turbidity (97%), good settling abilities, and lowest electrode consumption. However, the final COD values in the effluent are still significantly high for further discharge into sewage systems, thus additional treatment needs to be applied. Also, the final acidic pH, high values of electrical conductivity, and high temperature of effluent need to be solved in further treatment steps

Društveno-korisno učenje kao inovativan alat u poučavanju rješavanja okolišnih problema – što smo naučili u 10 godina?

Service-learning represents an innovative pedagogy that integrates academic learning with community service to address environmental issues based on experiential learning principles. This innovative pedagogy enhances higher education learning outcomes by fostering active engagement, real-world context, interdisciplinary insight, skills development, and civic engagement among students. The merging of service-learning contributes to a profound understanding of the subject matter, its practical applications, and personal and professional growth. This paper provides an overview of the implementation of service-learning in the STEM field, with a primary focus on the decade-long involvement of the Faculty of Chemistry and Technology in environmental protection projects. Through collaboration with the non-governmental organisation Sunce and partners from the University of Split, this initiative, led by environmental experts, has introduced a novel approach to higher education, facilitating knowledge expansion, skill improvement, and expertise development for both students and academic staff. The impact has been substantial, with the University of Split attaining the 21st position globally on the “World Universities with Real Impact” list for ethics in 2021, largely attributable to these service-learning projects. Service-learning has been integrated into the SEA-EU initiative, furthering its development at the University of Split, and establishing it as a pioneer in this field. Institutionalising service-learning in higher education requires the establishment of dedicated courses, integration into existing programmes, and the allocation of resources for academic staff, community partners, and students. Successful implementation requires a collaborative, iterative process involving careful planning, preparation, and assessment, ensuring that students benefit from meaningful opportunities to apply course content to real-world challenges while positively impacting the community.Društveno-korisno učenje (DKU) je obrazovni pristup koji spaja akademsko učenje s korisnim radom u zajednici da bi se riješili problemi okoliša utemeljeni na principima iskustvenog učenja. Taj inovativni pristup poboljšava ishode učenja u visokom obrazovanju nudeći studentima aktivan angažman, kontekst stvarnog svijeta, interdisciplinarne uvide, razvoj vještina i uključenost građana. Uključivanje DKU-a potiče dublje razumijevanje materijala kolegija, njegove praktične primjene te osobni i profesionalni rast. Ovaj rad daje pregled implementacije DKU učenja u STEM području, uglavnom se fokusirajući na desetljetnu uključenost Kemijsko-tehnološkog fakulteta u projekte zaštite okoliša. Suradnjom Udruge za zaštitu prirode i okoliša Sunce s partnerima sa Sveučilišta u Splitu, ova inicijativa, koju vode stručnjaci za okoliš, uvela je nov pristup visokom obrazovanju. Omogućila je studentima, nastavnicima i suradnicima da prošire svoja znanja, unaprijede svoje vještine i razviju stručnost. Utjecaj je bio znatan, a Sveučilište u Splitu zauzelo je 21. mjesto u svijetu na popisu “Svjetska sveučilišta sa stvarnim utjecajem” u kategoriji etike u 2021., uglavnom zahvaljujući DKU projektima. DKU je integriran u inicijativu SEA-EU i nastavlja se razvijati na Sveučilištu u Splitu, postavši predvodnik u tom području. Institucionalizacija DKU-a unutar visokog obrazovanja zahtijeva razvijanje DKU kolegija, integraciju DKU-a u postojeće programe i osiguravanje resursa za nastavno osoblje, partnere u zajednici i studente. Uspješna implementacija zahtijeva kolaborativni, iterativni proces koji uključuje pažljivo planiranje, pripremu i evaluaciju. Taj pristup osigurava studentima smislene prilike za primjenu sadržaja kolegija na izazove iz stvarnog svijeta, a istodobno pozitivno utječu na zajednicu

Ružička days : International conference 16th Ružička Days “Today Science – Tomorrow Industry” : Proceedings

Proceedings contains articles presented at Conference divided into sections: open lecture (1), chemical analysis and synthesis (3), chemical and biochemical engineering (8), food technology and biotechnology (8), medical chemistry and pharmacy (3), environmental protection (11) and meeting of young chemists (2)

Učinkovitost obrade elektrokoagulacije kombinirane s različitim veličinama čestica prirodnog zeolita

In a previous study, the larger size of synthetic zeolite particles was highlighted as better choice for electrocoagulation combined with zeolite (ECZ). This choice resulted in a smaller rise in pH and temperature, a more significant decline in turbidity as well as chemical oxygen demand (COD), and lower electrode wastage, but with greater damage to the electrode surface. The focus of this study was to determine whether natural zeolite of three different particle sizes has the same effect on the ECZ process. The Taguchi method L9 was employed in planning the experiments, with particle sizes of natural zeolite ranging up to 600 μm, three different electrode materials (carbon steel, aluminium alloy, and sacrificial zinc anode), current density in the range of 0.003–0.018 A cm–2, and contact time in the range 10–30 min. The Taguchi optimisation results revealed a more significant decrease in COD and turbidity with the smallest particle size of natural zeolite used (90 µm) and with Al electrodes. Evidently, the zeolite particle size, together with the zeolite composition, had a significant influence on the reduction in COD and turbidity. Anode consumption ranged from 0.0172 to 0.6469 g, with minor cathode consumption evident on all electrode materials. Optical microscopy analysis indicated significant corrosion of the anodes, particularly with the largest natural zeolite particle size of 160–600 µm, while minor corrosion damage was also observed on the cathodes.Prethodno istraživanje istaknulo je veće čestice sintetskog zeolita kao bolji izbor za provedbu hibridnog procesa elektrokoagulacije kombinirane sa zeolitom (EKZ), budući da rezultira manjim porastom pH i temperature, znatnijim smanjenjem kemijske potrošnje kisika (KPK) i mutnoće, manjom potrošnjom elektroda, no uz veće oštećenje površine elektrode. Cilj ovog rada je ispitati pokazuje li prirodni zeolit triju različitih veličina čestica isti učinak na EKZ proces. Eksperimenti su planirani prema L9 Taguchi metodi, s veličinama čestica prirodnog zeolita do najviše 600 μm, trima različitim materijalima elektroda (ugljični čelik, aluminijske legure i žrtvene cinkove anode), gustoćom struje u rasponu 0,003 – 0,018 A cm–2 te kontaktnim vremenom u rasponu 10 – 30 min. Rezultati Taguchi optimizacije pokazuju znatnije smanjenje KPK i mutnoće primjenom čestica prirodnog zeolita manjih od 90 µm i Al elektrode. Očigledno je da veličina čestica zeolita, kao i sastav zeolita, znatno utječe na smanjenje KPK i mutnoće. Potrošnja anode je u rasponu 0,0172 – 0,6469 g, dok je manja potrošnja katode također uočena na svim materijalima. Analiza optičkim mikroskopom pokazuje značajnu koroziju anoda, a koje su više oštećene s najvećim česticama prirodnog zeolita (160 – 600 µm), dok su manja korozijska oštećenja uočena i na katodama

Effect of the solid/liquid ratio on zinc and cadmium uptake on natural and iron-modified zeolite - Batch scale design

235-245Zinc and cadmium uptake on natural (NZ) and iron-modified zeolite (IMZ) has been investigated through the two sets of experiments, first one with varying S/L ratios at a constant initial metal concentration and second one with different initial metal concentrations at a single S/L ratio. Results confirm the importance of choosing an optimum S/L ratio in achievement of the maximum removal efficiency with the lowest zeolite mass. Two different methods for the design of batch reactor have been applied to overcome the effect of the S/L ratio. The first approach applied the operating line method with the Dubinin-Radushkevich isotherm, and the second one applied the Rayleigh's method of dimensional analysis. The excellent agreement between predicted and experimentally obtained results for the amount of metal removed per gram of zeolite as well as error functions confirm the applicability of both methods in the batch scale design independently of the S/L ratio

Application of mathematical empirical models to dynamic removal of lead on natural zeolite clinoptilolite in a fixed bed column

123-131This study examined the applicability of the mathematical empirical models by Bohart-Adams, Wolborska, Thomas and Yoon-Nelson on lead removal from aqueous solutions on a fixed bed of natural zeolite. Applicability of these models has been evaluated by fitting the experimental breakthrough curves with the curves obtained from the applied model. Experimental results have shown that the values of removal capacities calculated from model are close to the value of the experimentally obtained capacity at the exhaustion point. The Thomas and Yoon-Nelson models have shown excellent fit for all examined range of the breakthrough curves; therefore these models have been used for simulation of breakthrough curves for different bed depths and flow rates. The results show that the successful prediction is achieved when the empty bed contact time (EBCT) was in the experimentally confirmable range. Among all examined models, the Thomas model was found to be the most suitable one for simulation of the breakthrough curve of lead uptake on fixed bed of natural zeolite in a wide range of EBCT values