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Predmet istraživanja ovog master rada fokusiran je na tehnologiji flekso štampe u cilju tretmana žute flekso grafičke boje primenom Fenton procesa, kao i ispitivanju uticaja pojedinih parametara na efikasnost obezbojavanja. Fenton proces predstavlja jedan od najefikasnijih unapređenih procesa oksidacije koji se primenjuje za tretman otpadnih voda koje imaju visok sadržaj teško degradabilnih jedinjenja. Bazira se na generisanju hidroksil radikala iz vodonik-peroksida u prisustvu jona gvožđa kao katalizatora pri kiseloj pH vrednosti i ambijentalnim uslovima. Tokom eksperimenta ustanovljen je izražen uticaj pH vrednosti na odigravanje heterogenog Fenton procesa, dok je uticaj ostalih faktora zanemarljiv. Takođe je ustanovljeno da smanjenje pH vrednosti dovodi do povećanja efikasnosti obezbojavanja sintetičkog rastvora žute boje.

The paper reports removal of organic Black (Key) dye from real printing wastewater using nano zero valent iron particles as a catalyst in Fenton-like treatment. The degradation efficiency of Black diazo dye via Fenton-like treatment is reported to be 61% under established optimal process conditions: [Fe2+] = 0.75 mgL-1, pH = 2, [H2O2] = 1 mM, within a reaction time of 75 min. The absorption spectra of Black dye clearly indicate that dye degradation is a slow process with difficult decomposition of aromatic structures, due to the cleavage of diazo bonds by hydroxyl radicals. The physico-chemical characterizations (measurements of pH, electrical conductivity, temperature, turbidity, chemical oxygen demand, biochemical oxygen demand, total organic carbon, anionic surface-active substances and phosphorus content) as well as toxicity study (Vibrio fischeri bacteria) revealed the complex nature of printing effluent. Increased conductivity and biochemical oxygen demand content after Fenton treatment imply the formation of various byproducts and intermediates, formed in a solution during dye degradation. The mineralization percentage of Black dye of 58% is followed with 47% of chemical oxygen demand reduction. Results of toxicity test on Vibrio fischeri bacteria indicate that both untreated and treated printing effluents belong to moderate toxic samples with 58% and 67% of toxicity inhibition, respectively. Among three evaluated kinetic models (the first-order, the second-order, and Behnajady– Modirshahla–Ghanbary), experimental results fitted very well to the Behnajady - Modirshahla - Ghanbary model, indicating high initial rate of Black dye degradation.

Predmet istraživanja ovog master rada fokusiran je na tehnologiji flekso štampe u cilju tretmana crne flekso grafičke boje primenom Fenton procesa, kao i ispitivanje uticaja pojedinih parametara na efikasnost obezbojavanja. Fenton proces predstavlja jedan od najefikasnijih unapređenih procesa oksidacije koji se primenjuje za oksidaciju/koagulaciju voda koje imaju visok sadržaj površinski aktivnih materija kao i mnogih drugih teško degradabilnih jedinjenja. Bazira se na generisanju hidroksil radikala iz vodonik-peroksida jonima gvožđa kao katalizatorima pri kiseloj vrednosti i ambijentalnim uslovima. Tokom eksperimenta ustanovljeno je da koncentracija katalizatora i pH vrednost u najvećoj meri doprinose odigravanju i efikasnosti heterogenog Fenton procesa. Takođe je ustanovljeno da smanjenje pH vrednosti dovodi do povećanja efikasnosti obezbojavanja sintetičkog rastvora crne boje.

The presence of a large number of micropollutants in the environment, including priority and emerging substances, poses a significant risk to surface and groundwater quality. Among them, trichlorobenzenes are widely used in the syntheses of dyes, pesticides, solvents, and other chemicals and have been identified as priority pollutants by the European Water Framework Directive. The main goal of this study was to investigate the behavior of 1,2,3-trichlorobenzene (TCB) during the sulfate radical–based advanced oxidation processes (SR-AOPs) involving UV activation of persulfate or peroxymonosulfate (UV/S2O82− and UV/HSO5− processes). For this purpose, TCB was subjected to SR-AOPs in synthetic water matrices containing humic acids or hydrogencarbonate and natural water samples and a comparative evaluation of the degradation process was made. The toxicity of the oxidation by-products was also assessed. The evaluation of TCB degradation kinetics results using principal component analysis indicates that the efficacy of the SR-AOPs was highly dependent on the pH, initial oxidant concentration, UV fluence, and matrix characteristics. In natural waters, TCB degradation by the UV/S2O82− process proved to be most effective in acidic conditions (pH 5), while the UV/HSO5− process showed the highest efficacy in basic conditions (pH 9.5), achieving a maximum TCB degradations of 97–99%. The obtained results indicate that UV/S2O82− and UV/HSO5− as new generation oxidation processes have significant potential for TCB removal from water and result in only minor toxicity after treatment (14–23% of Vibrio fischeri bioluminescence inhibition).

Surface roughness is an important indicator of the quality of the machined surface. One of the methods that can be applied to improve surface roughness is ball burnishing. Ball burnishing is a finishing process in which a ball is rolled over the workpiece surface. Defining adequate input variables of the ball burnishing process to ensure obtaining the required surface roughness is a typical problem in scientific research. This paper presents the results of experiments to investigate ball burnishing of AISI 4130 alloy steel with a high-stiffness tool and a ceramic ball. The experiments were conducted following a randomized full factorial design for different levels of input variables. The input variables included the initial arithmetic mean roughness (the initial surface roughness), the depth of ball penetration, the burnishing feed, and the burnishing ball diameter, while the output variable was the arithmetic mean roughness after ball burnishing (the final surface roughness). The surface roughness modeling was performed based on the experimental results, using regression analysis (RA), artificial neural network (ANN), and support vector regression (SVR). The regression model displayed large prediction errors at low surface roughness values (below 1 μm), but it proved to be reliable for higher roughness values. The ANN and SVR models have excellently predicted roughness across a range of input variables. Mean percentage error (MPE) during the experimental training research was 29.727%, 0.995%, and 1.592%, and MPE in the confirmation experiments was 34.534%, 1.559%, and 2.164%, for RA, ANN, and SVR, respectively. Based on the obtained MPEs, it can be concluded that the application of ANN and SVR was adequate for modeling the ball burnishing process and prediction of the roughness of the treated surface in terms of the possibility of practical application in real industrial conditions.

The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20–180 mg L−1), iron concentration (0.75–60 mg L−1), pH (2–10) and hydrogen peroxide concentration (1–11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

This paper examines the impact of the CO2 laser parameters on the tensile strength, which is one of the most important properties of paper packaging in the process of cutting paper material. The study was performed on a paper material sample Fbb Board/Ningbo Spark C1S Ivory Board by examination of the influence of four independent variables: paper material grammage, cutting speed, laser power, and resolution on the tensile strength by using definitive screening design. Optimum process conditions of four variables that maximize the tensile strength were predicted and validated accordingly. Results confirm that laser power, paper material grammage, and cutting speed are the main process parameters that mostly affect the tensile strength. Besides individual parameters, two statistically significant interactions were obtained: laser power and cutting speed, and cutting speed and laser resolution. Maximum tensile strength values (20.37 N/mm) were achieved using the laser power of 60.6%, cutting speed of 3.24%, resolution of 2500 Hz, and a paper material grammage of 326.85 g/m2. With laser power at middle values and at a lower speed, a maximum tensile strength value can be obtained. Increasing the laser power and cutting speed will produce a slight lowering of tensile strength.

Predmet istraživanja ovog master rada zahvata područje iz oblasti flekso štampe u cilju tretmana magenta flekso grafičke boje primenom Fenton procesa, kao i ispitivanje uticaja pojedinih parametara na efikasnost obezbojavanja. Fenton proces je vrlo efikasan u degradaciji različitih vrsta boja. Zasniva se na dodatku Fentonovog reagensa, koji je mešavina vodonik-peroksida i jona gvožđa i bazira se na generisanju hidroksil radikala. Kao katalizator Fenton procesa korišćene su čestice nano nula valentnog gvožđa. “Zelena”sinteza nanomaterijala je sprovedena korišćenjem opalog lišća sa drveta hrasta koje raste u Nacionalnom parku Fruška Gora. Ispitivanje efikasnosti obezbojavanja vodenog rastvora grafičke boje vršeno je serijom eksperimenata na aparaturi za JAR test.

Ekološki uticaj mangana na grafičko okruženje utvrđen je kroz određivanje sadržaja mangana u štampanim ofset uzorcima i migracije mangana iz uzoraka u deponijsko tlo, kiseo i neutralan rastvor. Takođe, izvršena je i procena rizika migracije mangana određivanjem doze koja je dospela u medij životne sredine.

Heterogeneous Fenton catalyst Fe2(MoO4)3 was prepared and the process efficiency was evaluated for oxidation of water-based Cyan flexo dye in synthetic aqueous solution and printing wastewater. The removal process of printing dye was analyzed by UV/VIS spectrophotometry, while dye mineralization was evaluated by the determination of total organic carbon content and chemical oxygen demand. Four determinants of the heterogeneous Fenton system, including initial dye concentration, iron concentration, pH and hydrogen peroxide concentration were investigated. Statistical method, definitive screening design was applied to generate optimal operational conditions of the four variables, which maximizes the process of dye removal. The initial dye concentration of 20 mgL-1, catalyst dosage of 0.75 mgL-1, pH of 2 and H2O2 concentration of 11 mM were chosen as the best operational conditions, contributing to 82% of the process efficiency. The Fenton process efficiency of 79% was achieved within the treatment of printing wastewater under optimal conditions for a 90 minute reaction time. The maximum COD removal efficiency was 61.1%, while 67% mineralization was achieved. The obtained results confirmed synergistic effect of Fe3+ and MoO4 2− which contributed to high catalytic activity and high heterogeneous Fenton efficiency. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 34014 and Grant no. III43005]

The electrocoagulation/flotation treatment (ECF) was employed for the reduction of copper from the waste printing developer in a batch study by using four different aluminum and iron electrode combinations with independent ECF parameters such as current density, interelectrode distance and operating time. The individual and interactive effects of the three main independent ECF parameters were studied by using the response surface methodology. Based on the results, parameters for high copper removal efficiency (95.5%) from the waste printing developer by the ECF were: Al(−)/Al(+) electrode combination with an interelectrode distance of 1.0 cm, operating time of 10 min and a current density of 4 mA cm−2. Moreover, the kinetic study of the ECF treatment of waste printing developer demonstrated that the removal of copper follows the pseudo second-order model with current dependent parameters. For immobilization process of copper in waste ECF sludge, the solidification/stabilization (S/S) treatment was conducted with Portland cement, lime, bentonite, and local clay as immobilization agents. The efficiency of the S/S treatment was monitored by applying leaching tests with one extraction fluid during a certain time. Therefore, using ECF and S/S treatments, copper from the printing effluent can be safely disposed into the environment.

The paper presents an approach to solving the problem of modelling and prediction of surface roughness in CNC turning process. In order to solve this problem an experiment was designed. Samples for experimental part of investigation were of dimensions 30 × 350 mm, and the sample material was GJS 500 - 7. Six cutting inserts were used for the designed experiment as well as variations of cutting speed, feed and depth of cut on CNC lathe DMG Moriseiki-CTX 310 Ecoline. After the conducted experiment, surface roughness of each sample was measured and a data set of 750 instances was formed. For data analysis, the Back-Propagation Neural Network (BPNN) algorithm was used. In modelling different BPNN architectures with characteristic features the results of RMS (Root Mean Square) error were controlled. Specially analysed were the RMS errors realised by different number of neurons in hidden layers. For the BPNN architecture with one hidden layer the architecture (4 – 8 - 1) was adopted with RMS error of 3,37%. In modelling the BPNN architecture with two hidden layers, a considerable amount of architectures was investigated. The adopted architecture with two hidden layers (4 - 2 - 10 - 1) generated the RMS error of 2,26%. The investigation was also directed at the size of the data set and controlling the level of RMS error.

Starting from the assumption that wastewater treatments can have a significant impact on the interactions between microplastics (MPs) and various pollutants in different matrices, a focus must be directed on examination of classic and redesigned treatments to remove synthetic dyes in the presence of MPs from wastewater. This paper investigates the potential application of Fenton-like process for the removal of water-based printing dye (Cyan) from aqueous solution containing MPs in a form of granulated polyethylene (PEg). The influence of five quantitative parameters on decolorization efficiency was investigated: initial dye concentration (20-180 mgL-1), nano zero valent iron (nZVI) dosage (0.75-60 mgL-1), PEg concentration (1-10 gL-1), hydrogen-peroxide concentration (1-11 mM) and pH value (2-10). A novel statistical approach, definitive screening design, resulted with the optimization process which yielded highest removal efficiency of 92% under following conditions: initial dye concentration of 155 mgL-1, nZVI dosage of 55 mgL-1, PEg concentration of 2.35 gL-1, H2O2 concentration of 2 mM and pH value 2.5. Available data indicate that in the future, wastewater containing MPs will dictate ways to reuse this water in terms of closing the water material cycle and reducing environmental pollution. Therefore, the industrial wastewater reuse is an important component of sustainable wastewater management practices, namely, water resource augmentation and pollutant reduction.

Fenton oxidation process has obtained large applicative use for efficient water remediation, whereby overall reaction efficiency could be improved by developing advanced Fenton catalysts. In order to synthesize iron nanoparticles with higher catalytic activity, a simple and eco-friendly method using FeCl3 and aqueous plant extract (oak leaves) was applied in this paper. The nano zero valent iron particles were used as a catalyst in Fenton treatment to remove organic dye from aqueous solution. The objective of this study was to optimize Fenton-like process for the removal of black printing dye using a recently developed design of experiment method - definitive screening design. This novel design framework significantly reduces the number of experiments required to estimate the model parameters and to establish the optimum operation conditions. The experiments were carried out in a batch mode technique, investigating the influence of dye concentration (20 - 180 mgL-1), nanoparticles dosage (0.75 - 60 mgL-1), H2O2 concentration (1 - 11 mM) and pH value of the solution (2 - 10) on the decolorization efficiency. The Fenton-like process resulted with 79% of dye removal from aqueous solution under the optimal process conditions: dye concentration of 180 mgL-1, nanoparticles dosage of 0.75 mgL-1, H2O2 concentration of 1 mM and pH of 2. Increasing the pH value to slightly acidic or near neutral (5-7) medium resulted with slight decrease in the process efficiency (69.14 - 62.63%), but a limitation in the form of sludge generation is noticeable.

Large quantities of solid waste from different industries are commonly disposed in landfills, where can generate wide range of environmental problems. Therefore, the aim of this paper is to give insight on the usage of various waste materials as oxidation catalysts in different Fenton processes for dye removal. In that manner the circular value chain of these materials will be reinforced, obtaining disposal cost reduction and further value addition. Some of industrial wastes (fly ash, electric arc furnace dust, red mud, coal bottom ash, activated carbon from biomass, etc.) that have been used to catalyse Fenton reaction in various researches are reviewed from optimization point of view. Both types of optimization, one-factor-at-a-time (OFAT) and response surface methodology (RSM) are investigated. The study revealed that factors as catalyst concentration, pH value, hydrogen peroxide concentration, dye concentration and reaction time are main factors that influence final Fenton capacity as oxidation process catalysed with reviewed waste materials.

U radu je prikazano tretiranje otpadne vode Fenton-sličnim procesom primenom nano nula valentnog gvožđa kao katalizatora. Uzorak otpadne vode generisane nakon štampanja cijan bojom uzet je iz flekso štamparije koja se nalazi u Novom Sadu. „Zelena” sinteza nanomaterijala je sprovedena korišćenjem opalog lišća sa drveta hrasta koje raste u Nacionalnom parku Fruška Gora. Ispitivanje efikasnosti obezbojavanja vodenog rastvora grafičke boje vršeno je serijom eksperimenata na aparaturi za JAR test.

In this work, the decolorization efficiency of Reactive Red 120 (RR120) synthetic solution using ferrioxalate (CuOFeB) and Al, Fe-bentonite (AlFeB) catalysts in the solar-assisted Fenton process was evaluated, as well as impact of H2O2 photolysis on the process efficiency.The photo-Fenton oxidation of dye has been investigated using a concentrating solar parabolic reactor with constant solar radiation of 550 W/m2 and 950 W/m2 for spring and summer periods, respectively. Experimental data has proved that photolysis of hydrogen peroxide has an important role in the process of decolorization, achieving a decolorization efficiency over 80.78% at pH 7. Under the optimal reaction conditions, both catalysts showed a good stability in the processes with dye removal over 90%. The mineralization efficiency depends on the intensity of the solar radiation, wherein ∼50% was achieved under the higher solar intensity. Comparing reaction rate it is important to note that the larger specific surface area of AlFeB (155.83 m2/g) makes him a superior catalyst and thus solar-assisted Fenton process with this catalyst fast and efficient. Based on the decolorization rate constants, the examined processes can be placed in the following order: AlFeB (950 W/m2) > AlFeB (550 W/m2) > CuOFeB (950 W/m2) > CuOFeB (550 W/m2). These findings are confirmed on real effluent, whereby a greater degree of decolorization (91.89%) and mineralization (43%) has been achieved with AlFeB catalyst compared to CuOFeB (30.09% and 15%) during the process.

The paper investigates the potential use of nano zero-valent iron (nZVI) particles as a cheap, natural and effective catalyst in the Fenton-like system for the removal of water-based Magenta flexographic dye from aqueous solution. The functional nZVI was successfully synthesized within an environmentally friendly method, by using the natural product extract, oak leaves (OAK-nZVI). The process of Magenta removal was optimized using statistically designed experiment. The influence of four quantitative parameters on decolorization efficiency was investigated: initial dye concentration (20–180 mgL-1), OAK- nZVI dosage (0.75–60 mgL-1), H2O2 concentration (1–11 mM) and pH value (2–10). The results of statistical analysis show that OAK-nZVI dosage and pH significantly contribute to the decolorization efficiency, while the concentration of H2O2 has a significant influence on their impact. The optimization yielded highest removal efficiency of 91.95% under following conditions: initial dye concentration of 180 mgL−1, OAK-nZVI dosage of 60 mgL−1, H2O2 concentration of 11 mM and pH value 2. Optimization results were experimentally verified. Treatment of real effluent under optimized experimental conditions resulted within 84.06% Magenta removal after a reaction time of 60 min. The absorption spectra of Magenta dye clearly indicate the changes in the molecular structure in the form of the destruction of azo bond in the chromophore, leading to the decolorization of dye solution. Based on the GC–MS analysis, the mechanism for Fenton-like oxidation of Magenta was proposed.

© 2017 Elsevier B.V. The possibility of applying hexagonal two dimensional (2-D) electrokinetic ex-situ system on the sediment contaminated with nickel (Ni) has been tested. Three experiments have been performed in order to determine the effect of the continued lack of electricity during the night as well as the effect of electric current oscillations during the use of solar panels. The efficiency of the treatment has been monitored by changing pseudo-total concentration of Ni on defined locations in electrokinetic cell. At the end of the treatment pollution assessment has been evaluated based on the pseudo-total concentration of Ni in sediment and in the leached water. Also, we implemented a modified mathematical model to simulate transport of nickel during electrokinetic remediation of nickel contaminated sediment with the goal to anticipate the time required for the removal of Ni. The results indicate very high efficiency of Ni removal during all three experiments. It can be explained by the fractions present, which can migrate more easily and those are subjected to the processes of electric migration, electric osmosis but also diffusion. In the interest of reducing the energy consumption together with the cost of remediation of the contaminated medium, the treatment in which solar-green energy has been applied, may be considered as the suitable solution for remediation of the sediment selected. The implemented mathematical model has indicated great congruence with the results of the experiment and can predict the time necessary for electrokinetic remediation of the nickel contaminated sediment.

The main objective of this study was to gain more detailed knowledge of how four selected polycyclic aromatic hydrocarbons (PAHs) interact on six nondegradable types of microplastics (MPs) and one biodegradable plastic (BP) in two water matrices. The results were evaluated using the popular Freundlich and Langmuir isotherm models, as well as a new modified mathematical model. The modified mathematical model was developed to additionally elucidate the adsorption mechanism, to investigate transfer kinetics of PAHs and to predict the variation of adsorption rate and capacity as a function of time. The adsorption kinetics of selected PAHs onto MPs and biodegradable plastic were described best by the pseudo-second order kinetic model (R2 = 0.810–0.999), implying that chemisorption is possibly the adsorption mechanism. The results of the adsorption isotherm study also indicated that adsorption of PAHs on selected types of microplastics was best described by the Langmuir model, implying that adsorption of PAHs is more dominant on powdered types of MPs in both synthetic and real water matrices. On the other hand, the lowest adsorption affinity was achieved for adsorption of PAHs on polylactic acid, indicating that this type of biodegradable plastic would have significantly less impact on the transport and distribution of PAHs through environment.

This work studies the adsorption of heavy metal ions (Cu(II), Pb(II) and Cr(VI)) in aqueous solutions on amino-functionalized multiwalled carbon nanotubes (MWCNTs-NH2) in the ppb concentration range (50-3000 �g/l) as a function of contact time, initial concentration of heavy metal ions and the presence of four inorganic electrolyte anions (Cl-, SO42-, NO3-, PO43-). The adsorption of heavy metals from aqueous solution was studied using different kinetic models. The results showed that the adsorption process is best fitted with the pseudo-second-order model indicating that the process is controlled by chemisorptions through electrostatic attraction and chemical interaction/complexation between the metal ions and the surface functional groups of MWCNTs-NH2. The intra-particle diffusion model showed that diffusion is slow, but did not govern the rate of the overall adsorption process. The effects of Cl-, SO42-, NO3- and PO43- anions on the adsorption of Cu(II), Pb(II) and Cr(VI) are variable (improvement, reduction, no impact).

In this study, solar cells were used to generate an electric field for the electrokinetic remediation of metal contaminated sediment (Nickel, Cadmium, Zinc). For determination of metals mobility, bioavailability and potential toxicity, sequential extraction procedure, simultaneously extracted metals (SEM) and acid-volatile sulphide ratios (AVS) were performed before, during and after treatment.After 21 days of treatment, 63% Ni, 82% Cd and 58% Zn was removed from the anode region. The application of the electric field changed the chemical composition of the sediments. The risk assessment analysis based on pseudo total metals content, the risk assessment code and the relationship between SEM and AVS, indicates that a simple singular approach for risk assessment analysis and evaluation of the quality of sediments is not enough.

Nickel-contaminated sediment can be remediated by electrokinetic techniques. In practical application, nickel may migrate into deep layers and potentially pollute unpolluted layers. In this study, the influence of different types of electric field operation modes on nickel migration in sediment layers was studied. The following experiments were conducted: without current application (NC), with horizontal electric field (HEF), with vertical electric field (VEF), and 2D electric field (horizontal and vertical). The following Ni overall removal efficacies were achieved: 48.9, 49.4, 55.7, and 58.1 after VEF, NC, 2D, and HEF, respectively. Using a vertical electric field in 2D and VEF resulted in less Ni found in the vertical sediment bed (25% and 60%, respectively). The available Ni content in a contaminated sediment bed decreased significantly after using the electrokinetic treatments: 46%, 62%, and 79% after HEF, VEF, and 2D, respectively. Vertical electric field is the most efficient for Ni removal...

In the printing plate developing process, the offset printing developer undergoes changes, as well as enrichment by the various chemicals, i.e. metals, organic binders and photosensitive compounds. The objective of this study was to investigate the electrocoagulation/flotation (ECF) treatment efficiency for the removal of copper, turbidity and organic substances from the waste offset printing developer (WOPD). The effect of operational parameters, such as electrode materials, current density, interelectrode distance and operating time, was studied. Also, the response surface analysis was applied to evaluate the effect of main operational variables and to get a balanced removal efficiency of investigated WOPD parameters by ECF treatment. The removal efficiency increases significantly with the increasing of operating time and mainly increases with the increasing of current density. The obtained results show that the interelectrode distance and combinations of electrodes determine the removal efficiency of copper, turbidity and organic substances. Based on the obtained results, the optimized parameters for the ECF treatment removal of investigated WOPD parameters were identified as: Al(−)/Fe(+) electrode combination with interelectrode distance of 1.0 cm, operating time of 5 min and current density of 8 mA cm −2 . This study confirms the practical feasibility of ECF method for treating real printing industrial effluent under optimum conditions.

In packaging, plastic films are very often applied as overprinting materials. The printing properties of plastic films depend on the value of the surface free energy. Usually, during storage but before printing, the surface free energy is decreasing as a result of ageing. The aim of this study was to analyse the influence of elevated temperature and UV radiation on ageing properties and variation of the free surface energy for three commercially available plastic films: polyethylene, polypropylene and polyethylene terephthalate. The investigation was done experimentally, and the surface free energy was calculated using two approaches, Owens-Wendt and van Oss-Chaudhury-Good. The time change of polar fractions was also analysed. The calculation results were compared and it was concluded that UV radiation causes more changes in surface free energy than elevated temperature. In some cases, surface free energy values calculated with the applied methods show similar trends.

The chemical and biological trait approach have been applied to sediment pollution assessment of the Veliki Bački canal (Serbia) –VBC. For this assessment, pseudo-total metal contents, pollution load index (PLI), contamination factor (CF), enrichment factor (EF), sequential extraction procedure (SEP), pore water metal concentrations, geoaccumulation factor (Igeo), sediment quality guidelines (SQGs) and risk assessment code (RAC) have been used. Furthermore, the phytotoxic effects of the contaminated sediment have been assessed according to the physiological and morphological trait changes of the test plant species (maize, white mustard, barley and cucumber) in a bioassay. The chemical analysis has shown that an assessed sediment from VBC is extremely polluted with Cd, Zn, Ni whereas pore water is polluted with Cu, Zn, Ni. The results which have been acquired in plant bioassays indicate the different sensitivity of the plants. While pore water from the contaminated sediment had no effect on maize traits, it considerably inhibited the physiological and morphological traits of barley, cucumber and white mustard. These species are potentially good indicators of impaired sediment quality.

The objective of this study was to investigate the possibility of heavy metals (copper, zinc and nickel) removal from the waste fountain solution by the electrocoagulation/flotation (ECF) treatment. After the printing process, the fountain solution changes its composition due to direct contact with different printing materials (plates, inks, etc.) and becomes enriched with metals. The effect of operational parameters, such as electrode materials and combinations, current density, interelectrode distance and operating time, was studied. Also, response surface methodology (RSM) was applied to evaluate the effect of main operational variables and to get a balanced removal efficiency of metals from waste fountain solution by ECF treatment. The iron/iron electrode combination yields a higher percentage of copper and zinc removal efficiency (>95% and >80%, respectively), while for nickel the aluminum/iron and iron/aluminum electrode combinations (>95 and >85%, respectively) proved to be more successful. The optimum interelectrode distance was 1.0 cm (for copper) and 1.5 cm (for zinc and nickel) for all current densities. Heavy metal removal efficiency increases with the increase of electrolysis time for all electrode combinations. Also, the increase of current density improves the ECF removal efficiency. Based on the results obtained through RSM, the optimized parameters for the ECF waste fountain solution treatment for metal removal were identified as: Fe(−)/Al(+) electrode with interelectrode distance of 1.5 cm, operating time of 60 min and current density of 8 mA cm−2. Overall, the ECF treatment was proven very efficient in the removal of heavy metals from the waste fountain solution under optimum conditions.

For evaluation of oxidative degradation of industrial azo dye Rosso Zetanyl B-NG (RZ B-NG), three clay supported nanoscale zero-valent iron materials were synthesized: bentonite, kaolin and native clay-supported nanoscale zero-valent iron (B-nZVI, K-nZVI and NC-nZVI). All clays used as a support material not only dispersed and stabilized nanoscale zero valent iron (nZVI) but also improved the adsorption and degradation of dye as they consequently improved heterogeneous Fenton oxidation. Under the optimal conditions, for the used nanomaterial concentrations of 112, 168 and 224 mg/L for B-nZVI, NC-nZVI and K-nZVI, the decolourization efficiencies achieved were 92.7, 92.1 and 91.6% and appropriate TOC removals were 57.8, 57.2 and 50.7% in the same order. The best catalytic performance was exhibited when B-nZVI was used. These results correlate with the specific surface area and mesoporous structure of the synthesized materials. They contributed to Fenton reaction enhancement by generating effective reaction sites for potential adsorption and subsequent oxidative degradation of the azo dye. Based on these results, all clay supported nanomaterials have proved to be superior heterogeneous Fenton-like catalysts for removing azo dyes from wastewater.

Purpose The objective of this research was to apply the same immobilization (stabilization/solidification) clay-based treatments to sediment contaminated with different metals (Pb, Cd, Ni, Zn, Cu, Cr) with different distributions and availabilities in sediment. We also examined the possibility of using clay as an immobilization agent without the application of thermal treatment, in order to reduce the economic cost of this expensive remediation procedure.

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]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 were6 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 were1.5, 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.

The work is concerned with the sorption and desorption behaviour of lindane on four humic acid fractions (HAs) and two humin fractions, sequentially extracted from Ludas lake sediment. All sorption isotherms, fitted to a Freundlich model, were nonlinear. The isotherm linearity increased from 0.757 for the first extracted HA to 0.944 for the ninth HA showing a positive correlation with atomic H/C ratio, while a negative correlation between sorption coefficient and aliphaticity of the isolated HAs was observed. It has been shown that the sorption processes may be strongly influenced by the physical conformation of and accessibility to sediment organic matter (SOM), as demonstrated by high Koc and low n values of humin samples. Despite exhibiting the most nonlinear sorption isotherms, humin samples did not show a pronounced sorption-desorption hysteresis, while the most significant hysteresis was observed for three HA samples. These results support the hypothesis that the aromatic domains in SOM influence strongly the sorption and desorption behaviour of lindane. Our findings may be helpful in understanding the distribution, transport and fate of lindane in soils and sediments.