Climatic chamber tests to evaluate the catalytic action of heavy metals in the sulphation process

Research conducted on the degradation of cultural and architectural heritage caused by the deposition of air pollutants indicates that both sulphur dioxide and particulate matter produced by the combustion of fossil fuels are the main agents responsible for the deterioration of carbonate materials. The main chemical degradation process is the sulphation of the substrate which consists in the initial conversion of sulphur dioxide (SO2) into sulphuric acid (H2SO4) and the subsequent reaction of sulphuric acid with calcium carbonate. This leads to the formation of black crusts, which are composed of gypsum inside which particulate matter is embedded. Heavy metals adsorbed on the carbonaceous particles enable the sulphation of the substrate by acting as catalysts in both stages of the process. This research aims to evaluate which heavy metals activate the sulphation process by carrying out targeted exposure tests in climatic chambers.