Initial Methyl Orange Concentration Research Articles

β-Lactoglobulin amyloid fibrils supported Fe(III) to activate peroxydisulfate for organic pollutants elimination

In this study, Fe(III) was successfully loaded on the β-Lactoglobulin amyloid fibrils (Fe(III)@β-LGAF) by the in-situ method for efficiently activating peroxydisulfate (PDS) to remove organics in water. Methyl orange (MO) was used as the model contaminant to explore the influences of key parameters in the Fe(III)@β-LGAF/PDS system, including the Fe(III)@β-LGAF dose, PDS dosage, initial MO concentration, and beginning pH value. The results indicated that 94.2% MO was eliminated within 20 min under the optimized conditions of 1 g/L Fe(III)@β-LGAF, 1 mmol/L PDS, 30 mg/L MO, and pH 5. The synthesized Fe(III)@β-LGAF manifested a certain excellent stability and applicability for the PDS activation and other typical organic pollutants degradation. Various characterization methods were applied to characterize the properties of Fe(III)@β-LGAF before and after the oxidation reaction. The radical scavenging test and electron paramagnetic resonance analyses testified that singlet oxygen was the dominant active species in the synergistic process, which exhibited a stronger selective oxidation capacity than the hydroxyl and sulfate radicals. Hence, the synthetic material Fe(III)@β-LGAF could provide a new reference for the heterogeneous Fenton-like reaction.

Degradation of Methyl Orange by ozone microbubble process with packing in the bubble column reactor

ABSTRACT The performance of the ozone microbubble(MB) process for the degradation of Methyl Orange (MO) in a bubble column reactor with added packing was investigated. The highest decolorization efficiency of 96.04% was achieved by the ozone MB process with packing, which was 10.17% and 62.02% higher than that of the ozone MB process without packing and the ozone millimeter bubble(MLB) process, respectively while keeping other operating parameters the same. In addition, the saturation gas holdup, ozone mass transfer coefficient, and decolorization rate constant of the ozone MB process with packing were 15.32%, 0.260 min−1, and 0.027 min−1, respectively, which were much better than those of the ozone MB process without packing and the ozone MLB process. The study also suggested that within a certain porosity range, the types of packings did not affect the performance of the ozone MB process in the degradation of MO. Moreover, the optimum operating conditions were initial concentration of MO of 30 mg/L, initial pH of 3, circulating liquid flow of 75 L/h, and ozone dosage of 0.56 mg/L. The decolorization efficiency was 99.28% within 120 min.

3D mathematical modeling of external mass transfer effect in high-rate adsorption process

The effect of external mass transfer on the high-rate adsorption system was evaluated in the present study. In the experimental section, the removal of methyl orange (MO) was carried out by using surfactant modified chitosan-clinoptilolite at specific conditions such as the optimum adsorbent dosage of 11 g L−1, solution pH of 3.5, contact time of about 3 min and constant temperature of 30 °C. The characterization of adsorbent showed the porosity value of 0.064 and the BET surface area of 10.5 m2 g−1. These features of adsorbent established the high-rate adsorption process in which the shape of decay curves is not smooth and the concentration of adsorbate falls quickly. In high-rate adsorption processes, the external mass transfer mechanism has a significant effect on total mass transfer at early time of adsorption. The pore volume and surface diffusion model (PVSDM) were applied for predicting MO concentration decay curves. This model and its parameters could not estimate properly the concentration of MO at the early time of the adsorption process. To overcome this problem, in addition to optimization of surface diffusion coefficient (Ds), the external mass transfer coefficient (ke) was optimized and the effect of those parameters was studied in three dimensions. The optimization provided a better agreement between the model and experimental data in such a way to reduce the error rate. To show better the effect of external mass transfer, Biot number (between (2.15 and 24.05) × 10−3) was applied and it revealed that the adsorption mechanism was controlled by external mass transport. The high external surface area illustrated that in all values of ke and initial concentration of MO, surface diffusion is the dominant mechanism in intraparticle diffusion and the low porosity of adsorbent limited the penetration of adsorbate species into the adsorbent cavities, whereby the pore volume diffusion could be considered negligible.

Soft-template solvent thermal method synthesis of magnetic mesoporous carbon-silica composite for adsorption of methyl orange from aqueous solution.

A facile soft-template solvent thermal strategy was developed to prepare mesoporous carbon-silica composite (MMCS) by using furfuryl alcohol (FA) as carbon precursor, Pluronic copolymer P123 as template, hydrated iron nitrate as iron source, and teraethylorthosilicate as silicon source and it was applied for the removal of methyl orange (MO). The as-synthesized MMCS with abound of hydrophilic groups processed a high specific surface area, large pore volume, and good magnetic response. With the increased amount of FA, the surface area and functional groups increased, promoting the adsorption effect. The maximum adsorption capacity of MO on MMCS can be high to 113.1mgg-1 at pH 4 with 150mg L-1 initial MO concentration. The adsorption isotherm, kinetic, and thermodynamics were all studied and the results showed the adsorption process well fitted Langmuir adsorption isotherm and pseudo-second-order model. Additionally, it was shown that the adsorption process could not be interfered by the co-existence of PO43-, NO3-, CO32-, SO42-, and real water matrix. And the proposed adsorbent can remove MO in three practical water samples with satisfied removal rates ranging from 92.8 to 99.8%. Thus, the MMCS prepared in this study could be utilized as an alternative adsorbent for the removal of methyl orange from practical aqueous solution.

Photocatalytic Efficiency of Hybrid Titanium Dioxide Nanowires/Reduced Graphene Oxide (TiO2NWs/RGO) for Degradation of Methyl Orange Dye

The aim of this research is to improve the photocatalytic efficiency by implementation of titanium dioxide nanowires/reduced graphene oxide (TiO2NWs/RGO) hybrid photocatalyst for dye degradation. The hybrid photocatalyst TiO2NWs/RGO was prepared using fabrication method. The physico-chemical properties of the photocatalyst was investigated by FTIR, XRD, SEM TGA, BET and their photocatalytic efficiency was evaluated for methyl orange degradation. Almost 100% of methyl orange was degraded by TiO2NWs/RGO hybrid photocatalyst under UV light within 210 min using 1.0 g at initial concentration of methyl orange were 10 and 20 ppm. This is due to the 1D/2D heterostructures of TiO2NWs/RGO hybrid photocatalyst that leads to the larger surface area, unique morphological and crystallinity properties, as well as excellent mobility of charge carriers and thermally stable structure

Comparative study on photooxidation of methyl orange using various UV/oxidant systems

Abstract In the present work, a comparative study of the photooxidation of an aqueous solution of Methyl Orange (MeO) has been realized using H2O2 and IO3 −, BrO3 −, ClO3 −, ClO4 −, BO3 − ions in the presence of UV low pressure mercury lamp (UV-C light at λ max = 254 nm). The initial concentration of MeO in all experiments was 6 × 10−5 mol L−1. The degradation rate of MeO follows pseudo-first-order kinetics in all UV/Oxidant systems. The highest degradation rate of MeO was in the BrO3 −/UV254nm system. Different systems were compared for an oxidant concentration of 10−2 mol L−1 and the obtained results showed that decolorization followed the decreasing order: BrO 3 − /UV 254 nm > IO 3 − /UV 254 nm > H 2 O 2 /UV 254 nm > BO 3 − /UV 254 nm > ClO 3 − /UV 254 nm = ClO 4 − /UV 254 nm = UV 254 nm . The optimization of oxidants concentration for each process was determined (10−2 mol L−1 for IO3 − which gives almost the same k app for 5 × 10−3, 10−2 mol L−1 for BO3 − and 5 × 10−2 mol L−1 for H2O2). No degradation of MeO in presence of ClO3 − and ClO4 − because these ions do not absorb at 254 nm, therefore they do not generate radical species which degrade organic pollutants. The mineralization was also studied where it was reached 97% after 5 h of irradiation for both H2O2/UV254 nm and BO3 −/UV254 nm systems.

Statistical analysis and optimization of photodegradation efficiency of methyl orange from aqueous solution using cellulose/zinc oxide hybrid aerogel by response surface methodology (RSM)

The photodegradation efficiency of cellulose-X/zinc oxide-Y (CA-X/ZnO-Y) aerogels was studied to degrade methyl orange (MO) as an organic dye pollutant from an aqueous solution under UV light irradiation. In this study, the initial pH of the solution (3, 7, and 11), the photocatalyst dosage (3, 6, and 9 g L -1 ), the initial concentration of solution MO (10, 20, and 30 ppm), and the concentration of cellulose in CA-X/ZnO-Y hybrid aerogel (3, 6, and 9 wt%) were selected as four variable parameters, whereas the photoderadation performance was selected as the response. Moreover, the response surface methodology (RSM) analysis was carried out to investigate the influence of four various experimental factors at different times on the degradation of MO. The adequacy result of the proposed models displays that total of the proposed models can predict the photodegradation efficiency of MO by CA-x/ZnO-y aerogel. The optimization results of the process showed that pH = 3 and concentration of MO = 10 ppm, photocatalyst dosage (9 g L -1 ), and MCC concentration (9 g) are the optimal level of the studied parameters. Also, the results showed that desirability of 0.96 confirms the acceptance and applicability of the model where the RSM model is a helpful technique for the optimum conditions design.

Response surface modeling of the Removal of Methyl Orange Dye from Aqueous Solution using Magnesium Oxide Nanoparticles Immobilized on Chitosan

In this work, the chitosan-based magnesium oxide nanoparticles (CS-MgONP) composite was used as an adsorbent for the removal of organic dye methyl orange (MO). The adsorbent characterization was carried out using X-ray diffraction (XRD), Field emission scanning electron scanning microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy. The faster equilibrium, i.e. at an agitation time of 30 min, indicated the faster adsorption capability of the prepared adsorbent CS-MgONP. The central composite design (CCD) of response surface methodology (RSM) was used to evaluate the impact of process parameters in the range of pH (6-10), CS-MgONP dosage (0.1-0.5g/L), MO concentration (10-30mg/L), and temperature (283-323K) at an optimal agitation period of 30 min. Under optimum conditions of pH=7.93, CS-MgONP dosage=0.4g/L, initial MO concentration=15mg/L and temperature=313 K, 96.42% removal of MO was achieved with a desirability of 0.805. The adsorption of MO onto CS-MgONP was best fitted with the Langmuir adsorption isotherm, with an uptake capacity of 237.5 mg/g and followed the pseudo-second order kinetics. The thermodynamic studies showed positive enthalpy and negative Gibbs free energy that confirmed the spontaneous and endothermic process. Due to the fast equilibrium agitation period, i.e.30 min and high adsorption capacity, the adsorbent CS-MgONP proved to be an excellent choice for dye removal.

Investigation onto the performance and mechanism of visible light photodegradation of methyl orange catalyzed by M/CeO2 (M=Pt, Ag, Au)

In this paper, M/CeO2 (M=Pt, Ag, Au) photocatalysts were prepared and used for visible light degradation of methyl orange (MO) with H2O2 as a sacrificial reagent. Utilizing X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), N2 physical adsorption (BET), X-ray photoelectron spectroscopy (XPS), photocurrent characterization and electrochemical impedance spectroscopy, etc., the structure, morphology, chemical state, and optical properties of the catalyst were investigated. The effects of the amount of catalyst, the initial concentration of methyl orange, the pH value of the solution and the number of reuses on the photocatalytic degradation efficiency of MO were studied. The results showed that under optimized reaction condition of 15 mg 2Pt/CeO2 catalyst, the initial concentration of MO was 20 mg/L, pH=5, the reaction time was 195 min and the amount of H2O2 was 0.2 mL, the degradation percentage of MO reached 75.8%. The main active species of photodegradation are hydroxyl radicals and superoxide radicals, which was determined by free radical capture experiments and combined electron spin resonance (ESR). The photocatalytic mechanism based on work function difference and electron transfer was also discussed in detail.

Controllable synthesis of cubic magnetic MgFe2O4 derived from MgFe-LDHs for efficient removal of methyl orange

A novel cubic magnetic MgFe2O4 derived from MgFe-layered double hydroxides (MgFe-LDHs) has been constructed by a combination of facile urea hydrothermal method and calcinations method and applied for the efficient removal of methyl orange (MO) with a maximum adsorption capacity of 535 mg g−1. The studies of formation mechanism of cubic MgFe-LDHs demonstrate the type of ferric salt and reaction time are two most important parameters influencing their cubic structures. Besides, calcinations temperature can not only decide magnetic performance of MgFe2O4, but also not change its cubic structure. Then the structural and surface properties of cubic magnetic MgFe2O4 were investigated by various characterization techniques. In addition, batch adsorption experiments were carried out to investigate the effects of different parameters such as the initial concentration of MO, pH, temperature and time on the adsorption behavior of MO on MgFe2O4. The kinetics, isotherm and thermodynamics of the adsorption of MO by MgFe2O4 were studied in detail. Moreover, adsorption mechanism of MO by MgFe2O4 was studied deeply. At last, MO could be desorbed from MgFe2O4 by 0.1 M NaOH solution and reused at least three times, indicating cubic magnetic MgFe2O4 is an effective and promising adsorbent for the removal of dye pollutants.

Fixed-Bed Adsorption Column Studies for the Removal of Methyl Orange from Water Using Polyethyleneimine-Graphene Oxide Polymer Nanocomposite Beads

Continuous fixed-bed column studies were performed using nanocomposite beads made up of chitosan, polyethyleneimine, and graphene oxide as adsorbents for the removal of methyl orange (MO) in water. The effects of different operating parameters such as initial MO concentration (5, 10, and 15 ppm), bed height (10, 17.5, and 25 cm), and flow rate (27, 43, and 58 mL/min) were investigated using an upward-flow fixed-bed column set-up. The breakthrough curves generated were fitted with Adams-Bohart, Thomas, Yoon-Nelson, and Yan et al. models. The results showed that Yan et al. model agreed best with the breakthrough curves having an R2 as high as 0.9917. Lastly, design parameters for a large-scale adsorption column were determined via scale-up approach using the parameters obtained from column runs.

Investigation of operation parameters on the removal efficiency of methyl orange pollutant by cellulose/zinc oxide hybrid aerogel

In this study, Cellulose/Zinc Oxide-x (CA/ZnO-x) hybrid aerogel with various concentrations of Zn2+ ion is synthesized through the hydrothermal method and used for organic pollutant removal. The CA/ZnO-x hybrid aerogel was characterized by XRD, UV–Visible, DRS, FTIR, FESEM, EDS, BET, LC-MS-MS analyses. In the present study, CA/ZnO-x hybrid aerogel as photocatalyst was used to investigate the influence of the photocatalytic degradation of methyl orange (MO) from an aqueous solution under UV irradiation. The morphology of CA/ZnO-x hybrid aerogels exhibited that the ZnO rice grain-like shape were successfully synthesized on the cellulose aerogel matrix. Also, the influence of various factors such as photocatalyst dosage, pH, initial concentration of MO, and irradiation intensity was investigated on the photocatalytic degradation rate of MO. The results revealed that the highest degradation efficiency and mineralization rate of MO were about 99.02% and 51.68%, respectively, after 90 min under UV irradiation using CA/ZnO-0.4 photocatalyst when pH = 3, C0 = 10 ppm, photocatalyst dose = 9 g L−1 under the 300 W UV light irradiation. Furthermore, the synthesized photocatalyst exhibited a considerable firmness and easily separated from an aqueous solution for reuse.

Diatom Biosilica Doped with Palladium(II) Chloride Nanoparticles as New Efficient Photocatalysts for Methyl Orange Degradation.

A new catalyst based on biosilica doped with palladium(II) chloride nanoparticles was prepared and tested for efficient degradation of methyl orange (MO) in water solution under UV light excitation. The obtained photocatalyst was characterized by X-ray diffraction, TEM and N2 adsorption/desorption isotherms. The photocatalytic degradation process was studied as a function of pH of the solution, temperature, UV irradiation time, and MO initial concentration. The possibilities of recycling and durability of the prepared photocatalysts were also tested. Products of photocatalytic degradation were identified by liquid chromatography–mass spectrometry analyses. The photocatalyst exhibited excellent photodegradation activity toward MO degradation under UV light irradiation. Rapid photocatalytic degradation was found to take place within one minute with an efficiency of 85% reaching over 98% after 75 min. The proposed mechanism of photodegradation is based on the assumption that both HO• and O2•− radicals, as strongly oxidizing species that can participate in the dye degradation reaction, are generated by the attacks of photons emitted from diatom biosilica (photonic scattering effect) under the influence of UV light excitation. The degradation efficiency significantly increases as the intensity of photons emitted from biosilica is enhanced by palladium(II) chloride nanoparticles immobilized on biosilica (synergetic photonic scattering effect).

A highly photoresponsive and efficient molybdenum-modified titanium dioxide photocatalyst for the degradation of methyl orange

The degradation of azo dyes in aquatic environments is still challenging due to their stability and perpetual effect. This work demonstrates the application of highly ultraviolet-responsive titanium dioxide/molybdenum photocatalyst to degrade methyl orange. A series of titanium dioxide/molybdenum photocatalyst with different molybdenum concentrations (1–10 wt%) were synthesized by a facile wet impregnation method. The introduction of molybdenum has favorably induced changes in surface morphology, crystallite size, optical absorption, and specific surface area, which have collectively enhanced the photocatalytic performance of titanium dioxide/molybdenum photocatalyst on the removal of methyl orange. A systematic investigation on the influencing parameters such as photocatalyst dosage, initial methyl orange concentration, and initial pH was investigated, and the optimum conditions were achieved. The best-performing titanium dioxide/molybdenum (3 wt%) photocatalyst yielded a 94.5% methyl orange photodegradation efficiency within 120 min of irradiation. The dopant concentration, photocatalyst dosage, and pH were investigated to validate the optimized conditions for titanium dioxide/molybdenum on methyl orange removal using response surface methodology via the Box–Behnken design. The present results demonstrated that both the superoxide radical and hydroxyl radical play a primary role in the degradation mechanism. This study provides fresh insight that the successful structural modification of titanium dioxide by molybdenum could enhance the photocatalytic removal of dye wastewater.

Enhancing efficiency and photocatalytic activity of TiO2-SiO2 by combination of glycerol for MO degradation in continuous reactor under solar irradiation

This study evaluated the photocatalytic performance of a combination of TiO2-SiO2 film and glycerol for the degradation of methyl orange (MO) dye in wastewater passing through a continuous-flow reactor. A sol–gel TiO2-SiO2 film was synthesized and coated on glass beads as a thin layer using a conventional dip-coating technique. Our XRD and SEM analyses demonstrated that the TiO2-SiO2 nanoparticles contain an anatase (α-TiO2) phase, which enhanced photocatalytic properties. The obtained film was white in color, with a thickness of 0.9–1.2 mm, according to the amount of TiO2-SiO2 that was deposited on the glass beads, which ranged from 1.8 to 2.1 g/l. The photocatalytic activities of the film was evaluated using a continuous-flow reactor, where the effects of initial pH, hydraulic retention time (HRT), UV intensity, glycerol concentration, and initial MO concentration were investigated. Optimized operating conditions were obtained with an initial pH of 7, glycerol concentration of 0.5 g/L, HRT of 7 min, UV intensity exceeding 20 W/m2, and an initial MO concentration of 10 mg/L, which resulted in 91% dye removal efficiency from the water. The correlation between photocatalytic degradation using TiO2-SiO2 in combination with glycerol, and irradiation time, exhibited a pseudo-first-order model.

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.

The degradation of organic dye contaminants in wastewater and solution from highly visible light responsive ZIF-67 monodisperse photocatalyst

Zeolitic imidazolate framework ZIF-67 with a pore-structural network has many potential applications in photocatalysis fields due to their intrinsic properties such as high porosity and large surface area. ZIF-67 is prepared under a one-step hydrothermal reaction from cobalt salt in methanol. The morphological and photocatalytic characteristics of ZIF-67 are performed by XRD, SEM, UV–Vis, PL spectroscopy, and BET. The as-synthesized nanoparticles have a nearly monodisperse structure with a large size of ~600 ​nm. In addition, these ZIF-67 micropores show an excellent efficiency for the methyl orange (MO) photodegradation under visible-light irradiation. In particular, more than 88% of MO is degraded within 1 ​h when using 0.5 ​g ​L−1 of ZIF-67. Besides, the photocatalytic and kinetic performances of ZIF-67 are investigated by optimizing pH value, initial MO concentration in solution, and initial dose of used catalyst. ZIF-67 nanocrystals are demonstrated to be a remarkable material with high photostability and easy reusability.

Studying the Adsorptive Behavior of Poly(Acrylonitrile-co-Styrene) and Carbon Nanotubes (Nanocomposites) Impregnated with Adsorbent Materials towards Methyl Orange Dye.

In this study, a polymeric (acrylonitrile-co-styrene) P(AN-co-St) composite was impregnated with adsorbents, such as sulfonated and multiwall carbon nanotubes (MWCNTs), to increase the adsorptive characteristics of the nanocomposite upon the removal of methyl orange (MO) dye under different conditions. A novel nanocomposite copolymer mixture of P(AN-co-St) and SP(AN-co-St) was used. MWCNTs were prepared by a low-cost chemical vapor deposition (CVD) process. Variation in MO adsorption onto the three nanocomposites was examined in an aqueous solution via the batch technique with respect to contact time, initial MO concentration, adsorbent dosage, pH, and temperature. The surface of the nanocomposites was characterized by a scanning electron microscope (SEM), particle size distribution (PSD), Fourier transform infrared (FTIR), and Raman analysis. The experimental data showed that the efficiency of P(AN-co-St)/ MWCNT removal increased under the conditions of an acidic pH (3 and 5) with an agitation speed of 140 rpm, a sorbent weight of 0.01 g, and 20 mg of initial dye. The maximum sorption capacities were 121.95, 48.78, and 47.84 mg g−1 for the P(AN-co-St)/ MWCNTs, SP(AN-co-St), and P(AN-co-St) composites, respectively, as assessed by the Langmuir model. Additional isotherm models, such as the Freundlich, Temkin, and Halsey models, were used to examine the experimental data. A pseudo-second-order model was found to be more fitting for describing the sorption.

Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles

The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater.

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.