Color Removal Rate Research Articles

Bioadsorption and enzymatic biodecolorization of effluents from ethanol production plants

Distillery effluent must be handled in compliance with the demands and obligations of Environmental Quality Standards (EQS). As Iranian bioethanol plants often face the problem of high color content, therefore, an efficient decolorization process is required to determine the quality of effluent so as to meet demanded standards. The existing color in effluent is identified as Melanoidins, which is adsorbed by fungal mycelia or biodegraded. In this work, the biodecolorization mechanism was studied using Aspergillus fumigatus UB260. A color removal rate of 47% was obtained at an incubation time of 96 h at 30 °C. FTIR spectrum proved the presence of Melanoidins. SEM micrographs showed the accumulation of specified pigments in the mycelia. The release of color from fungal mycelia to 0.5 N NaOH proved the color adsorption on the surface of mycelia. Poly-acrylamide gel electrophoresis analysis (SDS/PAGE) proved that the presence of protein molecules in bio-decolorization culture. There was no existence of a trace amount of protein in the raw distillery wastewater. The decolorization was perceived as of dual mechanism.

Esparto paper industry wastewater treatment by adsorption onto powdered activated carbon

ABSTRACT The discharge of Esparto paper industrial wastewater (EPIW) of SNCPA Company of Kasserine – Tunisia in nature without any treatment can cause harmful effects to the environment. To reduce this danger, several treatment processes have been implemented, in particular, the adsorption technique. The present original study consists of using powdered activated carbon (PAC) to treat EPIW. The tests were carried out on different chemical oxygen demand (COD) concentration of EPIW ranging from 2 to 20 g/L. The influence of initial COD concentration, adsorbent dose, pH and contact time were investigated at temperature of 25 ± 2°C. The equilibrium results were modelled and assessed via Freundlich, Langmuir, Temkin and Dubunin–Radushkevich isotherms models. The error analysis was evaluated by three error functions: the average relative error deviation, the Marquardt’s percent standard error deviation and the Sum of the squares of the errors. The results showed that COD removal efficiency, maximum adsorption capacity and colour removal rate were 94%, 190 mg/g and 90%, respectively, for pH = 6, an adsorbent dose of 75 g/L, initial COD concentration of 9.3 g/L and contact time of 60 min. Besides, the main characteristics values of treated EPIW (BOD, TCOD, pH and Salinity) at natural conditions were 200 ± 30 mg O2/L, 1300 ± 50 mg O2/L, 7.2 ± 0.1 and 1.7 g/L ± 0.1, respectively, which were below the ISO-14,000 standards conditions for release in public sewerage system. Furthermore, both the higher value of correlation coefficients (R2) and the lower value of SSE have shown that Freundlich model provided the best fits to adsorption experimental results.

Experimental study on the optimisation of azo-dyes removal by photo-electrochemical oxidation with TiO2 nanotubes

An experimental investigation is here presented on the photo-electrochemical removal of Methyl Orange (MO), selected as a model of the organic dyes, contained in wastewaters. The process is carried out in an electrochemical flow reactor, in which titania nanotubular electrode is irradiated with a simulated solar light. Design of Experiments (DOE) technique is used to plan the experimental campaign and investigate on the single and combined effects of applied current, electrolyte flow rate, and initial MO concentration, on the specific reaction rate. The results of the DOE analysis, also combined with the study of the distribution of the intermediate products, confirm a reaction mechanism mediated by OH radicals; high applied current and low reactant concentration resulted as favourable conditions to achieve high specific reaction rate of color removal.

New laser-based method for the synthesis of stable and active Ti/SnO2–Sb anodes

The main drawback impairing the application of highly electrocatalytic SnO2–Sb anodes in the removal of recalcitrant pollutants from wastewater is their short service life. Here, we report the synthesis of Ti/SnO2–Sb anodes with improved stability through a CO2 laser as the primary heating source. The influence of different calcination temperatures (400, 500, 600 °C), and varied composition of the solvent in the precursor solution, on the stability and activity of the anodes, were investigated. Notably, the use of the CO2 laser heating method at 600 °C improves the service life up to 5-fold as compared to the conventionally prepared anodes. The laser-made Ti/SnO2–Sb anode calcined at 600 °C exhibits the best electrocatalytic performance with the fastest color removal rates in the oxidation of methylene blue dye. Therefore, for the first time, Ti/SnO2–Sb anodes with superior properties were produced by a fast method employing CO2 laser, envisaging its future applications in wastewater treatment.

Preparation of bead-type NiOx(OH)y catalyst for hypochlorite conversion and reactive brilliant red K-2BP degradation

In order to develop a low-cost NaClO/NiOx(OH)y process instead of Fenton method for treating refractory wastewater, a convenient bead-type hypochlorite conversion NiOx(OH)y catalyst was prepared by simply impregnating Ni-precursor over alumina and then oxidizing with persulfate (PS) in strong alkali solution. The influence of catalyst preparation conditions on the synthesis of NiOx(OH)y was studied. A series of batch experiments were carried out to verify the effective conversion of NaClO and investigate the influence of different parameters. Orthogonal test showed that Ni2+ concentration had the greatest effect on the catalyst performance, while PS dosage had the least effect. The best combination of catalyst preparation parameters is impregnation of the γ-Al2O3 beads in 1.5 M Ni2+ solution followed by oxidation in a mixture of 5 % PS and 1.94 % NaOH. The best catalyst sample was characterized by XRD, SEM and FTIR. XPS tests showed that the oxygen content in the catalytic layer increased with the Ni2+ solution concentration, and the oxygen content in the catalytic layer with the best performance reached 90.22 %. SBET of the samples is 283−292 m2 g−1; Ni(OH)2 accounted for ∼2/3 of the nickel content and NiOOH accounted for ∼1/3. The catalyst significantly improved COD and color removal rate of reactive brilliant red (RBR) K-2BP with low operation cost. The scavenger furfuryl alcohol proves the important role of atomic oxygen in decolorization of RBR K-2BP by NaClO/NiOx(OH)y system. During the reuse of the catalyst, the catalytic performance did not decline. The prepared catalyst has great potential in wastewater treatment.

Removal of the Rhodamine B Dye at Ti/Ru0.3Ti0.7O2 Anode Using Flow Cell System

The electrochemical oxidation of the Rhodamine B dye (Rh-B) was carried out using dimensionally stable type anode (DSA, Ti/Ru0.3Ti0.7O2). The work was performed using the electrochemical flow cell system. The effect of several operating factors, such as supporting electrolytes, current density, electrolysis time, temperature, and initial concentration of Rh-B dye, were investigated. The UV-visible spectroscopy and chemical oxygen demand (COD) measurements were conducted to monitor the removal and degradation of Rh-B. The best color removal achieved was found to be 98.3% after 10 min applying 3.9 mA·cm−2 as a current density using 0.07 mol·L−1 of NaCl. Meanwhile, the highest COD removal rate (93.0%) was obtained for an applied current density of 3.9 mA·cm−2 as the optimal operating condition after 180 min reaction time, with 2.98 kW h·m−3 as energy consumption. This shows that the best conditions for color removal are not certainly the same as those for the COD removal. The rises in the concentration of NaCl, and applied current increased the Rh-B color removal rate. The decline in Rh-B dye concentration followed pseudo-first-order kinetics. The obtained values of apparent rate constant were increased by increasing chloride ion concentration. It is concluded that the electro-oxidation on DSA electrode using a flow cell is a suitable process for the removal of Rh-B dye in aqueous solutions.

Application of polymeric ferric sulfate combined with cross-frequency magnetic field in the printing and dyeing wastewater treatment

Polymeric ferric sulfate (PFS) was pretreated with a self-made alternating frequency magnetic field for coagulation printing and dyeing (PD) wastewater treatment. The effects of PFS dosage, magnetization intensity, frequency, and time on the removal of chemical oxygen demand (COD), color and turbidity of PD wastewater were investigated. The results indicated that the magnetized PFS significantly improved the removal efficiency in wastewater treatment. When the initial COD, color and turbidity of printing and dyeing wastewater was 464 mg/L, 180 degrees, and 54.8 NTU respectively, the maximum removal rate of COD, color and turbidity was 87.9%, 80.1%, and 95.2% respectively, under the condition of cross frequency magnetic field magnetization PFS. Moreover, the PFS treatment combined with cross-frequency magnetic field could greatly reduce the pollution of iron ions released from iron-based coagulant during wastewater treatment. Characterization of magnetized PFS flocculant by fourier transform infrared spectroscopy, ultraviolet and visible spectrophotometry, and scanning electron microscopy suggested that magnetic crystal with larger size can be formed on the surface of PFS particles.

Cobalt phthalocyanine-TiO2 nanocomposites for photocatalytic remediation of textile dyes under visible light irradiation

CoPc(COOH)[Formula: see text]-TiO[Formula: see text] nanocomposites to be used as efficient visible light photocatalysts were obtained by modifying TiO2 nanoparticles with cobalt(II) tetracarboxyphthalocyanine (CoPc(COOH)[Formula: see text]). The photocatalyst was then characterized by ultra-violet diffuse reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The UV-DRS spectra showed that the absorbance spectrum of the modified catalyst was shifted to the visible region. Different textile dye solutions of Reactive Red 180, Acid Red 88 and Direct Orange 46 were efficiently degraded under visible light. Color removal rates were established to be 30%, 53% and 47% after 180 min for RR180, AR88 and DO46 dyes, respectively. The optimum catalyst concentration was determined to be 1 g/L of CoPc(COOH)[Formula: see text]-TiO[Formula: see text]. Development of the CoPc(COOH)[Formula: see text]-TiO[Formula: see text] nanocomposite photocatalyst enabled the utilization of visible light irradiation for efficient photodegradation of organic textile dye solutions.

Fabrication of a self‐doped TiO2 nanotube array electrode for electrochemical degradation of methyl orange

Self‐doped TiO2 nanotube array (DTNA) electrodes were fabricated through anodic oxidation combined with cathodic reduction. The morphology and structural features of pristine TiO2 nanotube arrays and DTNA electrodes were studied through scanning electron microscopy, X‐ray diffractometry, and X‐ray photoelectron spectroscopy. An accelerated life test was used to test the electrode service lifetime and thus the electrode's stability. The service lifetime of the DTNA electrode prepared at constant 40 V for 6 hr was approximately 338.7 hr at constant 1 mA/cm2 in a 1 M NaClO4 solution. Methyl orange (MO) was employed as the degradation probe for measuring electrochemical oxidation performance. The color removal rate of 200 mg/L MO of the DTNA electrode (85.2% at 1 mA/cm2) was greater than that of the Ti/IrO2 electrode (31.1% at 1 mA/cm2). The larger the surface area of the DTNA electrode is, the more conductive the electrode is for the degradation of organic substances. Organic degradation on the DTNA electrode occurred primarily through an indirect pathway (producing [∙OH]).

Textile Wastewater Treatment for Water Reuse: A Case Study

The reduced natural waters and the large amount of wastewater produced by textile industry necessitate an effective water reuse treatment. In this study, a combined two-stage water reuse treatment was established to enhance the quality and recovery rate of reused water. The primary treatment incorporated a flocculation and sedimentation system, two sand filtration units, an ozonation unit, an ultrafiltration (UF) system, and a reverse osmosis (RO) system. The second treatment included an ozonation unit, a sand filtration unit, and UF and RO systems. The color removal rate increased with the increasing ozone dosage, and the relational expression between the ozone dosage and color removal rate was fitted. Ozonation greatly reduced the color by 92.59 and 97.27 times during the primary and second ozonation stages, respectively. RO had the highest removal rate. The combined processes showed good performance in water reuse treatment. The treated, reused water satisfied the reuse standard and surpassed the drinking water standard rates for chemical oxygen consumption (CODcr), color, NH3-N, hardness, Cl−, SO42−, turbidity, Fe3+, and Cu2+. The operating cost of reuse water treatment was approximately 0.44 USD·m−3.

Optimization of Dyeing Wastewater Treatment with New Eco-friendly Polysilicate Ferromanganese

To improve the efficiency of the removal of dye wastewater, a new type of coagulant "polysilicate ferromanganese (PSFM)" has been synthesized using sodium silicate, ferrous sulfate, and potassium permanganate. Three dyes (direct red, disperse blue, and active yellow) were used for the coagulation tests. The effects of the alkalinity and turbidity on the performance of PSFM were studied. The experimental results show that PSFM performs well with respect to the coagulation of the direct red and disperse blue dyes. The color and TOC removal efficiencies reach 99.2%, 95.4% and 98.5%, and 93.8%, respectively. The coagulation performance is better than that of the conventional coagulants polysilicate iron (PSF), Al2(SO4)3, and FeCl3. The color and TOC removal rates of PSFM for the active yellow dye reach 56% and 51%, respectively. Turbidity has no significant effect on the coagulation efficiency of PSFM. The purification efficiency and alkalinity depend on the amount of dye to be removed. The best alkalinity for the direct red, disperse blue, and active yellow dyes is 50 mg·L-1, 0 mg·L-1, and 75 mg·L-1, respectively. In addition, PSFM has been characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The Zeta potentials of the mixed solutions and flocs during coagulation were also determined. The main indicators of PSFM coagulation are positively charged polynuclear complexes produced by hydrolysis of Fe+ and Mn+ and the bridging polymerization of polysilicon. The adsorption of hydrated manganese dioxide and hydroxyl oxide may also be included.

Process optimization and enhanced decolorization of textile effluent by Planococcus sp. isolated from textile sludge

Abstract The aim of present study is to isolate and characterize the indigenous bacterial isolates from textile industry effluents and sludge samples and investigate their decolorization ability, along with the influence of various process parameters on decolorization. Nine different bacterial strains were isolated from textile unit site in which one isolate (TS2O), having greater ability towards color removal was identified as Planococcus sp. by 16S rDNA sequencing. Optimization of decolorization process parameters was performed using Taguchi method in which five factors at two levels have been applied in L-8 orthogonal array. Maximum color removal rate (45%) has been obtained by 2% nitrogen, 1% carbon, 10% effluent, at pH 8 and 25 °C. The decolorization rate has been improved to 55% by adding peptone (0.5%w/v) as best nitrogen source and further up to 60% with dextrose (0.5%w/v) as best carbon source. A significant improvement up to 78% decolorization was observed during process parameter optimization with this statistical approach. Hence, this method validates its usefulness to treat various industrial wastewaters economically.

Solar heterogeneous photocatalysis (ZnO/UV) for textile dyes removal

AbstractSolar photocatalytic studies were carried out using zinc oxide (ZnO) as a catalyst for the removal of the cationic methylene blue (MB) dye, and the anionic dye reactive red 198 (RR198), from simple and binary mixed solutions. The following parameters were experimentally investigated: catalyst concentrations (50–250 milliliters [ml]), initial pH of the solution (5, 7, and 9), and time of exposure (20–120 minutes [min]). The catalyst concentration has been found to be the variable with the greatest significance of the three, leading to degradation rates of up to 98% and 100%, for MB and RR198 dyes, respectively. When it comes to the RR198 dye, considerable decolorization rates (up to 75%) were achieved even at the shortest time interval (20 min). The results indicated that, especially for the RR198 dye, the majority of the color removal during the photocatalysis process was due to the adsorption of the dye onto the ZnO surface. Batch scale experiments were performed by mixing both MB and RR198 dyes in order to simulate a synthetic effluent. Color removal rates up to 98% were achieved after 90 min of sunlight exposure. Experiments in a pilot‐plant based on compound parabolic collectors were performed under the same conditions, and similar results were obtained. In addition, organic matter removal was investigated and rates up to 70% were achieved. The results showed the feasibility of the solar photocatalysis process with ZnO to achieve considerable rates of color removal from wastewater containing dyes from different classes.

The Kinetic Model for Decolorization of Commercial Reactive Red 120 Azo Dye Aqueous Solution by the Fenton Process and Study the Effect of Inorganic Salts

The degradation of a commercial azo dye Reactive Red 120 (RR120) in synthetic aqueous solution using Fenton's oxidation has been studied. The influence of different reaction parameters such as pH, hydrogen peroxide, ferrous sulfate, and the RR 120 concentration on the oxidative degradation of RR 120 have been appraised. The optimal reaction conditions were determined and it was found to be pH = 3.50, [H2O2] = 1.1×10-3 M, [Fe2+] = 1.0×10-4 M for [RR 120] = 7.5×10-5 M. Under optimal conditions, 96.0% decolorization efficiency of dye in aqueous solution was achieved after 15 min of reaction. The effect of azo bond loading (Lazo bond), from 0.25 to 1.0, and pH values from 2.5 to 5.0 were estimated on RR 120 color removal kinetic rates. A correlation between the kinetic of the color removal rates (ln k2) versus Lazo bond was carried out at the different pH levels. The color removal rate increased linearly with decreasing Lazo bond, in the order of pH: 3.5 > 5.0 > 2.5. All the experimental data were analyzed using the first and second-order kinetic models. The second-order provides the best correlation of the data. 67% Chemical Oxygen Demand (COD) removal efficiency of the RR 120 were achieved after 15 min of reaction by fixing the initial H2O2/Fe2+ molar ratio, COD loading factor (LCOD), and pH at 11, 0.25 and 3.5, respectively. Also, the effects of various inorganic anions (such as Cl−, SO42-, CO32-, etc.) on the oxidation efficiency of Fenton were studied. This study can benefit planners who deal with contaminated textile wastewater using chemical treatment by advanced oxidation technologies.

Electrochemical degradation of Mordant Blue 13 azo dye using boron-doped diamond and dimensionally stable anodes: influence of experimental parameters and water matrix.

In this work, the electrooxidation as environmentally clean technology has been studied to the degradation of Mordant Blue 13 azo dye (MB13) using boron-doped diamond (p-Si/BDD) and oxide ruthenium titanium (Ti/Ru0.3Ti0.7O2 (DSA)) anodes in various water matrices: distilled water (DW), hot tap water (HTW), and simulated wastewaters with (SWS) and without surfactant (SW). The influence of experimental parameters, such as current density, initial dye concentration, electrolysis time/specific charge, and pH on the MB13 degradation rate, current efficiency, and energy consumption, has been determined. The enhanced rate of both color and chemical oxygen demand (COD) removal in sulfate aqueous solutions with BDD was observed, which indicates that sulfate (SO4-•) radicals along with •OH ones might be responsible for the degradation process. The MB13 decolorization process obeyed a pseudo-first-order reaction kinetics with the apparent rate constant from 7.36 × 10-2 min-1 to 4.39 × 10-1 min-1 for BDD and from 9.2 × 10-3 min-1 to 2.11 × 10-2 min-1 for DSA depending on the electrolysis conditions. The effect of water matrix on the decolorization and COD removal efficiency has been evaluated. Inorganic ions, mordant salt, and surfactant contained in simulated effluents decelerated the COD decay compared to DW and HTW for the both anodes; meanwhile, they differently affected the discoloration process. A comparison of the specific energy consumption for each electrocatalytic material under different experiment conditions has been made. The BDD electrode was more efficient than the DSA to oxidize the MB13 dye in all kinds of water.

Quick start-up and performance of microbial fuel cell enhanced with a polydiallyldimethylammonium chloride modified carbon felt anode

It is of significant importance to simultaneously shorten the start-up time and enhance the electricity generation performance for practical application of microbial fuel cell (MFC). In this paper, the polydiallyldimethylammonium chloride (PDDA) modified carbon felt (PDDA-CF) electrode was prepared and used as the anode of PDDA-MFC. The anode significantly enhanced the start-up speed and electricity generation and dye wastewater degradation performances of the PDDA-MFC. The start-up time of PDDA-MFC is only 9 h, which is only 7.5% that of the unmodified carbon felt anode MFC (CF-MFC). The charge transfer resistance, the maximum output voltage and the maximum output power density of PDDA-MFC were 9.7 Ω, 741 mV and 537.8 mW m-2 respectively, which were 70.3% lower than, 1.7 times and 3.3 times greater than those of CF-MFC respectively. In addition, the color and chemical oxygen demand (COD) removal rates of Reactive Brilliant Red X-3B for PDDA-MFC reached 95.94% and 64.24% at 24 h respectively, which were 41.5% and 51.2% higher than those of CF-MFC respectively. Due to the electrostatic attraction of PDDA, the adhesion and metabolic mass transfer rate of exoelectrogens are accelerated, thus the PDDA-CF electrode has excellent electrochemical properties and bio-affinity. This paper provides a new idea to enhance the start-up speed and performance of MFC simultaneously.

Coagulation performance of cucurbit[8]uril for the removal of azo dyes: effect of solution chemistry and coagulant dose.

Dye wastewater has attracted significant attention because of its wide pH range and high content of color. In this work, the coagulation performances of cucurbit[8]uril for the removal of color from acid red 1 (AR1), orange II (OII), and Congo red (CR) dye wastewaters were investigated. Experimental results showed that color removal rates of greater than 95% for AR1, OII and CR were achieved at pH 6.0, when the dosage of cucurbit[8]uril was 1.51, 3.01 and 0.38 mmol·L-1, respectively. Under identical conditions, the color removal efficiencies of AR1 and CR were higher than OII, due to the larger molecular weights and more active hydroxyl and amino groups. Moreover, steady increases in AR1, OII and CR removal rates were recorded with increasing ionic strength. Such increases may be related to the reduction in thickness of the surface solvent membrane surrounding the dye colloids at high ionic strengths. Furthermore, Fourier transform infrared spectra demonstrated that no new bonds or functional groups were formed during coagulation, which indicates that the removal of AR1, OII and CR was primarily a physical process. The hydrogen bonds and inclusion complexes formed between cucurbit[8]uril and AR1, OII and CR contributed to the removal of color in coagulation predominantly.

Pretreatment of water-based seed coating wastewater by combined coagulation and sponge-iron-catalyzed ozonation technology

Coagulation–sedimentation combined with sponge iron/ozone (CS-SFe/O3) technology was applied to pretreat water-based seed coating wastewater (WSCW) from pesticide manufacturing. Coagulation with polyferric sulfate at a dosage of 1.5 g L−1 and a pH of 8.0 was effective, with color and chemical oxygen demand (COD) removal rates of 96.8 and 83.4%, respectively. SFe/O3 treatment further reduced the organic content in the effluents, especially concerning the degradation of aromatic pollutants, as demonstrated via ultraviolet–visible spectrophotometry (UV–vis), excitation-emission matrix (EEM) fluorescence spectrometry, and gas chromatography-mass spectrometry (GC/MS) analyses. The residual color and COD values of the effluent were 581.0 times and 640.0 mg L−1, respectively, under optimal conditions (ozone concentration of 0.48 mg L−1, SFe dosage of 20.0 g L−1, initial pH of 9.0, and reaction time of 30 min). Organic pollutants were also degraded by the high amounts of HO, which may have been generated via the transformation of ozone into HO on the SFe's surface and in the solution. Meanwhile, the biochemical oxygen demand (BOD5)/COD ratio of the WSCW increased, which indicates that the biodegradability improved significantly. The amount of iron leached from SFe particles was 4.5 mg L−1, which shows that the SFe catalyst has good stability. The operating cost of the combined CS-SFe/O3 technology was estimated at approximately 2.79 USD t−1. The results of this study suggest that the application of the combined CS-SFe/O3 technology in WSCW pretreatment can be beneficial for removing suspended solids, degrading recalcitrant pollutants, and enhancing biodegradability for the subsequent bioprocessing treatment.

C.I. REACTIVE BLACK 5 BOYARMADDESİNİN FOTOKALİTİK RENK GİDERİMİ

In this study, the use of H2O2 (hydrogen peroxide)/UV (Ultraviolet) process, from the advanced oxidation processes used for industrial wastewater treatment, has been investigated on photocatalytic color removal of C.I. Reactive Black 5 dye. The samples were examined for hydrogen peroxide initial concentration, temperature, pH, color and COD (chemical oxygen demand) values. The color removal rates reached were 99.71% in neutral medium, 99.86% in acidic medium and 94.81% in basic medium. Furthermore, the corresponding COD removal rates were 38.91% and 41.44% and 20,73, respectively. It was observed that the fastest color removal at the initial concentration of 0.5 ml/l H2O2 occurred in acidic medium (99% color removal rate at 55 min). Experiments were carried out by changing the initial concentration of hydrogen peroxide in the acidic medium, which reached the fastest color removal results. It was observed that the concentration increase increased the rate of decolorization (99% color yield time: 30 min) compared to the concentrations of 0.5 and 2.5 ml/l H2O2 in these experiments. However, between hydrogen concentrations of 2.5 ml / l and 5 ml / l H2O2 there was no difference in the increase in the amount of peroxide. As a result, photocatalytic removal of color obtained for C.I. Reactive Black 5; showed that H2O2/UV application can be used successfully in the treatment of industrial wastewater.

ACID ORANGE 52 DYE DEGRADATION BY ELECTROCATALYTIC PLUS PHOTOCATALYTIC TECHNIQUE AND INTERMEDIATES DETECTION

The degradation efficiency of Acid Orange 52 dye in an aqueous solutions using the combination of electrocatalytic and photocatalytic processes has been studied. Electrocatalytic and photocatalytic methods in practice reckon among advanced oxidation processes (AOPs). The effect of catalyst B dosage and irradiarion time on the rate of mentioned dye degradation was studied in the photocatalytic process. It was shown, that when Acid Orange 52 simulated dye wastewater was treated by electrocatalytic technique under optimal conditions with catalyst A, the decolorization treatment effect was 95 % in visible part of light spectrum (464 nm) and 38.6 % in ultraviolet part (270 nm), respectively. When the combined electrocatalytic-photocatalytic technique was processed with catalysts A and B, the color removal rate of dye could reach 99.3% (464 nm) and 91.5% (270 nm), respectively. The large amount of products of small mole weight was formed in the course of oxidation reaction. Moreover, the obtained values of chemical oxygen demand (COD) and total organic carbon (TOC) witnessed, that the combination of electrocatalytic and photocatalytic processes could significantly improve the biodegradability of dye as a whole．It was shown, that the removal rate of COD and TOC, respectively, were 54.3% and 72.8%. The reaction intermediates were determined by electrospray ionization-mass spectrometry (ESI-MS) analysis, and as a result, the probable degradation mechanism (pathway) has been proposed. The results of the work may be useful as theoretical bases for designing effective resource-saving, technically efficient and economically sound wastewater treatment systems, containing hardly biodegradable azo dyes.Forcitation:Zhao H., Zhong H., Sun L., Xia D., Nevsky A.V. Acid Orange 52 dye degradation by electrocatalytic plus photocatalytic technique and intermediates detection. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 111-118