**3. Conclusion**

464 Corrosion Resistance

Fig. 10. Chemical structure of the constituents of CNSL, (a) anacardic acid, (b) cardanol, (c)

Other examples include furan, polycaprolactone, glycerol, gums, proteins, pectin, drugs and others, which are also used in corrosion resistance (Hussain et al., 2002; Fabbri et al., 2006; Velayuthama et al., 2009; Umoren, 2008; Umoren et al., 2009; Zuo et al., 2005; Sugama, 1995; Abdallah, 2004; Obot et al., 2009). The role of antibacterial and antifungal drugs like Clotrimazole, Fluconazole, Cefixime, Ampicillin, Ampiclox, Cloxacillin, Tetracycline, Methocarbamol, Orphenadrine, Penicillin G, Azithromycin, and others, in corrosion resistance is basically as corrosion inhibitors. The inhibition mechanism is based mainly on adsorption, significantly influenced by the presence of functional groups –CHO, –N=N, R–OH, steric factors, aromaticity, electron density, molecular weight of inhibitor and others (Abdullah, 2004; Obot, et al., 2009; Naqvi et al., 2011; Eddy et al., 2010). Drugs may often compete with "green" corrosion inhibitors. Similarly, gums (Raphia hookeri gum, gum Arabic) also exert their anticorrosion effect as corrosion inhibitors through the formation of films on metal surface via adsorption and thus, blocking off the corrodents present in the

cardol and (d), 2-methyl cardol.

environment (Umoren, 2008).

**2.10 Others** 

Renewable resource based derivatives are cost-effective, abundantly available, biodegradable, environmentally benign alternatives for corrosion resistant coatings, paints and inhibitors. With advancements in knowledge and updated instruments and techniques available, further research in the field may be focussed on the enhanced use of the lesser and highly explored biomaterials for the development of anticorrosion agents in hand with "green" coating technology, for high performance high solids, hyperbranched, waterborne, hybrid and composite coatings that may compete with their petro-based counterparts, both in the terms of cost and performance, in near future. Though we have come a long way, much remains to be done on our palette; we still have a long way to go and explore.
