**6.4 Experimental conditions**

All experiments were carried out in an aerated medium, pH = 5 and current of 0.04 A. The steel sample represents the anode of the electrochemical cell, while the zinc plate represents the cathode leaving a distance of 1 cm between them. The zinc plating of the steel was carried out for 30 min, with gentle stirring, by partially immersing the steel sample and the zinc electrode in the chloride bath. To determine the weight of deposited zinc on surfaces, all substrates were weighed before and after electroplating. At the end of the process, the samples were removed from the bath, cleaned with distilled water and air dried [14].

### **6.5 Quality of the deposited zinc layer**

The thickness of the deposited zinc layer was measured with an Elektro-Physik (eXacto) apparatus and the adhesion of the coated zinc to the substrate was examined by the ASTM D3359 method [20]. For the adhesion test, an "X" was etched on the film and an attached adhesive tape was applied to the samples, and then removed strongly. This test is macroscopic and more qualitative. The gloss of the zinc deposits was measured using a Poly Gloss meter with a large beam of white light at a measuring angles of 20°, 60° and 85°. Calibration was performed automatically using a highly polished black standard built into the gloss meter. The final gloss values were the average of three measurements taken for each coating.

#### **6.6 Potentiodynamic polarization measurements**

Potentiodynamic polarization measurements were performed in seawater with the coated samples as working electrode, a platinum rod as counter electrode and a saturated calomel electrode (SCE) as a reference electrode. A controlled computer (Voltalab PGZ 301) instrument with Voltamaster 4 software was employed for this purpose. The measurements were applied in the potential range of ±1500 mV at a sweep rate of 1 mV/s.

#### **6.7 Gravimetric measurements**

To evaluate the corrosion resistance of the electrodeposited substrates, weight loss measurements were made. Each sample coated in chloride baths containing different concentrations of the extracts was partially immersed in seawater (corrosive medium). Measurements were collected every five days for a month and the Eq. (1) was used to determine the corrosion rate [21]:

$$\text{CR} = \frac{\text{w}}{\text{At}} \tag{1}$$

**295**

**Table 2.**

**Table 1.**

*Reducing Emerging Contaminants Ensuing from Rusting of Marine Steel Installations*

results are presented in **Table 1** for MDE, **Table 2** for EAE and **Table 3** for BE.

Via **Tables 1**–**3** we noted that there is an increase in the deposited mass, thickness and adhesion when increasing the concentration of MDE (1.6 g/l). However, for EAE and BE, these parameters reached a maximum value at 1.2 g/l and then decreased, indicating that the better deposit (nucleation and growth) is found in these concentrations. The obtained results may be related to two considerations: the first one is that the adsorption of additives on the surface, leads to a partial coating of the steel, thus blocking the active sites and causing a decrease in the nucleation rate. The second consideration is that the additive will complex with one of the electroactive species in the solution, therefore the step of dissociation of the complex introduces a new kinetic constant before the redox reaction of the electroactive species at the electrode surface [22]. Furthermore, and according to ASTM D 523 [23] regulations, we observed that the deposits obtained with the addition of the extracts were matt. However, when adding different concentrations (1.2; 1.4 and 1.6 g/l) of BE, the deposits were semi-gloss. In addition, all measured thicknesses

The corrosion resistance of the electrodeposited mild steel was tested in seawater at 298 K to evaluate the effect of adding extracts to the chloride baths. The electrochemical parameters such as Ecorr, icorr and CR are collected in **Table 4** for

From **Tables 4**–**6**, it can be seen that the addition of the investigated extracts as additives gave rise to significant decreases in current densities as well as the corrosion rate compared to the sample obtained without extracts addition. This indicates that the studied extracts strongly modified the quality of the deposit producing coatings more resistant to corrosion and therefore lessening the formation of biofilms, which represent one of emerging contaminants. It is also noted that the dependence of the

**C (g/l) Mass deposited (g) Thickness (**μ**m) Adhesion Brightness (GU)** Without extracts 0.0423 15 + Matt 05.30 1 0.0248 8.67 + Matt 14.15 1.2 0.0395 13.92 + Matt 02.30 1.4 0.0424 15.12 ++ Matt 01.75 1.6 0.0481 17.15 ++ Matt 19.10

**C (g/l) Mass deposited (g) Thickness (**μ**m) Adhesion Brightness (GU)** Without extracts 0.0423 15 + Matt 05.30 1 0.0450 15.99 ++ Matt 08.60 1.2 0.0551 19.60 ++ Matt 14.65 1.4 0.0477 16.20 ++ Matt 19.40 1.6 0.0366 12.11 + Matt 09.70

*Mass, thickness, brightness and strength adhesion of the deposited zinc layer in the presence of MDE.*

*Mass, thickness, brightness and strength adhesion of the deposited zinc layer in the presence of EAE.*

*DOI: http://dx.doi.org/10.5772/intechopen.95493*

Where: + adhesion is strong, ++ adhesion is very strong.

were in agreement with ASTM A879 and ASTM B633 [24].

**7.2 Potentiodynamic polarization measurement**

MDE, **Table 5** for EAE and **Table 6** for BE.

w: average weight loss. A: total area of one mild steel specimen. t: immersion time.
