Application of calcium oxide cycle method in mass deacidification

Abstract Paper documents serve as vital archives preserving human civilization, yet acidification remains the primary factor causing their deterioration. To protect these cultural treasures from acid damage, researchers typically apply alkaline substances through non-aqueous or aqueous solvent systems in batches of paper. However, these methods may cause environmental pollution or demonstrate low processing efficiency. This study proposes a novel approach: utilizing calcium oxide to deacidify acidic paper through air circulation exposure. Experimental results show that treated paper samples achieved stable pH values of 8.20–8.80 with uniform deacidification. Both the overall pH and alkali storage levels met cultural heritage protection standards (the pH values are between 8.00 and 8.50, and the alkali reserve is not less than 0.6 wt% CaCO3 equivalent). Microscopically, this process enables deep calcium carbonate deposition while maintaining intact fiber structures. Notably, the treated samples showed negligible impacts on tensile strength, tear index, folding endurance, and zero-distance tensile strength, with minimal visible changes in appearance.