## 4 Conclusions  
The effects of spray drying parameters on the morphology, encapsulation efficiency, loading capacity and moisture content of microspheres were evaluated, and the release rate of BTA was determined in an aqueous solution. According to the discussed results, the best processing condition was obtained with an aspirator setting of 100%, an inlet temperature of 170 \({}^{\circ}\)C, a pump rate of 2.5 mL/min, and a drying gas flow rate of 440 L/h. This processing condition was selected based on its high product yield (63%), associated with a less pronounced burst release, after which a more gradual release profile of the encapsulated corrosion inhibitor is obtained. The presented results provide relevant information on the influence of inlet temperature and spray flow rate on the loading and release of BTA in CMC-Na microspheres. This information is crucial to understand the implications of spray drying processing parameters on materials to be used in applications that rely on the amount of active species available (loading), as well as on their release behavior, to achieve their intended purposes. However, a fast release of BTA occurs, which limits the applicability of these micro reservoirs. Chemical modification by crosslinking might be useful to reduce CMC-MS permeability, and to provide better control on the release of BTA, in turn, leading to better performance in corrosion inhibiting applications. Considering the growing interest around the application of agro-industrial cellulose residues for the development of new technologies, the obtained CMC microspheres address a novel eco-friendly microreservoir for corrosion inhibitor storage, reducing production costs and negative environmental impacts when compared to other commonly used materials. Moreover, although spray drying is not a conventional methodology for the encapsulation of corrosion inhibitors, this study supports the possibility of using this technique as an advantageous method to obtain an on-demand corrosion inhibitor delivery system for incorporation in organic coatings. Overall, the obtained results reveal the development of an environmentally friendly aqueous methodology based on the spray drying technique combined with a raw material with almost no ecological impact, CMC-Na, contributing to innovative material and corrosion-inhibitor reservoir preparation. The following are available online at [[https://www.mdpi.com/article/10.3390/app12041800/s1](https://www.mdpi.com/article/10.3390/app12041800/s1)]([https://www.mdpi.com/article/10.3390/app12041800/s1](https://www.mdpi.com/article/10.3390/app12041800/s1)), Figure S1: Size distribution histograms of BTA.CMC-MS at (a) 170 \({}^{\circ}\)C and 440 L/h, (b) 170 \({}^{\circ}\)C and 600 L/h, (c) 180 \({}^{\circ}\)C and 440 L/h, (d) 180 \({}^{\circ}\)C and 600 L/h, (e) 190 \({}^{\circ}\)C and 440 L/h, and (f) 190 \({}^{\circ}\)C and 600 L/h. F.C. carried out the experimental work; F.C. and I.S. were responsible for the developed methodology; F.C., I.S. and J.T. contributed to the conceptualization; C.E.B.M. validated the experiments; C.E.B.M., M.A.C.B. and J.T. supplied the resources necessary for the development of the experimental work; work and project administration were supervised by C.E.B.M., M.A.C.B., J.T. and M.G.S.F. ; F.C. and I.S. contributed to data analysis and interpretation; original draft was prepared by F.C. ; reviewing and editing of the manuscript was carried out by I.S., M.G.S.F., C.E.B.M. and J.T. ; C.E.B.M., M.A.C.B. and J.T. were responsible for funding. All authors have read and agreed to the published version of the manuscript. This work was developed in the scope of the project PVE-CAPES (n\({}^{\circ}\) 88881.064969/2014-01), and financed by the national agency CAPES. The authors gratefully acknowledge the support of UFPR, SENAI-PR and UA for the infrastructure, CNPq for the productivity fellowship (C.E.B. Marino-303126/2019-1), CAPES for financial support, and the Electron Microscopy Center of UFPR (CME-UFPR).