**3. Results and discussion**

The structural analysis of the tragacanth gum/chitosan/ZnO nanoprism material was performed by X-ray diffraction (XRD) (**Figure 2**).

As seen in **Figure 2**, according to XRD analysis, strong peaks were observed at 2θ = 13°, 31°, which corresponds to the tragacanth gum/chitosan/ZnO crystalline planes. In the experiments, crystalline-structured tragacanth gum/chitosan/ZnO nanoprisms provided the advantage of obtaining a high surface area for higher interaction and reaction of sensing tragacanth gum/chitosan/ZnO nanoprism thin film on gold transducer-reactive dye with high electron mobility in terms of crystalline structure. SEM and EDX analyses of the prepared tragacanth gum/chitosan/ ZnO nanoprisms were performed (**Figure 3**).

The EDX technique was employed to obtain some information on the spatial distribution of the corresponding elements. The EDX analysis of tragacanth gum/ chitosan/ZnO nanoprisms provides the average percentage of zinc (Zn) and oxygen (O) at different points. All these suggest efficient preparation and presence of targeted atoms in tragacanth gum/chitosan/ZnO nanoprisms. The polymer matrix (tragacanth gum/chitosan) provides enormously large surface area for dispersion that helps ZnO to grow in the form of nanoprisms with higher reactivity for redox processing. The homogenous dispersion of ZnO in polymer matrix enhances conductivity and stability of the nanostructure. The complementary properties of tragacanth gum/chitosan/ZnO nanoprism generate a synergistic effect to enhance the electrochemical performance and provide improved charge exchange efficiency and stability during redox cycling.

Cyclic voltammetry measurements were performed to analyze the electrochemical sensor performance of tragacanth gum/chitosan/ZnO nanoprism-coated gold

**7**

red 35 (Eqs. (1)–(3)).

*A Novel Electrochemical Sensor for the Detection of Reactive Red Dye to Determine Water Quality*

transducer. Current-voltage curves of tragacanth gum/chitosan/ZnO nanoprismcoated gold transducers against reactive red 35, reactive yellow 15, and reactive black 194 were obtained, respectively, in [−1, +10] V range with a scan rate of 50 mV/s at room temperature in real-time measurements by Ebtro voltammetric

*(a) SEM and (b) EDX analysis of tragacanth gum/chitosan/ZnO nanoprisms.*

**Figure 4** shows the comparative current-voltage curves of tragacanth gum/ chitosan/ZnO nanoprism-coated gold transducers against reactive red dye, reactive yellow dye, and reactive black dye in [−1, +10] V range with a scan rate of 50 mV/s at room temperature. The measured current responses were due to either oxidation or reduction of the reactive dye analytes over the entire cycle at the surface of the bare gold transducers. The current peaks arised from redox reactions between tragacanth gum/chitosan/ZnO nanoprism and reactive red dye molecules observed. The curves showed that there are no peaks arising from reactive yellow and black dye molecules as redox reactions did not occur between tragacanth gum/chitosan/ZnO nanoprism and reactive yellow and black dye molecules. The goal of this research was to evaluate the performance of the tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer of the voltammetric electrochemical sensor in discriminating different reactive dyes in water. In this context, we focused on the electrochemical sensing capability tragacanth gum/chitosan/ZnO nanoprisms against to reactive dye-consisted water. The electrochemical oxidation of reactive red dye-consisted water was observed using the scan rate of 50 mV/s at room temperature over a potential range of −0.2 to 0.8 V. In **Figure 4**, current-voltage curves of tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer indicated a prominent redox peak for reactive red dye, while the other tragacanth gum/chitosan/ZnO nanoprism-coated gold transducers indicated no redox peak for reactive yellow and black dyes in water.

<sup>−</sup> branches of the reactive

(2)

→ Zn<sup>0</sup> (1)

2− + Zn<sup>0</sup> + 2H<sup>+</sup> (3)

−

2− + 2H<sup>+</sup> + 2e

*DOI: http://dx.doi.org/10.5772/intechopen.92280*

electrochemical workstation (**Figure 4**).

**Figure 3.**

The redox peak was attributed to a large number of SO3

SO3

Zn2+ + SO3

Zn2+ + 2e<sup>−</sup>

2− + H2O → SO4

2− + H2O → SO4

**Figure 2.** *XRD analysis of tragacanth gum/chitosan/ZnO nanoprisms.*

*A Novel Electrochemical Sensor for the Detection of Reactive Red Dye to Determine Water Quality DOI: http://dx.doi.org/10.5772/intechopen.92280*

**Figure 3.** *(a) SEM and (b) EDX analysis of tragacanth gum/chitosan/ZnO nanoprisms.*

transducer. Current-voltage curves of tragacanth gum/chitosan/ZnO nanoprismcoated gold transducers against reactive red 35, reactive yellow 15, and reactive black 194 were obtained, respectively, in [−1, +10] V range with a scan rate of 50 mV/s at room temperature in real-time measurements by Ebtro voltammetric electrochemical workstation (**Figure 4**).

**Figure 4** shows the comparative current-voltage curves of tragacanth gum/ chitosan/ZnO nanoprism-coated gold transducers against reactive red dye, reactive yellow dye, and reactive black dye in [−1, +10] V range with a scan rate of 50 mV/s at room temperature. The measured current responses were due to either oxidation or reduction of the reactive dye analytes over the entire cycle at the surface of the bare gold transducers. The current peaks arised from redox reactions between tragacanth gum/chitosan/ZnO nanoprism and reactive red dye molecules observed. The curves showed that there are no peaks arising from reactive yellow and black dye molecules as redox reactions did not occur between tragacanth gum/chitosan/ZnO nanoprism and reactive yellow and black dye molecules. The goal of this research was to evaluate the performance of the tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer of the voltammetric electrochemical sensor in discriminating different reactive dyes in water. In this context, we focused on the electrochemical sensing capability tragacanth gum/chitosan/ZnO nanoprisms against to reactive dye-consisted water. The electrochemical oxidation of reactive red dye-consisted water was observed using the scan rate of 50 mV/s at room temperature over a potential range of −0.2 to 0.8 V. In **Figure 4**, current-voltage curves of tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer indicated a prominent redox peak for reactive red dye, while the other tragacanth gum/chitosan/ZnO nanoprism-coated gold transducers indicated no redox peak for reactive yellow and black dyes in water. The redox peak was attributed to a large number of SO3 <sup>−</sup> branches of the reactive red 35 (Eqs. (1)–(3)).

$$\text{Zn}^{2+} + \text{2e}^{-} \rightarrow \text{Zn}^{0} \tag{1}$$

$$\text{SO}\_3^{2-} \text{ + } \text{H}\_2\text{O} \rightarrow \text{SO}\_4^{2-} \text{ + } 2\text{H}^+ \text{ + } 2\text{e}^- \tag{2}$$

$$\text{Zn}^{2+} + \text{SO}\_3^{2-} + \text{H}\_2\text{O} \rightarrow \text{SO}\_4^{2-} + \text{Zn}^0 + 2\text{H}^\* \tag{3}$$

After these obtained results, sensor measurements were performed for determining reactive red dye. The different concentrations of reactive red dye were tested on tragacanth gum/chitosan/ZnO nanoprism-coated gold transducers in [−1, +10] V range with a scan rate of 50 mV/s at room temperature. Current peaks arised from redox reactions which came from between tragacanth gum/chitosan/ ZnO nanoprism and reactive red dye molecules increased with increasing reactive red concentration in the range of 25–100 ppm. As the concentration of the reactive red dye molecules in the water increases, redox reactions increase the sensitivity of the sensor. Prepared tragacanth gum/chitosan/ZnO nanoprismbased electrochemical sensor detected 25 ppm reactive red dye in 1 min at room temperature.

The reproducibility of the tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer was investigated by analyzing reactive red dye for four times. To ascertain the reproducibility results, the cyclic voltammetry experiments were carried out using the transducers under similar conditions. The peak currents for reactive red dye have not changed much even after a week. This showed the stability of the tragacanth gum/chitosan/ZnO nanoprism-coated gold transducer.

#### **Figure 4.**

*Current-voltage curves of tragacanth gum/chitosan/ZnO nanoprism-coated gold transducers against (a) reactive red dye, reactive yellow dye, and reactive black dye and (b) different reactive red dye concentrations in 25–100 ppm, [−1, +10] V range with a scan rate of 50 mV/s.*

**9**

Turkey

**Author details**

**Acknowledgements**

Rifat Kolatoğlu1

Adıyaman, Turkey

, Nuray Beköz Üllen5

Maltepe University, Istanbul, Turkey

2 ABB Electronics, Istanbul, Turkey

Cerrahpaşa, Istanbul, Turkey

provided the original work is properly cited.

Elif Tüzün4

*A Novel Electrochemical Sensor for the Detection of Reactive Red Dye to Determine Water Quality*

In this study, for environmental monitoring of reactive dye-consisting wastewater, the novel tragacanth gum/chitosan/ZnO nanoprism-based electrochemical sensor was prepared and tested via cyclic voltammetry technique. The electrochemical measurement results indicate that prepared tragacanth gum/chitosan/ZnO nanoprism-based electrochemical sensor has a higher sensitivity against reactive red dye than reactive yellow dye and reactive black dye in water. Prepared tragacanth gum/ chitosan/ZnO nanoprism-based electrochemical sensor detected 25 ppm reactive red dye in 1 min at room temperature. This study reveals new high-potential sensing material for the detection of reactive dye-consisting wastewater with high sensitivity and short response time. It is the first time that the sensing interaction of tragacanth gum/chitosan/ZnO nanoprisms and reactive red dye was explained.

, Enes Aydin1,2, Mehtap Demir1,3, Ahmet Yildiz4

This research was supported by TUBITAK Project 216M421.

3 Department of Metallurgy and Material Engineering, Adiyaman University,

4 Department of Chemistry, İstanbul University-Cerrahpaşa, Istanbul, Turkey

5 Department of Metallurgical and Materials Engineering, İstanbul University-

6 Department of Renewable Energy Technology, Maltepe University, Istanbul,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: nevintasaltin@maltepe.edu.tr

1 Department of Electrical-Electronics Engineering, Sensor Technology Laboratory,

, Nevin Taşaltın1,6\* and Ayben Kilislioğlu4

, Selcan Karakuş4

,

*DOI: http://dx.doi.org/10.5772/intechopen.92280*

**4. Conclusions**

*A Novel Electrochemical Sensor for the Detection of Reactive Red Dye to Determine Water Quality DOI: http://dx.doi.org/10.5772/intechopen.92280*
