Fixation of alkyl phosphate using waste incineration fly ash

摘要

Waste incineration fly ash (Fa),pretreated by washing with distilled water and heating at 1000degC in air,was treated with various concentrations of octyl phosphate [C_8H_(17)OPO_3H_2(OP)] aqueous solution by stirring at 25degC for 3 h and aging at 85degC for 24 h.X-ray fluorescence and X-ray diffraction measurements indicated that the major element of Fa is Ca which exists as CaO and gehlenite (2CaO cenrte dot Al_2O_3 centre dot SiO_2).Treating Fa in OP solutions dissolved the CaO and gehlenite to form calcium octyl phosphate (C_8H_(17)OPO_3Ca centre dot n H_2O),which is composed of a multilayer alternating dicalcium phosphate dihydrate (CaHPO_4 centre dot 2H_2O)-like phase and a bimolecular layer of octyl groups of the phosphates.Increasing the OP concentration increased the fixed amount of OP and amount of recovery after the treatment.The fixed amount and amount of recovery steeply increased during stirring at 25degC,and were almost unchanged by aging.These facts allow us to infer that Fa is available to fix alkyl phosphate ions such as OP.