**5.2 Industrial applications**

*Colloids - Types, Preparation and Applications*

rewet ability and vice-versa [1, 20].

using energy-related aspects together [37, 38].

**4.6 Inhibitor**

**4.7 Emulsification**

etc. [5].

**5. Applications**

**5.1 Biological activity**

hydrophobic group length in the chain present in the surfactant. Whereas, the fall in the concentration of gemini imidazoline surfactant resulted in a decreased in the

Surfactants are used as corrosion inhibitors; they act as a protector on metal surfaces from corrosion. The gemini surfactants are amphiphilic, hence develops an affinity at metal/metal oxide–water interfaces for adsorption phenomena which leads to creating a barrier on metals and metal oxides surfaces and inhibits corrosion [36]. Imidazoline plays a vital role in corrosion inhibition as the imidazoline ring bond with the planar alignment to the surface of the metal. Further studies showed that the imidazoline inhibits the corrosion by blocking, activating, and

A property of surfactants at the interface. Emulsification is a process that forms an emulsion between two immiscible liquids such as oil suspended in water [36]. Emulsification is an important property for gemini imidazolinium surfactants for the formation of the emulsion. The emulsification power of a surfactant varies with the length of the spacer group. It is directly proportional to the spacer chain length. Stable emulsions are required in drug formulation, cosmetics, solubilizations,

The antimicrobial activity of surfactants based upon the surface-active properties, hydrophobic chain length, and concentration. Gawali et al. (2019) synthesized the cationic Gemini surfactants and mentioned their application. The synthesized Gemini surfactants were assessed to check the biocidal activity contrary to a variety of bacteria such as Bacillus subtilis, *E. coli*, *Staphylococcus aureus*, and *P. aeruginosa*. The R = C7H15 [2-Octyl-1-diethylenediaminimidazoline based gemini surfactant (GSCTDH)] and R = C11H23 [2-dodecyl-1-diethylenediaminidazoline based gemini surfactant (GSLTDH)] compounds showed good microbial activity. The R = C13H27 [2-Tetradecyl-1-diethylenediaminimidazoline based gemini surfactant (GSMTDH)] surfactant was inactive for *Pseudomonas aeruginosa* but showed active behavior for Bacillus subtilis, *E. coli*, *Staphylococcus aureus*. The R = C15H31 [2-Hexadecyl-1-diethylenediaminimidazoline based gemini surfactant (GSPTDH)] compound showed biocidal activity against *E. coli*, *Staphylococcus aureus*. The GSCTDH surfactant compound containing the highest antimicrobial activity amongst the other Gemini synthesized compounds. As the compound showed the biocidal activity against the bacteria (gram-positive and negative), they can be considered to use as an antimicrobial agent in the form of surfactants. The test result showed the variation in the sensitivity of Gemini compound towards the gram-positive and gram-negative bacteria, they were more sensitive to gram-positive bacteria as compared to gram-negative bacteria. The reason behind that could be the behavior of the outer membrane of the bacteria which was less permeable in the case of gram-negative bacteria [39]. The surfactant having low critical micelle concentration values shows good corrosion inhibitor property due to their absorption quality

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The gemini imidazoline surfactant with quaternary imidazolinium salts is used as a dispersant, emulsifiers, bleach agent, ant-static agent, and fabric softener as they show the better result as compared to the traditional surfactant and also have a mild effect on clothes, to eyes, and their biodegradability. Gemini imidazoline surfactant solubility is low in water [21]. They can be used for drug entrapment, oil recovery, also a probable vehicle for the transference of bioactive particles, for cleaning purpose, used as aerosol application [43].
