Preparation of aluminium ammonium calcium phosphates using microwave radiation

Microwave radiation was used in the acquisition of aluminium ammonium calcium phosphates. The substrates such as CaCO₃, H₃PO₄, aqueous ammonia were reagent grade, whereas Al(OH)₃ was prepared afresh. The influence of process parameters (pH 6 ± 2, molar ratios of Al³⁺: Ca²⁺: PO ₄ ^3? in the substrates, respectively 0.31: 0.62: 1; 0.5: 0.5: 1; 0.72: 0.36: 1) on the phase composition and the product properties was determined. Statistical software STATISTICA 10 was used for planning and evaluation of the experiments. The process parameters making it possible to acquire the material with the anticipated physicochemical properties were determined based on statistical evaluation of the planned research by the plan fractional factorial design at three levels 3^(k?p). The phase composition of the samples was studied using XRD analysis. The specific surface area was calculated using the BET method and the particle size was determined by LSM. Materials with a molar ratio of Al³⁺: Ca²⁺ and Al³⁺: NH ₄ ⁺ in the range of 0.07–0.76 and 0.75–3.4, respectively, with an absorption oil number of 36–56 g per 100 g, S _BET within 8.2–73 m² g^?1, and particle size in the range of 156–252 nm were obtained.