## 3 Results and Discussion
### Green Corrosion Inhibitors  
The results for group B descriptors (corros* AND (inhib* or inib*)) AND (green OR environmental sustainable OR eco-friendly)) were less expressive when compared to those of group A, but indicate interest in the development of this class of inhibitors. A total of 2263 articles resulted from the Web of Science, about 9% of the number for group A (25,407), and 7 articles in SciELO. For Derwent, INPI and Orbit, 989, 10 and 632 patents were found, respectively. The articles found in the SciELO database describe the use of various materials as green inhibitors, as listed in Table 3. Among the possible inhibitors evaluated there were: coffee powder [32], caffeine [33], _Aniha canellila_[34], _Hibisco-colibri_[35], mango and orange peels [36], garlic [37] and castor bean [38]. All materials (Table 3) were analyzed to discover whether they inhibit carbon steel corrosion in acid medium and showed inhibition efficiencies above 80%. The exception was babassu coconut oil, with 56.45% efficiency [39]. Figure 2 shows the percentages of the top 10 IPC (International Patent Classification) codes used for patents found in the Derwent database. Most of it related to code C09D 5/08, referring to: coating compositions (paints, varnishes or lac  
Figure 1: Quantitative numbers of articles and patents recovered for group A descriptors over the last 10 years for (**a**) international searches and (**b**) specific searches for Brazil. \begin{table}
\begin{tabular}{c c c c c} \hline
**Inhibitor** & **Medium** & **Metal** & **Inhibition** & **Reference** \\ \hline Coffee powder & Acid & Carbon steel & 94.83\% & [PERSON] et al. 2020 [32] \\ \hline Caffeine & Acid & Carbon steel & 92.40\% & [PERSON] et al. 2014 [33] \\ \hline Aniba canellilla & Acid & Carbon steel & 97.00\% & [PERSON] et al. 2018 [34] \\ \hline Hibisco-colibri & Acid & Carbon steel & 97.50\% & [PERSON] et al. 2019 [35] \\ \hline Mango and orange peels & Acid & Carbon steel & 94.00\% & [PERSON] et al. 2014 [36] \\ \hline Castor bean & Acid & Carbon steel & 83.00\% & [PERSON] et al. 2017 [38] \\ \hline Garlic peels & Acid & Carbon steel & 95.14\% & [PERSON] et al. 2017 [37] \\ \hline Babassu coconut oil & Acid & Carbon steel & 56.45\% & [PERSON] et al. 2019 [39] \\ \hline White tea & Acid & Carbon steel & 90.20\% & [PERSON] and [PERSON], 2019 [40] \\ \hline \end{tabular}
\end{table} 
Table 3: Main information regarding the articles retrieved from the SciELO database for group B descriptors. their physical nature or effects produced; filling pastes and anti-corrosion paints. The other codes are related to section C, chemistry and metallurgy. Figure 3 shows the distribution of patents over the last 10 years (2011 to 2020) found in Orbit software. There was a significant increase in deposits related to green corrosion inhibitors from 2013 onwards, about 140% more when compared to 2012. This increase in the number of deposits is related to a movement promoted by the United Nations (UN) in 2008. Through its general secretary, Mr. [PERSON], who called for the World Intellectual Property Organization's (WIPO) greater commitment and intervention in relation to the role of technology and industrial development on climate change issues. In addition, it called for mechanisms to enable greater harmonization for the concepts of \"green\" technologies existing in each WIPO country member. Thus, green patent programs were initiated worldwide [41]. Although this movement began in 2008, the implementation process in the countries along with their respective patent offices was gradual. It started in the United Kingdom (2009), followed by Australia (2009), South Korea (2009), Japan (2009), United States (2009), Israel (2009), Canada (2011), Brazil (2012), China (2012) and Taiwan (2014) [42]. Figure 2: Percentages of the top 10 IPC codes for patents recovered from the Derwent source with the B group of descriptors.