**6. Conclusions**

*Corrosion Inhibitors*

*5.2.2 Cassava leaf (CL)*

*5.2.3 Cassava stem (CS)*

tannin [41]. Cassava bark (CB) consist of two layers namely; the outer skin and inner skin [42], both layers combine together serves as agro-waste and since annual production is high and it has been reported that the bark consist of 5–10% of the cassava root [42–44], the amount of agro-waste that can be generated from cassava

Cassava leaves are sometimes considered as agro-waste, though it has other applications such as animal feed [42, 45], medicinal application (Aro, 2008) and pack-cyaniding of mild steel [45]. Cassava leaves are also known for their high HCN content, low energy, bulkiness and their high tannin content [42, 45]. Cassava leaves are nutritionally valuable products and cassava plant could yield 7–15 tonnes of leaves per hectare, which accounts for an additional 1 tonne of valuable protein and 2.5 tonnes of carbohydrate per hectare [42]. Up to 6% of cassava leaves can be

Cassava stem is the largest waste generated from cassava plantation after harvest, up to 400 bundles can be obtained per hectare (Information and Communication Support for Agricultural Growth in Nigeria, 2015). From the estimated amount of cassava stem waste generated it shows that enough can be obtained for processing into useful application. Cassava stem can be fed to pigs,

CPENPs which comprises of cassava bark nanoparticles (CBNPs) [47], cassava leaf nanoparticles (CLNPs) [48] and cassava stem nanoparticles (CSNPs) [48] were obtained by first soaking for 24 h, after which ball milling for 60 h was carried out, to achieve a particles size below 100 nm which were estimated by SEM/Gwyddion software, XRD and TEM [47, 48]. Trace elements such as O, Si, Ca, K, Fe and S, were revealed using EDX, which are hetero-atoms and can be added to coatings to help in inhibiting corrosion on metal surfaces [47, 48]. Elements like Si and Ca would improve the strength of coatings as well as reduce corrosion rate of coated metals [47, 48]. XRD revealed compounds such as SiO2, CaCO3, Ca2(SO4)2H2O and CaC2O4(H2O), these compounds would help in improving the mechanical properties of alloys or composites and coatings. SiO2 if added to coatings will improve the coating hardness, while the presence of CaCO3 in coatings will form a precipitate that will serve as a protective film on the surface of the metal, thereby protecting the metal from corrosion. FTIR result revealed the nature of bond that exist in the CLNPs and GC–MS result showed various organic compounds that were presence in the CLNPs [48]. These organic compounds can be classified as fats, waxes, alkaloids, proteins, phenolics, simple sugars, pectins, mucilages, gums, resins, terpenes, starches, glycosides, saponins and essential oils. All of which helps improve the properties of metallic coatings [47, 48]. This chapter discuss the synthesis and characterization of CPENPs which can be used as additives to coatings for corrosion protection, especially coatings for oil and gas applications due to the properties as discussed by Kolawole et al. [46–48]. Therefore, CPENPs should not be left to waste as they are useful for additives in coatings. These will add value to the CPENPs that is usually dumped in the

bark is significant. CB is used for animal feed [42], biogas [43].

obtained from the total production of cassava [42].

poultry, dairy cattle [45] and biochar production [46].

environment and also reduces environmental pollution.

**5.3 Synthesis of cassava plant extract nanoparticles (CPENPs)**

**70**

Utilization of cassava plant extract (bark, leaf and stem) nanoparticles as green corrosion inhibitors incorporated into paint or coatings as an additive. The cassava plant part waste utilized will reduce the amount of waste contributing to environmental nuisance. The cassava plant solid extract (bark, leaf and stem) will serve as wealth creation to the farmers and value addition to the cassava waste. The developed corrosion resistant paint will enhance corrosion resistant of API 5 L X65 steel pipeline used in the oil and gas industries. Since the world production of cassava is about 268 million tonnes annually, the cassava waste generated will be significantly high, therefore the developed corrosion resistant paint will be cheaper and efficient because of the presence of heteroatoms and organic compounds which help in inhibiting corrosion.
