Facile Two-Step Deposition of Calcium Oxalate Film on Dolomite to Improve Acid Rain Resistance

Abstract

The deposition of a calcium oxalate layer on dolomite demonstrates potential application in stone culture heritage conservation. However, due to insufficient coverage and the presence of cracks, the film’s usefulness is restricted. In this investigation, we used a simple two-step procedure to create a cohesive and uncracked film. The findings show that the protective layer provides better coverage of the dolomite surface without causing cracks and significantly improves acid resistance. Furthermore, after the simple two-step treatment, the color and adhesive strength of dolomite substrates remained nearly unchanged.

Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam): A Novel Precursor of Calcium Oxalate Coating for Carbonate Stone Substrates

“…To date, only a limited number of classes of inorganic compounds have been tested as conservation agents for carbonate stone substrates [17], including alkaline earth hydroxides [18,19], re-mineralizing calcium carbonate [20], or salts such as diammonium hydrogen phosphate (NH 4 ) 2 (HPO 4 ) [10,21,22]. In recent decades, a renewed interest has been focused on the use of ammonium oxalate (NH 4 ) 2 (C 2 O 4 ) (AmOx) as a passivating and protective agent [23][24][25][26][27], whose reaction with calcium carbonate results in the formation of calcium oxalate (CaOx) hydrate Ca(C 2 O 4 )•nH 2 O (n = 1; whewellite, K sp = 2.0 × 10 −9 ; n = 2, weddellite, K sp = 3.8 × 10 −9 at 25 • C; Equation ( 1)) [28][29][30][31][32][33]:…”