Characterization of ashes from greenhouse crops plant biomass residues using X‐ray fluorescence analysis and X‐ray diffraction

Abstract

A characterization of ashes obtained by thermal treatments on greenhouse crops plant biomass residues is presented. The chemical analysis, by X‐ray fluorescence (wavelength‐dispersive X‐ray fluorescence), and phase analysis, by X‐ray diffraction, of the resultant ashes are reported. Thermal treatments of selected samples of these residues increase the relative amounts of inorganic Mg, Si, P, and S in the ashes, being these amounts as high as increasing temperature. As an opposite effect, Na, Cl, and K contents decrease as increasing temperature by a volatilization process of the chlorides, as confirmed by X‐ray diffraction. The crystalline phase analysis of the ashes demonstrates the formation of inorganic constituents of the biomass, including alkaline chlorides and calcium salts (calcite, anhydrite, and apatite). Progressive thermal treatments induce the formation of new silicate phases (akermanite and grossularite) and silica (α‐quartz and cristobalite). Furthermore, the particle size of the starting biomass samples does not influence the evolution of the crystalline phases by thermal treatments. In contrast, a previous leaching using water and subsequent heating at 1,000 °C produces the formation of periclase (MgO), lime (CaO), and the silicate gehlenite, without the presence of anhydrite. This study is interesting for future investigations on the residues as a profitable biomass source for energy production and sustainable large‐scale management. Some potential applications of the resultant ashes can be proposed.

The Management of Agricultural Waste Biomass in the Framework of Circular Economy and Bioeconomy: An Opportunity for Greenhouse Agriculture in Southeast Spain

“…However, there has been research that highlights the importance of waste from tomato and pepper crops as a new source of renewable energy [111,112]. Although their high moisture content reduces their caloric value [113] and makes them inefficient for biofuel production and gasification processes [61,114], some investigations suggest that combined heating and carbonic enrichment systems for greenhouses could be implemented by exploiting the combustion of these materials [115,116].…”