Erythrosine Adsorption from Aqueous Solution via Decorated Graphene Oxide with Magnetic Iron Oxide Nano Particles: Kinetic and Equilibrium Studies

In this research, first graphene oxide (GO) was synthesized using modified Hummers method and thence via a multi-step procedure, surface of GO was decorated with Fe3O4 nanoparticles (GO-Fe3O4). Thereafter, developed nanoparticles were characterized using FTIR, XRD and SEM analyses and their magnetic properties confirmed using VSM analysis. Moreover, performance of the GO-Fe3O4 for the removal and adsorption of Erythrosine dye from the aqueous solution under variable conditions including pH, phosphate buffer solution (PBS), adsorbent content, stirring time, electrolyte concentration, solution content and temperature were examined. In this regard, for obtained solutions from the chicken slaughterhouse and hospital sewage disposal system containing 20, 50 and 70 mg mL–1 Erythrosine dye, GOFe3O4 nanoparticles adsorbed from approximately 94% to 97% of the total dye, respectively. What is more, the highest adsorption capacity was obtained at 149.25 mg/g by means of Langmuir model. The obtained results clearly showed that GO-Fe3O4 nanoparticles present a fabulous performance for the absorption and removal of dyes form disposal systems.


Introduction
Erythrosine or Acid Red 51 (C.I. 45430, E127) is a xanthene class and water soluble synthetic dye that frequently use as a food colorant. 1 Erythrosine is a common dye in various industries and has wide range of applications in numerous fields including cosmetics, drugs, food industry especially for biscuits, chocolate, luncheon meat, sweets and chewing gums. 2 Several biodegradability evaluations on dyes revealed that azo dyes are not likely to be biodegradable under aerobic condition. 2,3 In this matter, more and more studies were performed to determine the adsorption capacity and capability of natural and treated vegetal materials including peat, 4 sugar cane bagasse, 5 bio-mass, 6 eucalyptus bark 7,8 and other biological materials with animal sources such as chitin and chitosan. 8 Erythrosine (C 20 H 6 I 4 Na 2 O 5 ) or 2-(6-Hydroxy-2,4,5, 7-tetraiodo-3-oxo-xanthen-9-yl) benzoic acid mixture with industrial or civil wastewater can highly affect the nature and cause severe damages to the public health, 9 thereby it is very essential to detect and remove these kinds of impurities from the sewage disposal systems. However, application of multivariate analyses in adsorption studies is rather limited. 10 What is more, high toxicity of Erythrosine is one of the basic reasons for many environmental studies to remove this harmful dye from wastewaters. In this case, various materials and techniques were used to minimize these kinds of impurities from wastewaters including photochemical degradation using TiO 2 nanoparticles, 11 biochemical degradation 12 and adsorption process. 11,[13][14][15][16] In addition, the adsorption isotherms indicated that phenol and methylene blue presenting a better adsorption rate compared with the erythrosine dye which is attributed to the large structure and the negative charge of dye molecules. 13 Generally speaking, adsorption of erythrosine by activated carbon is acceptable with a maximum capacity of 89.3 mg/g at 40 °C and pH = 7. The reported adsorption capacity is modest when compared to adsorption capacity of positively charged methylene blue (C.I. 52015). 17 Magnetic nanoparticles proved to be an effective removal agent for various kinds of wastes. 18,19 Herein, graphene oxide (GO) was first synthesized using modified Hummers method and then fabricated GO was enhanced via Fe 3 O 4 nanoparticles to improve their magnetic permeability and absorption rate. Afterward, fabricated GO-Fe 3 O 4 nanoparticles were used to remove erythrosine dye from the treated deionized water, hospital and chicken slaughterhouse sewer output under variable conditions.

Preparation of Erythrosine Solution
For preparation of erythrosine solution, first 0.1 g of erythrosine dye poured into a 1000 mL volumetric flask along with deionized water (100 µg mL -1 ) and then dissolved to reach homogenous solution. This solution was used to prepare other solutions with different concentrations.

3. Preparation of Phosphate Buffer Solution (PBS)
For preparation of (PBS), 100 mL phosphoric acid (0.1 molar) poured in a beaker and then the pH of the suspension was set on 7 using pH meter and 1 mL solution of sodium hydroxide and hydrochloric acid.

4. Preparation of Graphene Oxide (GO)
In this study, GO nanoparticles were fabricated using modified Hummers method. 20,21 In this case, first 10 g graphite poured into a round-bottom flask and then 2 L H 2 SO 4 was added to the vessel and stirred for 30 min (500 rpm) at room temperature (RT). Thence 110 mL H 3 PO 4 was added to the suspension, stirred for further 30 min (500 rpm at RT) and thereafter the temperature of the suspension was decreased to less than 5 °C using ice bath. Next, 50 g KMnO 4 was slowly added to the suspension and stirred (500 rpm) for 30 min. In the next step, the temperature of the suspension was smoothly increased to about 50 °C and then stirred for (500 rpm) 72 h. Afterward, the suspension was poured in a vacuum Erlenmeyer flask and some pieces of ice cubes (made from deionized water) were poured into the flask. Thereupon, 10 mL H 2 O 2 was poured in the suspension very slowly and then the vacuum Erlenmeyer flask was filled with deionized water. The resulting suspension was kept without stirring for 48 h for further fillers sedimentation. Afterward, the suspension was filtered and washed with HCl for removal of metal ions, and then remained fillers on the filter paper were washed with deionized water in order to set their pH at 7. Filtered and washed nanoparticles were dried for 1 h at 80 °C in a heating oven and thence placed in a humidity absorbing chamber for 48 h.

5. Preparation of Decorated Graphene Oxide with Iron Oxide Nanoparticles (GO-Fe 3 O 4 )
For the production of GO-Fe 3 O 4 nanoparticles, first, 3.89 g FeCl 3 and 4.55 FeSO 4 poured into 320 mL deionized water and stirred for 1 h at 80 °C. Thence, 0.0844 g ultrasonicated GO in 100 mL deionized water (at 300 W for 10 min) were added to the previous suspension and stirred for further 1 h at 80 °C. Thereafter, 40 mL NH 3 was slowly added to the resulting suspension and thereafter stirred for 24 h at 80 °C. Next, finalized suspension was vacuum filtrated and washed with deionized water to neutralize the fabricated GO-Fe 3 O 4 nanoparticles.

6. Nanoparticles Evaluation Methods
For evaluation of developed fillers performance for removal of erythrosine dye from aqueous solutions, first 15 mL erythrosine dye (100 µg mL -1 ) and 2 mL PBS (with Mousavi et al.: Erythrosine Adsorption from Aqueous Solution ... pH = 7) poured into a 50 mL volumetric flask and then filled with deionized water. Thereafter, 0.2 g of GO-Fe 3 O 4 poured into the resulting suspension and then stirred for 2 min at 500 rpm. Afterward, the beaker containing the resulting suspension was put on a strong magnet for 1 min for sediment of GO-Fe 3 O 4 nanoparticles. Experimental evaluation showed that erythrosine dye has a peak at 523 nm in visible light region (can be seen in section.3.1). In this case, for determination of erythrosine removal rate, the adsorption rate by fillers were examined at 523 nm wavelength. In the final stage, the dye removal rate (%) was calculated using the following equation: 22 Where the C i and C f are the initial dye concentration (before reaction with GO-Fe 3 O 4 ) and the final dye concentration (after reaction with GO-Fe 3 O 4 ), respectively.

7. Choosing the Maximum Wavelength (λ max )
Maximum wavelength peak related to the erythrosine dye was determined via UV-vis spectroscopy in the visible-light region ranging from 400 to 700 nm. In this matter, the maximum wavelength for the erythrosine dye was saw at 523 nm. Therefore, the final adsorption rate by developed fillers was measured at the fixed wavelength of 523 nm during all processes.

1. Examination of Fabricated GO-Fe 3 O 4 Nanoparticles
In this section, specifications of fabricated GO-Fe 3 O 4 nanoparticles were evaluated using FTIR, XRD, VSM and SEM analyses. In Fig. 1 (a), FTIR results of Fe 3 O 4 , GO and GO-Fe 3 O 4 can be seen, respectively. As can be seen in the spectrum of Fe 3 O 4 (red color), peaks in region between 530-630 cm -1 are correspond to the stretching vibration mode of Fe-O. In this case, broad and strong peak at 575 cm -1 is correspond to the Fe 3 O 4 and indicate the successful synthesize of Fe 3 O 4 nanoparticles. [23][24][25] Moreover, peaks at 923 and 1108 cm -1 are related to the sp 2 alkene C-H band (disubstituted-E) and stretching vibration of inplane C-H, respectively. Besides, peak with wavenumber 1616 cm -1 is belong to the FeOO -, 24 while peaks in region between 2838-2921 cm -1 are belong to the C-H stretching vibration (sp 3 stretching of hexyl aliphatic side). Weak peaks in the region between 3500-3700 cm -1 are belong to the amine N-H. Furthermore, broad and strong peak at 3424 cm -1 is correspond to the hydroxyl functional group (-OH). 24 In addition, as shown in the GO spectrum (Figure 1 (a) green color), GO was successfully synthesized with compatible functional groups including carboxyl (1715 cm -1 ), hydroxyl (3398 cm -1 ) and epoxide (1057 cm -1 ) which provide the possibility of molecular attachment between GO and Fe 3 O 4 nanoparticles. In GO spectrum, peaks with wavenumbers 584, 854, 891, 1006, 1165 and 1632 are correspond to the C=O in amides, C-H sp 2 , germinal disubstituted, vibration of a p-disubstituted phenyl group υ c-H in plane bending), C-OH in alcohols and C=C bonds (sp 2 C-X double bonds) in aromatic ring, respectively. 18 In Fig. 1 (a) (blue color), it can be seen that GO-Fe 3 O 4 was successfully synthesized. In this case, strong peak at 577 cm -1 , which known as the fingerprint of Fe 3 O 4 , 23-25 along with peak at 1627 cm -1 that correspond to the FeOO -, 24 clarify the molecular attachment of Fe 3 O 4 nanoparticles on the surface of GO. Furthermore, peaks with wavenumbers 940 and 3422 cm -1 are correspond to the sp 2 alkene C-H bond and hydroxyl functional group, respectively. Appearance of peaks at 577 and 1627 cm -1 along with disappearance of carboxyl and epoxide functional groups related peaks and decrease in the intensity of hydroxyl functional group in the GO-Fe 3 O 4 spectrum compared with GO and Fe 3 O 4 spectrums, confirm whether the successful decoration of GO with Fe 3 O 4 or molecular attachment of Fe 3 O 4 on the surface of GO. In fact, decrease in the intensity of hydroxyl functional group and disappearance of carboxyl and epoxide functional groups clarify the interaction between functional groups of GO and Fe 3 O 4 .
In addition, in Fig. 1 (b), XRD results for GO, Fe 3 O 4 and GO-Fe 3 O 4 can be seen, respectively. As can be seen in this figure, XRD results shows that GO nanoparticles were successfully synthesized, while they show a peak (2Ѳ) around 12.3 which is correspond to the inter planer spacing of 0.84 nm. 26 On the other hand, in Fig. 1 (b) it can be seen that related XRD peaks for Fe 3 O 4 and GO-Fe 3 O 4 are the same as each other, which are in accord of previous studies outcomes. [26][27][28] In this regard, the diffraction peaks (2Ѳ) at 30.

2. Examination of Erythrosine Dye
Removal Rate

2. 1. Effect of pH on the Erythrosine Removal Rate
Solution pH is one of the most important factors on the adsorption of pollutants. In this section, the effect of variable pH (ranging from 3-9) on the dye removal rate and final adsorption rate of Erythrosine dye from aqueous solution were examined. In this case, the final pH of the solution containing Erythrosine dye was fixed and regulated via addition of hydrochloric acid and sodium hydroxide. Moreover, in order to achieve the optimal pH, 15 mL of Erythrosine dye (100 µg mL -1 ) was poured into a 50 mL volumetric flasks and thence variable volumes of a solution containing hydrochloric acid and sodium hydroxide was added to the primary solution to regulate the pH on the desirable value. Afterward, 0.2 g of GO-Fe 3 O 4 was poured into the dye solution and stirred for 2 min (500 rpm) and then placed on a strong magnet for further sediment of fillers and adsorption of the dye by magnetic fillers. Thereafter, the level of dye adsorption rate was measured at wavelength of 523 nm. In Fig. 3 (a) and (c) the effect of variable pH on the dye removal rate and final adsorption of Erythrosine dye can be seen, respectively. As can be seen in this figure, increase in the pH of the suspension and neutralization of the suspension can enhance the dye removal rate, thus pH = 7 was selected as the optimal pH for the solution.

2. 2. Effect of PBS Content on the Erythrosine Removal Rate
In this section, effect of variable buffer content on the removal rate and final adsorption of the dye was eval- uated. In this regard, various volumes of PBS were added to the solution containing Erythrosine dye (at pH = 7), while the dye removal rate and final adsorption were recorded at 523 nm wavelength. Figure 3 (b) and (d), show the dye removal rate and final adsorption of the dye at various contents of PBS. Obtained results revealed that increase in the content of PBS up to 2 mL can lead to significant improvement in the dye removal rate, while the dye removal rate was levelled off at contents more than 2 mL. Therefore, 2 mL PBS was considered as the optimal buffer volume.

2. Effect of GO-Fe 3 O 4 Content on the Erythrosine Removal Rate
In this section, effect of adsorbent content on the dye removal rate and final adsorption rate of dye was ex-amined. In this regard, 15 mL of Erythrosine dye (100 µg mL -1 ) along with 2 mL PBS (with pH = 7) were poured into a 50 mL volumetric flask and then the flask was filled with deionized water. Afterward, same amount of the resulting suspension was poured into six different beakers and various amount of GO-Fe 3 O 4 ranging from 0.05 to 0.3 g was added to the suspension and sonicated for 2 min (500 rpm). Then, the resulting suspension was placed on a strong magnet for further 1 min and after fillers sediment, the dye removal rate and final adsorption rate of Erythrosine dye were measured at wavelength of 523 nm. In Fig. 4 (a) and (c), the effect of filler content on the dye removal rate and final adsorption can be seen, respectively. Obtained results showed that increase in the content of fillers up to 0.2 g can lead to significant improvement in the dye removal rate, while the level of removal rate was levelled off in contents more than 0.2 g, thereby 0.2 g GO-

2. 4. Effect of Stirring Time on the Erythrosine Removal Rate
In this section, effect of diverse mixing times (40-180 s) on the dye removal rate and final adsorption of dye at wavelength of 523 nm were examined. In this case, produced solution containing 2 mL PBS (pH = 7) along with 0.2 g GO-Fe 3 O 4 was stirred at different selected times. In Fig. 4, obtained results can be seen, which parts (b) and (d) showing the dye removal rate and final adsorption of dye from aqueous solution. Achieved results showed that by increase in the stirring time up to 2 min, the final dye removal rate remains at balanced amount. Therefore, 2 min stirring was considered as the optimal mixing time.

2. 5. Effect of Electrolyte Concentration on the Erythrosine Removal Rate
In this section, the effect of the electrolyte concentration on the dye removal rate and final adsorption of dye at wavelength of 523 nm was evaluated. For this matter, 15 mL of Erythrosine solution (100 µg mL -1 ) along with 2 mL PBS (pH = 7) and variable amount of 1 molar sodium chloride were poured into a 50 mL volumetric flask and afterward the flask was filled with deionized water. Thence, 0.2 g GO-Fe 3 O 4 was added to the suspensions containing various concentrations of electrolyte. Then, each beaker was placed on a strong magnet for 1 min and after sediment of fillers, the dye removal rate and final adsorption were calculated at wavelength of 523 nm, which can be seen in Figure 5 (a) and (c), respectively. Achieved results revealed that increase in the concentration of electrolyte has negligible effects on the dye removal rate and final ad- sorption rate. Moreover, addition of electrolyte to the suspension containing absorber and dye neutralizing the surface of the absorber that can furtherly decrease the absorption of dye molecules by the absorber's surface. On the other hand, electrolyte can lead to decrease in the ionization of dye molecules. This process ease the extraction of non-ionic compositions and leads to higher absorption of neutral dye molecules compared with ionic molecules with whether positive or negative charges.

2. 6. Effect of Solution Content on the Erythrosine Removal Rate
In this section, various volumes of solution (ranging from 50-250 mL) containing 1500 µg Erythrosine dye were examined to evaluate the effect of solution content on the dye removal rate and final adsorption of Erythrosine dye, which can be seen in Fig. 5 (b) and (d), respectively. Achieved results showed that increase in the solution content to more than 100 mL can lead to significant decrease in the percentage of dye removal rate and final adsorption. Furthermore, the maximum dye removal rate was observed at 50 mL solution volume.

2. 7. Effect of Temperature on the Erythrosine Removal Rate
In this section, effect of variable temperature (ranging from 5 to 60 °C) on the dye removal rate and the final adsorption of Erythrosine dye from aqueous solution was examined. A view of these results can be seen in Fig. 6 (a) and (b), respectively. Obtained results showed that increase in the temperature to more than 15 °C can highly enhance and improve the final dye removal rate.

Isotherm of Adsorption Process
In this section, adsorption performance of developed GO-Fe 3 O 4 nanoparticles was described through isotherm. In this case, distribution of metal ions between both liquid and solid phases were examined using Langmuir and Freundlich isotherm models via obtained results from experimental data.
In this regard, for examination of adsorption process isotherm by developed adsorbents, different solutions containing various amount of Erythrosine dye (30, 35 and 40 µg mL -1 ) were poured into a 50 mL volumetric flask along with 2 mL PBS (pH = 7). Afterward, each prepared solution was added to several beakers and then 0.2 g GO-Fe 3 O 4 was added to each beaker. Thence, the resulting suspension was stirred for 150 s and placed on a strong magnet for further sediment of fillers. Thereafter, adsorption rate of each prepared sample was evaluated at wavelength of 523 nm. Obtained data from experimental evaluation can be seen in Fig. 7 (a).
What is more, the Langmuir isotherm consider monolayer adsorption for a surface which containing a finite number of adsorption sites of uniform strategies without transmigration of adsorbate in the plane surface, [29][30][31] which is defined as follow: (2) Where C e /q e , C e , constant b and q max are the specification of adsorption, equilibrium concentration, maximum adsorption capacity and energy of adsorption, respectively. The liner plot of the adsorption specification (C e /q e ) versus the equilibrium concentration (C e ) can be  Fig. 7 (b). Obtained results show that Langmuir isotherm model is perfectly compatible with experimental data. On the other hand, the Freundlich isotherm is an empirical model which can be defined as follows. 32 (3) Where q e , C e , K f and n are the amount of adsorbed per amount of adsorbent at the equilibrium (mg/g), equilibrium concentration (mg/L), parameters that depend on the adsorbate and parameters that depend on the adsorbent, respectively. Mentioned equation ca be linearized and temperature dependence parameters such as K f and 1/n can be transformed into the liner form as follows: 33 (4) Where K f and n are the Freundlich constants based on the adsorption capacity and intensity, respectively. Freundlich equilibrium constants can be determined from plot of against, which can be seen in Fig. 7 (c). Achieved results from both Langmuir and Freundlich isotherm models shows that the experimental data are more compatible with Langmuir model than Freundlich model. Moreover, the related equations for Langmuir and Freundlich are as follow: Y = 0.0067 X + 0.0072 and R 2 = 0.9982 (5) Y = 0.1791 X + 1.9355 and R 2 = 0.9734 (6) In addition, obtained results from both experimental evaluation and simulation via Langmuir and Freundlich isotherm models indicated that increase in the concentration of adsorbent can lead to significant improvement in the final adsorption rate. Additionally, smaller correlation coefficient (R 2 ) of Freundlich isotherm than Langmuir isotherm shows that the Langmuir isotherm model is proper to predict the behavior of adsorption process. It also shows that the adsorption of dye on the adsorbent is monolayer. Additionally, the maximum adsorption capacity obtained by Langmuir isotherm model was obtained at 149.25 mg/g which is a considerable amount.

1. Kinetic Study of the Adsorption Process
In this section, the kinetic of GO-Fe 3 O 4 adsorption process was examined at variable time ranging from 0.5 to 3.5 min. Figure 8 (a), indicating that the adsorption process reached the balanced situation after 2.5 min, while increase in the concentration of adsorbent can highly improve the adsorption rate. Furthermore, adsorption process of Erythrosine dye via GO-Fe 3 O 4 was also examined using the pseudo-first order equation (Figure 8 (b)) and pseudo-second order equation (Figure 8 (c)). 34,35 According to the correlation coefficient of these two models, the dye adsorption process follows both pseudo-first order model and pseudo-second order equations; however, the pseudo-second order model is much more compatible with the experimental outcomes than the pseudo-first order model, which indicate the mechanism of chemical adsorption. The obtained line equations via these models and the correlation coefficients are as follow: 30 μg mL -1 → log (q e -q t ) = -1.5614t +2.4655, r = 0.9753 (7) 35 μg mL -1 → log (q e -q t ) = -1.1282t + 2.134, r = 0.9941 (8) 40 μg mL -1 → log (q e -q t ) = -0.8352t + 2.002, r = 0.9602 (9) In addition, in order to examine the kinetic based on the pseudo-second order model, the diagram of t/q t changes was illustrated based on t, which can be seen in Fig. 8 (c). The obtained line equations and the correlation coefficients are as follow: 30 μg mL -1 → t/q t = 0.01t + 0.0067, R 2 = 0.9918 (10) 35 μg mL -1 → t/q t = 0.0092t + 0.0045, R 2 = 0.9990 (11) 40 μg mL -1 → t/q t = 0.0086t + 0.003,

4. Performance of Fillers for Removal of Erythrosine dye From Real Samples
In this section, performance of developed GO-Fe 3 O 4 nanoparticles for removal of Erythrosine dye from real samples obtained from chicken slaughterhouse and hospital sewage disposal system was evaluated. In this case, various concentrations of Erythrosine dye (20,50 and 70 mg mL -1 ) were added to two real samples that were obtained from chicken slaughterhouse and hospital, respectively, and thence the adsorption rate of dye via magnetic fillers was investigated. For this matter, in two turns, 0.2, 0.5 and 0.7 mL of Erythrosine dye (10 µg mL -1 ) was added to two different volumetric flasks, respectively, which were filled with wastewater obtained from chicken slaughterhouse and hospital, respectively. Then, prepared solutions were passed through an adsorbent pillar, while the washing action was performed with 2 mL of 2 molar ammonia (NH 3 ) buffer (pH = 7). Afterward, the adsorption rate was measured at wavelength of 523 nm using UV-vis spectrophotometer. Achieved results can be seen in Table 1 and Fig. 8 (d). Calculated data within the Table  1 was measured based on the method that explained in the section 2.6. Furthermore, one of the most important parts of an adsorption study is to investigate the possible disturbance role of each ion during the adsorption process, which could be used to develop the research for real samples. By evaluation of possible disturbance factors, we can figured out whether a method is practical or not. In this regard, possible disturbance effect of various kinds of cations and anions were investigated. If a considered ion create more than 5% systematic error during the calculation, we consider that ion as the annoying ion which should be removed from the system. In order to examine the current adsorption process, 1 mL of Erythrosine dye (5 µg mL -1 ) was added to a volumetric flask, while the pH was set on 7. Thereafter, various amount of annoying ions were poured into a 100 mL beaker and then the beaker was filled with deionized water. Thence, via vacuum pump, each solution was passed through a pillar containing 0.1 g of adsorbent.
List of annoying kinds during the process can be seen in the Table 2.
Besides, in order to evaluate the standard deviation and repeatability of current method, the limit of detection (LOD) and relative standard deviations (RSD) were measured, respectively. The standard deviation can be calculated via the following equation: (13) Where the calculated S b and X are 5.67 and 0.0071, respectively. On the other hand, LOD can be measured via the following formula: Where K, m and S b are constant factor with value 3, standard curve slop and standard deviation, respectively. The measured value of LOD was determined to be 1.82 mg mL -1 . In addition, in order to evaluate the repeatability of the adsorption procedure, the final adsorption of solutions containing 100 and 250 mg mL -1 Erythrosine dye were re-   Tables 3 and 4, respectively ,while the RSD for concentrations 100 and 250 mg mL -1 was determined to be 2.3 and 4.79%, respectively. In this case, all of absorption rates were calculated based on the procedure that mentioned in section 2.6.

Conclusions
In this study, GO was fabricated via modified Hummers method and thence decorated with magnetite nanoparticles (Fe 3 O 4 ) through a multi-step manufacturing procedure. Thence, fabricated GO-Fe 3 O 4 nanoparticles were evaluated using FTIR, XRD, VSM and SEM analyses, and these analyses confirmed the successful synthesize of GO-Fe 3 O 4 and their fantastic magnetic properties. Thereafter, performance of developed fillers for the removal of Erythrosine dye from aqueous solutions under variable conditions and at variety of concentrations were examined and studied. Afterward, obtained experimental outcomes were used to evaluate the adsorption isotherm and kinetic of GO-Fe 3 O 4 nanoparticles. Finally, performance of developed magnetic nanoparticles for the removal of Erythrosine dye from real samples obtained from chicken slaughterhouse and hospital sewerage disposal system were investigated. Achieved results revealed the fantastic performance of GO-Fe 3 O 4 nanoparticles for removal of Erythrosine dye from various kinds of aqueous solutions under variety of conditions.

Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors