Fe3O4@MXene/rGO/PANI Composite: A Novel Sensing Material for the Electrochemical Detection of Orange II and Rhodamine B Food Dyes

doi:10.21203/rs.3.rs-4916842/v1

Download PDF

Research Article

Fe₃O₄@MXene/rGO/PANI Composite: A Novel Sensing Material for the Electrochemical Detection of Orange II and Rhodamine B Food Dyes

https://doi.org/10.21203/rs.3.rs-4916842/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

The sensitive and selective monitoring of food dyes is essential due to their potential carcinogenic effects on human as well as on living organisms. Herein, Fe₃O₄@MXene/rGO/PANI nanocomposite was prepared and successfully applied as a recognition layer for the sensitive and fast analysis of Orange II (OR II) and Rhodamine B (RB) via DPV. The prepared nanocomposites were described by XRD, SEM and FTIR analysis. The XRD results verified the crystalline nature of the composite. Successful fabrication of electrode surface was confirmed from CV, EIS and CC. Due to the outstanding electrochemical characteristics, high surface area, and good electrocatalytic activity of Fe₃O₄@MXene/rGO/PANI, the peak currents of dyes on modified GC electrode are considerably higher than among all studied electrodes. The detection conditions such as supporting electrolyte, amount of modifier, pH of the medium, accumulation potential and time were studied and optimized. Under optimized conditions, the designed sensor exhibited two linear ranges from 0.005–0.1 and 0.1–1 µM with detection limits of 0.56 nM and 0.42 nM for OR II and RB, which was attributed to the high surface area, strong accumulation ability and multiple active sites of Fe₃O₄@MXene/rGO/PANI. Futhermore, the stability of the designed sensor was analyzed for the detection of OR II and RB. The practical applicability of this sensor was also scrutinized for the analysis of OR II and RB in real samples and suitable results were obtained. Hence, this simple and effective methodology for detection of dyes has good potential for monitoring of environmental pollutants.

MXene

Graphene

Polyaniline

Electrochemical sensor

Detection

Orange II

Rhodamine B

Due to continuous increase in human population, the whole world is facing various issues linked to health, energy, food, and environmental contamination [1, 2]. In recent years, environmental pollution and energy crisis have gained the attention of the entire world. Various groups have been working to find out the main causes of rise in environmental pollution. One of its main issues are the rapid rise in population and large-scale industrialization. Today, one of the major issue world facing is water pollution [3]. To this end, industrial effluents of several synthetic dyestuffs into waters are the main contributor to water contamination [4, 5]. Their discharge not only severely pollutes surface and groundwater but also reduce the photosynthetic activity of marine life. These dyes are stable and nonbiodegradable due to their complex molecular structure and offered high toxicity upon consumption. However, amongst all synthetic dyes, azo dyes are more dangerous to human and marine life [6]. Azo dyes are the leading group of synthetic dyes used as coloring agents in pharmaceutical, cosmetics and food industries [7, 8]. They have one or more azo groups in which aromatic rings are replaced by sulfonate group and hydroxyl group etc. Rhodamine B is a synthetic basic dye belonging to xanthene family, being used in in paper, porcelain, textile, leather and paint industries [9, 10]. Also, it is used as fluorescent dye in biochemistry and analytical chemistry. However, RB show potential genotoxicity and carcinogenic activity at very low concentrations. In industrial effluents, the amount of RB is more than 100 mg/L, which adversely affects human as well as marine life. Countries like Europe, China and the United States banned the use of RB in foodstuffs [11, 12]. But, it is still used illegally in foodstuffs due to low price, strong stability and bright color. While, Orange II is an anionic azo industrial dye of the acid class. This dye has shown various health issues upon consumption such reducing cell volume and as lowering of red blood cells. But still, it can be found in trace quantities in certain foodstuffs such as chilli and sauces [13, 14]. In addition, it is still being utilized to preserve foods in China. Therefore, the detection and analysis of these dyes in industrial wastewaters and foodstuffs is very essential for ensuring the safety of human and aquatic life.

At present, various techniques have been stated for the study of dyes, like chromatographic techniques including high performance liquid chromatography (HPLC) [15], liquid chromatography coupled with mass spectrometry (LCMS) [16], fluorescence technique [17] and capillary electrophoresis [18]. Even though, these methods offered high sensitivity but some drawbacks such as time consuming, high instrumental cost and complicated procedure limited their applications. In this regard, electrochemical methods have gained attention due to its simple procedure, high sensitivity, low cost and fast operation cycle [19]. It is widely known that the performance of electroanalytical sensors is primarily evaluated by the electro-catalytic ability of the working electrode [20, 21]. Therefore, the modification of electrode surface with suitable material is very important to have best sensitivity. Over the years, various types of nanomaterials including carbon nanotubes [22], graphene [23], metal and metal oxide NPs [24–26] have been extensively used in the electrochemical sensing of environmental pollutants. Recently, two dimensional heterostructures have shown good electrochemical characteristics by improving the charge transfer activity among analyte solution and electrode surface. In these 2D materials, MXene’s unusual physio-chemical properties and 2D layered structure have made it new exciting nano 2D layered material. MXene was first produced by Naguib in 2011[27, 28]. Its sheets can be obtained via etching of Al layer of MAX. MXenes also offered some exceptional properties such as remarkable electrical conductivity, ultrathin morphology, easy surface modification which make it good electrode material for electrochemical sensing of environmental pollutants [29–31]. Therefore, MXene sheets are incorporated with iron oxide NPs to minimize the restacking of sheets. Among all transition metal oxide NPs, iron oxide NPs have good biocompatibility, low toxicity, good magnetic property and easy preparation method. To further improve the electro-catalytical properties of iron oxide and MXene nanocomposite, graphene and polyaniline [32, 33] can be added to enhance the electron transfer rate at the interface. Thus, to anchor more active sites on working electrode surface and to attain high affinity for the attachment of dyes, carbon based material graphene and polyaniline chains are anchored with the MXene, and iron oxide NPs.

Herein, firstly MXene was synthesized using HF as etchant. Then, the negatively charged MXene sheets were incorporated with Fe₃O₄ NPs which are synthesized by co-precipitation method. After that, graphene and polyaniline chains were anchored to facilitate the electron transfer kinetics. This new material solved the issue of restacking of MXene sheets and improved the electronic conductivity of iron oxide NPs. The as-prepared material Fe₃O₄@MXene/rGO/PANI was employed the electrochemical detection of OR II and RB dyes. The physical and morphological characterization of nanocomposite were tested by various methods such as XRD, FTIR and SEM. The surface properties were evaluated by cyclic voltammetry, choro-coulometery and impedance method. While the electrochemical sensing of dyes was evaluated by Differential pulse voltammetry. The detection parameters including effect of pH media, supporting electrolyte, volume of modifier, effect of time and potential were evaluated to have best sensing response. The designed sensor displayed good electrochemical response, and electrocatalytic activity towards the detection of these targeted dyes respectively. The sensor anti-interference ability and stability were also evaluated. Under optimal conditions, sensor exhibited limit of detection of 0.56 n M for OR II and 0.42 nM for RB. The sensor was tested successfully for the detection of dyes in real water samples.

2.1. Chemicals and apparatus

All chemicals and reagents employed in this study are of analytical grade. MAX powder was purchased from China. Ferric chloride (FeCl₃), methanol (CH₃OH), ferrous sulphate (FeSO₄), Orange II, Rhodamine B, pristine graphite powder, concentrated sulfuric acid, potassium permanganate, sodium nitrate, aqueous ammonia, hydrogen peroxide, aniline, ammonium peroxydisulfate, sodium chloride, potassium chloride, H₃BO₃, HCl, KCl, NaOH, H₃PO₄ and CH₃COOH were purchased from Sigma Aldrich. All used reagents and chemicals have purity ≥ 98.9%.

For physical and structural characterization of prepared nanocomposites, several techniques such as XRD, FT-IR and SEM were employed to get evidence about the several functional groups, signals and shapes of the material. The XRD patterns were recorded on the Lab XRD-6100 in a range from 10–80º with Cu as source of radiation. The FTIR spectra were obtained on IR Affinity-Is from 400 cm^− 1 to 4000 cm^− 1. The Morphology of the prepared nanocomposite was evaluated on Inspect S50 FEI instrument.

2.2. Synthesis of Fe₃O₄

Magnetic Fe₃O₄ NPs were synthesized by co-precipitation method. For this, stochiometric amounts of FeC1₃.6H₂O and FeSO₄.7H₂O were added into 100 ml of water and then resultant solution was stirred for 15 minutes at room temperature. After that, temperature was maintained to 80°C and solution was stirred for another 30 min. Then, NaOH solution was added into the above solution until pH 10 was attained. Here, NaOH act as a reducing agent. The obtained suspension was vigorously stirred for 2 h. Thereafter, the dark colored precipitates were collected, washed with DI water and dried in oven under vacuum environment at 60°C for about 12 h.

2.3. Synthesis of MXene

MXene (Ti₃C₂T_x) nanosheets were prepared by etching of aluminum layer from MAX (Ti₃AlC₂) precursor, according to previously reported method. For this, 0.5 g of MAX powder was gradually added into the 10 ml HF (40%) etching solution. The reaction was continuously stirred at room temperature for 24 h to achieve maximum etching. After etching, the obtained suspension solution was washed with DI water and then centrifuged at 4500 rpm for several times. Afterward, the sediment was washed again and again until the pH was 6. The resultant suspension was filtered via PTFE membrane. The obtained filtrate of MXene sheets was freeze-dried for 24h. For intercalation of MXene, DMSO was used to increase the spacing between its layers. Typically, 0.2 g of MXene sheets were poured in 20 mL of DMSO solvent and magnetically stirred for about 24 hrs. The resultant material was washed with DI water and centrifuged at 4200 rpm for 5 min. The precipitates were redispersed in DI water and then ultrasonicated for about 1 h. Again, it was centrifuged at 4500 rpm for about 30 min and dried in an oven under vacuum environment.

2.4. Synthesis of Fe₃O₄@MXene

Stoichiometric amounts of FeC1₃.6H₂O and FeSO₄.7H₂O were added gradually into multilayered MXene solution (100 mL, 1 mg mL^− 1) under argon atmosphere at 80^oC under constant stirring, followed by the addition of NaOH. The reaction mixture was stirred about 01 hr. After 01 hr, the pH of the reaction mixture was attained at 10 with NaOH. The resultant suspension solution was magnetically stirred for about 2 h before cooling. Afterwards, the dark-colored powder was collected, washed several times with DI water and dried under vacuum environment at 60°C for 12 h. The graphical representation is shown in Scheme 1.

2.5. Synthesis of GO and rGO

GO was produced from graphite powder via modified Hummer’s method [34]. For this, 1 g of graphite powder was mixed with 1 g of sodium nitrate. 50 ml of H₂SO₄ was added gradually into the above mixture which is place on ice bath. Afterwards, 6 g of KMnO₄ was poured into the resulting mixture under vigorous stirring for about three hours. Then, after 01 hour, ice bath was removed and mixture was continuously stirred for about 48 h. Next, slightly warm distilled water was poured into the obtained slurry followed by the addition of 20 ml of H₂O₂ to remove the unreacted KMnO₄. Afterwards, the product was washed serval times with distilled water to achieve neutral pH. The prepared GO was converted into rGO by using ammonia and hydrazine as a reducing agent. Typically, 10 ml of GO slurry was diluted with 0.09 L of DI water, which ultrasonicated for 30 min. After that, 30 µL of ammonia and 10 µL of hydrazine were added into the above mixture and heated it at 95°C for 01 hour. The final suspension was dried and manually grinded to get rGO-powder as shown in Scheme 2.

2.6. Synthesis of Fe₃O₄@MXene/rGO/PANI

In situ oxidative polymerization method was utilized to prepare polyaniline based Fe₃O₄@MXene/rGO/PANI nanocomposite. In this method ammonium peroxydisulfate (APS) is utilized as an oxidizing agent. Typically, Fe₃O₄@MXene (0.1 M) was prepared by dispersing 1 g of precursor Fe₃O₄@MXene in 90 ml of DI water for 30 minutes to form a suspension. At the same time, 25 mg of rGO was added into the above solution. The resulting suspension was ultra-sonicated for half-an-hour. After that, Fe₃O₄@MXene/rGO was added in 30 ml of 1 M HCl and stirred ultrasonically again for 30 min. To this mixture, 1 ml of aniline monomer was added under constant stirring to ensure the good dispersion of aniline into the Fe₃O₄@MXene/rGO. To proceed polymerization process under vigorous stirring it was cooled down to 0⁰C by an ice bath for 4 hours, 20 ml of 1 M APS solution was added slowly into the above mixture under constant stirring. Afterwards, the reaction solution was vigorously stirred for the 12 h. The obtained precipitates were added in an appropriate amount of acetone to stop the reaction. The final product was washed with DI water and acetone to remove unreacted APS. The prepared composite was dried at 70°C and grinded. The process for the preparation of nanocomposite is shown as Scheme-3.

.2.7. Fabrication of electrode and electrochemical measurements

Prior to surface modification, the working electrode surface was cleaned via polishing its surface with alumina slurry. After that, electrode surface was washed carefully with distilled water and ethanol and then dried. The sensing electrode was fabricated via drop casting method. For this, 1mg/ml slurry of prepared iron oxide nanoparticles was prepared via ultrasonication. After that, 5µL drop of nanoparticles slurry was drop casted on GCE and dried in air. In the similar manner other electrodes such as Fe₃O₄/GCE, rGO/GCE, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI/GCE were fabricated.

The electrochemical experiments were executed on a Gamry Potentiostat instrument (5000 E) with three electrode assembly (reference electrode: Ag/AgCl, working electrode: GCE, counter electrode: Pt wire). All electrochemical experiments were carried out at room temperature. The electrochemical surface features of the all modified electrodes were recorded in Fe(CN) ₆^3−/4− via the EIS, CV and CC. Cyclic voltammograms were recorded by scanning the potential from − 0.30 to + 0.70 V at the scan rate of 100 mVs^− 1. Whereas EIS was obtained in 0.1 mM potassium ferrocyanide in 0.1M KCl with frequency ranges from 100 kHz to 1 Hz. The DPV method was used to detect dyes (OR II and RB) in the potential range of 0.2 to 1.1V under optimal conditions.

3.1. Characterization of Fe₃O₄@MXene/rGO/PANI composites

3.1.1. XRD studies

To check the crystalline nature and composition of as-prepared nanocomposites, the XRD patterns of rGO, Fe₃O₄, MXene, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI nanomaterial were recorded and are shown in Fig. 1 (a-c). In the XRD pattern of Fe₃O₄, diffraction peaks indexed at 30.1°, 35.4°, 43.1°, 53.5° and 57.0° corresponds to the (220), (311), (400), (422), and (511) diffraction planes of Fe₃O₄ and these diffraction peaks are matched well with the JCPDS Card 19–0629 of Fe₃O₄ [36]. This confirms the presence of cubic spinal structure of nanoparticles. Additionally, there are no additional peaks of FeO and Fe₂O₃, which indicated the high purity of synthesized nanoparticles. XRD pattern of Fe₃O₄ showed sharp and strong peaks indicating its high crystallinity. MXene synthesized from MAX phase showed its peaks at 6.2°, 19.1°◦, 28.94°, 36.75°, 41.69°, 48.32° [37]. In the case of RGO, the diffraction peaks at 25.1° correspond to the (002) plane of rGO [35]. The additional peaks in the composite at 2θ = 13.5°, 19.6°, 25.1° corresponds to (011), (020), (200) planes of PANI, match with JCPDS card no (04-011-8282) [38] respectively. This shows the presence of semicrystalline peaks of PANI and its emeraldine salt. In addition to this, signal of rGO corresponds to (002) plane disappeared in the nanocomposite and diffraction planes of individual components also merged which demonstrated good interfacial interaction between rGO, Fe₃O₄, MXene and PANI.

3.1.2. FTIR studies

The FT-IR spectra indicated the active functional groups presence in the Fe₃O₄ nanoparticles, MXene, rGO and PANI. In Fig. 2, the intense band at 600 cm^− 1 is allocated to the Fe-O stretching mode. Two characteristic bands at 1105 and 550 cm^− 1 attributed to Ti-C and Ti-F for Ti₃C₂T_x. While the wide band in the range from 3600 to 3300 cm^− 1 is ascribed to OH and NH stretching modes, observed due to uncondensed amino groups and adsorbed H₂O. The typical peak of rGO is perceived at 1621 cm^− 1 which indicates the appearance of -C = C- matrix of graphene attained after the conversion of GO into rGO [35]. In composite, the several bands of PANI appeared at 788 cm^− 1, 920 cm^− 1 and 1123, 1490 cm^− 1, 1335 cm^− 1, 1630 cm^− 1 and 3360 cm^− 1 related to CH and NH stretching modes, benzoid ring and NH₂ bending modes. While, the bands at 1630 and 1490 cm^− 1 assigned to C = C benzoid ring and C = N quinoid stretching modes. The bands at 1630 and 1123 cm^− 1 are corresponds to C–N stretching modes and 788 cm^− 1 is related to C–H out of plane deformation [33]. All these bands stated the successful incorporation of precursors (Fe₃O₄, rGO, MXene and PANI).

3.1.3. SEM studies

The formation of Fe₃O₄ NPs doped MXene sheets was also confirmed from SEM analysis. The SEM result clearly shows the presence of Fe₃O₄ NPs into MXene sheets (Fig. 3). The structure of MXene with more spacing between the sheets is also seen which confirmed the formation of MXene sheets from MAX powder.

3.2. Electrochemical analysis of OR II and RB

3.2.1. Characterization of Fe₃O₄@MXene/rGO/PANI/GCE by EIS, CV and CC

The electrochemical features of bare GCE and four modified electrodes were documented in [Fe(CN)₆]^3−/4− redox couple by CV, EIS and CC. Figure 4 (a) displays the CV plots of bare, Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI modified GCE obtained in [Fe(CN)₆]^3−/4−. On all electrodes, well-defined redox peaks are seen. Among all electrodes, Fe₃O₄@MXene/rGO/PANI/GCE exposed higher current response and smaller potential difference. This could be due to the synergic effect between MXene, rGO, polyaniline and iron oxide NPs. The active surface area of the bare, Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI electrodes was evaluated by the Randles– Sevcik equation [33].

I_p =2.69×10⁵n^3/2AC⁰D^1/2v^1/2 (1)

Herein, I is the peak current, n denotes number of electron transfer, A is the active area, D is the diffusion coefficient, C-concentration of the redox probe, and v is the scan rate. The effective surface areas were calculated to be 0.45 cm², 0.70 cm², 0.83 cm², 0.85 cm², 1.02 cm² for bare GCE, Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI GCE’s.

EIS is an effective technique used to study the charge transfer properties of different electrodes. Figure 4b. displays the EIS plots of bare, Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI GCE’s recorded in [Fe(CN)₆]^3−/4−. Bare GCE offered highest resistance as compared to other studied electrodes which is due to the poor electron transfer kinetics between electrode and electrolyte. The Fe₃O₄@MXene/rGO/PANI/GCE revealed lowest resistance making it suitable for sensing applications. The excellent electrochemical properties of the Fe₃O₄@MXene/rGO/PANI electrode is due to the good electronic path provided by the combination of MXene, rGO and Fe₃O₄ and PANI. The heterogeneous rate constant k_o of bare GCE and four modified GC electrodes was calculated via following equation [39];

R_ct = RT/ (nF)²Ak_oC_o (2)

Where R_ct and R represenst charge transfer resistance and ideal gas constant. F, T and n shows the faraday constant, temperature and number of electrons transferred. A denotes to the surface area of working electrode and Co is bulk concentration. The obtained k_o values were 0.56 × 10^− 4 cms^− 1, 0.83× 10^− 3 cms^− 1_, 0.87× 10^− 3 cms^− 1, 0.95 × 10^− 3 cms^− 1, 1.1 × 10^− 3 cms^− 1, for bare GCE, Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI GCE’s respectively. The highest value of rate constant was achieved for Fe₃O₄@MXene/rGO/PANI electrode which indicated the fast electron kinetics between the interface of Fe₃O₄@MXene/rGO/PANI and [Fe(CN)₆]^3−/4.

Chronocoulometry (CC) is another electroanalytical technique that can be used to find the active surface area of studied electrodes. CC was employed using [Fe(CN)₆]^3−/4 as redox couple and obtained results are shown in Fig. 4c. The Q-t^1/2 plots of all studied electrodes were depicted in Fig. 4d. The effective surface area of bare and Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI GCE’s were calculated using Anson equation [40]

Q(t) = 2nFAcD^1/2t^1/2/π^1/2 + Q_ad + Q_dl (3)

where A, n, c and D refers to effective surface area, number of electrons transferred, conc. of [Fe(CN)₆]^{3− /4−} redox couple, and diffusion coefficient. While Q_dl and Q_ads shows the charge transfer via electric double layer and adsorption. The effective surface area of bare and Fe₃O₄, rGO, Fe₃O₄@MXene and Fe₃O₄@MXene/rGO/PANI GCE’s comes out to be 0.26, 0.45, 0.56, 0.70 and 0.89 cm². Among all studied electrodes, Fe₃O₄@MXene/rGO/PANI/GCE displayed the higher surface area. These results demonstrated that the synthesized nanocomposite could be used as sensing platform for the sensing of food dyes.

3.2.2. Optimization of Experimental Parameters

DPV offers high selectivity and sensitivity towards electrochemical analysis of toxic compounds. Therefore, DPV was utilized to optimize several experimental factors to have best sensing response of dyes on the modified electrode. These factors include supporting electrolyte, volume of the modifier, and pH of the solution, deposition time and potential.

Electrolyte plays an important role in attaining a well-defined peak of analyte. It affects the peak shape, potential, and intensity. For this, the analytes (Orange II and RB dyes) were analyzed in a various supporting electrolytes including Acetate Buffer (pH = 7), Britton Robinson Buffer (pH = 7), and Phosphate Buffer (pH = 7) and obtained results are shown in Fig. 5(a). The best signals were obtained in Briton Robinson buffer because it offers high peak current and well-defined peak shapes as compared to others electrolytes. Thus, BRB was chosen as the supporting electrolyte for further study.

The effect of various amounts of the synthesized nanocomposite on electrode surface was assessed by loading different amounts of Fe₃O₄@MXene/rGO/PANI on the GCE surface and results are shown in Fig. 5b. The highest response was perceived for 5µL coating of nanocomposite onto the electrode surface. The decline in peak signals for higher volumes could be due to the formation of thick film of nanocomposite on the electrode surface which restricts the conductivity and mass transfer. Hence, 5µL drop of Fe₃O₄@MXene/rGO/PANI suspension (1.0 mg mL^− 1) was used for modification of GCE.

Deposition potential is another vital factor that affects the sensitivity and selectivity in detection of dyes. Therefore, effect of deposition potential was obtained in a range from 0 to 0.4 V in BRB of pH 7. It is seen from Fig. 5c, peak currents of the analytes were increased with the increase of deposition potential and maximum current response was achieved at 0.2 V which shows the availability of the active sites for the deposition of analytes on the electrode surface. After 0.2 V, the peak current declined with the increase of potential which may be due to the saturation of active sites. Hence, the deposition potential 0.2 V was chosen for further investigation.

Deposition time has a major influence on the electroanalytical detection of compounds. For this, the effect of deposition time from 30 s to 210 s was studied to record the resultant response of analytes via DPV (Fig. 5d). Firstly, increase in peak current was observed and maximum current is achieved at 150 s. Beyond 150 s, current response of dyes on modified electrode was decreased which could be due to saturation of active sites. Therefore, considering both sensitivity and working efficiency, a deposition time of 150 s was selected for further investigations of dyes. Whereas the analytical data of different supporting electrolytes, loading amount of modifiers, potential and time on the current response of OR II and RB are shown as Fig. S₁-S₄.

pH of the electrolyte might have major effect on the oxidation-reduction process, when protons are involved. Thus, it is essential to select a suitable pH value of electrolyte for the detection and identification of compounds. Hence, the effect of pH was inspected on Fe₃O₄@MXene/rGO/ PANI/GC electrode in BRB buffer in a range from 4.0–8.0 for the determination of dyes. Figure 6 (a) displays the oxidation current signals at different pH values. The results exhibited that the oxidation peak signals increased gradually with increase in pH values and offered highest current signal at pH 7 and after that peak current signals decreased. The oxidation peak signals verses pH values are displayed in Fig. 6 (b). The results showed that the peak potentials were shifted toward more negative value with an increase in pH. This shift in peak potential is indicated the proton participation in the electron-transfer reaction. At low pH values, adsorption of azo dyes on Fe₃O₄@MXene/rGO/PANI modified electrode surface is linked to the involvement of protons on oxidation process. Whereas, the decline in peak currents at high pH is associated to the anion formation which prevents adsorption of dyes on modified GCE. Thus, pH value of 7.0 is chosen for further study.

3.2.3. Simultaneous detection of OR II and RB

Differential pulse voltammetry was utilized to examine the mixture of OR II and RB at bare, Fe₃O₄, rGO, Fe₃O₄@MXene, and Fe₃O₄@MXene/rGO/PANI GCE’s electrodes. Figure 7 shows the resultant voltammograms of these dyes and two oxidation peaks are appeared. OR II and RB peaks observed at 0.67 V and 0.85 V. A weak signal was seen at bare GCE. Compared to the bare electrode, the Fe3O4 modified GCE displayed a rise in peak current. While the reduced graphene oxide modified GCE offered higher current intensity in comparison to iron oxide modified electrode which is due to high surface area of rGO. The addition of Fe₃O₄ into MXene sheets significantly enhanced the peak currents of both dyes. The Fe₃O₄@MXene/rGO/PANI electrode offered the highest current response for identifying OR II and RB dyes. This improvement in current signal might be combined effect of the imine (= N-) and amine (-NH-) functional groups of polyaniline, in addition to the increased surface area of Fe₃O4 and conductive path provided by MXene sheets and rGO.

3.2.4. Analytical performance of the designed Sensor

DPV was studied to inspect the limit of detection dyes (OR II and RB) under optimized experimental conditions. Figure 8(a) shows the DPV curves of the various concentration of targeted analytes which revealed that the peak currents are strongly depends on the concentration of the analytes. While Fig. 8(b-c) shows the linear calibration curve recorded for various concentrations of OR II and RB dyes from 1 to 0.005 µM. From calibrated plots, detection limits were calculated by IUPAC guidelines and found to be 0.56 and 0.42 for OR II and RB. The designed sensor exhibited good sensitivity for quantifying targeted dyes. This was due to polyaniline functionalities such as (-NH, =N-) with a large surface area of Fe₃O₄@MXene/rGO. The detection limits of our designed sensor are compared with already stated sensors as depicted in Table 1.

Table 1

Comparison of LOD of present sensor with already reported sensors.
Analyte	Electrode	Limit of detection/ (nM)	Reference
RB	Cu-carbon sphere	100	[41]
RB	GCE	6.1	[42]
RB	SPZP/NAF^a	4.3	[43]
OR II	PSS/G^b	10	[44]
OR II	Fe₂O₃/MWCNTs-COOH/OP/CPE^c	100	[45]
OR II	ZnO/NH₂-fMWCNTs^d	0.57	[1]
OR II	Fe₃O₄@MXene/rGO/PANI	0.56	This Work
RB	Fe₃O₄@MXene/rGO/PANI	0.42	This Work
^a silica-pillared zirconium phosphate/nafion composite
^b poly(sodium p-styrenesulfonate)-functionalized graphenemodifed glassy carbon electrode
^cFe₂O₃ nano-materials/oxygen functionalized multi-walled carbon nanotubes/triton X-100
fied carbon paste electrode
^dzinc oxide nanoparticles /amino group functionalized MWCNT

3.2.5. Estimation of the Stability of the Designed Sensor

The stability of the designed sensor was assessed in terms of its reproducibility and repeatability. Under optimized conditions, sensor’s stability was evaluated in the presence of OR II and RB dyes via electrochemical methods. For determining the stability, eight differential pulse voltammograms were recorded on Fe₃O₄@MXene/rGO/PANI/GCE in BRB solution of pH 7 (Fig. S₅). A minor change in the current intensity was seen which suggested that the designed sensor exhibited good stability. To confirm that the reliability of the designed sensor, six independent Fe₃O₄@MXene/rGO/PANI/GCEs were developed via similar procedure (Fig. S₆). No significant deviation in the terms of current signal was observed as seen from Fig. 9 (a-b). The relative standard deviation values for both reproducibility and stability were calculated and had value less than 5%, which showed that the designed sensor is very precise and stable.

3.2.6. Validation of the Designed Sensor

Due to the existence of the various inorganic and organic species in the water, sensitive and selective identification of dyes is a major challenge. The effect of interfering species on current signal of targeted analytes depends upon on their redox potential as well as their interaction with the nanomaterial on electrode surface. Therefore, effect of interfering species on the current signal of food dyes (OR II and RB) were established using 50-fold higher concentration of various interfering species comprising Na¹⁺, K¹⁺, Cl¹⁻, NO₃¹⁻ glycine, 4-NP. The obtained results of designed sensor in the presence and absence of interfering species are displayed in Fig. 10 (a & b). It is observed that the current signals of both OR II and RB on Fe₃O₄@MXene/rGO/PANI/GCE were not much affected by the presence of interfering agents. Hence, the designed senor possessed excellent anti-interference ability.

3.2.7. Real Sample applicability of the designed sensor

To test the practical application of the designed senor, amount of OR II and RB are determined in tap water, drinking water and fruit juice via standard addition method. Initially, OR II an RB were not found in real samples. Then, known amount of these dyes were added by standard addition method and their responses were recorded via DPV. The obtained results of the detected recoveries and RSD are listed in Table 2 which showed that designed senor have demonstrated good sensitivity towards these dyes.

Table 2

Detection of OR II and RB dyes in real samples.
Sample	Analyte	Spiked amount (µM)	Amount Found (µM)	Recovery (%)	RSD (%)
Tap water	OR II	1.0	0.98	98	1.43
Tap water	RB	1.0	0.97	97	2.15
Drinking Water	OR II	1.0	0.97	97	2.15
Drinking Water	RB	1.0	0.96	97	2.15
Fruit Juice	OR II	1.0	0.99	99	0.71
Fruit Juice	RB	1.0	0.98	98	1.43

In this study, Fe₃O₄ decorated MXene/rGO/PANI nanocomposite was successfully synthesized via in-situ oxidation method, and employed as an active electrode material to develop an electrochemical sensor for the determination of OR II and RB. The presence of all peaks in XRD spectra confirmed the incorporation of iron oxide, rGO, MXene and PANI in composite. The experimental results exhibited that the nano-hybrid material have the individual material’s peak signifying that they are blending well, and it was also confirmed from FTIR results where the functional group and vibrational mode of all individuals are seen. Owing to the unique properties of Fe₃O₄@MXene/rGO/PANI material, such as strong adsorptive ability, more active sites, high surface area and good electronic property, the iron oxide decorated MXene/rGO/PANI nanocomposite enhanced the oxidation current of Orange II and Rhodamine B dyes. Under optimum conditions, designed sensor presented LOD with a value of 0.56 nM for OR II and 0.42 nM for RB calculated from the slope of calibration graph. In addition, the designed Fe₃O₄@MXene/rGO/PANI/GCE sensor exhibited good selectivity, excellent stability and good recoveries for the detection of dyes in real samples. This study offers a new methodology for the reliable and rapid sensing of dyes using Fe₃O₄@MXene/rGO/PANI material.

Author Contribution

MA, AA and TA: all experimental workAF and AA: Structural analysis and data validationIS and MW: Management of entire project

Acknowledgements:

The authors extend their appreciation to Taif University, Saudi Arabia for supporting this work through project number (TU-DSPP-2024-95). Authors also thankful the Institute of Chemistry, BJ Campus, The Islamia University of Bahawalpur-Pakistan and HEC-Islamabad, Pakistan.

M. Irfan, A. Shah, F.J. Iftikhar, M. Hayat, M.N. Ashiq, I. Shah, Electrochemical sensing platform based on functionalized multi-walled carbon nanotubes and metal oxide for the detection and degradation studies of orange II dye, ACS omega, 7 (2022) 32302–32312.
R. Al-Tohamy, S.S. Ali, F. Li, K.M. Okasha, Y.A.-G. Mahmoud, T. Elsamahy, H. Jiao, Y. Fu, J. Sun, A critical review on the treatment of dye-containing wastewater: Ecotoxicological and health concerns of textile dyes and possible remediation approaches for environmental safety, Ecotoxicology and Environmental Safety, 231 (2022) 113160.
S. Sharma, A. Bhattacharya, Drinking water contamination and treatment techniques, Applied water science, 7 (2017) 1043–1067.
S. Khalid, M. Shahid, I. Bibi, T. Sarwar, A.H. Shah, N.K. Niazi, A review of environmental contamination and health risk assessment of wastewater use for crop irrigation with a focus on low and high-income countries, International journal of environmental research and public health, 15 (2018) 895.
G.A. Ismail, H. Sakai, Review on effect of different type of dyes on advanced oxidation processes (AOPs) for textile color removal, Chemosphere, 291 (2022) 132906.
S.J. Hewlings, D.S. Kalman, Curcumin: A review of its effects on human health, Foods, 6 (2017) 92.
A. Gottlieb, C. Shaw, A. Smith, A. Wheatley, S. Forsythe, The toxicity of textile reactive azo dyes after hydrolysis and decolourisation, J. Biotechnol., 101 (2003) 49–56.
S.H. Hashemi, M. Kaykhaii, Azo dyes: sources, occurrence, toxicity, sampling, analysis, and their removal methods, Emerging freshwater pollutants, Elsevier2022, pp. 267–287.
Q. Lu, W. Gao, J. Du, L. Zhou, Y. Lian, Discovery of environmental rhodamine B contamination in paprika during the vegetation process, Journal of agricultural and food chemistry, 60 (2012) 4773–4778.
J. Ji, Y. Liu, X.-y. Yang, J. Xu, X.-y. Li, Multiple response optimization for high efficiency energy saving treatment of rhodamine B wastewater in a three-dimensional electrochemical reactor, Journal of environmental management, 218 (2018) 300–308.
X. Su, X. Li, J. Li, M. Liu, F. Lei, X. Tan, P. Li, W. Luo, Synthesis and characterization of core–shell magnetic molecularly imprinted polymers for solid-phase extraction and determination of Rhodamine B in food, Food chemistry, 171 (2015) 292–297.
A. Shah, M.S. Malik, A. Zahid, F.J. Iftikhar, A. Anwar, M.S. Akhter, M.R. Shah, M.A. Zia, M.N. Ashiq, A.H. Shah, Carbamazepine coated silver nanoparticles for the simultaneous electrochemical sensing of specific food toxins, Electrochimica Acta, 274 (2018) 131–142.
A. Yadav, A. Kumar, P.D. Dwivedi, A. Tripathi, M. Das, In vitro studies on immunotoxic potential of Orange II in splenocytes, Toxicology letters, 208 (2012) 239–245.
R. Singh, S. Khanna, G. Singh, Acute and short-term toxicity studies on orange II, Veterinary and Human Toxicology, 29 (1987) 300–304.
B. Tang, C. Xi, Y. Zou, G. Wang, X. Li, L. Zhang, D. Chen, J. Zhang, Simultaneous determination of 16 synthetic colorants in hotpot condiment by high performance liquid chromatography, Journal of Chromatography B, 960 (2014) 87–91.
G. Fang, Y. Wu, X. Dong, C. Liu, S. He, S. Wang, Simultaneous determination of banned acid orange dyes and basic orange dyes in foodstuffs by liquid chromatography–tandem electrospray ionization mass spectrometry via negative/positive ion switching mode, Journal of agricultural and food chemistry, 61 (2013) 3834–3841.
N. Pourreza, M. Zareian, Determination of Orange II in food samples after cloud point extraction using mixed micelles, Journal of Hazardous Materials, 165 (2009) 1124–1127.
S. Takeda, Y. Tanaka, Y. Nishimura, M. Yamane, Z. Siroma, S.-i. Wakida, Analysis of dyestuff degradation products by capillary electrophoresis, Journal of Chromatography A, 853 (1999) 503–509.
X. Zhu, G. Wu, C. Wang, D. Zhang, X. Yuan, A miniature and low-cost electrochemical system for sensitive determination of rhodamine B, Measurement, 120 (2018) 206–212.
H. Karimi-Maleh, H. Beitollahi, P.S. Kumar, S. Tajik, P.M. Jahani, F. Karimi, C. Karaman, Y. Vasseghian, M. Baghayeri, J. Rouhi, Recent advances in carbon nanomaterials-based electrochemical sensors for food azo dyes detection, Food and Chemical Toxicology, (2022) 112961.
R. Tariq, S. Zulfiqar, H. Somaily, M.F. Warsi, I. Ayman, F. Hanif, M. Akhtar, M. Aadil, Synthesis of carbon supported iron oxide nanochips and their composite with glutathione: A novel electrochemical sensitive material, Surfaces and Interfaces, 34 (2022) 102350.
Q. Zhao, Z. Gan, Q. Zhuang, Electrochemical sensors based on carbon nanotubes, Electroanalysis: An International Journal Devoted to Fundamental and Practical Aspects of Electroanalysis, 14 (2002) 1609–1613.
S. Wu, Q. He, C. Tan, Y. Wang, H. Zhang, Graphene-based electrochemical sensors, small, 9 (2013) 1160–1172.
L. Rassaei, F. Marken, M. Sillanpaa, M. Amiri, C.M. Cirtiu, M. Sillanpaa, Nanoparticles in electrochemical sensors for environmental monitoring, TrAC, Trends Anal. Chem., 30 (2011) 1704–1715.
F. Wang, S. Hu, Electrochemical sensors based on metal and semiconductor nanoparticles, Microchim. Acta, 165 (2009) 1–22.
G. Sriram, P. Patil, M.P. Bhat, R.M. Hegde, K.V. Ajeya, I. Udachyan, M. Bhavya, M.G. Gatti, U. Uthappa, G.M. Neelgund, Current trends in nanoporous anodized alumina platforms for biosensing applications, J. Nanomater., 2016 (2016).
M. Naguib, M. Kurtoglu, V. Presser, J. Lu, J. Niu, M. Heon, L. Hultman, Y. Gogotsi, M.W. Barsoum, Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2, Advanced materials, 23 (2011) 4248–4253.
M. Naguib, O. Mashtalir, J. Carle, V. Presser, J. Lu, L. Hultman, Y. Gogotsi, M.W. Barsoum, Two-dimensional transition metal carbides, ACS nano, 6 (2012) 1322–1331.
X. Tu, F. Gao, X. Ma, J. Zou, Y. Yu, M. Li, F. Qu, X. Huang, L. Lu, Mxene/carbon nanohorn/β-cyclodextrin-Metal-organic frameworks as high-performance electrochemical sensing platform for sensitive detection of carbendazim pesticide, Journal of Hazardous Materials, 396 (2020) 122776.
W. Zhong, F. Gao, J. Zou, S. Liu, M. Li, Y. Gao, Y. Yu, X. Wang, L. Lu, MXene@ Ag-based ratiometric electrochemical sensing strategy for effective detection of carbendazim in vegetable samples, Food Chemistry, 360 (2021) 130006.
K. Huang, Z. Li, J. Lin, G. Han, P. Huang, Two-dimensional transition metal carbides and nitrides (MXenes) for biomedical applications, Chemical Society Reviews, 47 (2018) 5109–5124.
D. Mahanta, N. Munichandraiah, S. Radhakrishnan, G. Madras, S. Patil, Polyaniline modified electrodes for detection of dyes, Synthetic metals, 161 (2011) 659–664.
M. Akhtar, A. Tahir, S. Zulfiqar, F. Hanif, M.F. Warsi, P.O. Agboola, I. Shakir, Ternary hybrid of polyaniline-alanine-reduced graphene oxide for electrochemical sensing of heavy metal ions, Synthetic Metals, 265 (2020) 116410.
W.S. Hummers Jr, R.E. Offeman, Preparation of graphitic oxide, Journal of the American Chemical Society, 80 (1958) 1339–1339.
P.S. Chauhan, K. Kumar, K. Singh, S. Bhattacharya, Fast decolorization of rhodamine-B dye using novel V2O5-rGO photocatalyst under solar irradiation, Synthetic Metals, 283 (2022) 116981.
R. Manna, S.K. Srivastava, Reduced graphene oxide/Fe3O4/polyaniline ternary composites as a superior microwave absorber in the shielding of electromagnetic pollution, ACS omega, 6 (2021) 9164–9175.
Y. Cui, M. Liu, H. Huang, D. Zhang, J. Chen, L. Mao, N. Zhou, F. Deng, X. Zhang, Y. Wei, A novel one-step strategy for preparation of Fe3O4-loaded Ti3C2 MXenes with high efficiency for removal organic dyes, Ceramics International, 46 (2020) 11593–11601.
H. Liu, Y. Wang, X. Gou, T. Qi, J. Yang, Y. Ding, Three-dimensional graphene/polyaniline composite material for high-performance supercapacitor applications, Materials Science and Engineering: B, 178 (2013) 293–298.
A. Shah, M. Akhtar, S. Aftab, A.H. Shah, H.-B. Kraatz, Gold copper alloy nanoparticles (Au-Cu NPs) modified electrode as an enhanced electrochemical sensing platform for the detection of persistent toxic organic pollutants, Electrochimica Acta, 241 (2017) 281–290.
F. Cai, Q. Wang, X. Chen, W. Qiu, F. Zhan, F. Gao, Q. Wang, Selective binding of Pb2 + with manganese-terephthalic acid MOF/SWCNTs: theoretical modeling, experimental study and electroanalytical application, Biosensors and Bioelectronics, 98 (2017) 310–316.
J. Sun, T. Gan, Y. Li, Z. Shi, Y. Liu, Rapid and sensitive strategy for Rhodamine B detection using a novel electrochemical platform based on core–shell structured Cu@ carbon sphere nanohybrid, Journal of Electroanalytical Chemistry, 724 (2014) 87–94.
L. Yu, Y. Mao, L. Qu, Simple voltammetric determination of rhodamine B by using the glassy carbon electrode in fruit juice and preserved fruit, Food Analytical Methods, 6 (2013) 1665–1670.
J. Zhang, L. Zhang, W. Wang, Z. Chen, Sensitive electrochemical determination of rhodamine B based on a silica-pillared zirconium phosphate/nafion composite modified glassy carbon electrode, Journal of AOAC International, 99 (2016) 760–765.
Y. Gao, Z. Xie, Y. Zhang, L. Zou, B. Ye, A simple and sensitive voltammetric method for the determination of orange II based on a functionalized graphene-modified electrode, Journal of AOAC International, 99 (2016) 1287–1294.
Z. Liu, H. Zhai, Z. Chen, Q. Zhou, Z. Liang, Z. Su, Simultaneous determination of Orange G and Orange II in industrial wastewater by a novel Fe2O3/MWCNTs-COOH/OP modified carbon paste electrode, Electrochimica Acta, 136 (2014) 370–376.

Schemes 1 to 3 are available in the Supplementary Files section

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

Fe₃O₄@MXene/rGO/PANI Composite: A Novel Sensing Material for the Electrochemical Detection of Orange II and Rhodamine B Food Dyes

Status:

Version 1

Abstract

Figures

1. Introduction

2. Experimental details

2.1. Chemicals and apparatus

2.2. Synthesis of Fe₃O₄

2.3. Synthesis of MXene

2.4. Synthesis of Fe₃O₄@MXene

2.5. Synthesis of GO and rGO

2.6. Synthesis of Fe₃O₄@MXene/rGO/PANI

3. Results and discussion

3.1. Characterization of Fe₃O₄@MXene/rGO/PANI composites

3.1.1. XRD studies

3.1.2. FTIR studies

3.1.3. SEM studies

3.2. Electrochemical analysis of OR II and RB

3.2.1. Characterization of Fe₃O₄@MXene/rGO/PANI/GCE by EIS, CV and CC

3.2.2. Optimization of Experimental Parameters

3.2.3. Simultaneous detection of OR II and RB

3.2.4. Analytical performance of the designed Sensor

3.2.5. Estimation of the Stability of the Designed Sensor

3.2.6. Validation of the Designed Sensor

3.2.7. Real Sample applicability of the designed sensor

Conclusion

Declarations

Author Contribution

Acknowledgements:

References

Schemes

Additional Declarations

Supplementary Files

Status:

Version 1

Fe3O4@MXene/rGO/PANI Composite: A Novel Sensing Material for the Electrochemical Detection of Orange II and Rhodamine B Food Dyes

Status:

Version 1

Abstract

Figures

1. Introduction

2. Experimental details

2.1. Chemicals and apparatus

2.2. Synthesis of Fe3O4

2.3. Synthesis of MXene

2.4. Synthesis of Fe3O4@MXene

2.5. Synthesis of GO and rGO

2.6. Synthesis of Fe3O4@MXene/rGO/PANI

3. Results and discussion

3.1. Characterization of Fe3O4@MXene/rGO/PANI composites

3.1.1. XRD studies

3.1.2. FTIR studies

3.1.3. SEM studies

3.2. Electrochemical analysis of OR II and RB

3.2.1. Characterization of Fe3O4@MXene/rGO/PANI/GCE by EIS, CV and CC

3.2.2. Optimization of Experimental Parameters

3.2.3. Simultaneous detection of OR II and RB

3.2.4. Analytical performance of the designed Sensor

3.2.5. Estimation of the Stability of the Designed Sensor

3.2.6. Validation of the Designed Sensor

3.2.7. Real Sample applicability of the designed sensor

Conclusion

Declarations

Author Contribution

Acknowledgements:

References

Schemes

Additional Declarations

Supplementary Files

Status:

Version 1

Fe₃O₄@MXene/rGO/PANI Composite: A Novel Sensing Material for the Electrochemical Detection of Orange II and Rhodamine B Food Dyes

2.2. Synthesis of Fe₃O₄

2.4. Synthesis of Fe₃O₄@MXene

2.6. Synthesis of Fe₃O₄@MXene/rGO/PANI

3.1. Characterization of Fe₃O₄@MXene/rGO/PANI composites

3.2.1. Characterization of Fe₃O₄@MXene/rGO/PANI/GCE by EIS, CV and CC