# Polypyrrole coated hematite sand (HS@Ppy) as a new catalyst for degradation of organic dye based on sulfate radicals

Abdellah Ait El Fakir, Zakaria Anfar, Amane Jada, Noureddine El Alem

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Abdellah Ait El Fakir, Zakaria Anfar, Amane Jada, Noureddine El Alem. Polypyrrole coated hematite sand (HS@Ppy) as a new catalyst for degradation of organic dye based on sulfate radicals. 7th International Conference on Intelligent Textiles & Mass Customisation (ITMC 2019), Nov 2019, Marrakech, Morocco. pp.012011, 10.1088/1757-899x/827/1/012011. [hal-03045391](https://hal.science/hal-03045391)

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# Polypyrrole coated hematite sand (HS@Ppy) as a new catalyst for degradation of organic dye based on sulfate radicals

To cite this article: A Ait El Fakir et al 2020 IOP Conf. Ser.: Mater. Sci. Eng. 827 012011

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EXTENDED ABSTRACT DEADLINE: DECEMBER 18, 2020

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# Polypyrrole coated hematite sand (HS@Ppy) as a new catalyst for degradation of organic dye based on sulfate radicals

A Ait El Fakir¹, ², Z Anfar¹, ², ³, A Jada², ³, ⁴, N. El Alem¹

¹ Laboratoire Matériaux et Environnement (LME), Université Ibn Zohr, Agadir, 8000, Morocco.

²Institut de Sciences Des Matériaux De Mulhouse (IS2M-UMR 7361 CNRS - UHA), France.

³ Université de Strasbourg, Strasbourg, F-67081, France.

⁴ Author to whom any correspondence should be addressed

amane.jada@uha.fr

**Abstract.** The present work deals with the degradation in water of organic dye such as Orange G by using sulphate radicals as oxidant. Thus, a new catalyst based on polypyrrole coated hematite sand particles, (HS@Ppy) was first prepared. Thereafter, sulphate radicals were produced by activating the persulfate (PS) agent in the presence of the HS@Ppy catalyst. The resulted HS@Ppy/PS system was finally mixed with Orange G aqueous solutions for dye degradation. The data indicate that polypyrrole shell coating amount in the HS@Ppy particles has a great influence on the Orange G degradation. The HS@Ppy/PS system exhibited the highest OG removal rate (the removal rate is 98 % after 15 minutes of reaction) as compared to the various systems: PS alone, HS@Ppy alone, or HS/PS alone.

## 1. Introduction

The discharge of wastewater into the environment, including dyes, is considered as a toxicological and aesthetic problem. Indeed, many industries (textiles, paper, leather, etc.) continue to generate various pollutants and toxic azo dyes [1,2]. Most of them are non-biodegradable, toxic and potentially carcinogenic compared to the previous work on the oxidation of organic pollutants by sulphate radicals SO⁺ [3-5]. In this present research, our objective is to find efficient and less expensive catalysts for the depollution of wastewater by the valorization of natural resources. In this sense, a natural and magnetic hematite sand (HS) catalyst has been used as a (persulfate) PS activating agent. This study provides enhanced catalytic properties of sand hematite as a new catalyst for the in situ remediation of waters contaminated with organic pollutants. Besides, this method is considered to be less expensive in terms of operating costs.

## 2. Material and Methods

The hematite sand used in this work was taken from the Taghazout beach, 23 km from the city of Agadir Morocco. The pyrrole monomer (Aldrich) was distilled before use. The preparation of our composite material (polypyrrole coated hematite sand (HS@Ppy)) was carried out by a simple polymerization with a known monomer / oxidant ratio. The physico-chemical properties of HS@Ppy were determined by using various structural, microstructural, and spectroscopic techniques such as XRD, FX, MEB/EDS, FTIR, and ATG. The catalytic degradation of dye by the HS@Ppy / PS system was carried out in a 100 mL beaker containing 50 mL of solution of dye at room temperature and with constant stirring. Catalyst

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(1 g.L⁻¹) and PS (Na₂S₂O₈) concentration was (45 mg.L⁻¹) were added to the reaction.

### 3. Results and discussions

Thermogravimetric analysis (TGA) under air atmosphere was employed to quantify the coating amount of Ppy shell (Figure 1). For HS@Ppy, the weight rise region was displaced by an obvious weight loss stage in 200-500 °C resulting from the decomposition of polymer shell. The total mass losses (Wₜ) are 22%, 18%, 16% and 10% for HS@Ppy-4 to HS@Ppy-1 respectively. The ratio of Ppy shell (Wₚₚ) was calculated by Equation (1):

$$W_{Ppy} = W_{T} - W_{H2O} \quad (1)$$

Where W<sub>H₂O</sub> the ratio of H₂O (<150 °C).

The results suggested the ratio of polypyrrole to vary from 8% to 20%. The influence of shell coating amount on Orange G degradation was investigated. HS@Ppy-3 exhibited the highest OG removal rate, and was used in the following experiments (Figure 2a). The catalytic performance of our catalysts has been shown in Figure 2b. It can clearly be seen that the HS@Ppy / PS system exhibits high fading efficiency with respect to the OG toxic molecule (the removal rate is 98 % after 15 minutes of reaction). In the absence of PS, the kill rate of OG was approximately 10 % after 18 min. This is probably due to the adsorption capacity of HS@Ppy / PS and that the PS was not able to degrade the OG directly without activating agent and without light irradiation.

<figure><img src="image_5.png" /><figcaption>Figure 1. TG curves of HS, HS@Ppy-1, HS@Ppy-2, HS@Ppy-3 and HS@Ppy-4.</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>**Figure 2.** (a) Orange G degradation with HS@Ppy-1, HS@Ppy-2, HS@Ppy-3 and HS@Ppy-4. (b) Orange G degradation by various catalytic PS systems. Conditions: [PS] = 2 mM, [HS@Ppy] = 1 g.L⁻¹, [OG] = 45 mg/L, room temperature, ambient pH.</figcaption></figure>

**4. Conclusion**

This study proposes a way for the preparation of a new natural catalyst based on hematite sand. The prepared polypyrrol coated hematite sand compounds were found very effective in activating the persulfate and producing large amount of sulfate radicals to degrade Orange G molecules.

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