Methyl Orange Removal Efficiency Research Articles

Removal of organic dye by biomass-based iron carbide composite with an improved stability and efficiency.

The efficiency of zero-valent iron (Fe0) for the degradation of contaminants in water or soil can be highly reduced by side reactions with oxygen or water. This work was conducted to test whether this drawback can be effectively suppressed by the carbonation of Fe0 with pyrolyzed biomass, which forms a Fe3C composite. The composite Fe3C was characterized and its reactivity and stability were assessed in batch tests with methyl orange (MO) as a model pollutant. The results indicated that the removal rate of MO on Fe3C composite was higher than that of Fe0 (7.587 mg/(g·min) vs. 4.306 mg/(g·min)) at pH 4, where the degradation mechanism was confirmed by high-performance liquid chromatography-mass spectrometry. More importantly, the produced iron oxide in the Fe3C composite was highly suppressed. Regeneration studies showed that after three times of cycling, the removal efficiency of MO on Fe3C composite was kept to 99.42%, but Fe0 almost lost its reactivity. In situ chemical reduction of a colorimetric redox probe (indigo-5, 5'-disulfonate, I2S) quantitatively demonstrated that Fe3C composite has the reduction kinetics of I2S obviously slower than Fe0, indicating that Fe3C composite improved the stability of incorporated Fe0 to resist the side oxidation.

Preparation of ZnTiO3/TiO2 Photocatalyst and Its Mechanism on Photocatalytic Degradation of Organic Pollutants

TiO2 is a promising photocatalysis for degradation of organic pollutants due to its innocuity. However, its widespread practical application was hindered by the fast combination speed of photogenerated electron-hole pairs and low quantum efficiency. In this study, we prepared ZnTiO3-TiO2 using the Sol-Gel method to get heterojunctions, which exhibit efficient separation of photogenerated electron-hole pairs. The photocatalytic performances of various ZnTiO3-TiO2 were evaluated by the removal efficiency of Methyl orange. The experimental results showed that the ZnTiO3-TiO2(ZnTiO3:TiO2=0.3), which was calcinated under 600℃, had the best photocatalytic activity under ultraviolet light. The photocatalyst was stable under a wide range of pH (2.5-12.5). The photocurrent and ESR analysis verified the superior photocatalysis of ZnTiO3-TiO2, which was attributed to the efficient separation of electron-hole pairs induced by the heterojunctions.

Box-Behnken design to optimize the synthesis of new crosslinked chitosan-glyoxal/TiO2 nanocomposite: Methyl orange adsorption and mechanism studies.

A crosslinked chitosan-glyoxal/TiO2 nanocomposite (CCG/TNC) was synthesized by loading different ratios of TiO2 nanoparticles into polymeric matrix of crosslinked chitosan-glyoxal (CCG) to be a promising biosorbent for methyl orange (MO). Box-Behnken design (BBD) in response surface methodology (RSM) was applied to optimize various process parameters, viz., loading of TiO2 nanoparticles into CCG polymeric matrix (A: 0%-50%), adsorbent dose (B: 0.04-0.14 g/50 mL), solution pH (C: 4-10), and temperature (D: 30-50 °C). The highest MO removal efficiency of 75.9% was observed by simultaneous interactions between AB, AC, and BC. The optimum TiO2 loading, adsorbent dosage, solution pH, and temperature were (50% TiO2: 50% chitosan labeled as CCG/TNC-50), 0.09 g/50 mL, 4.0, and 40 °C. The adsorption of MO from aqueous solution by using CCG/TNC-50 in batch mode was evaluated. The kinetic results were well described by the pseudo-first order kinetic, and the equilibrium data were in agreement with Langmuir isotherm model with maximum adsorption capacity of 416.1 mg/g. The adsorption mechanism included electrostatic attractions, n-π stacking interactions, dipole-dipole hydrogen bonding interactions, and Yoshida H-bonding.

Improved organic pollutants removal and simultaneous electricity production via integrating Fenton process and dual rotating disk photocatalytic fuel cell system using bamboo charcoal cathode

A coupling system combining Fenton process with dual rotating disk photocatalytic fuel cell (PFC) was developed to improve methyl orange (MO) removal and simultaneous electricity production, in which the (NH4)3PO4 modified bamboo charcoal (BC) was acted as cathode catalyst. Due to the existence of the N and P containing functional groups on the BC catalyst and the rotating electrode, the hybrid system could efficiently reduce oxygen to generate some hydroxyl radical and related species for MO removal. Therefore, Fenton-PFC-BC with rotation system showed a superior MO removal efficiency of 85%, 2.4 times higher than that in the traditional Fenton-PFC-Pt with aeration system. The radicals inhibition assays and hydrogen peroxide quantitative studies revealed that HO, h+ and O2− were primarily responsible for MO degradation. Furthermore, the MO removal performance for Fenton-PFC-BC with rotation system was investigated at different parameters (such as rotating speed, BC loading, pH and ferrous ion concentration) to obtain optimal operation conditions. Results of energy analysis and reusability experiment showed that the proposed Fenton-PFC-BC with rotation system provided a cost-effective and stable method for the organic degradation and energy recovery.

The influence of ZnO nanoparticles amount on the optimisation of photo degradation of methyl orange using decorated MWCNTs

In the current study, we want to optimise the removal efficiency of methyl orange using decorated multi-walled carbon nanotubes (MWCNTs) with different amount of ZnO nanoparticles. For this purpose...

Removal of methyl orange over TiO2/polyacrylamide hydrogel

The present work describes the preparation of titanium oxide impregnated polyacrylamide hydrogel (TiO2/PAM) by in-situ polymerization technique. The prepared hydrogel was characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. The physical properties (solvent content, swelling behaviour, porosity) of hydrogel were also studied by ASTM method. Further, results are revealing the formation of composite hydrogel with improved properties. Thus, obtained prepared hydrogel was used for removal of methyl orange dye from laboratory prepared water samples. The methyl orange removal efficiency and kinetics was evaluated by UV-Visible spectroscopy in different conditions. The results indicate the improvement in dye removal capacity due to impregnation of metal oxides in hydrogel matrix.

Surface modification of date seeds (Phoenix dactylifera) using potassium hydroxide for wastewater treatment to remove azo dye

Abstract In this study, a low cost carbon adsorbent was prepared from date seeds. Their surface was modified with potassium hydroxide for use as an adsorbent for the removal of synthetic dye (methyl orange (MO)) from aqueous solutions. The effects of initial MO concentration, adsorbent dosage and temperature were studied. A two-cubed (23) factorial design was carried out on the experimental data, with two replications for the process optimization. The results showed that all three factors and their interactions up to the third order were significant for the removal efficiency of MO. Maximum equilibrium adsorption capacity was 66.26 mg/g at 318 K.

Immobilized cells of Rhodococcus strain UCC 0004 as source of green biocatalyst for decolourization and biodegradation of methyl orange

Abstract The bulk presence of methyl orange is contributed by anthropogenic sources which poses substantial threat to health and the environment. Locally isolated Rhodococcus strains were used as alternatives to develop greener and cost effective methyl orange removal technology. Rhodococcus strain UCC 0004 in particular demonstrated complete removal of 0.5 g/L methyl orange after 2 days of incubation and this strain exhibited 513% higher methyl orange removal efficiency under static mode in comparison to agitated mode. Adopting the technology of immobilization enabled the decolourization of higher concentration of methyl orange which resulted in 66% greater methyl orange removal activity as opposed to the non-immobilized cells. Optimization of immobilization parameters at 0.4% (w/v) alginate concentration, 0.3 M CaCl2, 3 mm bead diameter and 50 beads led to improved methyl orange-decolourizing activity and reduced the time taken to achieve complete decolourization by 67%. The immobilized beads could be reused up to nine batches without significant loss of methyl orange-decolourizing ability which is advantageous economically. The immobilized cells demonstrated higher substrate affinity (Km = 0.3771 g/L) and accelerated rate of disappearance of methyl orange (Vmax = 0.05903 g/L/h) compared to free cells. No germination inhibition was observed on Triticum aestivum and Vigna radiata indicating complete removal of dye toxicity. The decolourization of methyl orange occurred through biodegradation as supported by complete disappearance of the major peak from UV–vis spectrum. Therefore, this strain has a huge potential to be developed as biological tool for efficient removal of wastewater containing methyl orange.

Insights on the role of organic matters of some Egyptian clays in methyl orange adsorption: Isotherm and kinetic studies

The role of organic matters (OM) of some Egyptian clay in Methyl Orange (MO) adsorption from aqueous solutions was tested for the first time. To elaborate this role, the raw Organic Matters-Rich Clays (OMRC) was calcinated at 500 °C/4 h to remove their associated OM by oxidation. Then the MO removal efficiency by both OMRC and its calcinated derivative (COMRC) was tested at different experimental parameters. The adsorption of MO by the studied adsorbents was pH- and time-dependent process and the equilibrium was attained after 60 min. The pseudo-second-order model with high determination coefficients (R2 > 0.999) fitted well the adsorption kinetics, while the intra-particle diffusion was not the rate governing step in MO adsorption by both adsorbents. The MO adsorption characteristics revealed that equilibrium data of OMRC and COMRC fitted well to the Freundlich and Langmuir models, respectively. Electrostatic interaction was the primary but not the only governing mechanism for MO adsorption by the investigated adsorbents; participation from hydrogen bonding mechanism was involved, with some preference for COMRC. The superiority of OMRC over COMRC in MO adsorption can be attributed to the involvement of oxygen- and nitrogen-bearing groups of both OM and clay minerals in the adsorption process on the contrary of COMRC in which only oxygen-bearing groups of the clay minerals were incorporated.

Comparison of the photocatalytic performance of TiO2/AC and TiO2/CNT nanocomposites for methyl orange photodegradation.

To enhance the photocatalytic degradation efficiency of TiO2 on methyl orange (MO) removal, TiO2/AC (activated carbon) and TiO2/CNT (carbon nanotube) composites were synthesized. The prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The photocatalytic performance of the obtained composites were investigated by the degradation of MO under UV irradiation (254 nm, 365 nm). The results revealed that the prepared nanocomposite showed higher MO degradation efficiency than pure nano-TiO2. Additionally, batch experiments of influencing factors, including H2O2 dosage, metal dopants, inorganic anions, chloride ion concentration and ultraviolet wavelength on the MO removal efficiency were also conducted. The results demonstrated that metal dopant and the presence of H2O2 significantly enhanced MO removal efficiency.

Removal of dyes from aqueous solution by sorption with fly ash using a hydrocyclone

Methyl orange is an anionic water-soluble carcinogenic azo dye. Excessive dye concentration in water is a major health concern worldwide. In this current study, experiments have been conducted to remove methyl orange from aqueous solution using fly ash as an adsorbent in a continuous mode by using a hydrocyclone. A spiral rib has been introduced in the cylindrical part of the conventional hydrocyclone to increase the performance and this hydrocyclone is called as a ribbed hydrocyclone. Experiments were carried out to analyse the performance of particle separation and dye removal efficiency of the ribbed hydrocyclone. The cut size d50 of the ribbed hydrocyclone was 21 μm at a slurry flow rate of 50 LPM. Maximum methyl orange removal efficiency was 66% for the initial concentration of 60 mg/l for the dose of 2 g/l at a slurry flow rate of 50 LPM. The novelty of the current study revealed that the ribbed hydrocyclone is more efficient than conventional one and it could be used for the removal of both fly ash and methyl orange in a continuous mode.

Optimization and modeling of methyl orange adsorption onto polyaniline nano-adsorbent through response surface methodology and differential evolution embedded neural network

Presence of pigments and dyes in water bodies are growing tremendously and pose as toxic materials and have severe health effects on human and aquatic creatures. Treatments methods for removal of these toxic dyes along with other pollutants are growing in different dimensions, among which adsorption was found a cheaper and efficient method. In this study, the performance of polyaniline-based nano-adsorbent for removal of methyl orange (MO) dye from wastewater in a batch adsorption process is studied. Along with this to minimize the number of experiments and obtain optimal conditions, a multivariate predictive model based on response surface methodology (RSM) is developed. This is compared with data-driven modeling using the artificial neural network (ANN) which is integrated with differential evolution optimization (DEO) for prediction of the adsorption of MO. The interactive effects on MO removal efficiency with respect to independent process variables were investigated. The fit of the predictive model was found to good enough with R2 = 0.8635. The optimal ANN architecture with 5-12-1 topology resulted in higher R2 and lower RMSE of 0.9475 and 0.1294 respectively. Pearson's Chi-square measure which provides a good measurement scale for weighing the goodness of fit is found to be 0.005 and 0.038 for RSM and ANN-DEO respectively, and other statistical metrics evaluated in this study further confirms that the ANN-DEO is very superior over RSM for model predictions.

Photocatalytic enhancement of immobilized TiO2-polyaniline bilayer (TiO2-PBL) system for decolorization of methyl orange dye

Immobilized TiO2-polyaniline (PANI) bilayer (TiO2-PBL) was fabricated on a glass plate for decolorization of methyl orange (MO). The thickness of TiO2-PBL was 25.55 μm with the ratio of 0.62:0.38 for TiO2 to PANI layer. It was observed that the TiO2-PBL system emitted less photoluminescence (PL) intensity than the TiO2 monolayer corresponding to better •OH radicals production with reduced band gap energy. The removal of MO from the solution after 90 min of treatment was 97% by TiO2-PBL and 53% by TiO2 monolayer which indicates the efficacy of the former system due to the synergistic photocatalytic-adsorption processes. The effect of prewashing (photoetching) of TiO2-PBL plate was pronounced as better removal efficiency of MO was observed for ten cycles under UV–vis and visible light irradiations. The results showed that the TiO2-PBL system has visible light active properties, reduces the recombination of photogenerated active species and enhances the photocatalytic oxidation of MO.

Facet-Dependent Cuprous Oxide Nanocrystals Decorated with Graphene as Durable Photocatalysts under Visible Light.

Three morphologies (octahedral, hierarchical and rhombic dodecahedral) of crystal Cu2O with different facets ({111}, {111}/{110}, and {110}) incorporating graphene sheets (denoted as o-Cu2O-G, h-Cu2O-G and r-Cu2O-G, respectively) have been fabricated by using simple solution-phase techniques. Among these photocatalysts, the r-Cu2O-G possesses the best photocatalytic performance of 98% removal efficiency of methyl orange (MO) with outstanding kinetics for 120 min of visible light irradiation. This enhancement is mainly due to the dangling “Cu” atoms in the highly active {110} facets, resulting in the increased adsorption of negatively charged MO. More importantly, the unique interfacial structures of Cu2O rhombic dodecahedra connected to graphene nanosheets can not only decrease the recombination of electron-hole pairs but also stabilize the crystal structure of Cu2O, as verified by a series of spectroscopic analyses (e.g., X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM)). The effective photocatalysts developed in this work could be applied to the efficient decolorization of negatively charged organic dyes by employing solar energy.

Enhanced electroreduction of CO2 and simultaneous degradation of organic pollutants using a Sn-based carbon nanotubes/carbon black hybrid gas diffusion cathode

Coupled electrochemical system (CES) for electroreduction of CO2 and simultaneous degradation of organic pollutants is a promising CO2 conversion method. However, its performance is severely restrained by insufficient reactants and low electroactive surface areas on the cathode material. Here, a series of novel Sn-based carbon nanotubes (CNTs)/carbon black hybrid gas diffusion electrodes (CNTx/ESGDEs) were fabricated and used as cathodes to enhance the performance of the CES with methyl orange (MO) as a target pollutant. The results show that at an appropriate content of CNTs, the CNTx/ESGDEs offered increased total pore area, porosity, electroactive surface area, and decreased charge transfer resistances. The current density, Faraday efficiency, formic acid production rate, MO removal efficiency, and COD removal efficiency were improved by 140%, 92%, 404%, 76%, and 131%, respectively, at 40 wt% CNTs probably due to enhancement in the electroactive surface area as well as reactant transfer. This study benefits the large-scale applications of CES.

Spectacular Selectivity in the Capture of Methyl Orange by Composite Anion Exchangers with the Organic Part Hosted by DAISOGEL Microspheres.

There is a paramount need in finding sorbents endowed with selectivity in sorption of certain dyes from their mixture with other dyes from the same family. In this context, novel composite anion exchangers (CANEXs) were fabricated here by an innovative approach using silica DAISOGEL as the host for an anion exchanger (ANEX) bearing vinylbenzyl N, N-diethyl 2-hydroxyethyl ammonium moieties. Information about the outer surface versus in-pore generation of ANEX as a function of silica morphology was acquired by scanning electron microscopy. It was demonstrated that the CANEX microspheres were able to selectively capture methyl orange (MO) in binary mixtures with either methylene blue (MB) as the cationic dye or Chicago Sky Blue 6B (CSB) as the competing azo dye. The adsorption kinetics of MO and CSB were well-fitted by a pseudo-second-order model, indicating that chemisorption controlled the sorption process. Isotherms of "H" type characterized the sorption of MO, whereas "L" type isotherms described the sorption of CSB. Langmuir and Sips isotherms were the most suitable models to describe the sorption process at equilibrium. Even if only about 10 wt % of the CANEX sorbents was involved in the sorption process, the maximum sorption capacity was 180.25 mg MO/g composite and 153.86 mg CSB/g sorbent. Moreover, the CANEX sorbents exhibited a spectacular preference for MO molecules in competition with CSB at pH 5.5. Selectivity coefficient for MO in the mixture with either MB or CSB was 370 and 38.4, respectively. Removal efficiency of MO remained up to 100% after 10 consecutive sorption/desorption cycles.

PVA/PDADMAC/ZSM-5 zeolite hybrid matrix membranes for dye adsorption: Fabrication, characterization, adsorption, kinetics and antimicrobial properties

Novel poly vinyl alcohol/poly (diallyldimethylammonium chloride)/ZSM-5 zeolite (PVA/PDADMAC/ZSM-5) membranes have been prepared by solvent casting route. They were characterized by techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and optical microscopy (OM). XRD analysis indicated an enhanced crystallinity for the PVA/PDADMAC matrix after zeolite incorporation. SEM and optical microscopic results confirmed that the zeolite particles were well distributed throughout the matrix. The membranes exhibited good thermal and mechanical stability as confirmed by TGA and universal testing machine (UTM) examinations. The membranes were applied as adsorbents for the removal of methyl orange (MO) dye from aqueous solutions. The effects of parameters such as zeolite content, contact time, initial concentration of dye, pH and temperature on the adsorption capacity was evaluated. It has been found that the membrane with 5 wt% zeolite loading exhibits a high MO removal efficiency (95%). Non-linear and linear forms of pseudo-first-order and pseudo-second-order models were used to study the adsorption kinetics. The results indicate that the adsorption of MO on the membrane follows pseudo-second-order kinetics. The equilibrium data was modelled by Freundlich and Langmuir isotherm in their linear and non-linear forms. A relatively higher R2 value for the Freundlich isotherm indicate that this model could fit the experimental data better than the Langmuir model. The recycling studies revealed that the adsorption efficiency of the membrane was unaltered even after four adsorption-desorption cycles.

Facile Synthesis of Flexible Methylsilsesquioxane Aerogels with Surface Modifications for Sound- Absorbance, Fast Dye Adsorption and Oil/Water Separation.

New flexible methylsilsesquioxane (MSQ) aerogels have been facilely prepared by a sol–gel process with methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) as co-precursors, followed by surface modification and ambient pressure drying. The microstructure, mechanical properties and hydrophobicity of these MSQ aerogels after surface modifications of hexamethyldisiloxane (HMDSO) and/or hexamethyldisilazane (HMDS) were investigated in detail, and the applications of surface-modified MSQ aerogels in sound-absorbance, fast dye adsorption and oil/water separation were evaluated, respectively. The MSQ aerogels surface-modified by HMDS possess flexibility, elasticity and superhydrophobicity, and demonstrate good performance in the mentioned applications. The resultant MSQ aerogel used in sound-absorbance has high frequency (about 6 kHz) acoustic absorptivity of up to 80%, benefiting from its macroporous structure and porosity of 94%, and it also possesses intermediate frequency acoustic absorptivity (about 1 kHz) up to 80% owing to its elasticity. This MSQ aerogel can selectively separate oil from oil/water mixtures with high efficiency due to its superhydrophobicity and superlipophilicity, resulting from a lot of methyl groups, density as low as 0.12 cm3·g−1 and a water contact angle as high as 157°. This MSQ aerogel can be assembled to be a monolithic column applied for fast dye adsorption, and shows selective adsorption for anionic dyes and removal efficiency of methyl orange of up to 95%.

Controlled synthesis of silkworm cocoon-like α-Fe2O3 and its adsorptive properties for organic dyes and Cr(VI)

Industrial wastewater containing both organic and inorganic pollutants is being generated all the time. Efficient materials are highly needed to purify the polluted water. Thus, a hierarchical structured α-Fe2O3 with excellent adsorptive property has been synthesized by using a facile hydrothermal method. It can be prepared in macroscopic quantity. The as-synthesized α-Fe2O3 with silkworm cocoon-like morphology shows high efficiency in adsorbing Congo red (CR), Methyl orange (MO) and Cr(VI). The removal efficiency of CR, MO and Cr(VI) can reach 99.2%, 83.9% and 100% under appropriate conditions. Besides, this α-Fe2O3 shows high adsorptive ability for mixed CR and Cr(VI) in aqueous solution and the final removal rates can reach 94.7% and 97.9%, respectively. The adsorption kinetics fits well with the pseudo-second-order kinetic model. The results indicate that the product may find potential application in purification of wastewater containing both organic and inorganic pollutants.

Efficient removal of anionic dyes from aqueous media using newly in situ synthesized triazine-based nitrogen-rich network-modified magnetic nanoparticles

In this research, a triazine-based polymeric network surface-modified magnetic nanoparticles (TPN/MNPs) were synthesized for the adsorption of anionic compounds. To obtain TPN/MNPs, melamine–terephthaldehyde polymeric network was synthesized in the presence of magnetic nanoparticles. After characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), the adsorption behaviors of methyl orange (MO) as model anionic dye on TPN/MNPs were investigated. Obtained results showed MO removal efficiency has not been influenced by pH (5–9) and high salt concentration (up to 10% w/v) of the solution. The adsorption isotherm was described by Langmuir model. The results indicated that TPN/MNPs adsorbed MO effectively with a large capacity of 80.6 mg g−1. The adsorption reached the equilibrium within 10 min and the kinetics followed pseudo-second-order model. The magnetic separation after adsorption was easily achieved, and TPN/MNPs could be quantitatively regenerated by washing with 1.0 mL of the mixture of methanol/0.1 mol L−1 HCl (50:50, v/v%) solution. The results confirmed that TPN/MNPs have the potential superiority in removal of MO from aqueous solution.