Biomass Mediated Conversion of Acidic Phosphogypsum into Alkaline Material through Thermal Treatments

Abstract

The application of phosphogypsum waste is limited to alkaline soil primarily due to its highly acidic pH. Its application can be widen for the acidic soil by converting phosphogypsum into alkaline material. In this context, conversion of acidic phosphogypsum into alkaline material by mixing banana peduncle biomass in powder form in different proportions followed by thermal pyrolysis treatments (300–700°C) were investigated. Acidic phosphogypsum pH (3.2) increased without biomass mixing to 6.3, 6.6 and 7.4 at 300, 500 and 700°C, whereas phosphogypusm-biomass-mixtures elevated pH to relatively higher values 6.7–7.2, 8.2–9.6 and 10.1–10.4 respectively. Alkaline pyrolysed material also contained carbon (25.8%), potassium (10%), and sulfur (12%) and their toxic flouride concentration was lesser (0.39%) than raw phosphogypsum (0.44%). The XRD analysis revealed formation of water soluble anhydrite, arcanite, potassium calcium sulfate and calcite mineral phases. These results established and highlights about process of conversion of phosphatic fertiliser industry acidic phosphogypsum waste to nutrient rich alkaline material by utilising banana peduncle biomass through thermal treatment. The reseach findings has implication towards phosphogypsum industrial waste management, value addition and potential for its alternative use in acidic soils.