Sanja Papić

Removal of some reactive dyes from synthetic wastewater by combined Al(III) coagulation/carbon adsorption process

This study was designed to investigate the removal of reactive dyes, C.I. Reactive Red 45 and C.I. Reactive Green 8, from wastewater using a two-step, Al(III) coagulation/activated carbon adsorption method. The effect of pH and coagulant dosage as well as the effects of contact time and a powdered activated carbon dosage on dye removal have been studied. The process was optimized with reasonable consumption of coagulant and quantity of obtained sludge. Coagulation as a main treatment process followed by adsorption achieved almost the total elimination of both dyes from wastewater with significant reduction (90%) of chemical oxygen demand (COD), total organic carbon (TOC) and adsorbable organic halide (AOX). Besides high efficiency of dye removal, the combined treatment process offers many advantages for potential application such as coagulant savings, minimal amount of sludge formation and also a economic feasibility since it does not require high costs for chemicals and equipment.

Decolourization and mineralization of commercial reactive dyes by using homogeneous and heterogeneous Fenton and UV/Fenton processes

The oxidative decolourization and mineralization of three reactive dyes in separately prepared aqueous solutions C.I. Reactive Yellow 3 (RY3), C.I. Reactive Blue 2 (RB2) and C.I. Reactive Violet 2 (RV2) by using homogeneous and heterogeneous Fenton and UV/Fenton processes have been investigated. The effects of H(2)O(2), Fe(2+) and Fe(0) concentrations, Fe(2+)/H(2)O(2) and Fe(0)/H(2)O(2) molar ratios at pH 3 and T=23+/-1 degrees C have been studied. Optimal operational conditions for the efficient degradation of all three dye solutions (100 mg L(-1)) were found to be Fe(2+)/H(2)O(2)=0.5mM/20mM and Fe(0)/H(2)O(2)=2mM/1mM. The experimental results showed that the homogeneous Fenton process employing UV irradiation was the most effective. By using this process, the high levels of mineralization (78-84%) and decolourization (95-100%) were achieved. Pseudo-first-order degradation rate constants were obtained from the batch experimental data.

Optimizing Polymer-Induced Flocculation Process to Remove Reactive Dyes from Wastewater

Since discharge limits are becoming stricter for industrial wastes, there is an intensive search for efficient and economical methods of pollution reduction. The polymer-induced flocculation process is described as the suitable treatment method for wastewater highly polluted by reactive dyes. According to preliminary tests, in which many flocculants were studied on two types of model reactive dyes wastewaters, a commercial cationic flocculant Levafloc R was shown to be most successful flocculating agent for dye removal. The optimum pH range and flocculant concentration was found. As the effect of mixing parameters on the process was significant, the optimum combination of the initial rapid mixing intensity, and duration of mixing in given flocculation tank geometry was also determined.

Metal complex dyes of nickel with schiff bases

Abstract Nickel complexes with Schiff bases 2-(2-pyridylmethyleneamino) phenol (PMAP) and 2-(2-quinolylmethyleneamino) phenol (QMAP) were prepared and the composition of the crystalline complexes was determined by elemental analysis, solubility, UV-Vis, IR and mass spectrometry. It was found that, for the Ni-PMAP complex, two ligands were bonded to one metal ion, giving a neutral complex with one molecule of water probably bonded in the inner sphere of the complex. With QMAP, nickel forms cationic complexes with a metal-to-ligand ratio of 2:2 and two molecules of acetate as anions. The solution properties of Ni-QMAP were investigated at different pH. The chromophoric properties of the complex were enhanced with increase in pH, while stability decreased with time. The application of QMAP as a spectrophotometric reagent for the determination of small amounts of nickel was investigated. Adherence to Beers law was observed from 0.00 to 5.00 μg/ml at pH 8, the most appropriate pH in respect to sensitivity and acceptable time stability of the complexes. Dyeing properties of both complexes were investigated on polyamide 66 and the influence of the addition of another phenyl ring to the ligand molecule on the dyeing properties of the complex is discussed.

Cleaner production processes in the synthesis of blue anthraquinone reactive dyes

Abstract One of the problems in reactive dye production is the soluble products which can pollute effluents, and which should not be discharged untreated into the open water. The production process of monochlorotriazine reactive dyes was studied using an anthraquinone reactive blue as a model. In order to decrease wastewater pollution, the production process was modified. The process stages were monitored using TLC. Different chromatographic systems were investigated; a selection of 12 chromatographic systems was made and it was established that the most favorable mobile phase for TLC of the investigated compounds was chloroform:isopropyl alcohol:ammonium hydroxide (2:4:1). Dye concentration in wastewater from the different synthesis procedures was determined spectrophotometrically. Process efficiency was estimated on the basis of production wastewater pollution. A coagulation/flocculation process was employed as a feasible method for the treatment of this type of wastewater. Optimal configuration of batch coagulation tank, applying rapid and slow mixing, was used. Inorganic coagulants (FeCl 3 6H 2 O and AlCl 3 6H 2 O) and a polymeric flocculant with 99.5% dye removal efficiency were used. On the basis of the experimental results, an economically more favorable and environmentally more friendly production procedure is postulated.

Treatment of wastewaters from dye industry

Abstract The characteristics of a coagulation process for the removal of colour from the organic dye industry wastewaters by inorganic coagulant or polymeric flocculant has been studied. Flocculation/precipitation was carried out using three coagulation agents to wastewater samples: FeCl3.6H2O, Levafloc R and Colfloc 3915. The optimum pH range for decolourization with polymeric flocculants was found to be between 6 and 7 while with inorganic coagulant it was between 2.5 and 4. Acceptable efficiency of wastewater decolourization, low total organic carbon (TOC) and chemical oxygen demand (COD) were obtained with 0.1 M solution of Fe(III) as an inorganic flocculant. The addition of 1% of volume fraction of liquid Levafloc R and Colfloc 3915 removed the colour almost completely.

Low frequency US and UV-A assisted Fenton oxidation of simulated dyehouse wastewater

The scope of the present study was to explore the treatment possibilities for the simulated dyehouse wastewater (WW) by the Fenton oxidation ultrasonic (US) or UV-A assisted. Composition of WW included reactive azo dye, C.I. Reactive Violet 2 (RV2), anionic surfactant (LAS) and auxiliary chemicals. An emphasis was put on the influence of the LAS on the treatment efficiency. To explore the pseudo-catalytic effect of LAS and reagent dosages on the extents of decolourization and mineralization, different experimental design techniques were utilized. Box-Behnken design was used as a base for optimization and determination of the influencing factors; numerical (Fe(2+/3+), H(2)O(2) and LAS concentration) and categorical factors (iron oxidation state and type of additional energy; US or UV-A). Furthermore, a mixture design methodology was applied. This two-step optimization approach lead to a single optimal point for two advanced oxidation processes studied in comparison. Models describing the dependency of the overall efficiency on influencing factors were obtained. Application of US/Fe(2+)/H(2)O(2) and UV-A/Fe(2+)/H(2)O(2) processes for the treatment of WW was assessed. Only 26% of mineralization was achieved by Fenton process alone applied for the treatment of the dyehouse effluent in 10-fold dilution, while 43% of mineralization was achieved by US or UV-A assisted Fenton after the 60 min.

Removal of Atrazine from Simulated Groundwater by AOTs

Abstract In this research degradation of atrazine from simulated groundwater by ozonation itself and the combination of ozone and UV photocatalysis using TiO2 have been investigated. It has been found that atrazine was degraded by photolysis alone but no reduction of TOC content has been noticed. However, with TiO2 photocatalyst involvement the rate of degradation has increased in comparison with photolysis itself. Reduction of TOC content was observed, too. Concerning preliminary results it has been found that ozonation itself was the most efficient in the pH range from 6 to 11. Ozonation process enhancement was achieved by introducing UV irradiation into the system. The use of TiO2 photocatalyst in the UV/O3 process slightly improved the overall performance. For all studied processes, the kinetics of atrazine degradation was monitored.

Decolorization and Mineralization of Reactive Dye by UV/Fenton Process

The photochemical degradation of C. I. Reactive Blue 2 (RB2) in aqueous solution has been studied using a homogeneous UV/Fenton process. The effects of applied H2O2, Fe2+ salt and RB2 concentrations at constant UV irradiation characteristics, the pH, and temperature were determined. By the application of 0.5 mM Fe2+ and 2.5 mM of H2O2 the complete color removal and mineralization extent of 73.8% were achieved. According to the color and TOC removal, it could be suggested that the studied UV/Fenton type process appeared as a viable technique for the treatment of wastewater containing such types of reactive dyes.

Sonochemical effectiveness factor (eUS) in the reactors for wastewater treatment by sono-Fenton oxidation: Novel considerations

A comprehensive algorithm was recently proposed for calculation of the sonochemical effectiveness factor and wastewater treatment modeling. The presented approach implies that ultrasound is an auxiliary source of free radicals in Fenton type reactions; introduction of ultrasound represents an enhancement of pollutant degradation rates. The sonochemical effectiveness factor was introduced in kinetic models as the eUS factor (Grčić et al., 2012 [1]). As a substantial follow-up, this study presents novel considerations. The eUS factor was modeled as a function of employed frequency, actual cavitation-related power intensity of ultrasound and a portion of the cavitationally active zone, i.e. dimensionless active volume. The effect of temperature was disregarded in the present model considerations. Cavitationally active zone in reactors was determined based on the erosion of aluminum foil, resulting in cone-shaped space arising from transducer. In the present study, sonochemical treatment of industrial wastewater containing HCOONa as organic pollutant was performed using different equipment: ultrasonic baths (UB1, UB2 and UB3), cylindrical reactor with homogenizer (HCR) and three-frequency hexagonal cell, i.e. ultrasonic pilot reactor prototype (PP). Explored frequency range was from 20 to 120 kHz. Homogeneous and heterogeneous Fenton-type sonochemical processes, US/Fe(II)(FeSO4,aq.)/H2O2 and US/Fe(II)(steel-plate)/H2O2, respectively, applied to industrial wastewater were investigated in terms of mineralization kinetics. Newly modeled eUS factor was introduced in corresponding kinetic models and the overall model was validated. Kinetic parameters of Fenton process were treated as independent of ultrasound, since eUS factor consists of cavitation-related phenomena responsible for the mineralization rate enhancement. In average, a 21% increase of mineralization efficiency was achieved using a single frequency, while more than 70% increase can be achieved by combining 20, 68 and 120 kHz in PP.