In-situ growth of Ba(OH)2 nanoparticles on bacterial cellulose: A composite material for reinforcement of ancient murals—A preliminary study

Abstract

Mural paintings, valuable cultural relics, face persistent damage issues. Ba(OH)₂ can transform into barium BaCO₃ in the atmosphere, improving its protective abilities. Challenges in synthesis and size control hinder its potential as a protective agent. In this study, a cost-effective composite of Ba(OH)₂ and bacterial cellulose (BC-Ba(OH)₂) was developed. The abundant -OH groups on the BC surface anchor and disperse Ba(OH)₂ nanocrystals, promoting in-situ growth of particles approximately 10 nm in size. The successful preparation of BC-Ba(OH)₂ was confirmed by techniques such as XRD, TEM mapping, and infrared spectroscopy. Moreover, the strong physical interaction between Ba(OH)₂ and BC helps prevent the migration and agglomeration of Ba(OH)₂ nanoparticles, thereby ensuring the long-term effectiveness of the reinforcing agent. Additionally, owing to the outstanding toughness and strength of BC, the formed 3D network structure effectively enhances the strength of mural structure. Through a series of performance tests, it was demonstrated that BC-Ba(OH)₂ exhibits superior permeability, consolidation strength and flexural strength in mural restoration compared to commercial Ba(OH)₂. It is noteworthy that experiments and DFT confirm that the increase in the carbonization rate is attributed to the nano effect and carrier effect. Using BC as a support not only reduces the particle size of Ba(OH)₂ but also optimizes the internal charge structure of Ba(OH)₂, enhancing its CO₂ adsorption capability. These results suggest a new direction for the development of emerging mural restoration materials.