Adsorption Capacity For Methyl Orange Research Articles

Preparation of carboxymethyl chitosan/phytic acid composite hydrogels for rapid dye adsorption in wastewater treatment

In recent years, chitosan has been used as a common raw material to prepare hydrogels for wastewater treatment. In this work, a series of carboxymethyl chitosan/phytic acid (CMCS-PA) composite hydrogels with various amounts of PA were prepared to remove methyl orange (MO) and Congo red (CR) dyes from aqueous solution. The composite hydrogels with well-defined structure were characterized by different techniques. The experimental results revealed that the hydrogel possessed stable porous structure with more wrinkles on the surface due to the formation of intermolecular hydrogen bonding between CMCS and PA during the in-situ polymerization process. More importantly, the optimal adsorption conditions of CMCS-PA were obtained by changing different adsorption factors: ratio of two molecules and pH. And the CMCS-PA (3:1) composite hydrogel presented great adsorption capacity for MO (13.62 mg/g) and CR (8.49 mg/g) at pH = 7 at room temperature. In addition, the hydrogel also showed great adsorption reusability and stability. This work promotes further development in composite hydrogels design and their applications of wastewater treatment.

Preparation of sodium alginate/polyvinyl alcohol composite nanofiber membranes for adsorption of dyes

In this research, electrospinning was used to prepare sodium alginate (SA)/polyvinyl alcohol (PVA) composite nanofiber membranes. Effects of electrospinning parameters on the morphology and fiber diameter were investigated, and an orthogonal design was chosen to optimize the parameters. The optimized nanofiber membranes were applied as an adsorbent for the removal of methylene blue (MB), basic fuchsin (BF), and methyl orange (MO). Kinetic and isotherm of adsorption and effects of different experimental conditions such as pH, contact time, and initial dye concentration on adsorption capacity were investigated. It was found that the optimum parameters for the nanofiber membranes were SA/PVA blend ratios (3:7), electric field strength (20 kV), flow rate (0.05 mL/h), and distance (12.5 cm) between the syringe needle and collector, and the mean fiber diameter of the optimized membranes was 99.58 nm. The adsorption of nanofiber membranes was well described by the pseudo-second-order adsorption kinetic model and the Langmuir model, indicating that the adsorption mechanism was chemisorption by a monolayer. Based on the Langmuir model, the adsorption capacities for MB, BF, and MO were 9.25 mg/g, 9.02 mg/g, and 7.35 mg/g, respectively.

Re-utilization of Chinese medicinal herbal residue: waste wormwood rod-derived porous carbon as a low-cost adsorbent for methyl orange removal.

A cost-effective approach was applied to prepare porous carbon samples by the simple carbonization of wormwood rod followed by salt activator (NaCl) activation. The effect of preparation parameters on the characteristics of the wormwood rod-based porous carbons (WWRs) were studied. The properties of these samples were investigated by SEM, BET surface area, X-ray diffraction, FT-IR spectra and X-ray photoelectron spectrometer. The prepared WWRs were applied as new adsorbent materials to remove methyl orange (MO). The experimental results indicated that WWR-800 activated at 800 °C possesses the best adsorption performance. Several factors that affected the adsorption property of the system such as the solution pH, dosing of adsorbent, initial dye concentration and ionic strength were examined. In addition, the thermodynamic parameters and kinetic parameters of MO with WWR-800 were studied. The results indicated that the adsorption of MO on WWR-800 was an endothermic process and non-spontaneous under standard conditions. The maximum equilibrium adsorption capacity of MO on WWR-800 was 454.55 mg/g. After five adsorption/desorption cycles, the adsorption capacity of MO on WWR-800 remained at 94%, which indicated that wormwood rod-based porous carbon possessed good reusability.

Preparation and characteristic of high surface area lignin-based porous carbon by potassium tartrate activation

In order to study the property of lignin-based porous carbon activated by potassium tartrate, the effects of activator types, activator/lignin mass ratio and activation temperature on the surface morphology, specific surface area and pore size distribution of alkali lignin based porous carbon materials were systematically investigated. Meanwhile, the methyl orange adsorption capacity and adsorption kinetics of the lignin-based porous carbon were also evaluated. The N2 adsorption-desorption experiment results showed that the specific surface area value of lignin-based porous carbon materials activated by potassium tartrate (APC-J), KOH (APC-K), and NaOH (APC-Na) are 947, 1113 and 762 m2/g, respectively. Meanwhile, APC-J has a special microporous structure, while the pore structures of APC-K and APC-Na are mainly mesopores. The best specific surface area of lignin-based porous carbon materials was 1911 m2/g obtaining from APC-J-2-8 sample (mass ratio 2:1, activation temperature 800 °C). The adsorption experiment of methyl orange (MO) showed that the adsorption kinetics of APC-J-2-8 conformed to the quasi-second-order kinetic model, mainly chemical adsorption. The isothermal adsorption process conforms to the Langmuir adsorption isothermal adsorption model, which is a single molecular layer adsorption, and the maximum adsorption amounts are 526.31 mg/g.

Removal of Methyl Orange from aqueous solution using Zeolitic Imidazolate Framework-11: Adsorption Isotherms, Kinetics and Error analysis.

Dyes, which are increasingly harmful to human health and ecology, are an environmental concern and their removal from wastewater is extremely required. It is also important for researchers to find relevant techniques to process these types of pollutants. This study examines the use of the synthesized imidazolate zeolite frameworks-11 (ZIF-11) by stirring method for the methyl orange (MO) dye removal from aqueous solution. The scanning electron microscopy, thermogravimetry, X-ray diffraction, and Fourier transform infrared spectroscopy, were used for the analysis of ZIF-11 particles, which exhibited highly porous, irregular and heterogeneous shapes and variable size. The MO removal was assessed by batch adsorption with ZIF-11 particles as adsorbent, whose efficiency was achieved at pH=8, stirring speed of 600 rpm, for a contact time of 40min and a dosage of 800mg/L of MO solution. The thermodynamic and kinetic analysis of the MO adsorption process was achieved successfully with the pseudo-second order kinetic model as well as Langmuir and Temkin isotherms, indicating the feasibility and spontaneity of the uniform distribution of MO molecules on the active sites of ZIF-11 particles. The calculated maximum adsorption capacity of MO on ZIF-11 particles was 178.57 mg/g, which is indicative of the potential adsorptive properties of the synthesised ZIF-11 for MO dyes.

Polyethyleneimine-grafted polyphosphazene microspheres for rapid and efficient capture of anionic dyes from wastewater

Developing novel adsorbent to capture organic contaminants from wastewater rapidly and efficiently is highly desirable for waste treatment and environmental restoration. Herein, we reported a new amino-rich spherical adsorbent (PZS-PEI) for highly-efficient uptake of anionic dyes from aqueous solution. The PZS-PEI adsorbent was fabricated through a two-step process including synthesis of PZS-Cl microspheres via room temperature polymerization of hexachlorocyclotriphosphazene with bis(4-hydroxyphenyl) sulfone and subsequent surface grafting reaction of PZS-Cl microspheres using branched polyethyleneimine (PEI). The microstructure of as-obtained PZS-PEI microspheres was fully characterized by scanning electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, zeta potential, and N2 adsorption test. The adsorption performance of the PZS-PEI microspheres towards organic dyes was evaluated through carrying out a series of studies including various influence factor analysis, adsorption isotherm, kinetics, and thermodynamics. Results show that the PZS-PEI adsorbent owned good adsorption selectivity towards anionic dyes, and the maximum adsorption capacities for methyl orange (MO), acid chrome blue K, eosin-Y reached 190.29, 152.90, and 92.34 mg/g at 25 °C, respectively. In addition, the uptake behavior of organic dye by the PZS-PEI adsorbent conformed to Freundlich isotherm and pseudo-second order kinetic model, and the adsorption process followed a three-stage intraparticle diffusion mode with an endothermic and spontaneous characteristic. Electrostatic interaction and hydrogen bonding were responsible for the highly-efficient adsorption of the PZS-PEI adsorbent towards typical anionic dye MO.

Valorization and Evaluation of Terminalia Ivorensis Fibrous Waste for Its Environmental Sequestration Potential for Industrial Anionic Dyes in Aqua System

ABSTRACT This research depicts the pragmatic sequestration capacity of ubiquitous Terminalia ivorensis tree bark (TITB) on toxic anionic dyes (congo red (CR), methyl orange (MO), chlorophenol red (CPR), and Eosin Y (EY)) from aqua system. Surface characterization of TITB by bulk density, Boehm titration, pH of point of zero charge (pHPZC), field emission-scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy revealed that TITB comprise rough intertwined texture with some functional moieties which adsorbed the industrial dyes. The adsorption capacities () of MO, CR, and EY were maximum at pH 2.0 (= 84.59, 92.67 and 92 mg.g−1 respectively) while that of CPR was maximum at pH 6.0 (= 99.05 mg.g−1). Langmuir monolayer coverage capacity () of TITB was obtained for the adsorption of EY, which was 142.45 mg.g−1. Adsorption kinetics conformed to pseudo-second order kinetic model with a rate constant, ≤ 0.9702 min−1. The change in Gibbs free energy (ΔG°) for the adsorption process was found to be negative showing that the maximum adsorption was spontaneous at operational temperatures for all dyes. Enthalpy and entropy change (∆H° and ∆S°) were positive for CR, MB, and EY describing endothermic form and increased disorderliness between the adsorbent-dye interface.

Adsorption Isotherm And Kinetic Models For Removal Of Methyl Orange And Remazol Brilliant Blue R By Coconut Shell Activated Carbon

Adsorption technology is one of the efficient and facile method used for wastewater treatment. In this research, coconut shell, an agricultural solid waste was converted into activated carbon via furnace induced and zinc chloride chemical activation techniques. The activated carbon was prepared at activation temperature of 600°C. Anionic dyes, Methyl Orange (MO) and Remazol Brilliant Blue R (RBBR) have been selected due to their harmful effect to the environmental and human. Various effect of parameter such as initial dye concentration, initial pH, adsorbent dosage and agitation speed in batch system were investigated to obtain the optimum condition for both dye adsorption on activated carbon. The optimum dye removal efficiency was around 99% when 5g/L of activated carbon was used. Pseudo-second-order model was the best fitted model with highest correlation compared to other kinetic models. The adsorption behaviour of MO was perfectly presented by the Freundlich model while RBBR was well described by Langmuir model. The maximum adsorption capacity for MO was 59.17mg/g and RBBR was 35.09mg/g. Fourier-transform infrared spectroscopy (FTIR) was utilised to analyse the chemical characteristics of activated carbon before and after adsorption.

Facile fabrication of polymeric quaternary ammonium salt hydrogel by radiation for dyes removal from aqueous solution

The effluents containing various dyes from the process industries raise esthetic problems and cause toxic impacts on aquatic and human life. Thus, the dye effluent must be adequately treated before being discharged into water-bodies. A cellulose-derived quaternary ammonium salt was treated by radiation to form hydrogel structure. The radiation dose effects on gel fraction and swelling properties were investigated. The hydrogel structure was characterized by IR and SEM analyses. The Zeta potential values at different pH were all greater than +30 mV, which indicating that the hydrogel possessed enough electrostatic attraction force to anionic ions. The adsorption behaviors of the polymeric quaternary ammonium salts hydrogel (PQH) towards methyl orange (MO), Congo red (CR), and Coomassie brilliant blue (CBB) are discussed. The pseudo-second-order mode well fitted the adsorption kinetics for all three dyes. The increasing order of the initial adsorption rate h0 was MO > CR > CBB. The Langmuir model well described the adsorption isotherms were well described by with the maximum adsorption capacity for MO, CR, and CBB being 628.93, 427.35, and 617.28 mg/g, respectively. HCl was used to regenerate the dye-loaded-hydrogel. The adsorption-desorption test demonstrated the good reusability of this hydrogel. Also, the PQH has selective adsorption of MO from RhB/MO mixing solution.

Functionalized waste cellulose with metal-organic-frameworks as the adsorbent with adjustable pore size: Ultralight, effective, and selective removal of organic dyes

In this work, we proposed a green and low-cost method to prepare novel waste cellulose/ZIF-67 composite aerogels as the adsorbent. These composites were fabricated by assembling ZIF-67 crystals into the three-dimension framework of cellulose aerogel derived from waste cigarettes. Due to the high specific surface area and electrostatic attraction, as-prepared waste cellulose/ZIF-67 aerogels had a high adsorption capacity for anionic dyes. The methyl orange was selectively adsorbed by waste cellulose/ZIF-67 compared to methyl blue. The maximum adsorption capacity for methyl orange reached to 134.36 ​mg ​g−1. Interestingly, this adsorption capacity can maintain above 80% after 5 cycles. Thus, as-prepared waste cellulose/ZIF-67 aerogels in this paper have an important potential application in waste water treatment as a selective adsorbent.

Investigation into the Adsorption of Methylene Blue and Methyl Orange by UiO-66-NO2 Nanoparticles.

In this work, the adsorptive removal of methylene blue and methyl orange by UiO-66-NO2 nanoparticles was studied. The influence of pH on the adsorption capacity was assessed. The kinetics of the adsorption process were investigated and compared with pseudo-first-order, pseudo-second-order, Elovich, and intraparticle models. The kinetics of the adsorption fits moderately with the pseudo-first-order, but perfectly fits with pseudo-second-order models, and has a very good fit with the Elovich and intraparticle models. The adsorption isotherms were measured and compared with the Langmuir and Freundlich models. The adsorption capacity of methyl orange (MO) on UiO-66-NO2 nanoparticles (142.9 mg/g) was over three times higher than that of methylene blue (MB) on the nanoparticles (41.7 mg/g). The discrepancy between these capacities was attributed to the presence of the -NO2 functional group, which caused a strong negative mesomeric effect in the metal-organic framework structure.

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

Methyl orange (MO) is a common anionic azo dye that is harmful to the environment and biology, so it must be treated innocuously before it can be discharged. Adsorption is an effective method to remove anionic dyes. Nanotube mineral is a natural one-dimensional adsorption material, and its unique morphology and structure endow it with good adsorption capacity. Although there are many related studies, there is a lack of in-depth discussions on the influence of nanotube’s composition and structure on the adsorption of dyes and other pollutants. In this paper, two kinds of natural one-dimensional silicate minerals [halloysite nanotubes (HNTs) and chrysotile nanotubes (ChNTs)] with similar morphology but slightly different compositions and crystal structures were used as adsorbents, and MO solution was used as simulate pollutants. It is the first time to discuss in depth the influence of the composition and structure of nanotube minerals on their charge properties and the adsorption performance of methyl orange dyes. It is found that HNTs and ChNTs have different adsorption capacity due to the difference of electronegativity between Al3+ and Mg2+ in the crystal, so they possess negative and positive charges respectively in near-neutral solution, which leads to the adsorption capacity of MO by ChNTs with positive charges which is greater than that of HNTs.

Comparative study of removing anionic contaminants by layered double hydroxides with different paths

A comparative study of anionic contaminants removal using layered double hydroxides (LDHs) by three different paths (ion-exchange, reconstruction and one-pot method) was investigated. The removal of targeted contaminants methyl orange (MO) and methyl red (MR) with similar structure from wastewater by these three methods were tested, respectively. The results of SEM revealed that LDHs obtained by the three methods showed different layered morphologies and the concentration of contaminant almost has no influence to the morphologies. In kinetic study, the removal behaviors of three methods were well described by pseudo-second-order model, and showed different patterns in intraparticle diffusion model, revealing that accessible active sites on the adsorbent were the main factor for different adsorption capacity of these methods. The isotherm experiments manifested that all removal data were well fitted by Langmuir models and revealed a charge-limited process. The adsorption capacity of MO was higher than that of MR by all these methods, and the one pot method had the largest adsorption capacity for MO and MR, which were 2.87 and 2.25 mmol/g respectively. The obtained samples were characterized by XRD and different interlayer spacings were observed by these three methods, which was caused by the amount and the arrangement of MO or MR. Molecular simulation was selected to calculate the change of chemical bond, electron transfer and bonding energy, explaining the different removal capacity of MO and MR.

Enhanced adsorption properties of organic ZnCr-LDH synthesized by soft template method for anionic dyes.

Organic ZnCr-LDH (ST-LDH) was synthesized by a facile one-step hydrothermal technique using methyl orange (MO) as a soft template agent, which can efficiently remove methyl orange (MO), Congo red (CR), and orange II (OII) from aqueous solution. The microstructure of ST-LDH by modifying changed obviously, from the cellular structure to the stacking structure formed by the face-face contact of hydrotalcite nanosheets, which resulted in much more exchangeable nitrate ions to remain in the interlayer space. The pre-insertion of benzene sulfonate as a pillar expanded the interlayer gallery, which facilitated the pollutant anions (MO, CR, and OII) into the interlayer of LDH in the subsequent adsorption process. The maximum adsorption capacity of ST-LDH for MO, CR, and OII was 4200.8 mg/g, 1252.0 mg/g, and 1670.6 mg/g, respectively, which is approximately 1.86 times, 1.8 times, and 2.32 times that of the pristine NO3-LDH, respectively. The removal mechanism of anionic dyes was determined as anion exchange between NO3- anions and dye molecules. The adsorption behavior for MO and OII is multilayer adsorption, while the adsorption behavior for CR is monolayer adsorption. The adsorption process mainly was controlled by the chemical bonding between the dye molecules and adsorbent active sites. The LDH can be effectively regenerated by photocatalysis after MO adsorption. The ST-LDH has a great potential to be used as a high-efficient adsorbent to remove anionic dyes from aqueous solution. The schematic illustration of the synthetic process of soft template agent modified and unmodified hydrotalcites by one-pot hydrothermal method and the adsorption process of MO by ST-LDH were shown in Fig. 12. Modified hydrotalcite (ST-LDH) was prepared using methyl orange (MO) as a soft template agent. Compared with unmodified hydrotalcite (NO3-LDH), the insertion of benzene sulfonate anions into the hydrotalcite layer resulted in the increase of the interlayer spacing from 8.269 to 8.654Å. The LDH host structure pre-intercalated by benzene sulfonate anions evolved into pillared materials in interlayer; benzene sulfonate anions as a column expanded the interlayer spacing of (003) base plane, which facilitated the pollutant anions (MO, CR, and OII) into the interlayer of ST-LDH and exchanged with NO3- anion in the subsequent adsorption process. It can be inferred that in the process of modification hydrotalcite by benzene sulfonate, a small amount of benzene sulfonate anions pre-inserted into the gallery of hydrotalcite with a monolayer model in the process of hydrotalcite modification, and its inclination angle is calculated to be about 29.1°. After ST-LDH sample adsorbed the MO molecules, dye molecules intercalated into the LDH host, and successful exchange with NO3- anions, the d003 value increased to 24.78 Å. A large amount of MO- anions were intercalated into the gallery of ST-LDH with a bilayer model according to the Freundlich isotherm model, and the tilting angle increases to 53.6°. The adsorption capacity of MO by ST-LDH was significantly enhanced to 4200.8 mg/g, which was much higher than that of NO3-LDH (2252.8 mg/g). Schematic illustration of the synthetic process of LDH materials and adsorption process of MO by ST-LDH.

Investigation of the efficiency of BiOI/BiOCl composite photocatalysts using UV, cool and warm white LED light sources - Photon efficiency, toxicity, reusability, matrix effect, and energy consumption

BiOI, BiOCl, and their composites (BiOI:BiOCl) with molar ratios from 95:5 to 5:95 were synthesized and tested in the transformation of methyl orange (MO) and sulfamethoxypyridazine (SMP) antibiotic, using three various LED light sources: UV LEDs (398 nm), cool and warm white LEDs (400–700 nm). The 80:20 BiOI:BiOCl photocatalyst showed the best adsorption capacity for MO and enhanced activity compared to BiOI and BiOCl. The apparent quantum yield (Φapp) of the MO and SMP transformation for cool and warm white light was slightly lower than for 398 nm UV radiation. The effect of methanol and 1,4-benzoquinone proved that the transformation is initiated mainly via direct charge transfer, resulting in the demethylation of MO and SO2 extrusion from SMP. The change of photocatalytic efficiency was followed during three cycles. After the first one, the transformation rates decreased, but there was no significant difference between the second and third cycles. The decreased efficiency is most probably caused by the intermediates, whose continuous accumulation was observed during the cycles. Ecotoxicity measurements confirmed that no toxic substances were leached from the catalyst, but the transformation of both MO and SMP results in toxic intermediates. Using 80:20 BiOI:BiOCl and LED light source, the energy requirement of the removal is about half of the value determined using TiO2 and a mercury vapor lamp. The effect of some components of wastewater (Cl−, HCO3− and humic acids), pH, and two matrices on the composite photocatalysts' efficiency and stability were also investigated.

Highly efficient removal of methyl orange from aqueous media by amine functional cyclotriphosphazene submicrospheres as reusable column packing material

Polyphosphazenes have an important place in material science because they allow functional diversity to be realized easily. In this study, for the first time, synthesis of cyclomatrix-type poly-(cyclotriphosphazene-co-4-(aminomethyl)-1,8-octanediamine) (Phz-AO) particles including different surface features and dimensions have been reported using different stoichiometric ratios of hexachlorocyclotriphosphazene and 4-(aminomethyl)-1,8-octanediamine. The use of Phz-AO (1:2) submicroparticles with spherical form and average dimension of 647.82 ± 22.23 nm as an adsorbent was researched for methyl orange (MO) anionic azo dye. Submicrospheres had significant potential for adsorption of negative charged MO and maximum adsorption capacity of 1244.7 mg.g − 1. The submicrospheres displayed high adsorption potential at pH ≤6 conditions thanks to their surface amine groups. The maximum adsorption capacity in synthetic textile wastewater was 912.75 mg.g−1 as experimental. While the adsorption kinetics had the pseudo second order model, the most suitable model for adsorption was the Langmuir isotherm. The thermodynamic parameters for MO adsorption with submicrospheres were 10.02 ± 1.81 kj.mol−1 for ΔH°, 61.08 ± 5.74 j.mol−1.K−1 for ΔS° and ΔG° (kj.mol−1)<0. In light of all data obtained, the Phz-AO (1:2) submicrospheres which can be easily prepared with a single-step reaction are expected to be a remarkable member of the super adsorbent material family.

Adsorption performance and mechanism of iron-loaded biochar to methyl orange in the presence of Cr6+ from dye wastewater

Biochar prepared from sludge and liriodendron leaves (SLAC) was modified by Fe3+ (SLAC-Fe), and they were used to remove methyl orange (MO) from single system and aqueous solution with Cr6+. The physical and chemical properties of biochar were characterized by BET, SEM, TEM, EDS, FTIR and XPS. The influences of initial MO concentration, adsorbent dose, pH, contact time and temperature on the adsorption of MO by biochar were investigated. The results indicated that SLAC-Fe had a higher removal efficiency for MO than SLAC. In the binary system, the maximum adsorption capacities of MO were 0.26 and 0.22 mmol/g with Cr6+ concentrations of 0.2 and 0.8 mmol/L, respectively. The adsorption kinetic model of pseudo-second-order fitted well with the experimental data of MO in single system. The equilibrium experimental data of MO in single and binary component systems were fitted well to Freundlich isotherm models. It was based on chemical and multilayer adsorption. It could be concluded that there was a competitive adsorption between Cr6+ and MO. The reason was that the HCrO4- and Cr2O72- competed with SO3- for the effective adsorption sites on the surface of SLAC-Fe, resulting in a reduction in the adsorption capacity of MO.

Controlled surface functionalization of Ni-S nanostructures for pH-responsive selective and superior pollutants adsorption

Herein, we developed a synthetic strategy to functionalize Ni-S nanostructures (NS) using a facile precipitation method at moderate temperature. The surface functionality of NS is controlled by varying amount of mixed surfactants to achieve the pH-responsive selective adsorption of anionic and cationic dyes and the adsorption of ciprofloxacin (CIP) and tetracycline (TC) antibiotics. Powder XRD diffraction pattern revealed the phase of NS was changed from α-NiS to mixed phases after functionalization. The surface area of functionalized NS was significantly enhanced by ~5 times of that unfunctionalized NS as 6.6 m2g−1 to 30.3 m2g−1. The NS selectively adsorbed methyl orange (MO) at pH 4.5 and methylene blue (MB) at pH 11.5 with separation efficiency values of 94.2% and 97.9% respectively. The maximum adsorption capacity for MO, MB, TC and CIP are obtained as 1526.3, 1031.2, 1540.8 and 632.4 mg g−1, respectively. The electrostatic interaction is predominantly involved in the adsorption of dyes whereas adsorption of antibiotics changed to hydrogen bonding and metal coordination. Thermodynamics parameters indicated exothermic and spontaneous adsorption of dyes. The optimized adsorbent is easily recyclable. Thus, the developed strategy of functionalization of nanostructures unveils a practical approach towards selective and efficient adsorption of organic pollutants.

Innovative Magnetite Based Polymeric Nanocomposite for Simultaneous Removal of Methyl Orange and Hexavalent Chromium from Water

One of the most important directions for environmental remediation is the effective removal of dyes and toxic heavy metals from water using newly fabricated nanoadsorbents. Here, magnetic Fe3O4 nanoparticles were combined with nitrogen-containing functional group polymers chitosan (CS) and polypyrrole (ppy) to synthesize a nanocomposite (polypyrrole@magnetic chitosan) useful for removing methyl orange (MO) and hexavalent chromium (Cr (VI)) from water. The physicochemical properties of the nanocomposite were determined using SEM, TEM, XRD, FT–IR, and TGA techniques. The effect of different factors on the adsorption system was studied including the contact time, pH, and the effect of co-existed ions. The kinetic study illustrated that the adsorption fit well with Langmuir isotherm. The maximum adsorption capacity of MO and Cr (VI) was found to be 95 and 105 mg/g, respectively. The reusability of the nanocomposite was studied for up to five cycles using 0.1 M NaOH as eluent with a slight decrease of adsorbent efficiency. Furthermore, the removal mechanism studied suggested the removal of MO via adsorption and Cr (VI) via chemical reduction and adsorption. This study suggests that a ppy@magnetic chitosan nanocomposite is a promising nanoadsorbent for removing MO and Cr (VI) from water.

Optimize the preparation of Fe3O4-modified magnetic mesoporous biochar and its removal of methyl orange in wastewater.

In this paper, Eichhornia Crassipes stems were used as biomass feedstock, and Fe2+ was used as the precursor solution to prepare Fe3O4-modified magnetic mesoporous biochar (Fe3O4@BC). By using Box-Behnken design (BBD) response surface methodology, the influences of three preparation parameters (X1 = Fe2+ concentration, X2 = pyrolysis temperature and X3 = pyrolysis time) on the adsorption of methyl orange (MO) by Fe3O4@BC were investigated, and a reliable response surface model was constructed. The results show that X1X2 and X1X3 have a significant influence on the adsorption of MO by Fe3O4@BC. The surface area and pore volume of Fe3O4@BC are controlled by all preparation parameters. The increase of pyrolysis time will significantly reduce the -OH on the surface of Fe3O4@BC and weaken its MO adsorption capacity. Through the numerical optimization of the constructed model, the optimal preparation parameters of Fe3O4@BC can be obtained as follows: Fe2+ concentration=0.27mol/L, pyrolysis temperature=405 °C, and pyrolysis time=3.2h. The adsorption experiment shows that the adsorption of Fe3O4@BC to MO is a spontaneous exothermic process, and the adsorption capacity is maximum when pH=4. The adsorption kinetics and adsorption isotherms of Fe3O4@BC to MO conform to the pseudo-second-order kinetics and Sips model, respectively. Mechanism analysis shows that electrostatic interaction and H bond formation are the main forces for Fe3O4@BC to adsorb MO. This research not only realizes a new way of resource utilization of Eichhornia Crassipes biomass but also enriches the preparation research of magnetic biochar.