Adsorption Of Methyl Orange Dye Research Articles

Synthesis of titanium phosphate/polypyrrole nanocomposites for removal of methyl orange from water

AbstractIn this paper, titanium (IV) phosphate (TiP), polypyrrole (PPy), and titanium (IV) phosphate‐polypyrrole (TiP/PPy) nanocomposites were synthesized for adsorption of methyl orange (MO) dye from water. X‐ray diffraction data showed the formation of pure samples with crystallite size 14.1 and 14.2 nm of TiP and TiP/PPy nanocomposite respectively. The specific surface area of TiP (77.127 m2 g−1) was higher than PPy (17.004 m2 g−1) and TiP/PPy nanocomposite (25.247 m2 g−1). The equilibrium adsorption capacity (qe) was found to be 9.801 and 30.69 mg g−1 for PPy and TiP/PPy nanocomposite respectively. The Langmuir model was successfully fitted, and the TiP/PPy nanocomposite (69.4 mg g−1) had a greater maximum adsorption capacity (qm) than PPy (51.9 mg g−1). The MO adsorption removal efficiency was dependent on the pH of the solution and was found to be 86.7% and 30.7% for TiP/PPy nanocomposite and PPy respectively at pH 4. Thermodynamics studied confirmed the spontaneous and exothermic nature of the adsorption process. The presence of common ions decreased MO adsorption capacity and the maximum decrease was found for sodium carbonate. Electrostatic interaction, π–π stacking, and hydrogen bonding were responsible for adsorption of MO dye on the TiP/PPy nanocomposite and PPy.

Single-step synthesis and modification of CTAB-hectorite for efficient adsorption of methyl orange dye

Hectorite modified with cetyltrimethylammonium bromide (CTAB) using a single-step synthesis and modification produced an efficient adsorbent for water treatment. Characterization analysis revealed that incorporating CTAB at 5–10 wt/wt increased the basal distances and the mesopore area of hectorite. The high concentration at 20–40 wt/wt deposited CTAB on the external surface of hectorite, consequently reducing the surface area. TGA-DTG analysis revealed that the surface-bound CTAB has lower thermal stability than the interlayered CTAB. CTAB-modified hectorite (40-Hec) showed the adsorption capacity of methyl orange at 164.28 mg/g, with 98.57% removal efficiency, significantly higher than hectorite. The adsorption of methyl orange followed the pseudo-second order kinetic and the Sips models. The Sips isotherm was suitable to describe the adsorption mechanism by monolayer physisorption. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) revealed that the adsorption of methyl orange on CTAB-modified hectorite is a spontaneous exothermic process and affected by the entropy of adsorption.

Investigation of Typha Latifolia (TL) as potential biosorbent for removal of the methyl orange anionic dye in the aqueous solution. Kinetic and DFT approaches

Novel fibers plant of Typha Latifolia pure (TL) and activated with sulfuric acid (TLs) were investigated as potential biodegradable and ecofriendly adsorbent for the removal of the methyl orange (MO) as anionic dye in the aqueous solution using different experimental parameters such as particle size, adsorbent mass, pH, contact time, initial methyl orange concentration and temperature, respectively. Two studied biosorbents (TL and TLs) were characterized using different techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray energy dispersion (EDS). The experimental results shown that the adsorption of methyl orange dye for the TL and TLs reaches a maximum of 72.61 and 93.23% (with pH =5 at room temperature), respectively. Then, the amount adsorbed of TL and TLs are 36 and 50.34 mg/g, respectively. The isothermal study was shown that the Langmuir model describes well the methyl orange adsorption through fibers plant. Further, DFT was investigated to understand the interactions between the most reactive sites in the fibers plant biosorbent and the MO anionic dye. The computational calculations again support our experimental data and fibers plant could be used as potential biosorbent for removal of the methyl orange dye in the aqueous solution.

Chitosan-Modified Biochar and Unmodified Biochar for Methyl Orange: Adsorption Characteristics and Mechanism Exploration.

In this study, shrimp shell-derived chitosan (CS) and rice husk-derived biochar (RHB) were produced; CS and RHB were then used to synthesize chitosan-modified biochar (CSBC) hydrogel beads. N2 adsorption (77K), SEM-EDX and FT-IR techniques were used to evaluate the physicochemical properties of the adsorbents. A batch experiment was conducted to test the methyl orange (MO) adsorption performance of RHB and CSBC. The results showed that the MO adsorption process was strongly pH-dependent. The kinetics were well described by the pseudo-second-order and intra-particle diffusion models, assuming the chemisorption and intraparticle diffusion mechanisms govern the adsorption process. Homogeneous adsorption for MO on the surface of RHB and CSBC was also assumed since the isotherm data showed the best-fit to the Langmuir model. Under the experimental conditions of initial pH 3, dosage 0.2 g, contact time 240 min and temperature 298 K, the maximum adsorption capacity of CSBC and RHB for MO dye adsorption was 38.75 mg.g−1 and 31.63 mg.g−1, respectively. This result demonstrated that biochar had better performance after modification with chitosan, which provided more functional groups (i.e., −NH2 and −OH groups) for enhanced electrostatic interactions and complexation between MO and CSBC. Overall, CSBC is an effective adsorbent for the removal of MO from aqueous solution.

Methyl Orange Dye Removal through Adsorption using TiO2 modified Montmorillonite Granule

This research was conducted to determine the characteristics of TiO2 modified montmorillonite granule and to determine the effectiveness of its filtration against methyl orange dye. Montmorillonite granule particles were made through a pressing process and continued with sintering at 900oC. The granules obtained were coated with TiO2 photocatalyst by the deep coating method. The montmorillonite granules were characterized using SEM-EDX and the methyl orange dye adsorption process was carried out using the column method. The SEM analysis showed that the granules is porous materials and the EDX confirm the increasing of TiO2 content in montmorillonite before and after being coated with TiO2 from 0.50% to 22.66%. The best adsorption effectiveness of methyl orange was 96.6% at the flow rate of 0.0083 L/hour, which occurred in the use of TiO2 modified montmorillonite granule.

3-Aminopropyl-triethoxysilane-Functionalized Tannin-Rich Grape Biomass for the Adsorption of Methyl Orange Dye: Synthesis, Characterization, and the Adsorption Mechanism.

A biomass amino silica-functionalized material was successfully prepared by a simple sol–gel method. 3-Aminopropyltriethoxysilane (APTES) was added to a tannin-rich grape residue to improve its physicochemical properties and enhance the adsorption performance. The APTES functionalization led to significant changes in the material’s characteristics. The functionalized material was efficiently applied in the removal of methyl orange (MO) due to its unique characteristics, such as an abundance of functional groups on its surface. The adsorption process suggests that the electrostatic interactions were the main acting mechanism of the MO dye removal, although other interactions can also take place. The functionalized biomass achieved a very high MO dye maximum adsorption capacity (Qmax) of 361.8 mg g–1. The temperature positively affected the MO removal, and the thermodynamic studies indicated that the adsorption of MO onto APTES-functionalized biomass was spontaneous and endothermic, and enthalpy is driven in the physisorption mode. The regeneration performance revealed that the APTES-functionalized biomass material could be easily recycled and reused by maintaining very good performance even after five cycles. The adsorbent material was also employed to treat two simulated dye house effluents, which showed 48% removal. At last, the APTES biomass-based material may find significant applications as a multifunctional adsorbent and can be used further to separate pollutants from wastewater.

Thermodynamics and kinetic studies of methyl orange dye adsorption in magnetic material-silica-zeolite (MM-Sio2-NZ) composite

Using methyl orange (MO) in dye industries can cause the accumulation of MO waste in aquatic systems, including seawater. A magnetic material-silica-zeolite (MM-SiO2-NZ) composite was investigated in vitro to adsorb methyl orange (MO) dye. MM-SiO2-NZ composite was characterized using FTIR, XRF, and VSM. Adsorption studies with pH, concentration, contact time, and temperature variations were carried out to determine the adsorption capacity. The MM-SiO2-NZ characterization results by FTIR showed the presence of OH groups from Fe-OH, Si-OH, and Al-OH, and there were Fe-O, Si-O, Al-O, Si-O-Si, and Si-O-Fe groups. The results of XRF characterization showed that the metal oxide content of Fe2O3 in magnetic material (MM) was 75.39% and decreased to 52.63% after the MM-SiO2-NZ composite was formed. The characterization using VSM indicated the magnetic properties of MM to be 44.083 emu/g, then decreased to 11.407 emu/g after being composited. The adsorption of MM-SiO2-NZ tends to follow the Langmuir adsorption isotherm with a Langmuir constant (KL) value of 1.332 L/mg. Furthermore, the adsorption kinetics followed the pseudo-second-order kinetics with a constant value (k2) of 3×10-2 g.mg/min. MO dye adsorption by MM-SiO2-NZ took place spontaneously with Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) values of -1.109 kJ/mol, -38.687 kJ/mol, and -12.402 kJ/mol, respectively.

Phoenix dactylifera mediated green synthesis of Mn doped ZnO nanoparticles and its adsorption performance for methyl orange dye removal: A comparative study

A comprehensive study on Phoenix dactylifera mediated green synthesis of ZnO, and different content (2%, 4%, 6%, 10%) of Mn doped ZnO nanoparticles (Mn@ZnO-NPs) were performed to evaluate the elimination of dispersing acid dye methyl orange (MO) from aqueous solutions. The as-synthesized ZnO and Mn@ZnO-NPs adsorbents were characterized by XRD, FT-IR, UV-VIS spectrophotometer, TEM, and point of zero charges (pHpzc). In accordance with the sorption capacity of the adsorbents, the 10% Mn@ZnO-NPs shows the optimal adsorption of MO dye. The adsorption results perfectly matched the pseudo-2nd order kinetic model and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity were recorded to be 87.72, 90.09, 91.74, 92.59, 96.15 mg/g for ZnO and 2%, 4%, 6%, and 10% Mn@ZnO-NPs, respectively at the pH 5, adsorbent dose 1.5 g/L, and 303 K. The thermodynamic data of all the systems confirms that the adsorption of MO was feasible and endothermic in nature. Regeneration study showed that after four successive ad-/de-sorption cycles, the absorption potential of ZnO and 10% Mn@ ZnO was not reduced more than 15%. The collective benefits of easy preparation, non-toxic and good removal efficiency towards anionic dye make Mn@ZnO-NPs as a novel adsorbent.

Efficient Adsorption Removal of an Anionic Azo Dye by Lignocellulosic Waste Material and Sludge Recycling into Combustible Briquettes

In recent years, the removal of dyes has emerged as a significant problem that attracted several researchers. The search for green and eco-friendly adsorbents has been a never-ending task in environmental protection to overcome this issue. Herein, almond shells (AS) were used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The AS was characterized using several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Adsorption experiments were carried out under different pH, temperature, and AS particle size conditions. Kinetic and isothermal studies revealed that MO adsorption on the AS reached equilibrium at 90 min, following the pseudo-second-order (PSO) kinetic model. The Langmuir adsorption isotherm was found the suitable adsorption model for MO adsorption on AS, showing a maximum adsorption capacity of 15.63 mg/g. Thermodynamic parameters such as the change in standard enthalpy (ΔH°), the change in standard entropy (ΔS°), and the change in standard free energy (ΔG°) indicated that the MO dye adsorption process is non-spontaneous, endothermic, and physical, which was further confirmed from FTIR analysis of AS samples after adsorption. The contaminated sludge was converted into biochar by slow pyrolysis at a temperature of 400 °C for 2 h. Biochar has been exploited for the manufacture of combustible briquettes.

Adsorption of methyl orange on ZnO supported by seawater-modified red mud

Abstract In this study, a novel adsorbent (SRM-ZnO) was prepared using zinc oxide supported on red mud in a seawater medium and was used for the adsorption of methyl orange (MO). It is expected to solve the recycling of red mud and prepare an economical adsorbent with high efficiency to adsorb dye wastewater. Material composition and morphology analyses showed that hydrotalcite compounds were attached on the surface of SRM-ZnO. The hydrotalcite compounds can increase the surface area of the modified red mud and thus increase the adsorption capacity of MO. The adsorption of MO dye on modified red mud conforms to the Temkin isotherm model and pseudo-second-order kinetic model. The adsorption behavior mainly includes physical interaction, supplemented with chemical interactions. Result also found that the adsorption of MO on SRM-ZnO is a spontaneous exothermic process.

Effect of time, pH, and temperature on kinetics for adsorption of methyl orange dye into the modified nitrate intercalated MgAl LDH adsorbent

• Nitrate intercalated MA LDH nanopowder was synthesized using coprecipitation method under refluxing condition. • The adsorption of MO dye onto MA LDH reached equilibrium within 1 hour and exhibited saturation adsorption of 583 mg/g. • Adsorption kinetics and isotherm were governed by the pseudo-second-order kinetic model and Langmuir model, respectively. The present work evaluated the potential of nitrate intercalated pristine MgAl layered double hydroxide (MA LDH) powder, for adsorption of methyl orange (MO) dye from an aqueous solution for reducing health hazards. Nitrate intercalated pristine MA LDH was synthesized in the particle size range between 60 and 120 nm by co-precipitation method in nitrogen atmosphere using reflux process. MO dye was adsorbed into MA LDH by the process of anion exchange to promote formation of MO intercalated MA LDH (MAMO LDH). Both MA LDH and MAMO LDH powders were characterized using XRD, FTIR, FESEM, and TGA analysis. In the adsorption process, all effective parameters such as adsorbent dose, adsorption time, temperature, pH, and MO dye concentration were studied in the batch process using UV visible spectroscopy. It was observed that the pH and temperature of the dye solution exerted a major impact on the kinetics of adsorption of MO dye into 10 mg of MA LDH. The adsorption kinetics at different temperatures such as 25, 40, and 50 °C were investigated, and found that pseudo second order kinetic fitted well with the kinetic data. Maximum adsorption percentage of MO dye into MA LDH nanoparticles hardly varied with an increase in temperature as suggested by 98.22% of MO adsorption at 25 °C as opposed to 98.66% adsorption at 40 and 50 °C within a maximum of 1-hour incubation time from 50 ml of aqueous solution containing 0.03 mg/ml of MO dye. Upto three regeneration cycles, nitrate intercalated MA LDH dye showed no significant decrease in adsorption capacity of MO dye from its aqueous solution. The adsorption isotherm was measured at a temperature of 40 °C and indicated that the Langmuir isotherm model fitted well with experimental data with a maximum adsorption capacity of 583 mg/g. Thermodynamic parameters, such as high negative value of ΔG and positive value of ΔH suggested that the adsorption process was spontaneous and endothermic in nature.

Synthesis, Characterization, and Application of Magnetized Lanthanum (III)-Based Metal-Organic Framework for the Organic Dye Removal from Water

A hybrid composite based on metal-organic framework (MOF) was chemically fabricated by embedding the magnetic Fe3O4 nanoparticles within amino-functionalized porous La-MOF (MOF/NH2) to produce a highly efficient and reusable composite of MOF/NH2/Fe3O4. Different proper techniques were used for the characterization of surface morphology and chemical arrangement of the prepared MOF/NH2/Fe3O4 composite. The characterization results using various techniques including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer, Emmett, and Teller analysis (BET), and vibrating sample magnetometer (VSM) approved the successful fabrication of MOF with amino arms on its surface besides the well magnetization using magnetic nanoparticles. The MOF/NH2/Fe3O4 composite showed enhanced adsorption capacity (618 mg/g) toward methyl orange (MO) anionic dye which is higher than many commercial reported adsorbents due to the presence of many types of adsorption sites (NH2 groups and lanthanum sites), large surface area of MOF, and the synergetic effect of magnetic nanoparticles. Moreover, the MOF/NH2/Fe3O4 composite showed selective adsorption of MO dye from dye mixtures owing to the electrostatic attraction. Also, the MOF/NH2/Fe3O4 composite retained over 90% of its efficiency for the dye removal even after six successive cycles. So, the present study provided a practical strategy for the design of functional MOF hybrid composites. Furthermore, due to the adaptability of its architectural form, it is a potential adsorbent material for industrial wastewater treatment uses.

Adsorptive removal of methyl orange dye from aqueous solution using populous leaves: Insights from kinetics, thermodynamics and computational studies

Abstract The present investigation reports an effective adsorption of methyl orange dye using the leaves of populous tree in five different forms. The physicochemical properties of all adsorbents were characterized using instrumental analyses such as Fourier transform infrared spectroscopy (FTIR), powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The feasibility of populous leaves for the adsorptive removal of methyl orange dye from aqueous solution was evaluated in a batch process by varying operational parameters such as adsorbent dosage (0.2–0.6 g), solution pH 3–12, initial dye concentration (5–100 ppm), and contact time (10–100 min). The equilibrium data was correlated by both Freundlich and Langmuir isotherms. The maximum Langmuir monolayer adsorptive capacity was found to be 90.44 mg/g at pH 3.0 and 303.15 K with coefficient of determination R2 = 0.9988 for L-arginine treated populous charcoal powder. The kinetic study revealed that the system obeyed pseudo-first order kinetic model for all the adsorbents (R2 > 0.93). The thermodynamic adsorption parameters showed that the adsorption process is exothermic. Using quadrate models and optimizing the conditions, the maximum adsorption capacity for all the adsorbents was observed at initial dye concentration (75 ppm), dosage of adsorbents (0.6 g) and pH (5). The computational chemistry was also used to validate the adsorption of methyl orange dye.

Synthesis and Characterization of Chitosan-Polyaniline-Manganese Dioxide Nanocomposite for Removal of Methyl Orange Dye

An ecofriendly polymer composite based on chitosan, polyaniline and manganese dioxide has been prepared using batch adsorption method and analyzed by Fourier transform infrared (FTIR), UV-vis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). FTIR results suggested the presence of functional groups like hydroxyl and amino groups and also shown a significant shift in IR bands in CS-PANI-MnO2 composite. The surface of composite was quite rough within the folds of pleated regions as observed from the SEM and TEM morphologies. The prepared composite was also utilized as an adsorbent for the treatment of methyl orange from the aqueous solution and achieved a reasonably good adsorption capacity of 96.2%. The biochemical oxygen demand (BOD) and chemical oxygen demand (COD) tests also suggested their suitability for the adsorption of methyl orange dye.

Enhanced adsorptive removal of toxic anionic dye by novel magnetic polymeric nanocomposite: optimization of process parameters

The novel magnetic manganese ferrite/polyaniline nanocomposite (MnFe2O4-PANI-NC) was prepared for eradication of toxic anionic methyl orange (MO) dye from wastewater at almost neutral pH condition by impregnating polyaniline onto manganese ferrite. The characterization properties of MnFe2O4-PANI-NC was found by XRD, FEGSEM, TEM, FTIR, VSM, and BET analysis to analyze the adsorption process. The MO dye removal efficiency by sono-assisted adsorption was found to be 90.03% at solution pH 6.0 and sonication time 15 min, whereas the batch stirring and shaking gives the MO dye removal of ∼65% to ∼74% at same experimental condition. The adsorption kinetics followed pseudo-second order kinetics model with additional effect of intra-particle diffusion. The linear fitting of isotherm model followed Langmuir isotherm with equilibrium adsorption capacity of 175.44 mg/g at room temperature. The MO dye adsorption mechanism onto MnFe2O4-PANI-NC can be described by the synergistic effect of electrostatic interaction and π–π dispersive bonding between anionic MO dye molecules and positively charged MnFe2O4-PANI-NC surface. The central composite design (CCD) predicts the maximum MO dye removal of 99.01% at optimum condition of sonication time 14 min, MnFe2O4-PANI-NC dose 0.5 g/L and initial methyl orange (MO) dye concentration 10.0 mg/L. The MnFe2O4-PANI-NC is found to be stable even after 5th consecutive cycle of adsorption-desorption without compromising its adsorptive potential. Thus the fabricated MnFe2O4-PANI-NC can be a potential adsorbent material for sono-assisted removal of MO dye for large scale application due to less dependency on solution pH, facile fabrication technique, and rapid as well as decent dye uptake capacity.

Influence of the alkyl chain length of surfactant on adsorption process: A case study

To investigate the effect of alkyl chain length of surfactant on the adsorption process behavior, the present study was applied the adsorption of anionic methyl orange (MO) dye using mineral pumice (NP) as natural adsorbent, and Dodecyltrimethylammonium bromide (DTAB), Tetradecyltrimethylammonium bromide (TTAB), and Cetyltrimethylammonium bromide (CTAB) modified pumice as namely DMP, TMP, and CMP, respectively. Due to the differences in the alkyl chain length of the surfactants, the effect of chain length on the MO dye adsorption process can be evaluated. For an understanding of the physical and chemical structure of adsorbents, XRF, SEM, BET, and FTIR analyses were performed. The effect of contact time, initial MO concentration, adsorbent dosage, and solution pH was studied. Langmuir, Freundlich, Jovanovic and Temkin isotherm models were used for fitting of the experimental data. Based on the results of the isotherm models and also calculating the errors of each model, the highest match was obtained with Langmuir isotherm, and the maximum adsorption capacities for NP, DMP, TMP, and CMP were 6.43, 18.13, 28.60, and 31.73 mg/g, respectively. Also, the results of kinetic studies showed that the data are in maximum agreement with the pseudo-second-order kinetic model. Therefore, it can be concluded that an extended surfactant chain increases the adsorption capacity, and it can be found that one of the effective factors in the adsorption processes is the hydrophobic interactions of the modifiers.

Photocatalytic Performance of MWCNTs/TiO2 Nanocomposites: Conventional vs. Microwave-Assisted Synthesis

Multi-walled carbon nanotubes-titanium dioxide (MWCNTs-TiO2) nanocomposites were synthesized via microwave-assisted synthesis and conventional hydrothermal method, comprising of well-crystallized anatase TiO2 nanoparticles with different MWCNTs contents. TiO2 nanoparticles synthesized by the rapid thermal decomposition of tetra-butyl titanium (Ti(OC4H9)4) in the presence of acid treated MWCNTs, were attached on the surface of MWCNTs by means of chemical bonds under microwave irradiation. The addition of MWCNTs did not influence the structure of anatase TiO2. The photocatalytic performance evaluation of composite materials was conducted under UV and visible light using methyl orange (MO) as a typical pollutant. The enhancement in photocatalytic efficiency of nanocomposites was clearly observed by the presence of MWCNTs, which could contribute to improve the adsorption of MO dye, absorption of more light and also obstruct the photogenerated electron-hole pair's recombination.

Adsorption of Methyl Orange Dye onto Raw Maize Cob and Maize Cob Activated Carbon: Isotherms and Thermodynamic Studies

This study was aimed to evaluate the adsorption of Methyl orange (MO) onto raw maize cob (RMC) and maize cob activated carbon (MCAC) from aqueous solution using batch adsorption studies. The produced adsorbents were characterized by Scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The influence of contact time, dosage, concentration, temperature, and pH were investigated as well as Isotherm and Thermodynamic studies. Effect of contact time showed that Methyl orange adsorption were found to reach equilibrium within 125 and 110 minutes with optimum percentage removal of about 86.98% and 94.57% for raw maize cob and maize cob activated carbon respectively. The dye removal efficiency was found to increase with increasing initial dye concentration from 10 mg/L to 100 mg/L, and adsorption efficiency was found to be high at lower pH. However, increase in the dosage of the adsorbents lead to the increase in the adsorption process. The equilibrium adsorption data were analyzed using four adsorption models: Langmuir, Freundlich, Temkin, and D-R. The results revealed that MO with raw maize cob and maize cob activated carbon fit well to Freundlich with R2 value 0.977 and Temkin with R2 value 0.990 respectively and mean adsorption energy calculated from D-R shows it is physical adsorption and also values of enthalpy and Gibbs free energy proves that. Values of activation parameters such as free energy changes (∆G), enthalpy change (∆H) and entropy change (∆S) were calculated using Van't Hoff equation. All ∆G values were negative indicating that the adsorption was feasible and spontaneous. The result indicated that RMC and MCAC can be used for removal of MO from aqueous solution. The maize cob waste which is discarded as waste material was found to be effective adsorbent for the removal of Methyl orange dye from aqueous solution. Â

Oxygen Functionalized and Pristine Carbon Nanotubes Efficiency for Adsorption of Methyl Orange Dye

Pristine and oxygen functionalized multi-walled carbon nanotubes were used as adsorbent for removal of Methyl Orange (MO) dye. The adsorption was carried out under different pH values. The analysis of results indicated that the adsorption characteristics of the MO dye by pristine carbon nanotubes (P-CNTs) and oxygen functionalized carbon nanotubes (O2-CNTs) are highly influenced by the pH of the medium. The study report that the best pH medium of solution for the adsorption of MO on both CNTs was acid medium. The point of zero charge (pzc) of O2-CNTs and P-CNTs were determined as function of pH. The pzc of P-CNTs and O2-CNTs are found to be 4.7 and 3.9, respectively. The adsorption data have been analyzed using Langmuir and Freundlich. Fitting the equilibrium adsorption data by Langmuir and Freundlich models shows that experimental data well explained by the Langmuir equation.

Adsorption Characteristics and Mechanistic Study of Immobilized Chitosan-Montmorillonite Composite for Methyl Orange removal

This work investigates the adsorption characteristics and mechanisms of immobilized chitosan-montmorillonite (CS-MT) composite for the removal of methyl orange (MO) dye. It was observed that the immobilized CS-MT has a rougher surface, lower swelling, higher adhesion strength and higher surface area than the immobilized CS. The adsorption of MO dye onto the immobilized CS-MT followed the pseudo-second-order kinetic model, whereas at equilibrium, the Langmuir model best described the MO adsorption. The maximum adsorption capacity, qm of the immobilized CS-MT at 30, 45 and 60 °C were 154.4, 82.8 and 64.9 mg g−1, respectively. The thermodynamic study showed that the process of MO adsorption onto the immobilized CS-MT was exothermic in nature. The main adsorption mechanism of MO dye on immobilized CS-MT can be assigned to electrostatic attractions, n–π stacking interaction, dipole–dipole hydrogen bonding interactions and Yoshida H-bonding. Overall, the immobilized CS-MT does not only offer relatively high adsorption capacity, but also facilitates the treatment operation reusability and easy recovery of the adsorbent.