<p>Pri proizvodnji kvalitetnog belog konzumnog šećera iz šećerne repe, srećemo se sa problemom prisustva makromolekularnih jedinjenja u soku šećerne repe koja su štetna pa ih je neophodno odstraniti. Uklanjanje ovih jedinjenja, koja čine oko 60 % od ukupno sadržanih nesaharoznih materija u soku šećerne repe, zasniva se na principu taloženja uz primenu različitih koagulanata (najčešće jedinjenja koja sadrže pozitivne jone kalcijuma). Međutim, afinitet vezivanja kalcijuma sa nepoželjnim makromolekulima iz soka šećerne repe je mali, pa su potrebne velike količine ovog jedinjenja u svakodnevnoj proizvodnji šećera.</p><p>Cilj istraživanja obuhvaćenih ovom doktorskom disertacijom usmeren je ka primeni alternativnih koagulanata sa dvo- i trovalentnim katjonima, pre svega soli aluminijuma i bakra koja izlazivaju proces razelektrisavanja makromolekula soka šećerne repe. Merenjem elektrokinetičkih potencijala utvrđene su optimalne količine koagulanata potrebne za uspešnu koagulaciju makromolekularnih jedinjenja iz soka šećerne repe. Ispitivan je i uticaj drugih procesnih veličina kao što su pH, koncentracija makromolekula i uticaj brzine mešanja na efikasnost taloženja makromolekula. Predložen je mehanizam razelektrisavanja makromolekularnih jedinjenja kao i model dvojnogelektričnog sloja koji okružuje koloidne čestice u soku šećerne repe. Ispitivana su dva model-rastvora komercijalno raspoloživih pektina u koncentracijama koje odgovaraju koncentracijama u soku šećerne repe kao i jedan model-rastvor proteinskog preparata. Ispitivani sistemi su tretirani rastvorima CuSO<sub>4</sub> i Al2(SO<sub>4</sub>)<sub>3</sub> i rastvorima njihovih smeša u različitim odnosima. Dokazano je, za sva tri ispitivana preparata, da su manje količine Cu<sup>+2</sup> jona u odnosu na Al<sup>+3</sup><sup> </sup>jone potrebne za sniženje vrednosti Zeta potencijala na nulu. Međutim, zbog mogućih nepoželjnih efekata CuSO<sub>4</sub> u obradi hrane, Al(SO<sub>4</sub>)<sub>3</sub> bi se mogao upotrebiti umesto tradicionalnog koagulanta CaO, kako zbog manje potrošnje koagulanta, tako i zbog očuvanja životne sredine. Cilj eksperimenata sa smešama je ispitivanje mogućnosti poboljšanja koagulacionih karakteristika često korišćene soli Al2(SO<sub>4</sub>)<sub>3</sub>, dodavanjem malih količina Cu<sup>+2</sup> jona. Međutim, čiste soli su pokazale bolja koagulaciona svojstva. Istraživanja sa flokulantima, odnose se na odabiranje najpogodnijeg tipa i optimalne količine flokulanata, uz primenu predloženih koagulanata. Najveća efikasnost čišćenja soka šećerne repe, uočena je nakon primene anjonskog flokulanta koncentracije 3 mg/dm<sup>3</sup>. Dokazano je da ovaj tip flokulanata dodatno smanjuje vrednost Zeta potencijala prisutnih makromolekula čime se smanjuje potrebna količina ispitivanih koagulanata CuSO<sub>4 </sub>i Al(SO<sub>4</sub>)<sub>3</sub>.</p><p> </p><p> </p><p><br /><br /> </p><p> </p> / <p>During production of full quality consumed white sugar from sugar beet, there is a problem of the presence<br />of macrom olecular compounds in sugar beet juice, which are harmful and we have to be removed.<br />Separation ofthese compounds, which make around 60% oflotal non-sucrose compounds in sugar beetjuice,<br />is done by the principle of sedimentation with different types of coagulants (mostly compounds with calcium<br />ion). However, affinity of calcium binding with undesirable macromolecules fiom sugar beet juice is not<br />significant and in that way it is necessary a lot of quantities of this compound throughout daily production of<br />sugar.<br />The aim of this doctoral thesis is to consider the application of alternative coagulants with divalent and<br />trivalent cations, especially the salt of aluminum and cooper, which cause the process of dischargeable<br />macromolecules in sugar beet juice.<br />Optimal quantities of coagulants needing for the efficient coagulation of macromolecules compounds from<br />sugar beet juice were determined by means of measuring of electrokinetic potentials. It was investigated the<br />influence of other process variables such as pH, concentration of macromolecules and the impact of speed<br />mixing on the efficiency of sedimentation of macromolecules.<br />Mechanism of discharge of macromolecules compounds as well as the model of double electric layer<br />surrounding colloidal particles in sugar beetjuice are suggested for sugar beetjuice clarification.<br />Two model solutions of pectin are investigated together with one model solution of protein. Their<br />concentration correspond to concentration of these macromolecules in sugar beet juice. All investigated<br />systems were treated by using both solutions of CuSO4 as well as Al2(SO4)3 and slutions of their mixtures in<br />different proportion.<br />It was proven for all three investigated samples that fewer quantities of Cu+2 ions compared to the values of<br />Al+3 ions are needed to reach zero Zeta potential. However, due to possible undesirable effects of CuSO4 on<br />food processing, Al2(SO4)3 is proposed instead of traditional coagulant CaO, not only because of lower<br />consumptions of coagulants but owing to protection of the environment.<br />The objective in the experiments with mixtures was to investigate enhancement of coagulated characteristics<br />with commonly used salt Al2(SO4)3 by adding small quantities of Cu+2 ions. It was proven that pure salts<br />showed better-coagulated properties.<br />Further investigation was focused to selection of the most appropriate type and optimal quantity of chosen<br />flocculants. The highest efficiency of clarification of sugar beet juice was noticed by applying anion<br />flocculants of concentration 3 mg/dm3. It was shown that this type of flocculants additionally decreased the<br />value of Zeta potential of present macromolecules which further reduce required quantity of investigated<br />coagulants CuSO4 and Al2(SO4)3.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)71293 |
| Date | 04 February 2008 |
| Creators | Kuljanin Tatjana |
| Contributors | Lević Ljubinko, Đurić Mirjana, Karlović Elvira |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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