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An anodic oxidation process with graphite anode coated with lead dioxide (G/β-PbO2) was optimized for the degradation of methylene blue (MB) and the treatment of real textile wastewater. The G/β-PbO2 anode was prepared by the electrochemical precipitation method. The scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses confirmed the successful coating of graphite substrate with the β-PbO2 film. The effect of four independent variables including pH, reaction time, current density, and electrolyte concentration of Na2SO4 on the performance of the electrochemical oxidation system was modeled by using a complete central composite design and was then optimized by genetic algorithm method. The accuracy of the proposed quadratic model by CCD was confirmed with p-value 0.9. The optimum conditions for solution pH, reaction time, current density, and Na2SO4 electrolyte concentration were obtained to be 5.75, 50 min, 10 mA/cm2, and 78.8 mg/L, respectively. In these conditions, the experimental removal efficiencies of MB using G/β-PbO2 and graphite anodes were 96.2% and 68.3%, respectively. The electrochemical removal of MB using both G/β-PbO2 and graphite anodes well followed the pseudo-first-order reaction (R2 > 0.9). Cyclohexane, cyclohexa-2,5-dien-1-ylium, and N-(sec-butyl) aniline were the most abundant intermediates identified by LC-MS analysis. However, the complete mineralization of MB was achieved in 60 min. The optimized anodic oxidation process successfully improved the biodegradability of real textile wastewater ( B O D / C O D > 0.4 ).

The performance of the persulphate/Mn3O4 nanoparticles (PS/Mn3O4) oxidation process was investigated for the degradation of acid blue 113 (AB113) azo dye. XRD, N2 adsorption-desorption analysis, FE...

The experiments were designed based on the central composite design (CCD) and were analyzed and modeled by response surface methodology (RSM) to demonstrate the operational variables and the interactive effect of four independent variables on two responses. The results showed that the adsorption rates of both phenolic compounds (bisphenol A and pentachlorophenol) were increased by increasing contact time and adsorbent dose. The highest phenolic compounds adsorption was obtained at a pH of 6. Based on the analysis of variance of the results obtained from different models, a quadratic model was chosen to estimate the removal of phenolic compounds by the adsorption process using modified sorbent. The linear regression coefficient (R2) between experiments and different response values in the model was 0.96 for bisphenol A and 0.75 for pentachlorophenol. The optimum values for the studied variables were the pH of 6, the adsorbent dose of 4.2 g/L, the contact time of 65 min, and the concentration of the phenolic compounds of 40 mg/L. Under the mentioned conditions, the removal efficiency of pentachlorophenol and bisphenol A by the adsorbent was 93.1% and 87.06%, respectively. According to the results, the modified adsorbent in the removal of phenolic compounds follows the Freundlich isotherm and pseudo-second-order kinetics. The results showed that the adsorption onto modified adsorbent was able to provide the relatively high removal efficiency of phenolic compounds. This method can also be used to treat wastewater from petroleum and petrochemical industries containing phenolic compounds.

The magnetic chitosan was prepared and characterized using FT-IR, SEM, and XRD techniques. The adsorbent was used for uptake of phenol in water. The sorption was modeled based on central composite design (CCD) - response surface methodology (RSM) method for independent variables pH, time, adsorbent dosage and phenol concentration; suggesting a quadratic polynomial model with p-value

In this study, thermochemical degradation of furfural by sulfate radical has been investigated to find the best-operating conditions. For this purpose, the response surface methodology (RSM) based on central composite design (CCD) was applied to optimize the five independent variables of thermally activated persulfate (TAP)/nZVI oxidation process including pH, PS concentration, furfural concentration, nZVI dosage, and heat. The ANOVA results (“P > F value”

A three-dimensional electrochemical reactor with Ti/SnO

Traditional planar PbO

Multi-component reactions (MCRs) are important tools in combinatorial chemistry because of their capability to prepare target compounds in high yields with superior atom economy. 1 Heterogeneous ca...

Background and Objectives: Synthetic dyes are an important group of additivesused in food products, and because of health concerns about consuming population, the application of these compounds is needed to be enough controlled. The aim of this study was to investigate the types and frequencies of the dyes used in making pastries in the confectionery of Tuyserkan city. Materials and Methods: In this cross-sectional study investigated the types of consumed dyes in confectionery’s pastries of Tuyserkan city. A total of 80 samples including wet and dry pastries are randomly sampled from 17 confectioneries. The steps of the experiment consisted of degreasing the sample, purification, and determining the type of dye were down by using Tin Layer Chromatography (TLC) method. All charts used in the study were drowned by Excel Software (2013). Results: The results indicate, among the total 80 samples, 17 samples contained no dye, 15 samples with natural dye, 44 samples with permitted synthetic dyes, and 4 samples have non-permitted synthetic dyes. Moreover, of all the synthetic dyes, 8 samples contained Quioline yellow dye, 10 samples with Sanset yellow dye, 8 samples with Azorubine dye, 5 samples with Brilliant blue dye, 5 samples with ponceau 4R, and 4 (5%) samples have Allura Red. Conclusions: This study showed a remarkable part of used dyes in the confectionery of Tuyserkan city is non-permitted. Therefore, it is proposed to reduce the amount of synthetic dyes by restriction in distribution, more controlling by health departments, and increasing the awareness in consumers and manufactures.

Furfural is a toxic chemical compound that is widely applied as a solvent in a great many of industries, and it can cause many problems to the human beings and environment. Various methods of removing furfural from the wastewaters have been studied. AOPs methods are utilized for the elimination of a vast majority of the pollutants due to their high efficiency as well as for their lack of creating secondary contamination. Therefore, the present study aims at comparing the efficiency of UV/ZrO2 and UV/H2O2/ZrO2 photocatalytic processes in removing furfural from aqueous solutions. The solution’s initial pH, furfural’s concentration, zirconium catalyst dosage and time were investigated as the parameters influencing the removal efficiency by the two foresaid processes, and the effect of H2O2 addition in various concentrations into UV/H2O2/ZrO2 process was also evaluated. Spectrophotometer device was employed to assay the concentration of the residual furfural. The results indicated that the pH of the environment, the amount of the nanoparticle and H2O2 input concentration largely influence the furfural omission. The optimal condition for the removal of furfural in UV/ZrO2 process in an initial concentration of 20 mg/L, a pH equal to 3, a catalyst dose of 0.25 g/L during a period of 60-min time was 81.6%, and it was 99% for UV/H2O2/ZrO2 process in a pH equal to 7 with the addition of H2O2 for a concentration of 0.75 mL/L under the same conditions. Generally, it can be concluded that UV/H2O2/ZrO2 and UV/ZrO2 photocatalytic processes can effectively be applied to remove furfural from the aqueous solutions, especially in lower concentrations.

The electrocatalytic performance of porous carbon felt/PbO2 and planar titanium/PbO2 anodes in a three-dimensional electrochemical reactor (3DER) equipped with granular activated carbon (GAC) particle has been studied for synergistic degradation of diuron herbicide (DIU) and treatment of pesticide wastewater. The results showed that porous carbon felt/PbO2 anode in addition to high stability can provide around three times more surface area than titanium/PbO2 for degradation reactions. Optimization of DIU degradation in 3DER system with carbon felt/PbO2 anode was performed by a five-level rotatable central composite design. The TOC mineralization rate under optimal conditions (pH = 4.7, current density = 13.5 mA cm−2, Na2SO4 concentration = 0.04 M and DIU concentration = 40 mg L−1) for the 3DER system with carbon felt/PbO2 and titanium/PbO2 anodes after 50 min were 100% and 63.8%, respectively. However, the electrocatalytic efficiency of carbon felt/PbO2 and titanium/PbO2 anodes in the absence of GAC particles to remove TOC was 85.5 and 42.7%, respectively. The energy consumed in the 3DER system equipped with carbon felt/PbO2 anode was 2.28 times less than the 3DER system with titanium/PbO2. The contribution of direct and indirect oxidation of DIU in 3DER degradation systems was determined by radical scavenging technique. The safety of the anodes was evaluated for Pb2+ leakage. The DIU degradation pathway was proposed based on the intermediates identified by LC-MS. The performance of optimized 3DER systems was evaluated for treatment of real pesticide wastewater. The chemical oxygen demand (COD) removal efficiency after 300 min of reaction in the 3DER system with carbon felt/PbO2 and titanium/PbO2 electrodes was 95% and 62.5%, respectively.

In this study, the electrocatalytic synergy of the graphite/β-PbO2 anode and granular activated carbon (GAC) particles electrodes for bisphenol A (BPA) degradation are investigated in a three-dimensional electrochemical reactor (3DER). The graphite/β-PbO2 anode was prepared by anodic deposition method and the electrocatalytic properties of lead oxide film were studied by FESEM, XRD, EDX-mapping, linear sweep voltammetry and accelerated lifetime test techniques. The effect of five independent variables including pH, Na2SO4 concentration, current density, GAC amount, and reaction time on the system response was optimized by an orthogonal central composite-genetic algorithm (OCCD-GA). The results showed that β-PbO2 crystals were deposited as completely compact pyramidal clusters on the graphite surface. In addition, the service life and oxygen evolution potential (OEP) for the electrocatalytic layer of β-PbO2 were 90 h and 2 V, respectively. Based on the developed quadratic model (R2 > 0.99 and p-value

A three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon (3DER-GAC) particle electrodes were used for degradation of 2,4-dichlorophenol (2,4-DCP). Process modeling and optimization were performed using an orthogonal central composite design (OCCD) and genetic algorithm (GA), respectively. Ti/SnO2–Sb/β-PbO2 anode was prepared by electrochemical deposition method and then its properties were studied by FESEM, EDX, XRD, Linear sweep voltammetry and accelerated lifetime test techniques. The results showed that lead oxide was precipitated as highly compact pyramidal clusters in the form of β-PbO2 on the electrode surface. In addition, the prepared anode had high stability (170 h) and oxygen evolution potential (2.32 V). A robust quadratic model (p-value 0.99) was developed to predict the 2,4-DCP removal efficiency in the 3DER-GAC system. Under optimal conditions (pH = 4.98, Na2SO4 concentration = 0.07 M, current density = 35 mA cm−2, GAC amount = 25 g and reaction time = 50 min), the removal efficiency of 2,4-DCP in the 3DER-GAC system and the separate electrochemical degradation process (without GAC particle electrode) were 99.8 and 71%, respectively. At a reaction time of 80 min, the TOC removal efficiencies in the 3DER-GAC and the separate electrochemical degradation system were 100 and 57.5%, respectively. Accordingly, the energy consumed in these two systems was calculated to be 0.81 and 1.57 kWh g−1 TOC, respectively. Based on the results of LC-MS analysis, possible degradation pathways of 2,4-DCP were proposed. Trimerization and ring opening reactions were the two dominant mechanisms in 2,4-DCP degradation.

Traditional planar PbO2 anodes have been used extensively for the electrocatalytic degradation process. However, by using porous PbO2 anodes that have a three-dimensional architecture, the efficiency of the process can be significantly upgraded. In the current study, carbon felt (CF) with a highly porous structure and a conventional planar graphite sheet (G) were used as electrode substrate for PbO2 anodes. Both CF/β-PbO2 and G/β-PbO2 anodes were prepared by the anodic deposition method. The main properties of the electrodes were characterized by XRD, EDX-mapping, FESEM, and BET-BJH techniques. The electrocatalytic degradation of diuron using three-dimensional porous CF/β-PbO2 anode was modeled and optimized by a rotatable central composite design. After optimizing the process, the ability of porous CF/β-PbO2 and planar G/β-PbO2 anodes to degrade and mineralize diuron was compared. The electrocatalytic degradation of the diuron was well described by a quadratic model (R2 > 0.99). Under optimal conditions, the kinetics of diuron removal using CF/β-PbO2 anode was 3 times faster than the G/β-PbO2 anode. The energy consumed for the complete mineralization of diuron using CF/β-PbO2 anode was 2077 kWh kg−1 TOC. However, the G/β-PbO2 anode removed only 65% of the TOC by consuming 54% more energy. The CF/β-PbO2 had more stability (115 vs. 91 h), larger surface area (1.6287 vs. 0.8565 m2 g−1), and higher oxygen evolution potential (1.89 vs. 1.84 V) compared to the G/β-PbO2. In the proposed pathways for diuron degradation, the aromatic ring and groups of carbonyl, dimethyl urea, and amide were the main targets for HO • radical attacks.

Azo dyes can lead to a number of problems in the environment due to the presence of benzene rings in their structure. Therefore, the removal of these pollutants is necessary before being discharged directly into the environment. This experimental study aimed to evaluate the degradation capability of Acid Blue 113 (AB113) by the ultrasound (US)/H2O2/Fe2+ and US/S2O8 2–/Fe2+ processes. The effects of variables like initial pH, Fe2+, H2O2, and S2O8 2– and initial AB113 concentrations on the removal efficiency were investigated using a 20-kHz batch ultrasound generator. The impact of aeration was also examined under optimum conditions; in addition, analysis of wavelength scan of AB113 dye was done. The results showed that the maximum rate of decolorization occurred at pH 3 for both processes. In US/H2O2/Fe2+ process, H2O2 (2.5 mM), Fe2+ (0.05 mM), and reaction time (45 min) were selected as the optimum conditions with a removal efficiency of 93.5. Under the same conditions, 94.3 of the dye was removed via the US/S2O8 2–/Fe2+ process. Moreover, aeration decreased the efficiency for both processes. Further, aeration improved the efficiency of US waves used solely. The highest change in the UV–Vis spectrum of AB113 was observed for US/H2O2/Fe2+, US/S2O8 2–/Fe2+, S2O8 2–/Fe2+, and H2O2/Fe2+. © 2017 Desalination Publications. All rights reserved.

The present study investigates the synergistic performance of the sonophotolytic-activated ZnO/persulfate (US/UV/ZnO/PS) process in the decolorization of acid blue 113 (AB113) dye from aqueous solution and its feasibility for the treatment of real textile wastewater. Decolorization of AB113 solution was modeled by central composite design-response surface methodology (CCD-RSM) and artificial neural network (ANN) approaches and optimized by CCD-RSM and genetic algorithm (GA) approaches. Statistical metrics indicated that both CCD-RSM and ANN approaches seemed satisfactory. However, the results of statistical fit measures indicated a relative superiority of CCD-RSM as compared to the ANN approach. The results of optimization of the process parameters by CCD-RSM and GA approaches appeared to be similar as follows: pH = 6.1, reaction time = 25 min, US power density = 300 W/L, ZnO = 0.88 g/L and PS = 2.43 mmol/L. The synergistic effect of the hybrid US/UV/ZnO/PS process in comparison with its individual processes (US, UV, ZnO, and PS) was found to be 54.3%. Quenching experiments discovered that and HO are the main oxidizing radicals in a mildly acidic condition of the reaction solution. The removal efficiency of AB113 in the presence of some anions decreased in the order of bicarbonate > sulfate > phosphate > nitrate > chloride. Further, the reusability feasibility of ZnO showed that the ZnO material retained its photocatalytic property after five successive cycles of reusability test, while Zn2+ ion concentration in the reaction solution was measured to be 2.81 mg/L. The findings also indicated that the integrated process application suppresses extremely chemical and electrical costs. The study of the feasibility of the US/UV/ZnO/PS process in the treatment of real textile wastewater was done by determining COD, TOC and BOD5/COD ratio. Results demonstrated that the 96.6 and 97.1% reduction of COD and TOC was achieved after 5 and 7 h reaction time, respectively. The obtained BOD5/COD ratio changed from about 0.15 (for non-treated wastewater) to about 0.61 with increasing reaction time from zero to 90 min. In conclusion, the hybrid US/UV/ZnO/PS system can be proposed as a novel and promising approach to be utilized as a pretreatment technique before a biological treatment process to facilitate the biological treatment of recalcitrant textile wastewater.

In this paper, the degradation of Acid Black 1 (AB1) and Acid Blue 113 (AB113) of azo dyes was studied by electro-Fenton process using an iron electrode to generate Fe2+ ions in a batch reactor. In order to reach the maximum efficiency of the process, effective parameters such as: solution pH, operating time, current density, H2O2, and dye concentration were investigated. The experimental data indicated that pH, H2O2 and dye concentration played an important role in the process. The results showed that decolorization decreased with increasing pH; for instance, the maximum decolorization efficiencies 27 and 47% were obtained, respectively, for AB113 and AB1 at pH 11 and reaction time = 10 min. The best conditions for both dyes were obtained at reaction time of 10 min, pH 3.0, H2O2 concentration of 100 mg/L and current density of 5 mA/cm2. In this case, COD removal rates were, respectively, 83.5 and 92.3% for AB113 and AB1 after 30 min.

Oil refinery wastewater is characterized by high values of temperature and furfural concentration. Furfural is a toxic and non-biodegradable substance in aqueous media that its absorption through the skin causes acute neurological and pulmonary effects. In this study, a heat-activated persulfate (HAP) system in combination with reduced graphene oxide-supported nano zero-valent iron catalyst (nZVI-rGO) was developed for oil refinery wastewater treatment. Five operational parameters regarding furfural removal were statistically modeled by an orthogonal central composite design (OCCD) and then optimized by genetic algorithm (GA) technique. The main characteristics of the nZVI-rGO as well as its reusability were investigated by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy mapping (EDX-mapping), X-ray diffraction analysis (XRD) and vibrating sample magnetometer (VSM) analysis. The optimum values for the solution temperature, nZVI-rGO dosage, persulfate (PS) concentration, solution pH and reaction time were predicted to be 70 °C, 1.25 g L−1, 4.28 mmol L−1, 5.46 and 50 min, respectively. Under the optimized conditions, the experimental furfural removal efficiency in HAP/nZVI-rGO and HAP oxidation systems were obtained to be 97.80 and 68.20 %, respectively. Sulfate radical ( S O 4 • - ) has greater participation in furfural mineralization than hydroxyl radical ( H O • ). The major intermediates resulting from the furfural mineralization were short-chain acids including acetic acid and formic acid. Regardless, almost complete furfural mineralization was achieved after 100 min of the oxidation reaction. The optimized HAP/nZVI-rGO process was able to significantly improve the biodegradability of wastewater by more than 2 times.

A hybrid persulfate (PS) activation system based on sonication (US) and nZVI-reduced graphene oxide catalyst (PS/US/nZVI-rGO) was investigated to degrade nonylphenol (NP). Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy mapping (EDX-mapping), X-ray diffraction analysis (XRD) and vibrating sample magnetometer (VSM) analyses confirmed the successful synthesize of nZVI-rGO catalyst. The effect of five independent variables on NP degradation efficiency in the PS/US/nZVI-rGO oxidation system was optimized by a five-level full central composite design (CCD). The Adequacy and validity of the proposed model for predicting NP degradation were confirmed with P-value S O 4 • - ) plays the major role of NP degradation in the PS/US/nZVI-rGO oxidation system. The most abundant reaction intermediates caused by the degradation of NP (m/z = 220) were compounds with m/z

The performance of a binary persulfate activation system based on the simultaneous use of heat (TAP) and ZnO coated granular activated carbon (ZnO-GAC) catalyst was investigated for the degradation of Acid Blue 113 (AB113) azo dye and the treatment of textile industry wastewater. FESEM, XRD, FTIR, EDX-mapping and BET analyses confirmed the successful loading of ZnO nanoparticles onto the GAC substrate. The effect of five independent variables on AB113 removal in the TAP/ZnO-GAC oxidation system was optimized by a 5-level full central composite design (CCD). All experiments were performed in a 6250 mL volume reactor. Adequacy and validity of the proposed model were confirmed with p-value S O 4 · - was the predominant radical species in the TAP/ZnO-GAC system. The optimized TAP/ZnO-GAC process effectively improved the biodegradability of real textile wastewater samples ( B O D / C O D > 0.4 ).

The simultaneous use of persulfate (PS) and nano-Mn3O4 was investigated as an advanced oxidation process for furfural degradation and oil refinery wastewater treatment. The synthesized Mn3O4 nanoparticles were characterized by XRD, BET, BJH and FESEM-EDS and then successfully used as a heterogeneous catalyst for PS activation. The effects of five independent variables on the performance of nano-Mn3O4/PS system were investigated and optimized using a 5-level-5-factor full Central Composite Design (CCD). Accordingly, CCD developed a reduced quadratic polynomial model with P-value

Aims: Organophosphates are well-known as an important group of poisons. The aim of the current study is to investigate acetylcholinesterase enzyme (ACHE) level in workers' blood of a poison-producing industry and its relationship with annual poison production and the use of personal protective equipment (PPE). Materials and Methods: This cross-sectional study was conducted during 2012–2015 on 84 workers from different units of a poisons-producing industry and a 20-person control group. The PPE used during the years of study includes Asphalt gloves, rubber gloves, and mask felt. The AChE level was detected based on the modified Ellman method. Results: The maximum AChE level was observed in the control group. In addition, the minimum was found in the workers in 2015. The mean AChE level in the control group was significantly higher than that in the worker (P < 0.05). The mean AChE level in the workers based on the study years was significantly different, but this was not significant between the blood samples taken in the years of 2014 and 2015. Furthermore, it was found that both poisons-producing amount and PPE distribution were enhanced more during the past year of the study, while the poison amount entering to the body decreased. Conclusion: It was deduced that the AChE level in workers' blood was lowered with increasing at the exposure years due to irreversible effects. It is also observed that growth at the PPE application acted as an important parameter to decline exposure to poisons and subsequently various health complications.

Azo dyes are the greatest classes of synthetic dyes, which are widely used in the textile industries. This study aimed at examining Acid Black 1 (AB1) removal from aqueous solution thermal activated persulfate using silica (SiO2). The effects of operational parameters such as initial pH, initial concentration of AB1, SiO2 dosage, and persulfate concentration were investigated and the chemical oxygen demand content was considered as a response. The results indicated that the removal efficiency had a direct relationship with concentration of SiO2 and persulfate up to their optimum values, and was inversely correlated with the alkaline pH and elevated concentrations of AB1. Moreover, the removal efficiency was increased significantly by increasing the silica concentration from 25 mg/L to 100 mg/L. Ultimately, AB1 was completely removed after 45 minutes.