Waste to energy residues in sustainable spiral economy cycle: alkalizing properties of sunflower husk ash for future green applications

Abstract

As a combustion by-product, biomass ash is classified as waste. Actually, depending on the biomass type, it contains various valuable chemical elements. The current study investigates opportunities for utilization of biomass ash in two forms - sunflower husk ash (SHA) and sunflower husk ash granules (SHAG) based on their alkalizing properties. Experiments and measurements of pH were conducted with different concentrations (67 and 100 g/L) of SHA and SHAG in 30 ml of deionized water, with and without stirring, at contact times between 0 and 96 hours. The investigated materials demonstrated good alkalizing properties – pH rose from 6.8 to an average value of 11.09 and remained stable over time. The raw materials were characterized through X-ray fluorescence (XRF), X-Ray Diffraction (XRD), and scanning electron microscopy–energy dispersive X-ray (SEM-EDX) analyses, as additional analyses were applied on the solid and liquid phases after filtration. The performed analyses confirmed that both investigated materials dominantly consisted of alkaline compounds, such as Potassium, Calcium and Sodium. The obtained results are prerequisite for further utilization of this by-product as a green chemical material for pH increasing with different applications, such as soap production, soil stabilization manufacturing, and wastewater decontamination from heavy metals.