Methyl Orange Removal Efficiency Research Articles

A porous Fe‐based porphyrinic metal–organic framework for highly effective removal of organic azo‐dye

With the rapid development of the global dye industry, a series of environmental problems affecting the ecosystem and human health has been perceived. In this work, a porous porphyrin catecholate iron‐based metal–organic framework (MOF) (PorphCat‐Fe) has been prepared and evaluated for the first time for adsorptive removal of azo‐dye methyl orange (MO) pollutant from aqueous media. Consequently, various MO adsorption factors using PorphCat‐Fe MOF were studied and optimized. PorphCat‐Fe was able to remove about 98% of the pollutant from the water within 20 min in the batch experiments with maximum adsorption capacity of 232.5 mg g−1. Under optimum conditions, the limit of detection (LOD) was found to be 0.8 μg L−1. The MOF could maintain its adsorption efficiency toward MO in the real samples. The combination of electrostatic attractions, hydrophobic and π–π interactions, and iron‐organic coordination bonding make PorphCat‐Fe able to show the superior MO adsorption capacity. Remarkably, the removal efficiency of MO was nearly unchanged after five regeneration sequences on PorphCat‐Fe. This effort offers the ability for application of MOFs beyond metal‐carboxylate linkers in wastewater remediation.

Light driven Aspergillus niger-ZnS nanobiohybrids for degradation of methyl orange

Inorganic-microbial hybrid systems have potential to be sustainable, efficient and versatile chemical synthesis platforms by integrating the light-harvesting properties of semiconductors with microbial cells. Here, we demonstrate light-driven photocatalytic semiconducting Aspergillus niger cells-ZnS nanoparticles for enhanced removal of the dye methyl orange. Chemically synthesized ZnS nanoparticles exhibited a zinc blende pattern in X-ray diffraction, had a dimension of 20–90 nm with a band gap (Ebg) of 3.4 eV at 1.83 × 1018 photons/second. Biologically synthesized ZnS nanoparticles of 40–90 nm showed a hexagonal pattern in the X-ray powder diffraction spectra with an Ebg 3.7 eV at 1.68 × 1018 photons/second. At a methyl orange (MO) concentration of 100 mg/L, dosage of 0.5 × 105 mol catalyst and pH 4, a 97.5% and 98% removal efficiency of MO was achieved in 90 min and 60 min for, respectively, chemically and biologically synthesized ZnS nanobiohybrids in the presence of UV-A light. The major degradation products of photocatalysis for chemically synthesized ZnS nanobiohybrids were naphtholate (C10H7O m/z 143) and hydroquinone (C9H5m/z 113). For the biologically synthesized ZnS nanobiohybrids, the degradation products were hydroquinone (C9H5m/z 113) and 2-phenylphenol (C12H10O m/z 170).

Persulfate activation by novel iron–carbon composites for organic contaminant removal: Performance, mechanism, and DFT calculations

• Novel Fe–C was prepared that can efficiently degrade organic pollutants. • Effects of important parameters on MO degradation were investigated. • Primary reactive oxygen species examined by quenching experiments and ESR. • Possible pathways proposed based on LC-MS and DFT calculation calculations. Persulfate (PDS) activation is an effective approach for removing organic pollutants from industrial wastewater, but a more cost-effective catalyst is required. In this study, novel iron–carbon (Fe–C) granules were successfully prepared by a facile calcination method and were applied to PDS activation. Radical quenching experiments, electron spin resonance spectroscopy, and electrochemical analyses were performed to investigate the removal efficiency of methyl orange (MO) by the Fe–C/PDS process and the effects of influencing factors such as the Fe–C dosage, PDS concentration, initial pH, and MO concentration. Fe–C was observed to have a pore structure and abundant functional groups that are beneficial for PDS activation and pollutant removal. The MO removal mechanisms of the Fe–C/PDS process included adsorption, degradation, and co-precipitation, among which the degradation process consisted of radical and non-radical pathways involving the formation of SO 4 −· , · OH, O 2 −· , and 1 O 2 as well as electron transfer. Calculations based on density functional theory were used to propose potential degradation pathways of MO. The Fe–C/PDS process exhibited high adaptability to inorganic anions and natural organic matter in aquatic environments and high removal efficiencies of various organic pollutants.

Combination of electrocoagulation and adsorption processes to remove methyl orange from aqueous solution

The purpose of this study was to investigate the performance of an integrated EC–adsorption system to remove methyl orange from aqueous solution. In this study, the integrated EC–adsorption system consisted of two electrodes, which were kept at 2 cm, and an iron electrode used as the cathode and stainless steel sieve box as the anode which filled by modified pumice as an adsorbent whereas the effective surface of electrodes was 3 × 10 cm. To improve the performance of the anode, pumice was used as an adsorbent due to its characteristics such as low specific gravity, porous and light structure, impermeability to sound and heat, and high abrasive power. The surface of pumice was also modified with Cetyltrimethylammonium bromide (CTAB) surfactant to improve the anode performance. The main process variables including initial concentration 50–150 mg/L, pH (3–11), adsorbent dosage (0.5–1.5 g) and voltage (30–50 V) were examined to find an optimum condition. Each run took 1 h, and the volume of the system was 1.5 L also during the experiment an aquarium pump for aeration and mixing was applied. The experimental design was conducted by Design-Expert software, and the Box–Behnken method was used to examine the four variables at three levels. The 3-D diagrams were analyzed for interaction between parameters so, the best optimal conditions for the removal of methyl orange was obtained at C i = 50 mg/L, pH = 7, adsorbent dosage = 1 g, V = 40 V, which result of removal yield was 93.1 %. According to ANOVA result’s, initial concentration and interaction between initial concentration and pH have the most impacts on the methyl orange removal among other factors which the coefficients are 9.16 and 7.10, respectively. • A novel combined electrocoagulation–adsorption system is prepared to remove methyl orange. • Adsorbent modified by CTAB to increase the adsorbent capacity, and SEM tests are taken before and after the modification. • The ranking of the importance of the parameters was determined. • The maximum methyl orange removal efficiency is obtained at neutral pH and accurate adsorbent dosage.

Efficient photoelectrocatalytic degradation of azo-dyes over polypyrrole/titanium oxide/reduced graphene oxide electrodes under visible light: Performance evaluation and mechanism insights

Herein, polypyrrole/titanium oxide/reduced graphene oxide (PTi/r-GO) electrodes were prepared and successfully applied for the photoelectrocatalytic (PEC) degradation of methyl orange (MO) under visible light. Polypyrrole-TiO2 composites rich in p-n heterojunctions were first prepared, then modified with r-GO to improve the electrical conductivity and facilitate charge separation under visible light irradiation. The obtained PTi/r-GO composites were then deposited onto a titanium mesh, which served as the working electrode in PEC experiments. A MO removal efficiency of 93% was achieved in 50 min using PTi/r-GO electrode under PEC conditions (Xe lamp, λ > 420 nm, bias of 0.6 V, 0.1 M Na2SO4 electrolyte), which was far higher than MO removal efficiencies under electrocatalytic oxidation (22%) or photocatalytic oxidation (47%) conditions. This confirmed that excellent activity of the PTi/r-GO electrode under PEC conditions was due to a combination of electrochemical and photocatalytic oxidation processes (involving •OH and •O2− generation). Further, PTi/r-GO was very stable under the applied PEC conditions, with the MO removal efficiency remaining >90% after five cycles. PEC degradation pathways for MO on PTi/r-GO were explored, with a number of key intermediates in the MO mineralization process identified. Results demonstrate that PEC electrodes combining p-type polypyrrole, n-type TiO2 and rGO are very effective in the treatment of hazardous organic compounds in wastewater.

Preparation and characterization of lignin-derived hard templated carbon(s): Statistical optimization and methyl orange adsorption isotherm studies

In this study, lignin-derived zeolite templated carbon materials were fabricated to remove the organic contaminant, methyl orange. Response surface methodology with Box–Behnken design was used to optimize the adsorption parameters. Based on Box–Behnken design, a quadratic model was developed to correlate the adsorption variables with the response, removal efficiency. Analysis of variance revealed the adsorbent dosage as the most influential adsorption variable. Lignin derived ZSM-5 (PZ) and mordenite (PM) templated carbon materials exhibited high surface area; 476.0 and 716.0 m2/g respectively. The maximum theoretical adsorption capacity of PZ and PM for methyl orange was 514.0 and 225.0 mg/g, respectively. The experimental kinetic data best fitted to pseudo-second-order model for both the adsorbents. PZ adsorbent was also utilized to treat real wastewater containing dyes and achieved 40 % methyl orange removal efficiency. Adsorption thermodynamic study revealed the process as spontaneous, exothermic and also indicated the increment in entropy after adsorption.

Surface engineering of silica based materials with Ni–Fe layered double hydroxide for the efficient removal of methyl orange: Isotherms, kinetics, mechanism and high selectivity studies

Herein, low-cost diatomite (DE) and bentonite (BE) materials were surface modified with Ni–Fe layered double hydroxide (LDHs) (represented as NFD and NFB respectively), using a simple co-precipitation procedure for the removal of methyl orange (MO) dye from water. The adsorbents of both before and after MO adsorption have been studied by XRD, N2 adsorption-desorption isotherm, FTIR, FESEM-EDX and XPS characterization. The zeta potential analysis was used to observe the surface charge of adsorbents within the pH ranges of 4–10. The MO removal efficiency was significantly improved after LDHs modification, showing a 94.7% and 92.6% efficiency for NFD and NFB at pH 6, respectively. Whereas bare DE and BE have shown removal efficiency of 15.5% and 4.9% respectively. The maximum adsorption capacities of NFD and NFB using the Langmuir isotherm model were found to be 246.9 mgg−1 and 215.9 mgg−1 respectively. The designed NFD showed high selectivity towards anionic-based dyes from water and also the effect of salts shows the dye removal percentage was increased and decreased for the addition of Na2SO4 and NaCl, respectively. The reusability of NFD and NFB have been studied for a maximum of five cycles and they can remove MO up to four cycles. Therefore, the designed adsorbents can be very effective towards the removal of MO from water and they may be useful for dye-based wastewater treatment.

Application of the novel pH‐catalytic‐magnetic tri‐functionalities augmented bead for removal of organic dye pollutants

AbstractA tri‐functionality magnetic nanoparticles (MNPs) are crucial for environmental remediation. This research focused on the synthesis of pH‐catalytic‐magnetic polymer beads for dye removal by using phase inversion technique. In 15 wt% of polyethersulfone (PES) polymer possessed the highest porosity (80%) was used in the synthesis of MNPs‐PES beads. The methylene blue (MB) removal efficiency of MNPs‐PES beads and PES beads was 72.94% and 62.67%, respectively. Similarly, the removal efficiency of methyl orange (MO) dye is higher for MNPs‐PES beads (38.56%) compared to PES beads (34.16%). Besides, the removal efficiency for MB dye by MNPs‐PES beads increased from 77.59% to 96.90% when solution pH increased from 3 to 9 while removal of MO dye increased from 61.14% to 74.35% when solution pH decreased from 9 to 3. Moreover, the removal efficiency for MB dye increased from 72.94% to 93.43% when H2O2 is added. Additionally, MNPs‐PES beads were recollected successfully using external magnet. These indirectly proved that the MNPs‐PES beads were responsive towards the tri‐functionalities of pH‐catalytic‐magnetic. Lastly, the adsorption of MB dye onto MNPs‐PES beads were fitted well to Langmuir isotherm model and pseudo‐second‐order model with both correlations R2 of more than 0.98.

Application of TiO2/ZnFe2O4/glycine nanocatalyst to the treatment of methyl orange dye from aqueous solution: Impacts of dissolved mineral salts on dye removal efficiency

This study aimed to remove one of the frequently used dyes in textile industries, Methyl Orange, from pollutant water with TiO2/ZnFe2O4/Glycine nanocatalyst under UV irradiation. The TiO2/Glycine/ZnFe2O4 nanocatalyst was synthesized through the sol-gel method and characterized by XRD, XRF, FT-IR, UV-Visible DRS, BET, FE-SEM, and EDX analyses. Process factors, including initial dye concentration (10-30 ppm), nanocatalyst dosage (0.5-1.5 g/L), initial pH solution (3-11), and irradiation time (30-150 min), were investigated by central composite design. The removal efficiency of Methyl Orange was 80% under optimal conditions (dye concentration: 20 ppm, nanocatalyst dosage: 1 g/L, irradiation time: 120 min, and pH=6.5). The effects of mineral salts such as NaHCO3, NaCl, Na2SO4, KCl, MgSO4, and CaCl2 with the concentrations of 50-800 ppm on the dye removal efficiency were examined under the optimal conditions. Low concentrations of NaCl, KCl, and CaCl2 had adverse effects on MO removal efficiency, while the dye removal efficiency raised at their high levels (RNaCl.800=74.52%). An increase in concentrations of MgSO4 and Na2SO4 led to deactivation effects on the dye removal efficiency and reaction rate constant (MgSO4 deactivation: 36%). There was an upward trend in the pollutant removal efficiency and reaction rate constant using NaHCO3 (RNaHCO3.800=82.4% and kNaHCO3.800=20.84 day-1).

Effects of PbO2/Pb3O4 ratio alteration for enhanced electrochemical advanced oxidation performance

PbO2, PbO2/Pb3O4 composite, and Pb3O4 were synthesized respectively via the simple hydrothermal method under different reaction durations (3–48 ​h). All the prepared samples were used as anode materials to decontaminate methyl orange (MO) to explore the corresponding electrochemical advanced oxidation performance. The detailed experimental designs suggested that the combination of PbO2 and Pb3O4 offered enhanced electrochemical advanced oxidation performance, which was due to possible synergistic effects. XPS results suggest that the content of adsorbed oxygen species (Oads) is obviously higher in PbO2/Pb3O4 composite. It is very likely due to more oxygen vacancies in the crystal structure of PbO2/Pb3O4 composite, which will adsorb more oxygen species, promote charge transfer and provide more electrochemical active surface area to generate oxidizing agents. Besides, the presence of Pb3O4 can suppress the oxygen evolution and improve the accelerated life. Meanwhile, the effects of current density, catalyst loading amount and initial MO concentration on electro-catalysis degradation of MO were explored. Experimental results suggested that MO removal efficiency was 94.3%, the reaction kinetic constant could reach 2.08 ⅹ 10-2 min-1, and COD removal efficiency was 34.2% after 150 ​min of reaction under optimized conditions: current density was 5 ​mA ​cm-2, catalyst loading amount was 1 ​mg ​cm-2 and initial MO concentration was 50 ​mg ​L-1. Furthermore, possible degradation mechanisms of MO was proposed according to the analyzed results obtained from UV–Vis and HPLC-MS.

Efficient and Rapid Photocatalytic Degradation of Methyl Orange Dye Using Al/ZnO Nanoparticles.

ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage (1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO NPs, their photocatalytic degradation of methyl orange (MO) dye was investigated. The calcination temperatures at 200, 300 and 400 °C in forming structure of ZnO NPs led to spherical nanoparticle, nanorod and nanoflake structures with a well-crystalline hexagonal wurtzite, respectively. The ZnO NPs calcined at 200 °C exhibited the highest specific surface area and light absorption property, leading to the MO removal efficiency of 80% after 4 h under the Ultraviolet (UV) light irradiation. The MO removal efficiency was approximately two times higher than the nanoparticles calcined at 400 °C. Furthermore, the 5% Al/ZnO NPs exhibited superior MO removal efficiency of 99% in only 40 min which was approximately 20 times enhancement in photocatalytic activity compared to pristine ZnO under the visible light irradiation. This high degradation performance was attributed to the extended light absorption, narrowed band gap and effective suppression of electron–hole recombination through an addition of Al metal.

Do Gas Nanobubbles Enhance Aqueous Photocatalysis? Experiment and Analysis of Mechanism

The performance of photocatalytic advanced oxidation must be improved in order for the technology to make the jump from academic research to widespread use. Research is needed on the factors that cause photocatalysis to become self-limiting. In this study, we introduced, for the first time, nanobubbles continuously into a running photocatalytic reactor. Synthetic air, O2, and N2 bubbles in the size range of 40 to 700 nm were added to a reaction system comprising P25 TiO2 photocatalyst in stirred aqueous solution excited by UV-A lamps, with methyl orange as a target contaminant. The removal of methyl orange was tested under conditions of changing pH and with the addition of different radical scavengers. Results indicated that the oxygen and air nanobubbles improved the photocatalytic degradation of methyl orange—the removal efficiency of methyl orange increased from 58.2 ± 3.5% (N2 aeration) to 71.9 ± 0.6% (O2 aeration). Dissolved oxygen (DO) of 14.93 ± 0.13 mg/L was achieved using O2 nanobubbles in comparison to 8.43 ± 0.34 mg/L without aeration. The photodegradation of methyl orange decreased from 70.8 ± 0.4% to 53.9 ± 0.5% as pH increased from 2 to 10. Experiments using the scavengers showed that O2− was the main reactive species in photocatalytic degradation under highly dissolved oxygen conditions, which also accounted for the observation that the removal efficiency for methyl orange decreased at higher pH. However, without photocatalyst, nanobubbles alone did not improve the removal of methyl orange, and nanobubbles also did not increase the degradation of methyl orange by only photolysis. These experiments show that oxygen and air nanobubbles can act as environmentally friendly catalysts for boosting the performance of photocatalytic water treatment systems.

Construction of Novel Z-Scheme N-CQDs/Sn3O4 Heterojunction for Excellent Photocatalytic Degradation of Organic Pollutant

The construction of heterojunction can improve the transfer and separation efficiency of photogenerated electron-hole pairs, which is conducive to the photocatalytic removal of pollutant. In this work, a novel Z-scheme N-CQDs (Nitrogen-doped carbon quantum dots)/Sn3O4 heterojunction was synthesized by a facile hydrothermal method. N-CQDs were evenly dispersed on the surface of Sn3O4, which is helpful for the formation of heterostructured interface between N-CQDs and Sn3O4. As-prepared N-CQDs/Sn3O4 heterojunctions exhibited superior visible light photocatalytic activity to pure Sn3O4 for the degradation of methyl orange (MO). Especially, the 1.25% N-CQDs/Sn3O4 sample displayed the optimal photocatalytic activity with a 78% removal efficiency of MO under visible light illumination for 80 min. The improvement of photocatalytic behavior could be mainly attributed to the formation of Z-scheme heterostructure between N-CQDs and Sn3O4 interfaces, which not only increases the photoinduced charges separation efficiency but also reserves the high energy electrons and high energy holes, as well as the higher specific surface area. Active species trapping experiments demonstrated that superoxide radical and holes are important active species during the photocatalytic degradation process. This work provides a novel insight into the design and synthesis of Sn3O4-based heterojunction for removal of organic pollutants.

Comparative study on the removal of different-type organic pollutants on three-dimensional hexagonal-tungsten trioxide/reduced graphene oxide nanorod arrays: adsorption and visible light photodegradation

A series of self-supporting three-dimensional (3D) hexagonal-tungsten trioxide/reduced graphene oxide (h-WO3/rGO) nanorod arrays photocatalyst are synthesized by simple hydrothermal method without substrate. By selecting cationic dye methylene blue (MB), amphoteric dye rhodamine B (RhB) and anionic dye methyl orange (MO) as model organic pollutants, the experiments indicate that the 3D h-WO3/rGO photocatalyst shows a synergistic effect of adsorption and photocatalysis under visible light irradiation for the removal of MB and RhB. WrG1 which adding 1 wt% graphene oxide (GO) during synthesis demonstrates optimal adsorption and degradation activity and the bandgap energy (Eg) of WrG1 is 2.02 eV. Adsorption removal efficiency of MB, RhB and MO are 96.0%, 62.4% and 10.9% and the total removal efficiency of MB, RhB and MO are 99.3%, 84.8% and 18.3% by 0.3 g/L WrG1, respectively. Moreover, holes (h+) were the main active species for the photocatalytic degradation of organic pollutants. This work revealed the adsorption and photocatalysis activity of three different charge dyes on the h-WO3/rGO, which facilitates in understanding the removal mechanism in combination with other analytical methods and the impact of photocatalyst chargeability on degradation of organic pollutants. The visible light bifunctional catalyst h-WO3/rGO as adsorbent and photocatalyst presents a great potential in removal cationic and amphoteric organic pollutant from wastewater without additional treatment under ambient conditions.

Insight into the synergistic photocatalytic-adsorptive removal of methyl orange dye using TiO2/chitosan based photocatalyst

The removal of methyl orange (MO) dye has been studied using TiO2/chitosan-montmorillonite (TiO2/Cs–MT) bilayer photocatalyst which also functions as an adsorbent. The dye removal experiments were conducted in the dark and under UV–Vis light irradiation via adsorption and photocatalysis-adsorption processes, respectively. The adsorption modelings were employed on the dark experimental data and compared with the immobilized and suspended Cs–Mt counterparts. It was found that the bilayer photocatalyst closely followed the adsorption properties of immobilized Cs–Mt which obeyed the pseudo-second-order kinetic and film diffusion models. Fluorescent analysis revealed that the charge separation was enhanced in the presence of Cs–Mt as a sub-layer of TiO2. Under light irradiation, the photocatalytic activity of TiO2/Cs–MT corresponded to its adsorption counterpart trend and was optimized at pH 6.5 and 20 mg L−1 of MO dye solution. High removal efficiency and synergism of MO by TiO2/Cs–MT over TiO2 single layer were observed throughout the 10 cycles of application due to contribution of adsorption of Cs–Mt sub-layer and photocatalysis by TiO2 top layer.

Enhancing photodegradation activity of g-C3N4 via decorating with S-doped carbon nitride quantum dots by in situ polymerization

In this work, sulfur doped carbon nitride quantum dots (S-CNQDs) were prepared by one-pot copolymerization using melamine and thiourea as starting materials. The composite (g-C3N4/S-CNQDs), showing enlarged surface area, was fabricated by one-step in situ polymerization. The composites displayed much better photocatalytic activity than pristine g-C3N4 in degradation of methyl orange (MO) under UV–visible light irradiation. The removal efficiency of MO reached by 94.3% under visible light (λ ​> ​420 ​nm) illumination within 80 ​min, whereas it was nearly 100% under UV–visible light (λ ​> ​350 ​nm) irradiation within 40 ​min. The enhanced photocatalytic activity of composites is attributed to the doping of S-CNQDs, which leads to higher separation of photo-generated electron-holes, extended visible light response and more active sites. Additionally, the potential mechanism of photocatalytic degradation on MO by g-C3N4/S-CNQDs was proposed. This work presented a simple way for constructing S-CNQDs-based g-C3N4 catalyst.

Simultaneous removal of methyl orange and Cr(VI) using polyethyleneimine-modified corncob-derived carbon material

Polyethyleneimine (PEI) modified corncob-derived carbon material (CCM) was prepared by the simple wet-impregnation technique. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), and nitrogen isothermal adsorption/desorption measurements were used to compare the structural differences between the CCM and the PEI-modified CCM (PEI-CCM). In the single-pollutant removal experiment, the PEI-CCM showed high adsorption capacities for methyl orange (MO) and Cr(VI). However, the CCM only showed high adsorption capacity for MO. Moreover, the PEI-CCM exhibited high removal efficiencies in the simultaneous removal of MO and Cr(VI), with final removal efficiencies of 100% and 95%, respectively. The reusability experiment of PEI-CCM indicated that, after four recycles, PEI-CCM maintained high performance with the removal efficiency of MO and Cr(VI) decreased less than 3% and 16%, respectively. The prepared PEI-CCM could be a high-performance adsorbent for the simultaneous removal of MO and Cr(VI) from water containing multiple pollutants.

Novel axial substituted subphthalocyanine and its TiO2 photocatalyst for degradation of organic water pollutant under visible light

Abstract In this study, highly reactive TiO2 modified by a novel axial substituted subphthalocyanine H12SubPcB-OPHCOOH (SubPc) was successfully prepared. TiO2/SubPc nanoparticles had been fabricated via a Solvothermal method. The approaches of DFT and TD-DFT were utilized to research the electronic structure and optical spectra in the subphthalocyanines. The photocatalytic abilities of the present nanocomposites were investigated by degrading the methyl orange (MO) and bromophenol blue (BB) in irradiance of visible light. The removal efficiency of MO and BB over TiO2/SubPc (25:1) was 5.28 and 1.41 times higher than pure TiO2, respectively. Furthermore, the reusability studies showed that the photocatalytic activity of TiO2/SubPc could be maintained over 85% after 5 recycles.

Electrochemical Oxidation of Methyl Orange Dye by Stainless Steel Rotating Cylinder Anode

Methyl orange dye was successfully removed from simulated waste water in a batch mode electrochemical reactor with a stainless steel rotating cylinder anode. Effects of MO concentration, supporting electrolyte concentration, applied current, pH, and anode rotation rate were studied in terms of MO removal percentage and COD removal percentage. The study showed that both the removal efficiency of methyl orange and COD removal percentage decrease with the increase in MO initial concentration, and increase with increase in supporting electrolyte concentration, applied current, anode rotation rate, and pH value up to 7. Degradation reaction was found to be a first order reaction and the reaction rate constant was determined at different values of initial MO concentrations.

Response Surface Methodology for Photo Degradation of Methyl Orange Using Magnetic Nanocomposites Containing Zinc Oxide

Magnetic graphen oxide (Fe3O4-GO) is applied for preparation of Fe3O4-GO-ZnO (MGOZ) nanocomposite as photocatalyst. The photocatalysts are characterized by FTIR and UV spectrophotometer. FTIR results confirm the presence of Zn–O bonds and Fe–O bonds that are attributed to the ZnO and Fe3O4, respectively. The removal efficiency of methyl orange (MO) is compared using MGOZ and Fe3O4-ZnO at different irradiation time (ranging from 5 to 40 min) and pH (in the range of 3 to 11). The experimental results show that the removal efficiency of MO using MGOZ and Fe3O4-ZnO enhanced with respect to the irradiation time. Meanwhile the lowest and highest removal efficiency are obtained at pH = 7 and pH = 3, respectively. The comparison between removal efficiency of MO using MGOZ and Fe3O4-ZnO reveals that GO has a significant effect on the photocatalytic activity. Meanwhile, the removal efficiency of MO using MGOZ is higher than that of Fe3O4-ZnO. The statistical analysis of results using design of experiments (DOE) and Duncan’s multiple range test at α = 0.05 confirm that irradiation time, pH and their interactions have a significant effect on the removal efficiency of MO.