Green sodium hydroxide for industrial purposes. A short review

• Published in: Journal of environmental chemical engineering 2025-02, Vol.13 (1), Article 114972
• Main Authors: Contreras, Ricardo R., Almarza, Jorge, Rincón, Luis, Ruiz, Claudia
• Format: Article
• Language: English
• Subjects: Causticization; Chlor-Alkali process; Green chemistry; Green sodium hydroxide; NaOH recovery; Tritanate causticization
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.114972

Sodium hydroxide is the most common strong base used in the chemical industry worldwide. Industrially, it is produced by variations of the electrolytic Chlor-Alkali process, which have important differences in terms of environmental sustainability. We begin this review by exploring the three primary techniques linked with the Chlor-Alkali process (current traditional production of NaOH). Additionally, we carried out a comparative study considering the use of these process to obtain a sodium hydroxide with both a low carbon footprint and environmental impact (green NaOH). Moreover, alternative processes for NaOH generation or recovery are discussed, including the causticization with sodium trititanate, whose comparative parameters indicate it is the most sustainable process to produce NaOH. Furthermore, sustainable desalination, electrolysis of brine, bipolar electrodialysis membrane, and production of NaOH from coal fly ash enriched in gallium were evaluated. Electrolysis of sodium carbonate was considered as a technology under investigation. Finally, we conclude this short review with a comparative discussion on the importance of conventional technologies and the respective advances in the production of “green NaOH”. [Display omitted] •The sodium trititanate process, considered a top option, reduces energy consumption in NaOH production by up to 80 %.•Green NaOH production lowers carbon footprint and offers a favorable ROI.•Chlor-Alkali process improvements, especially membrane methods, enhance sustainability.•Sustainable desalination and electrolysis of brine are promising for NaOH recovery and production.•Integration of NaOH recovery promotes a circular economy and green chemistry principles.