Ljiljana Rajic | Northeastern University (original) (raw)

Papers by Ljiljana Rajic

Separation and Purification Technology, 2021

H2O2 generation by 2-electron oxygen electroreduction reaction (2eORR) has attracted great attent... more H2O2 generation by 2-electron oxygen electroreduction reaction (2eORR) has attracted great attention as an alternative to the industry-dominant anthraquinone process. Electro-Fenton (EF) process, which relies on the H2O2 electrogeneration, is regarded as an important environmental application of H2O2 generation by 2eORR. However, its application is hindered by the relatively expensive electrode materials. Proposing cathode materials with low cost and facile synthetic procedures are the priority to advance the EF process. In this work, a composite cathode structure that uses graphitic granular bamboo-based biochar (GB) and stainless steel (SS) mesh (GBSS) is proposed, where SS mesh functions as current distributor and GB supports synergistic H2O2 electrogeneration and activation. The graphitic carbon makes GB conductive and the oxygen-containing groups serve as active sites for H2O2 production. 11.3 mg/L H2O2 was produced from 2.0 g GB at 50 mA after 50 min under neutral pH without external O2/air supply. The O-doped biochar further increased the H2O2 yield to 18.3 mg/L under same conditions. The GBSS electrode is also effective for H2O2 activation to generate ·OH, especially under neutral pH. Ultimately, a neutral Fe-free EF process enabled by GBSS cathode is effective for removal of various model organic pollutants (reactive blue 19, orange II, 4-nitrophenol) within 120 min, and for their partial mineralization (48.4% to 63.5%). Long-term stability of the GBSS electrode for H2O2 electrogeneration, H2O2 activation, and pollutants degradation were also examined and analyzed. This work offers a promising application for biomass waste for removals of organic pollutants in neutral Fe-free EF process.

Chemical Engineering Journal, 2019

Electrochemical synthesis of H2O2 offers a great potential for water treatment. However, a signif... more Electrochemical synthesis of H2O2 offers a great potential for water treatment. However, a significant challenge is the development of efficient cathode materials for the process. Herein, we implement a practical electrochemical cathode modification to support efficient H2O2 electrogeneration via the reduction of dissolved anodic O2. Graphite felt (GF) is in situ anodically modified by electrode polarity reversal technique in an acid-free, low-conductivity electrolyte. The modified GF exhibits a significantly higher activity towards O2 reduction. Up to 183.3% higher H2O2 yield is obtained by the anodized GF due to the increased concentrations of oxygen-containing groups and the hydrophilicity of the surface, which facilitates electron and mass transfer between GF and the electrolyte. Another significant finding is the ability to produce H2O2 at a high yield under neutral pH and low current intensity by the modified GF (35% of the charge need to produce the same amount by unmodified GF). Long-term stability testing of the modified GF showed a decay in the electrode’s activity for H2O2 production after 30 consecutive applications. However, the electrode regained its optimal activity for H2O2 production after a secondary modification by electrode polarity reversal. Finally, in situ electrochemically modified GF is more effective for removal of reactive blue 19 (RB19, 20 mg/L) and ibuprofen (IBP, 10 mg/L) by the electro-Fenton process. The modified GF removed 62.7% of RB19 compared to only 28.1% by the unmodified GF in batch reactors after 50 min. Similarly, 75.3% IBP is removed by the modified GF compared to 57.6% by the unmodified GF in a flow-through reactor after 100 min.

International journal of electrochemical science

In this work we present the results of a laboratory study to assess the possibility of Fe/C and F... more In this work we present the results of a laboratory study to assess the possibility of Fe/C and Fe/Cu galvanic cell utilization for Cu removal from a kaolin model matrix as an electrokinetic treatment without electricity consumption. In addition, we examine improving the desorption of Cu ions from kaolin particles by acidification. Several experiments were conducted: conventional (ECC), Fe/C galvanic cell (GC1), Fe/Cu galvanic cell (GC2), Fe/C galvanic cell with kaolin acidification (GC3) and Fe/Cu galvanic cell with kaolin acidification (GC4). The following removal efficacies were achieved: 44% for ECC, 20% for GC1, 37% for GC2, 46% for GC3 and 45% for GC4. The Fe/Cu galvanic cell resulted in better removal efficacy as metallic Cu was deposited at the cathode. Acidification of kaolin prior to treatment contributed to Cu2+ desorption and thus improved removal efficacy, especially during GC3. This work demonstrates that an Fe/Cu galvanic cell can be used for electrokinetic treatment ...

Izvod Vodotok Krivaja je najduže prirodno vodno telo (109 km) koje se celom svojom dužinom nalazi... more Izvod Vodotok Krivaja je najduže prirodno vodno telo (109 km) koje se celom svojom dužinom nalazi na teritoriji AP Vojvodine (Srbija). Na osnovu holandske direktive za kvalitet sedi-menta ustanovljeno je da je sediment Krivaje izuzetno zagađen bakrom i cinkom. Rezultati sekvencijalne ekstrakcione procedure su ukazali da ovi metali pokazuju umerenu opasnost po akvatičnu sredinu čime je pokazano da jedan kriterijum za procenu kvaliteta sedimenta nije dovoljan. Za remedijaciju ovog sedimenta odabran je tretman solidifikacije/stabilizacije (S/S) lokalnom glinom sa visokim kapacitetom katjonske izmene (70,2 meq/100g) i velikom specifičnom površinom (630 m 2 g –1). Ova tehnologija, koja uključuje mešanje vezivnog materijala sa kontaminiranim materijalom, štiti životnu sredinu imobilišući štetne kompo-nente. Radi procene dugoročnog ponašanja S/S smeša, rađeni su testovi izluživanja u skla-du sa ANS (American National Standard) difuzionim testom u periodu od 90 dana. Dobijeni rezultati ukaz...

TheScientificWorldJournal, 2010

The assessment of the quality of sediment from the Great Backi Canal (Serbia), based on the pseud... more The assessment of the quality of sediment from the Great Backi Canal (Serbia), based on the pseudo-total lead (Pb) and cadmium (Cd) content according to the corresponding Dutch standards and Canadian guidelines, showed its severe contamination with these two metals. A microwave-assisted BCR (Community Bureau of Reference of the Commission of the European Union) sequential extraction procedure was employed to assess their potential mobility and risk to the aquatic environment. Comparison of the results of sequential extraction and different criteria for sediment quality assessment has led to somewhat contradictory conclusions. Namely, while the results of sequential extraction showed that Cd comes under the high-risk category, Pb shows low risk to the environment, despite its high pseudo-total content. The contaminated sediment, irrespective of the different speciation of Pb and Cd, was subjected to the same immobilization, stabilization/solidification (S/S) treatments using kaolinit...

Hemijska industrija, 2013

Electrochimica Acta, 2012

This study investigates the possibility of simultaneous application of the moving anode technique... more This study investigates the possibility of simultaneous application of the moving anode technique and increased cathode compartment length as an enhanced electrokinetic treatment of lead-contaminated sediment from the River Tamis. The moving anode technique was employed to improve Pb desorption from sediment particles whilst the increased cathode compartment length was meant to prevent hydroxyl ions from penetrating into the sediment, to avoid metal precipitation and accumulation. Overall lead removal efficacies from the sediment were 38% and 62% after the conventional and enhanced treatments, respectively. Water electrolysis at the implemented anodes resulted in: (a) H + formation (lowering pH) causing more Pb ions to desorb from the sediment particles and (b) oxygen formation causing the redox potential to become more positive, resulting in lead reorganisation from the oxidizable fraction into more soluble fractions (can be removed by electromigration). The increased cathode compartment length prevented hydroxyl ions penetration into the sediment. Finally, the sediment after the enhanced treatment was Class1/2 according to the Dutch standard. We thus demonstrate that the simultaneous use of the moving anode technique and increased cathode compartment length is an effective technique for electrokinetic removal of lead from sediment which does not involve adding chemicals into the system.

Contaminated Sediments: 5th Volume, Restoration of Aquatic Environment, 2012

Electrochimica Acta, 2015

ABSTRACT In this study, we evaluate the use of different stainless steel (SS) materials as cost-e... more ABSTRACT In this study, we evaluate the use of different stainless steel (SS) materials as cost-effective cathode materials for electrochemical transformation of trichloroethylene (TCE) in contaminated groundwater. Ni, which is present in certain SS, has low hydrogen overpotential that promotes fast formation of atomic hydrogen and, therefore, its content can enhance hydrodechlorination (HDC). We a flow-through electrochemical reactor with a SS cathode followed by an anode. The performance of Ni containing foam cathodes (Fe/Ni and Ni foam) was also evaluated for electrochemical transformation of TCE in groundwater. SS type 316 (12% Ni) removed 61.7% of TCE compared to 52.6% removed by SS 304 (9.25% Ni) and 37.5% removed by SS 430 (0.75% Ni). Ni foam cathode produced the highest TCE removal rate (68.4%) compared with other cathodes. The slightly lower performance of SS type 316 mesh is balanced by the reduction in treatment costs for larger-scale systems. The results prove that Ni content in SS highly influences TCE removal rate.

Environmental Engineering Science, 2013

Enhanced electrokinetic (EK) removal of Cr, Cu, and Zn from sediment by using original and modifi... more Enhanced electrokinetic (EK) removal of Cr, Cu, and Zn from sediment by using original and modified integrated ion exchange (IIXÔ) cathodes was investigated. IIX cathode design and EK device process modifications were made to improve performance: separation of IIX cathode components (IIXS), combination of modified IIX cathode with pulsed electric field (IIXSP), and separation of IIX cathode components with addition of an anion exchange resin compartment (IIXA). After using the IIXSP, overall Cr, Cu, and Zn removal efficacies were significantly improved compared with the other treatments investigated. No improvements in overall Cr, Cu, and Zn removal efficacies were achieved by utilization of IIXA. Nevertheless, significant removal efficacies occurred at the anode region since distribution of the alkaline front was prevented. However, metal accumulation in the cathode region occurred. This was a consequence of metal cation complexation with Clreleased from the anion exchange resin that changed the direction of metal migration. Enhancing EK remediation of Cr-, Cu-, and Zn-contaminated sediment can be achieved by using a modified IIX cathode.

Electrochimica Acta, 2015

ABSTRACT In this study we investigate the influence of humic substances (HS) on electrochemical t... more ABSTRACT In this study we investigate the influence of humic substances (HS) on electrochemical transformation of trichloroethylene (TCE) in groundwater from limestone aquifers. A laboratory flow-through column with an electrochemical reactor that consists of a palladized iron foam cathode followed by a MMO anode was used to induce TCE electro-reduction in groundwater. Up to 82.9% TCE removal was achieved in the absence of HS. Presence of 1, 2, 5, and 10 mgTOC L−1 reduced TCE removal to 70.9%, 61.4%, 51.8% and 19.5%, respectively. The inverse correlation between HS content and TCE removal was linear. Total organic carbon (TOC), dissolved organic carbon (DOC) and absorption properties (A = 254 nm, 365 nm and 436 nm) normalized to DOC, were monitored during treatment to understand the behavior and impacts of HS under electrochemical processes. Changes in all parameters occurred mainly after contact with the cathode, which implies that the HS are reacting either directly with electrons from the cathode or with H2 formed at the cathode surface. Since hydrodechlorination is the primary TCE reduction mechanism in this setup, reactions of the HS with the cathode limit transformation of TCE. The presence of limestone gravel reduced the impact of HS on TCE removal. The study concludes that presence of humic substances adversely affects TCE removal from contaminated groundwater by electrochemical reduction using palladized cathodes.

Hemijska industrija, 2012

ABSTRACT The Krivaja River is the longest natural water body (109 km) that flows completely withi... more ABSTRACT The Krivaja River is the longest natural water body (109 km) that flows completely within the borders of Serbian province of Vojvodina. In the absence of national legislation, the sediment quality was assessed in accordance with the Dutch classification methodology. It was found that the river sediment is highly contaminated with copper and zinc (192 and 1218 mg kg(-1), respectively), and as such is an extreme risk to the environment and human health. The solidification/stabilization (S/S) treatment with local clay, that has high capacity of cation exchange 70.2 meq/100 g and specific surface area of 630 m(2) g(-1), was employed for remediation of the contaminated sediment. The sequential extraction procedure showed that the copper and zinc have medium risk for the environment, with the percentage in the carbonate fraction of 18 and 22%, respectively. The results of sequential extraction are not in full agreement with the results of pseudo-total metal concentration in the sediment, which only confirms that the total metal concentration is not sufficient to define the real danger to the environment. Based on the pseudo-total metals concentration, the sediment is of Class 4 (Dutch standards). However, judging from the results of sequential extraction, the metals show medium risk. Obviously, these results have to be taken into account in the assessment of the sediment quality, remediation procedures and sediment disposal in general. After the treatment, the proportion of these two metals in the first fraction is significantly reduced (Cu less than 2%, Zn 10%) in most of samples. In order to determine the long-term behavior of S/S mixtures, leaching tests were conducted in accordance with semi-dynamic ANS diffusion test for 90 days. The results indicated that clay can effectively immobilize Cu and Zn: the cumulative leached fraction of copper in mixtures with clay was in the range from 0.001% (mixture with 80% clay) to 0.15% (mixture with 10% clay), and the cumulative leached fraction of zinc in the range of 0.06% (mixture with 80% clay) to 0.10% (mixture with 10% clay). The diffusion coefficients, ranging from 1.5x10(-12) to 3.7x10(-14) cm(2) s(-1), showed an effective immobilization of both metals which suggests that these metals are practically immobilized in S/S mixtures even if the level of clay is low. From the point of LX values, all S/S mixtures can be used for the controlled utilization, because the leaching indices ranged from 11.8 to 13.4 for both metals. In all clay and sediment mixtures the dominant leaching mechanism is diffusion (slope values of 0.35 to 0.60), which once again confirms the effectiveness of the applied treatment and can be expected that only a very small amount of contaminants would leach into the environment over time. Future research is heading in the direction of troubleshooting the accumulation of used natural adsorbent after treatment, the possibility of permanent disposal, its regeneration or the possibility of its application as construction material.

Pyrite ash (PA) is created by burning pyrite in the chemical production of sulphuric acid. The hi... more Pyrite ash (PA) is created by burning pyrite in the chemical production of sulphuric acid. The high concentration of iron oxide, mostly hematite, present in pyrite ash, gives the basis for its application as a source of catalytic iron in a modified Fenton process for anthraquinone dye reactive blue 4 (RB4) degradation. The effect of various operating variables such as catalyst and oxidant concentration, initial pH and RB4 concentration on the abatement of total organic carbon, and dye has been assessed in this study. Here we show that degradation of RB4 in the modified Fenton reaction was efficient under the following conditions: pH = 2.5;

Journal of Environmental Science and Health, Part A, 2013

In this article an assessment of the sediment metal pollution (cadmium, copper, chromium, lead, n... more In this article an assessment of the sediment metal pollution (cadmium, copper, chromium, lead, nickel, zinc) in the Veliki Backi canal (Serbia) was carried out using pseudo-total metal content, contamination factor (CF), pollution load index (PLI) and enrichment factor (EF). The study also encompassed pore-water metal concentrations and an assessment of sediment pollution based on the analysis of simultaneously extracted metals (SEM), acid volatile sulphides (AVS) and the sequential extraction procedure. The concentrations of metals are likely to result in harmful effects based on the comparison with sediment quality guidelines (Dutch, Canadian, US EPA - United States Environmental Protection Agency). The ratio of simultaneously extracted metals and volatile acid sulphides was found to be greater than 1 in only one location, which is already recognized as a place of high risk based on the criteria applied. Other samples had Σ[SEM]/[AVS] &amp;lt; 1, despite their high risk classification based on the applied criteria. According to the sequential extraction procedure, zinc and nickel exhibit high risk in most samples, whereas other metals show low and medium risk. The CF values for Cr, Cu and Zn were &amp;gt; 6 in most samples, which denotes very high contamination by these metals. The PLI values indicated moderate and high pollution. The EF values for all metals studied except for Cd in some cases were &amp;gt;1.5, suggesting anthropogenic impact. The obtained results will be invaluable for future activities regarding sediment monitoring and will facilitate the selection of appropriate criteria when evaluating sediment quality.

Process Safety and Environmental Protection, 2014

Please cite this article in press as: Prica, M., et al., The electrocoagulation/flotation study: ... more Please cite this article in press as: Prica, M., et al., The electrocoagulation/flotation study: The removal of heavy metals from the waste fountain solution. Process Safety and Environmental Protection (2014), http://dx.

Chemical Industry and Chemical Engineering Quarterly, 2011

... CI&CEQ 451 LJILJANA RAJIĆ BOŽO DALMACIJA SVETLANA UGARČINA PEROVIĆMALCOLM WATSON MILE... more ... CI&CEQ 451 LJILJANA RAJIĆ BOŽO DALMACIJA SVETLANA UGARČINA PEROVIĆMALCOLM WATSON MILENA DALMACIJA ... Total. Environ. 266 (2001) 195-202 [5] LM Ottosen, PE Jensen, Electro-remediation of heavy-metal contaminated soil. ...

Herbicides - Properties, Synthesis and Control of Weeds, 2012

Separation and Purification Technology, 2021

Chemical Engineering Journal, 2019

International journal of electrochemical science

TheScientificWorldJournal, 2010

Hemijska industrija, 2013

Electrochimica Acta, 2012

Contaminated Sediments: 5th Volume, Restoration of Aquatic Environment, 2012

Electrochimica Acta, 2015

Environmental Engineering Science, 2013

Electrochimica Acta, 2015

Hemijska industrija, 2012

Journal of Environmental Science and Health, Part A, 2013

Process Safety and Environmental Protection, 2014

Chemical Industry and Chemical Engineering Quarterly, 2011

Herbicides - Properties, Synthesis and Control of Weeds, 2012