# Enhanced Solubilisation of Insecticide Phosalone by Using Anionic and Cationic Surfactants in Aqueous Solution by Micellisation

Abdou Khadre Cissé, Nehou Diouf, Coumba Faye, Ibrahima Sarr, Souleymane Sambou, Aly Cissé, Boubacar Sidibé, Astou Ndiaye, El Hadji Tombé Bodian, Diène Diégane Thiaré, et al.

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Abdou Khadre Cissé, Nehou Diouf, Coumba Faye, Ibrahima Sarr, Souleymane Sambou, et al. "Enhanced Solubilisation of Insecticide Phosalone by Using Anionic and Cationic Surfactants in Aqueous Solution by Micellisation." Asian Journal of Chemical Sciences, 2024, 14, pp.137 - 147. 10.9734/ajocs/2024/v14i6340. [hal-04825378](https://hal.science/hal-04825378v1)

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# Enhanced Solubilisation of Insecticide Phosalone by Using Anionic and Cationic Surfactants in Aqueous Solution by Micellisation

Abdou Khadre Cissé a, Nehou Diouf a, Coumba Faye a,
Ibrahima Sarr a, Souleymane Sambou a, Aly Cissé a,
Boubacar Sidibé a, Astou Ndiaye a,
El Hadji Tombé Bodian a, Diène Diégane Thiaré a*
and Atanasse Coly a

a Laboratoire de Photochimie et d'Analyse (LPA), Faculté des Sciences et Techniques, Université Cheikh Anta Diop, BP 5005, Dakar, Sénégal.

## Authors' contributions

This work was carried out in collaboration among all authors. Author AKC conducted the investigation and drafted the original manuscript. Authors ND and CF contributed to the investigation and software work. IS and SS performed data curation and additional investigation. Authors AC and BS were responsible for software work and methodology development, while AN also contributed to methodology refinement. Author EHTB contributed to data visualization, investigation, and the drafting of the manuscript. Author DDT supervised the research, and contributed to drafting, reviewing, editing, and validating the manuscript. Author AC conceptualized the study, supervised the project, and was involved in drafting, reviewing, editing, and validating the manuscript. All authors read and approved the final manuscript.

## Article Information

DOI: https://doi.org/10.9734/ajocs/2024/v14i6340

**Open Peer Review History:**
This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/126926

## Original Research Article

Received: 21/09/2024

Accepted: 24/11/2024

Published: 28/11/2024

<footnote>*Corresponding author: E-mail: thiaredienediegane@yahoo.fr;</footnote>

<footnote>**Cite as:** Cissé, Abdou Khadre, Nehou Diouf, Coumba Faye, Ibrahima Sarr, Souleymane Sambou, Aly Cissé, Boubacar Sidibé, Astou Ndiaye, El Hadji Tombé Bodian, Diène Diégane Thiaré, and Atanasse Coly. 2024. "Enhanced Solubilisation of Insecticide Phosalone by Using Anionic and Cationic Surfactants in Aqueous Solution by Micellisation". Asian Journal of Chemical Sciences 14 (6):137-47. https://doi.org/10.9734/ajocs/2024/v14i6340.</footnote>
ABSTRACT

The objective of this study is to enhance the solubility of the insecticide phosalone in aqueous solution through micellisation. The cationic cetyltrimethylammonium chloride (CTAC) and the anionic sodium dodecyl sulfate (SDS) surfactants were used. The study employs a conductometric methodology to examine the interactions between the insecticide and the surfactant. The critical micellar concentration (CMC) and degree of counterions dissociation (α) of the surfactants were obtained at varying concentrations (0 to 3 µM) of the insecticide phosalone and temperatures between 301.15 and 321.15 K. In all cases, both parameters (CMC and α) demonstrated a decline in line with the increase in insecticide concentration and temperature. The thermodynamic parameters were calculated using the CMC versus temperature data. A positive value of ΔH° indicates that the micellisation process is endothermic. The negative values of ΔG° as a function of insecticide concentration and temperature demonstrate that the micellisation process is thermodynamically favorable and that the insecticide solubilises in the micelle core. The results of this study demonstrate that it is possible to solubilise a poorly soluble organic molecule by micellisation using conductivity alone, which is a valuable finding.

Keywords: CTAC; SDS; CMC; solubility; surfactants.

1. INTRODUCTION

To meet the food needs of a growing global population, there is a significant opportunity for world agricultural production to increase, particularly in developing countries. It is therefore essential to enhance agricultural yields and regulate production by protecting crops from pests. In light of this challenge, the deployment of phytosanitary products, or pesticides, represents an effective strategy for achieving this goal.

These products are designed to safeguard plants from parasitic fungi (fungicides), insect pests (insecticides), or even to eradicate weeds (herbicides) (Varca 2012). However, the majority of pesticides found in surface water and groundwater are not particularly soluble, which presents a challenge in their analysis. Moreover, the solubility of pesticides in water often presents obstacles to the implementation of spectroscopic techniques, such as UV absorption and fluorescence (Bodian et al. 2022, Sambou et al. 2021, Saleck et al. 2019). This requires the use of organic solvents or other supplementary reagents (Mendy et al. 2019).

With this in mind, we undertook a study of the use of phosalone in the Niayes agricultural zone of Senegal. Phosalone (S-[(6-chloro-2-oxo-1,3-benzoxazol-3(2H)-yl)methyl] O,O-diethylphosphorodithioate) is a organophosphate insecticide used to control a wide range of pests on certain crops, including grapes, apples, peas, potatoes, rice, and cotton (Majlesi et al. 2016, Aqa Sadat et al. 2020).

Phosalone inhibits acetylcholine activity, but its low water solubility can result in prolonged persistence in environmental matrices, particularly surface and groundwater (Altuntas et al. 2003). The insecticide has poor solubility in water (3.5 mg L⁻¹) at 298.15 K. The low solubility of the insecticide may result in limited microbiological and photochemical degradation in environmental matrices, which could lead to the persistence of the insecticide in surface and groundwater (Daneshvar et al. 2004).

Given the low solubility of phosalone insecticide in water, we have initiated a study of micellar solubilisation with the objective of facilitating the solubilisation of phosalone in an aqueous system. This will be achieved by forming mixed micelles with surfactants or by incorporating the insecticide into the interior of micelles.

The formation of micelles is dependent on the concentration of surfactants, which is influenced by the interplay of hydrophilic and hydrophobic interactions (Alam et al. 2021, Aguiar 2002). Amphiphilic molecules, such as surfactants, are effective at solubilising feebly soluble organic entities due to their inherent self-assembly properties (Alam et al. 2021, Aguiar 2002).

The micellisation process in surfactants is a thermodynamic phenomenon that can be studied using a variety of techniques, including isothermal calorimetry, surface tension, UV-visible, fluorimetry and conductometry (Banjare et al. 2020, Scholz et al. 2018). In this study, we employ the more straightforward and cost-effective conductometry technique to enhance
the solubility of the insecticide phosalone in anionic and cationic aqueous micellar media (Sarr et al. 2022, Sarr et al. 2017).

<figure><img src="image_3.png" /><figcaption>Fig. 1. Chemical structure of phosalone</figcaption></figure>

## 2. MATERIALS AND METHODS

### 2.1 Apparatus

This analytical study was conducted using a VWR® pHenomenal® CO 3100L Conductivity/TDS/°C Meter, Bench, which was accompanied by a measuring cell and a temperature sensor. Conductivity Accuracy ±0.5% of measured value, Conductivity Resolution Up to 0.001 µS/cm (depending on probe). The device was calibrated with a 0.01 M KCl solution exhibiting conductivities of 1278 µS cm⁻¹ and 1413 µS cm⁻¹ at temperatures of 293.15 and 298.15 K, respectively, using the appropriate standard curve. A VELP SCIENTIFICA magnetic stirrer (Healing Magnetic Stirrer) was utilized to facilitate the homogenization of the stock solutions. All weighing operations were conducted using a Sartorius U3600S electronic balance, with a precision of 0.1 mg. A variety of laboratory vessels, including beakers, test tubes, flasks, and micropipettes, were employed for the implementation of the diverse measurements.

### 2.2 Chemicals

The phosalone (99% pure) is sourced from Sigma-Aldrich, a company based in Germany. The surfactant molecules utilised are cetyltrimethylammonium chloride (CTAC, 98% m/m, in aqueous solution d= 0.968) with the empirical formula CH₃(CH₂)₁₅N(CH₃)₃Cl, and sodium dodecyl sulfate (SDS) with the empirical formula CH₃(CH₂)₁₁SO₄Na (98%, d = 1.01) are also procured from Sigma Aldrich. Fig. 1 depicts the chemical structure of phosalone, while Table 1 enumerates its physicochemical properties.

## 2.3 Solutions Preparation

The phosalone solution was prepared in distilled water at a pH = 7, with a concentration of 10⁻³ M. The stock solutions of the SDS and CTAC were prepared at a concentration of 0.1 M in distilled water. All solutions were stored in glass vials. The latter were then placed in a refrigerator, protected from light. The physicochemical properties of phosalone are presented in Table 1 (Suntio et al. 1988, Khan et al. 2016, Rahim et al. 2021).

## 2.4 Conductivity Measurement Procedure

The conductivity measurement procedure was employed to gain insight into the micellar behavior of the surfactant-phosalone mixture in aqueous media. The values of conductivity were recorded with the aid of a digital conductivity meter, which was equipped with a measuring cell and a temperature sensor. The temperature at which the solution is prepared is fixed at a specific value. Subsequently, 0.2 mL of the titrant solution is taken and poured into a beaker containing 150 mL of a solution with a known concentration of the insecticide. This volume is sufficient to immerse the electrode. Subsequently, the beaker is placed on a magnetic stirrer, which may facilitate the heating of the solution. The solution is simultaneously homogenized through stirring, and a reading of the specific conductivity is obtained. The recorded conductivity values of the mixture were plotted against the corresponding surfactant concentrations in order to determine the critical micelle concentration (CMC).

## 2.5 Determination of Method of Thermodynamic Parameters of Micelles

In order to ascertain the degree of spontaneity of the micellar self-aggregation reaction of insecticide with surfactants, we proceeded to determine the thermodynamic parameters of micellisation and the degree of ionisation α of the counterions.

The degree of micellar ionisation α of the counterions in the solution can be determined from the ratio of the slopes observed before and after the critical micelle concentration (CMC) (Raoul Zana). The micellar free energy (ΔG⁰) was calculated by solving the following equation: (1) (Aguiar 2002, Abram et al. 2015).
<table><caption>Table 1. Physicochemical properties of phosalone, SDS and the CTAC</caption><thead><tr><th>Physicochemical properties</th><th>Phosalone</th><th>SDS</th><th>CTAC</th></tr></thead><tbody><tr><td>Chemical formula</td><td>C<sub>12</sub>H<sub>15</sub>CINO<sub>4</sub>PS<sub>2</sub></td><td>C<sub>12</sub>H<sub>25</sub>NaO<sub>4</sub>S</td><td>C<sub>19</sub>H<sub>42</sub>NCI</td></tr><tr><td>Molecular weight (g mol<sup>-1</sup>)</td><td>367.8</td><td>288.38</td><td>319.5</td></tr><tr><td>Solubility (mg L<sup>-1</sup>)</td><td>298.15 K</td><td>10<sup>5</sup></td><td>440</td></tr><tr><td>Melting point (K)</td><td>318.15-321.15</td><td>477.15-480.15</td><td>505.15-507.15</td></tr><tr><td>Relative density 298.15 K</td><td>1.4</td><td>1.01</td><td>0.968</td></tr><tr><td>Vapor pressure (Pa) 298.15 K</td><td>4.54 10<sup>-8</sup></td><td>-------</td><td>-------</td></tr><tr><td>CMC (mM) 298.15 K</td><td>-------</td><td>8.2</td><td>1.3</td></tr><tr><td>DL50 (mg L<sup>-1</sup>)</td><td>120 (oral, rat)</td><td>1288 (oral, rat)</td><td>400 (oral, mouse)</td></tr></tbody></table>

$$ \Delta G^{\circ} = (2 - \alpha)RT\ln X_{CMC} \quad (1) $$

T = experimental temperature (K), R = universal molar gas constant, X<sub>CMC</sub> molar fraction of surfactant at the CMC, ΔH° = standard enthalpy.

$$ \Delta H^{\circ} = -T^{2} \frac{\partial}{\partial T} \left( \frac{\Delta G^{\circ}}{T} \right) \quad (2) $$

By replacing (1) in (2), the enthalpy of micellisation can be written as follows (Rahman et al. 2019)

$$ \Delta H^{\circ} = -RT^{2}(2 - \alpha) \frac{\partial}{\partial T}(\ln X_{CMC}) \quad (3) $$

The values of lnX<sub>CMC</sub> are observed to vary in a linear fashion with temperature, resulting in the formulation of equation (3). d/dT(lnX<sub>CMC</sub>) corresponds to the slope of the line lnX<sub>CMC</sub> = f(T). The entropy associated with the micellisation process can be calculated using the following: equation:

$$ \Delta S^{\circ} = \frac{1}{T} ((\Delta H^{\circ} - \Delta G^{\circ}) \quad (4) $$

# 3. RESULTS AND DISCUSSION

## 3.1 Effect of Phosalone on the Critical Micellar Concentration

The experiment entails monitoring the evolution of the specific conductivity of an initial solution of phosalone with a fixed concentration as a function of the variation in concentration of anionic surfactant SDS or cationic surfactant CTAC, which are added using a micropipette. The effect of phosalone concentration on the CMC and α of the two surfactants was evaluated at various temperatures (301.15, 306.15, 311.15, 316.15, and 321.15 K). For each temperature, the same trend in CMC and α as a function of insecticide concentration was consistently observed. The results obtained at 301.15 K was presented in Table 2. It is anticipated that ionic

surfactants will undergo complete ionisation in solution, thereby establishing a direct correlation between conductivity and surfactant concentration.

At the outset of the dosage regimen, a slight increase in specific conductivity is observed as a function of surfactant concentration. Subsequently, the surfactant dissolves in water, resulting in the formation of simple monomers. The monomeric surfactant molecules display enhanced mobility in comparison to their aggregated form (Daneshvar et al. 2004). In the vicinity of the critical micelle concentration (CMC), the monomers gradually assemble to form approximately spherical micellar aggregates. Upon reaching CMC, a pronounced and precipitous surge in the specific conductivity is observed. Subsequently, the linear enhancement of conductivity values with the increase in surfactant concentration proceeds with a smaller slope following the CMC. This results in a less pronounced increase in specific conductivity. The values of CMC, α, and ΔG° obtained at varying concentrations of phosalone are presented in Table 2.

As illustrated in Table 2, there is a notable decline in both CMC and degree of ionisation as the concentration of phosalone increases. The progressive decrease in CMC values as a function of insecticide concentrations suggests the presence of an interaction between phosalone and surfactants. This phenomenon may be attributed to the solubilisation of the phosalone insecticide in each of the surfactants utilised. In all instances, the absolute value of the free enthalpy of micellisation (ΔG°) is observed to increase with increasing phosalone concentration. In other words, the presence of the insecticide in aqueous solution results in an increased propensity for the formation of the micellar phase, which consequently reduces the CMC. From this, we can infer that phosalone functions as a co-surfactant in the micellisation
process (Debbabi et al. 2008). The variation in surfactant CMC as a function of phosalone concentration is illustrated in Fig. 2.

The plot of the curve of the critical micellar concentration as a function of the concentration of phosalone (CMC = f ([PSL]) allows us to see a progressive decrease in the CMC for increasing concentrations of the pesticide. However, this decrease is more significant at level of the anionic surfactant SDS (Singh et al. 2024). To properly explain this decrease in CMC in the presence of phosalone, it is important to see its chemical structure. Indeed, this molecule of chemical formula C₁₂H₁₅ClNO₄PS₂ with a hydrophobic part comprising the benzene ring and polar bonds (C-Cl, C=O, P=O, C-N) shows

that it has a very high permanent dipole moment (Broniatowski and Latka 2008). In solution, it demonstrates a robust capacity to interact with the tails of surfactants. It should be noted, however, that the non-polar sections of the molecule are also capable of interacting with the polar heads of surfactants. This phenomenon allows highly hydrophobic organic compound to make favorable associations for micellar solubilisation (Sarr et al. 2022, Sarr et al. 2017). The existence of this dipole moment shows that solubilisation takes place at the water/micelle interface. Phosalone increases the action of CTAC and SDS by adsorbing at the interface while at the same time decreasing the surface tension of the micelles. The results obtained are shown in Fig. 3.

<table><caption>Table 2. Micellisation parameters values as a function of phosalone concentration at 301.15 K</caption><thead><tr><th rowspan="2">Phosalone<br>Concentration x10<sup>6</sup><br>(M)</th><th colspan="3">SDS</th><th colspan="3">CTAC</th></tr><tr><th>CMC <sup>a</sup><br>(mM)</th><th>α (%) <sup>b</sup></th><th>ΔG° <sup>c</sup><br>(kJ mol<sup>-1</sup>)</th><th>CMC <sup>a</sup><br>(mM)</th><th>α (%) <sup>b</sup></th><th>ΔG° <sup>c</sup><br>(kJ mol<sup>-1</sup>)</th></tr></thead><tbody><tr><td>0.0</td><td>3.101</td><td>69.302</td><td>-43.289</td><td>2.975</td><td>78.113</td><td>-40.628</td></tr><tr><td>0.25</td><td>2.975</td><td>56.129</td><td>-47.955</td><td>2.849</td><td>76.728</td><td>-41.360</td></tr><tr><td>0.5</td><td>2.597</td><td>39.434</td><td>-54.629</td><td>2.597</td><td>70.333</td><td>-44.117</td></tr><tr><td>1.0</td><td>2.344</td><td>34.267</td><td>-57.246</td><td>2.344</td><td>49.372</td><td>-52.029</td></tr><tr><td>1.5</td><td>1.832</td><td>33.595</td><td>-59.554</td><td>1.961</td><td>43.517</td><td>-55.465</td></tr><tr><td>2.0</td><td>1.445</td><td>22.872</td><td>-65.511</td><td>1.832</td><td>33.038</td><td>-59.752</td></tr><tr><td>3.0</td><td>1.311</td><td>22.281</td><td>-66.587</td><td>1.575</td><td>32.393</td><td>-61.263</td></tr></tbody></table>

<figure><img src="image_4.png" /><figcaption>Fig. 2. CMC variation of SDS (A) and CTAC (B) as a function of phosalone concentration at 301.15 K</figcaption></figure>

<footnote><sup>a</sup> Critical micellar concentration; <sup>b</sup> Degree of dissociation; <sup>c</sup> Gibbs free enthalpy. M = mol L⁻¹</footnote>
<figure><img src="image_5.png" /><figcaption>Fig. 3. α variation of SDS (A) and CTAC (B) as a function of phosalone concentration at 301.15 K</figcaption></figure>

In both instances, a reduction of α is evident as the concentration of phosalone increases. The SDS surfactant demonstrates a more pronounced reduction of α, indicative of a substantial solubilisation of phosalone within the core of the micelles. This is attributable to an increase in hydrophobic attraction forces, which results in a reduction of α at the CMC.

## 3.2 Effect of Temperature on CMC

The same assay was conducted, with specific conductivity monitored as a function of surfactant concentration at varying temperatures and at a fixed concentration of phosalone (2.5x10⁻⁷ M). As indicated in section 2.5, the value of ΔH° is calculated using the provided equation 3.

The representative curve of lnXCMC = f(T) was used to obtain the term $\frac{d}{dT}(\ln XCMC)$ of equation 3, which is the slope (Fig. 4). Subsequently, the value of ΔS° was determined using equation 4, following the calculation of ΔG° using equation 1.

A review of the data presented in Table 3 reveals a significant correlation between temperature and CMC. It was observed that the concentration of CMC decreased with an increase in temperature. This results in the dehydration of the hydrophilic component (polar heads) of the surfactants, which favours micellisation. Moreover, the interaction of water molecules with hydrophobic groups (linear surfactant chains) may facilitate the process of micellisation by

increasing the solubility of the pesticide (Sarr et al. 2022, Sarr et al. 2017). Similarly, Thiaré et al. observed this phenomenon when analysing the insecticide fenvalerate in an inverse micellar medium using photoinduced fluorescence (Thiaré et al. 2024).

## 3.3 Thermodynamic Parameters

The thermodynamic parameters associated with the association reaction of surfactants with phosalone were calculated using equations (1), (2) and (3). The values of ΔG°, ΔH° and -TΔS° are presented in Table 3.

The negative values of free enthalpy (ΔG°) obtained indicate that the micellisation process is thermodynamically favourable (Sarr et al. 2022, Sarr et al. 2017, Thiaré et al. 2024). These values demonstrate a clear decrease with increasing temperature, which indicates that the solubility of phosalone increases with temperature.

Furthermore, the ΔH° values are positive in all cases and increase with temperature, indicating that the process is endothermic and that water molecules near the hydrophobic part of the surfactants are undergoing degradation. This demonstrates that heat is transferred from the surrounding environment to the micellar system, which is the underlying cause of the observed increase in the system's enthalpy. It is described as an energetically ascending process (Sarr et al. 2022, Sarr et al. 2017).
<figure><img src="image_6.png" /><figcaption>Fig. 4. Representation of lnX<sub>CMC</sub> as a function of temperature, SDS (A) and CTAC (B)</figcaption></figure>

In accordance with the principles of thermodynamics, if a process is endothermic, the variation in free enthalpy (ΔG°) must be negative. This is contingent upon the enthalpy factor (ΔH°) and entropy factor (TΔS°) exhibiting a positive and negative variation, respectively, with |TΔS°| being greater than ΔH°.

This is evidenced by the positive entropy variation observed in our study, which increases with temperature. The results demonstrate that the micellisation of the insecticide phosalone with SDS and CTAC is spontaneous.

### 3.4 Entropy-enthalpy Compensation

The enthalpy-entropy compensation can be obtained by utilising the linear relationship between ΔH° and ΔS°. As illustrated in Equation 4, when a process exhibits a positive enthalpy

change, it is also accompanied by an increase in entropy (ΔS° > 0). The fact that |TΔS°| is greater than ΔH° indicates that the association reaction between phosalone and surfactants (SDS and CTAC) is partially controlled by the entropy term. This demonstrates that the rise in enthalpy during micellisation is counterbalanced by the growth in disorder within the system. This expansion in entropy may be attributed to the aggregation of the hydrophobic component of the micelles, as well as the release of counterions (Aguiar 2002). A representative plot of ΔH° versus ΔS° is illustrated in Fig. 5.

The ΔH° plot according to ΔS° shows a linear curve, thus showing a compensation between enthalpy and entropy. A linear correlation between ΔH° and ΔS° with r² value from 0.987 to 0.994 was observed. ΔH° and Tc connote the enthalpy and compensation temperature.

<table><caption>Table 3. Micellisation parameters (CMC, X<sub>CMC</sub> and α) and thermodynamic parameters values at various temperatures</caption><thead><tr><th>Surfactant</th><th>T (K)</th><th>CMC (mM)</th><th>α (%)</th><th>ΔG° (kJ mol<sup>-1</sup>)<sup>d</sup></th><th>ΔH° (kJ mol<sup>-1</sup>)<sup>e</sup></th><th>ΔS° (kJ mol<sup>-1</sup>K<sup>-1</sup>)<sup>e</sup></th></tr></thead><tbody><tr><td rowspan="6">SDS</td><td>301.15</td><td>3.35</td><td>30.84</td><td>-48.32</td><td>45.59</td><td>0.312</td></tr><tr><td>306.15</td><td>2.97</td><td>34.78</td><td>-49.71</td><td>49.74</td><td>0.325</td></tr><tr><td>311.15</td><td>2.72</td><td>38.48</td><td>-50.91</td><td>54.83</td><td>0.340</td></tr><tr><td>316.15</td><td>2.34</td><td>38.54</td><td>-53.75</td><td>59.38</td><td>0.358</td></tr><tr><td>321.15</td><td>2.09</td><td>40.02</td><td>-59.48</td><td>62.50</td><td>0.380</td></tr><tr><td>301.15</td><td>2.22</td><td>32.99</td><td>-58.16</td><td>37.56</td><td>0.318</td></tr><tr><td rowspan="5">CTAC</td><td>306.15</td><td>2.09</td><td>36.42</td><td>-58.41</td><td>39.51</td><td>0.320</td></tr><tr><td>311.15</td><td>1.96</td><td>40.18</td><td>-58.53</td><td>42.23</td><td>0.324</td></tr><tr><td>316.15</td><td>1.83</td><td>44.07</td><td>-58.59</td><td>45.06</td><td>0.328</td></tr><tr><td>321.15</td><td>1.57</td><td>47.92</td><td>-59.28</td><td>46.97</td><td>0.331</td></tr></tbody></table>
<figure><img src="image_7.png" /><figcaption>Fig. 5. The enthalpy-entropy compensation of phosalone in SDS (A) and CTAC (B)</figcaption></figure>

<table><caption>Table 4. Compensation temperature (Tc) and compensation enthalpy of surfactants in the presence of 2.5x10⁻⁷ M in the temperature range studied</caption><thead><tr><td>Medium</td><td>Concentration (mol L⁻¹)</td><td>ΔH⁰ (KJ mol⁻¹)</td><td>Tc (K)</td></tr></thead><tbody><tr><td>SDS</td><td>2.5 10⁻⁷</td><td>-67.63</td><td>186.15</td></tr><tr><td>CTAC</td><td>2.5 10⁻⁷</td><td>-72.47</td><td>199.15</td></tr></tbody></table>

The values of ΔH⁰ and Tc illustrates the solute-solvent interaction. The Tc values of studied systems lie in the range of 186.15-199.15 K. The ΔH⁰ values were found to be negative in the SDS and CTAC and show an important participation of the hydrophobic part in the micellisation and in the stability of the micelle formed. The higher value of ΔH⁰ was found in SDS. Table 4 shows the values of ΔH⁰ and Tc.

## 4. CONCLUSION

In order to study the solubilisation process of some organic compounds and their interaction with surfactant solutions, we used the conductometric measurement method to solubilise the pesticide phosalone in SDS and CTAC. A study of the micellar properties of ionic surfactants used in the micellar solubilisation of phosalone was also carried out. These properties are the CMC and α. The application of these two surfactant molecules (CTAC and SDS) in the micellar solubilisation of the insecticide was carried out by measuring the conductivity at different temperature. The CMC values of ionic surfactant in aqueous medium decrease linearly with the concentration of phosalone and the

temperature. The results obtained from these studies showed that the temperature and the concentration of phosalone favor the formation of the micellar phase. The negative magnitudes of ΔG° in each case reveal the spontaneous micellisation, while the positive values of ΔH⁰ testify to the existence of an endothermic process. The analysis of the results based on the calculation of the thermodynamic parameters showed that phosalone solubilises in the micellar phase. In both cases, the solubilisation occurs at the water-micelle interface.

## DISCLAIMER (ARTIFICIAL INTELLIGENCE)

Author(s) hereby declare that NO generative AI technologies such as Large Language Models (ChatGPT, COPILOT, etc.) and text-to-image generators have been used during the writing or editing of this manuscript.

## CONSENT TO PUBLISH

All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
## ACKNOWLEDGEMENTS

We thank the Service of Cooperation and Cultural Action (SAC) of the French Embassy in Dakar (Senegal) for the financial support of this research.

## COMPETING INTERESTS

Authors have declared that no competing interests exist.

## REFERENCES

Abram, T., & Chfaira, R. (2015). Étude de la solubilisation micellaire ionique d'un polluant organique, cas du phénol. *Journal of Materials and Environmental Science*, **6**, 491-498.

Available: https://www.jmaterenvironsci.com/Document/vol6/vol6_N2/57-JMES-1100-2014-Abram.pdf

Aguiar, J. (2002). Thermodynamics and micellar properties of tetradecyltrimethylammonium bromide in formamide water mixtures. *Journal of Colloid and Interface Science*, **255**, 382-390.

Available: https://doi.org/10.1006/jcis.2002.8678

Alam, M. M., Mahbub, S., Hosen, M. M., Kumar, D., & Hoque, A. M. (2021). Conductivity and cloud point investigation of interaction of cationic and non-ionic surfactants with sodium carboxymethyl cellulose: Effect of polyols and urea. *Chemical Papers*, **75**, 3457-3468.

Available: https://doi.org/10.1007/s11696-021-01568-0

Altuntas, I., Delibas, N., Doguc, D. K., Ozmen, S., & Gultekin, F. (2003). Role of reactive oxygen species in organophosphate insecticide phosalone toxicity in erythrocytes in vitro. *Toxicology In Vitro*, **17**, 153-157.

Available: https://doi.org/10.1016/S0887-2333(02)00133-9

Aqa Sadat, S. A., Ilbeigi, V., Valadbeigi, Y., & Soleimani, M. (2020). Determination of pesticides phosalone and diazinon in pistachio using ion mobility spectrometry. *International Journal of Ion Mobility Spectrometry*, **23**, 127-131.

Available: https://doi.org/10.1007/s12127-020-00262-3

Banjare, R. K., Banjare, M. K., & Panda, S. (2020). Effect of acetonitrile on the colloidal behavior of conventional cationic surfactants: A combined conductivity, surface tension, fluorescence, and FTIR study. *Journal of Solution Chemistry*, **49**, 34-51.

Available: https://doi.org/10.1007/s10953-019-00937-4

Bodian, E. H. T., Thiaré, D. D., Bakhoum, J. P., Mbaye, O. M. A., Diop, N. A., Diaw, P. A., Le Jeune, B., Coly, A., & Giamarchi, P. (2022). Determination of flumethrin and tau-fluvalinate pyrethroid insecticides in surface and groundwater by photochemically induced fluorescence (PIF). *Analytical Letters*, **55**, 1980-1996.

Available: https://doi.org/10.1080/00032719.2022.2040524

Broniatowski, M., & Latka, P. D. (2008). Semifluorinated alkanes: Primitive surfactants of fascinating properties. *Advances in Colloid and Interface Science*, **138**, 63-83.

Available: https://doi.org/10.1016/j.cis.2007.11.002

Daneshvar, N., Hejar, M. J., Rangarangy, B., & Khataee, A. R. (2004). Photocatalytic degradation of an organophosphorus pesticide phosalone in aqueous suspensions of titanium dioxide. *Journal of Environmental Science and Health, Part B*, **39**, 285-296.

Available: https://doi.org/10.1081/PFC-120030242

Debbabi, K., Guittard, F., & Geribaldi, S. (2008). Novel highly fluorinated sulfamates: Synthesis and evaluation of their surfactant properties. *Journal of Colloid and Interface Science*, **326**, 235-239.

Available: https://doi.org/10.1016/j.jcis.2008.07.033

Khan, F., Sheikh, M. S., Rub, M. A., Azum, N., & Asiri, A. M. (2016). Antidepressant drug amitriptyline hydrochloride (AMT) interaction with anionic surfactant sodium dodecyl sulfate in aqueous/brine/urea solutions at different temperatures. *Journal of Molecular Liquids*, **222**, 1020-1030.

Available: https://doi.org/10.1016/j.molliq.2016.07.104

Majlesi, M., Massoudinejad, M., Hosainzadeh, F., & Fattahi, N. (2016). Simultaneous separation and preconcentration of
phosalone and chlorpyrifos in fresh vegetables using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography. *Analytical Methods*, 8, 3795-3801.

Available:https://doi.org/10.1039/C6AY00144K

Mendy, A., Thiaré, D. D., Sarr, I., Bodian, E. H. T., Sambou, S., Gaye-Seye, M. D., Coly, A., & Tine, A. (2019). Inclusion complex of o-phthalaldehyde-metolachlor with cyclodextrins using the thermochemically-induced fluorescence derivatization (TIFD) method and its analytical application in waters. *Journal of Solution Chemistry*, 48, 502-514.

Available:https://doi.org/10.1007/s10953-019-00862-6

Rahim, M. A., Mahbub, S., Ahsan, S. M. A., Alam, M., Saha, M., Shahriar, I., Rana, S., Halim, M. A., Hoque, A. M., Kumar, D., & Khan, J. M. (2021). Conductivity, cloud point, and molecular dynamics investigations of the interaction of surfactants with ciprofloxacin hydrochloride drug: Effect of electrolytes. *Journal of Molecular Liquids*, 322, 114683.

Available:https://doi.org/10.1016/j.molliq.2020.114683

Rahman, M., Hoque, A. M., Rub, M. A., & Khan, M. A. (2019). Interaction of cetyltrimethylammonium bromide with cefixime trihydrate drug at different temperatures and compositions: Effect of different electrolytes. *Chinese Journal of Chemical Engineering*, 27, 1895-1903.

Available:https://doi.org/10.1016/j.cjche.2018.10.022

Saleck, M. L. O., Thiaré, D. D., Sambou, S., Bodian, E. H. T., Sarr, I., Sarr, D., Diop, C., Gaye-Seye, M. D., Fall, M., & Coly, A. (2019). Photochemically-induced fluorescence (PIF) and UV-vis absorption determination of diuron and metalaxyl in well water, kinetic of photodegradation, and rate of leachability in soils. *Analytical Chemistry Letters*, 9, 806-815.

Available:https://doi.org/10.1080/22297928.2020.1712237

Sambou, S., Thiaré, D. D., Diaw, P. A., Sarr, I., Bodian, E. H. T., Mendy, A., Sarr, D., Gaye-Seye, M. D., & Coly, A. (2021). Analysis of diuron herbicide in Senegalese surface and groundwater depending on the

soil depth by photochemically induced fluorescence (PIF). *Journal of the Iranian Chemical Society*, 18, 2389-2396.

Available:https://doi.org/10.1007/s13738-021-02198-9

Sarr, I., Bodian, E. H. T., Sambou, S., Mendy, A., Thiaré, D. D., Diaw, P. A., Gaye-Seye, M. D., Coly, A., & Tine, A. (2017). Conductometric study of the interaction of insecticide profenofos with cationic and anionic surfactants in aqueous medium. *International Research Journal of Pure and Applied Chemistry*, 15, 1-9.

Available:https://doi.org/10.9734/IRJPAC/2017/37087

Sarr, I., Thiaré, D. D., Diaw, P. A., Bodian, E. H. T., Sambou, S., Kital, K., Mendy, A., Sarr, D., Fall, M., Delattre, F., & Coly, A. (2022). Solubility and thermodynamic micellization studies of the insecticide chlorpyrifos in aqueous medium. *Journal of Materials and Environmental Science*, 13, 70-81.

http://www.jmaterenvironsci.com

Scholz, N., Behnke, T., & Resch-Genger, U. (2018). Determination of the critical micelle concentration of neutral and ionic surfactants with fluorometry, conductometry, and surface tension: A method comparison. *Journal of Fluorescence*, 28, 465-476.

Available:https://doi.org/10.1007/s10895-018-2209-4

Singh, R., Gurung, J., Gogoi, A. J., & Pulikkal, A. K. (2024). Molecular interactions of cationic/anionic surfactants in presence of anionic antibiotic drug cloxacillin sodium at different temperatures: Micellization and thermodynamic studies. *Journal of Molecular Liquids*, 395, 123807.

Available:https://doi.org/10.1016/j.molliq.2023.123807

Suntio, L. R., Shiu, W. Y., Mackay, D., Seiber, J. N., & Glotfelty, D. (1988). Critical review of Henry's law constants for pesticides.

*Reviews of Environmental Contamination and Toxicology*, 1-59.

Available:https://doi.org/10.1007/978-1-4612-3850-8_1

Thiaré, D. D., Sarr, D., Delattre, F., Giamarchi, P., & Coly, A. (2024). Direct and reverse micellar-enhanced photo-induced fluorescence determination of fenvalerate in Senegalese surface and groundwater.

*Journal of Photochemistry and*
Photobiology A, 456, 115841.
Available:https://doi.org/10.1016/j.jphotoch
em.2024.115841

Varca, M. L. (2012). Pesticides residues in surface waters of Pagsanjan-Lumba

catchment of Laguna de Bay, Philippines.
*Agricultural Water Management*, **106**, 35-
41.

Available:https://doi.org/10.1016/j.agwat.2
011.08.006

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