The use of anodic linear sweep voltammetery analysis (ALSV) for characterization the copper anodes used for sulphur acidic waste solution treatment

This paper addresses on investigation the possibility of electrolytic treatment the sulphur acidic waste solution, obtained in the conventional electrolytic copper refining process. The copper anodes with non-standard nickel, lead, tin and antimony content were specially prepared for the refining process. Nickel content of all anodes was approximately 7.5 mass %, and the content of lead, tin and antimony was varied. Results, obtained using the standard electrochemical techniques, have indicated that the anodes could be used under the same conditions as well as in the conventional copper refining process

Analyzing the corrosion characteristics of anodes used for the sulphur acidic waste water treatment

This paper addresses on investigation the possibility of electrolytic treatment the sulphur acidic waste solution, obtained in the conventional electrolytic copper refining process. The copper anodes with non-standard nickel, lead, tin and antimony content were specially prepared for the refining process. Nickel content of all anodes was approximately 7.5 mass %, and the content of lead, tin and antimony was varied. It was observed, that anodes with O2 content lower than 200 ppm, were not passivated. Results, obtained using the standard electrochemical techniques, have indicated that the anodes with non-standard chemical composition could be used under the same conditions as well as in the conventional copper refining process

Uticaj mehano-hemijske aktivacije flotacijske jalovine na stepen izdvajanja korisnih komponenti

The presented results refer to the investigation of effect the mechanical-chemical activation of flotation tailings on copper, iron and sulfur leaching degree in the sulfuric-chloride solution with the addition of H2O2 as oxidant. A sample of the Bor flotation tailings (BFT) from the old Bor flotation tailing dump consists of pyrite and tailings as the main components, and is activated in a dry process of the vibro mill with (BFT1) and without (BFT2) addition of NaOH as the chemical reagent. Using the dry magnetic separation in thee high-gradient magnetic separator Sala, the samples were separated into magnetic and non-magnetic fraction, BFT MF and BFT NMF, respectively. Leaching of various treated samples showed that the highest level of copper leaching (98.7 wt %), was obtained for BFJ2 MF sample while the leaching degree of Fe and S was higher in non-magnetic fractions, up to 92.46 wt % in BFT1 NMF sample for Fe and 80.62 wt % for S in BFT2 NMF sample.Prikazani rezultati odnose se na ispitivanje uticaja mehano-hemijske aktivacije flotacijske jalovine na stepen izluženja bakra, gvožđa i sumpora u sumporno-hloridnom rastvoru uz dodatak H2O2 kao oksidansa. Uzorak borske flotacijske jalovine (BFJ) sa lokacije starog borskog flotacijskog jalovišta sadrži 23% pirita i 75,23% jalovine kao osnovne komponente, a aktiviran je suvim postupkom u vibro mlinu bez i sa dodatkom NaOH kao hemijskog reagensa, uzorci BFJ1 i BFJ2, respektivno. Suvom magnetnom separacijom u visokogradijentnom magnetnom separatoru 'Sala', uzorci su razdvojeni na magnetičnu i nemagnetičnu frakciju, BFJ MF i BFJ NMF, respektivno. Luženje različito tretiranih uzoraka pokazalo je da je najviši stepen izluženja bakra, 98,7 %, postignut kod uzorka BFJ2 MF dok je stepen izluženja Fe i S viši kod nemagnetičnih frakcija, i kreće se do 92,46 % kod uzorka BFJ1 NMF za Fe i 80,62 % za S iz uzorka BFJ2 NMF

Subjective experience of architectural objects: A cross-cultural study

The purpose of the present study was to compare Serbian and Japanese participants in their subjective experience of Serbian and Japanese architectural objects. Subjective experience was operationalized through the ratings on the bipolar scales (e.g. pleasant-unpleasant). In the Preliminary study 1, a set of twelve rating scales was generated. In the Preliminary study 2 twelve Serbian and twelve Japanese architectural objects were specified. In the main experiment two groups of participants, twenty-one Serbian and twenty Japanese, rated twelve Serbian and twelve Japanese objects. A factor analysis extracted three dimensions of subjective experience: Beauty, Firmness and Fullness. Analysis of variance have shown that both Serbian and Japanese participants agreed that Japanese architectural objects looked more beautiful and firmer than Serbian objects. These finding is generally in line with perceptualist hypothesis that stimulus constraints are more effective than culture. However, interactions revealed some cultural differences that are consistent with culturalist hypothesis: compared to Serbian participants, Japanese participants rated Japanese architectural objects as more beautiful, whereas, compared to Japanese, Serbian participants rated Serbian objects as less fragile and emptier than Japanese objects. Generally, our study have shown that Serbian (Western) and Japanese (Eastern) participants show general similarity in their subjective experience of architectural objects

Metode ispitivanja interkristalne korozije na konstrukcijama od nerđajućh čelika na terenu

Determination of the susceptibility of austenitic stainless steel X5CrNi18-10 to intergranular corrosion (IGC) is performed by measuring the corrosion potential Ecorr in a drop of a test solution with specific chemical composition. It has been shown that a good correlation exists between the results obtained by Ecorr measurements in a drop of the test solution and the results obtained by the double loop electrochemical potentiokinetic reactivation method (DL EPR). The results are confirmed by SEM analysis of the stainless steel surface after the IGC test. The method of Ecorr measurements is a simple non-destructive method that provides qualitative information on the susceptibility of the stainless steel to IGC. The DL EPR method is a quantitative method that can determine small differences in the susceptibility of stainless steel to IGC. Simple and cheap equipment is required to perform Ecorr measurements. The method is easy to perform on stainless steel structures in the field.Određivanje sklonosti austenitnog nerđajućeg čelika X5CrNi18-10 prema interkristalnoj koroziji izvršeno je na osnovu merenja korozionog potencijala Ekor u kapi rastvora definisanog sastava. Pokazano je da postoji dobra saglasnost dobijenih rezultata sa rezultatima ispitivanja interkristalne korozije primenom metode elektrohemijske potenciokinetičke reaktivacije sa povratnom petljom (DL EPR). Dobijeni rezultati su potvrđeni SEM analizom površine čelika posle ispitivanja interkristalne korozije navedenim metodama. Metoda merenja Ekor u kapi rastvora je jednostavna, nerazarajuća metoda koja daje kvalitativne podatke o sklonosti čelika prema interkristalnoj koroziji, dok je DL EPR metoda kvantitativna, kojom se mogu odrediti male razlike u sklonosti nerđajućih čelika prema interkristalnoj koroziji. Za izvođenje ispitivanja metodom merenja Ekor u kapi rastvora potrebna je znatno jeftinija i jednostavnija oprema. Ova metoda se lako izvodi na gotovim konstrukcijama, na terenu

Study of red clover wild populations from the territory of Serbia for the purpose of pre-selection

The aim of this paper was to evaluate the agronomic value of red clover (Trifolium pratense L.) wild populations. The analyzed material was gathered on the territory of Serbia and it was estimated which populations could be involved in the breeding program. 17 red clover populations were included in the research. Investigation was carried out at the experimental field of the Institute for forage crops, Krusevac, Serbia. The field trial was performed during three years (2008 - 2010) when data about morphological (green mass, dry mater, plant height, number of stems, number of lateral branches, number of internodes, length and width of a middle leaf lamina) and basic chemical parameters (quantity of crude proteins, crude fiber, ash, fat, NFE) were collected. In this paper, results of the research were processed by application of analysis of variance (ANOVA) and multivariation methods. Cluster analysis based on morphological traits resulted in formation of three clusters and the traits with the largest influence on grouping were: green mass, plant height, length and width of a leaf. Principal component method confirmed this separation and resulted in even more clear grouping of populations. Cluster analysis and PCA method were also applied to the traits of dry matter quality, when four clusters were formed, and the traits with the largest influence on grouping were percentages of protein, fat and fiber. Using both set of traits and several types of analyses contribute to grouping of populations which promise most and whose positive traits such as: high green mass yield, number of stems as well as the percentage of proteins can be combined for the purpose of getting synthetic varieties

Decopperization process of waste solutions from conventional copper electrolysis

This paper is adresses on treatment of sulphuric acid waste solutions obtained during the conventional copper metallurgical activities. Mother liquor is a part of this solutions and it is generated during the regeneration process of copper bleed solution. Copper, nickel and sulphuric acid are the main components and the other registered impurities are: As, Se, Fe, Sb, Zn, Bi, Pb, Cl ions. Aim to copper removing from the mother liquor, the decopperization process on the industrial scale equipment, is investigated. Investigation was done using the rectangular insoluble lead anodes alloyed with 6 wt.% of antimony at current value of 13 000 A, identical to the current in a commercial copper refinery plant. A few parameters as so as: current, cell voltage, electrolyte temperature, electrolyte flow rate, level of electrolyte, were monitored during the test. Comparing the values of copper content in the solution before and after the decopperization of copper, it was found that it decreased of about 80 wt. % of the initial value. Chemical characterization of the sludge obtained on cathode has shown that it is a material with copper content of about 90 wt. %

Elektrohemijsko taloženje i fazna struktura legura Ni-W

The induced deposition of W in the presence of iron-group metals has been known for a long time without a proper understanding of the mechanism of codeposition. Hints were made by several authors, concerning primarily a similar case of codeposition of Mo, which were not sufficiently substantiated by proper kinetic investigation as the research was oriented mainly toward practical aims. In the present investigation induced deposition of W with Ni was studied primarily from the point of view of the composition and phase structure of the resulting Ni-W alloy. The method of anodic linear sweep voltammetry was used to analyze deposits obtained at a rotating disc electrode, as it was proven to be a good tool for analysis of thin-layered deposits. The polarisation diagram was found to exhibit a sharp current maximum and a subsequent decay at potentials at which Ni deposition starts. As some W oxide is found to deposit at less negative potential the sharp rise of current and the maximum are ascribed to catalytic effect of the oxide for hydrogen evolution, larger than that of depositing Ni-W alloy. The deposit was found to exhibit two peaks upon anodic dissolution, both at significantly more positive potentials than that of Ni dissolution. The first peak is of limited quantity of electricity independent of the amount of the deposit, the increase of the latter being reflected in the second peak only. An aging effect was found rendering an alloy requiring much more positive potentials for dissolution than those for dissolution of freshly deposited alloys.Taloženje volframa u prisustvu metala grupe gvožđa, indukovano taloženje, je fenomemen koji je odavno poznat. Međutim, mehanizam kodepozicije nije razjašnjen. Dosadašnja istraživanja indukovanog taloženja ( i to najčešće molibdena ) prvenstveno su bila usmerena ka primeni u praksi, a nedovoljno praćena odgovarajućim kinetičkim ispitivanjima. U ovom radu ispitivano je indukovano taloženje W sa Ni prvenstveno sa stanovišta sastava i fazne strukture dobijenih Ni-W legura. Metoda anodne linearne promene potencijala (ALSV) upotrebljena je za analizu prevlaka dobijenih na rotirajućoj disk elektrodi. Na katodnim polarizacionim dijagramima taloženja nađen je oštar strujni maksimum na potencijalu koji odgovara početku taloženja Ni. Pad struje se može pripisati sporijem izdvajanju vodonika na leguri Ni-W, nego na oksidu volframa koji je se dobija pri manje negativnim potencijalima. Na anodnim voltamogamima rastvaranja javljaju se dva karakteristična strujna vrha, oba na potencijalima znatno pozitivnijim od onih koji odgovaraju rastvaranju čistog Ni. Količina naelektrisanja koja odgovara prvom strujnom vrhu je ograničena odnosno, povećanje količine naelektrisanja pri taloženju odražava se u odgovarajućem porastu naelektrisanja drugog anodnog strujnog vrha. Nađeno je da se legure, koje su stajale na sobnoj temperaturi u toku nekoliko časova posle taloženja, rastvaraju na znatno pozitivnijim potencijalim od onih koje su ispitivane neposredno posle taloženja, što ukazuje na stabilizaciju procesom u čvrsoj fazi

Magnesium-Gold Alloy Formation by Underpotential Deposition of Magnesium onto Gold from Nitrate Melts

Magnesium underpotential deposition on gold electrodes from magnesium nitrate-ammonium nitrate melts has been investigated. Linear sweep voltammetry and potential step were used as electrochemical techniques. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were used for characterization of obtained electrode surfaces. It was observed that reduction processes of nitrate, nitrite and traces of water (when present), in the Mg underpotential range studied, proceeded simultaneously with magnesium underpotential deposition. There was no clear evidence of Mg/Au alloy formation induced by Mg UPD from the melt made from eutectic mixture [Mg(NO3)(2).6H(2)O + NH4NO3.XH2O]. However, EDS and XRD analysis showed magnesium present in the gold substrate and four different Mg/Au alloys being formed as a result of magnesium underpotential deposition and interdiffusion between Mg deposit and Au substrate from the melt made of a nonaqueous [Mg(NO3)(2) + NH4NO3] eutectic mixture at 460 K

Elektrohemijska sinteza elektroprovodnih polimera

Electroconducting polymers from the group of synthetic metals are extensively investigated due to numerous properties perspective in practical application. These materials may be synthesized by both chemical and electrochemical procedures. Chemical synthesis is suitable when bulk quantities of the polymer are necessary and up to date it presents dominant commercial method of producing electroconducting polymers. Nevertheless, the electrochemical synthesis has its advantages; it avoids usage of oxidants since conducting polymeric material is obtained at anode upon application of positive potential, leading to increased purity. On the other hand, since the polymer is deposited onto electrode, further electrochemical characterization is facilitated. Owing to actuality of the research in the field, this text aims to describe important aspects of electrochemical synthesis of electroconducting polymers, with special emphasis to polyaniline and polypyrrole.Tradicionalno shvatanje o polimerima kao odličnim izolatorima izmenjeno je sedamdesetih godina prošlog veka kada su naučnici uspeli da sintetizuju poiliacetilen čija je provodljivost bila bliska metalnoj. Ova činjenica ukazala je na novo svojstvo polimernih materijala i lansirala potpuno novo multidisciplinarno naučno polje, popularno nazvano, sintetički metali. Iako je danas pojmom elektroprovodnih polimera obuhvaćena velika grupa jedinjenja koja su klasifikovana prema prirodi prenosioca naelektrisanja, naziv elektroprovodni polimeri se najčešće koristi u literaturi upravo za polimerne materijala iz grupe sintetičkih metala koji poseduju elektronsku provodljivost kao posledicu specifičnosti molekulske strukture. Pored zahteva molekulske structure, koja podrazumeva konjugovani sistem dvostrukih veza, za provodljivost elektroprovodnih polimera neophodno je dopovanje. Termin dopovanje, iako preuzet iz terminologije klasičnih neorganskih poluprovodnika, podrazumeva u mnogome drugačiji proces. Dopovanje elektroprovodnih polimera podrazumeva oksidaciju tokom koje se, u cilju održavanja elektroneutralnosti polimernog lanca, uvodi stehiometrijska količina jona (anjona). Terminom dopovanje obuhvaćena je i protonacija polimernog lanca kiselinom, u slučaju polianilina, a nedavno je potvrđena i u slučaju polipirola. Kako je, na ovaj način, uvedena velika količina jona izmenjenja je polazna struktura elektroprovodnog polimera, tako da svojstva nastalog materijala zavise u velikoj meri od svojstava dopanta. Iako su na početku razvoja ove oblasti, elektroprovodni polimeri bili sintetizovani hemijskim postupcima, sticanjem uvida u mehanizam hemijske sinteze koja podrazumeva oksidativnu radikalnu polimerizaciju, postalo je jasno da se ovi materijali mogu dobiti i elektrohemijskim postupcima. Elektrohemijska sinteza ima prednosti, pošto se polimer dobija oksidacijom na elektrodama (anodama), čime je izbegnuta upotreba oksidacinog sredstva i omogućena veća čistoća proizvoda. Sa druge strane, elektroprovodni polimer je u većini slučajeva dobijen u obliku prevlake na elektrodi, pa je njegova dalja karakterizacija elektrohemijskim tenikama olakšana. Interesovanje za oblst sinteze elektroprovodnih polimera ne jenjava, pa je ovaj tekst posvećen osnovnim principima elektrohemijskih postupaka sinteze sa posebnim osvrtom na najpopularnije elektroprovodne polimere, polianilin i polipirol