Synthesis and characterization of arsenate antimonic acid AAAc(1 : 1)

摘要

The AAAc(1:1) was synthesized in water by As_2O_3 and Sb_2O_3 with molar ratio of 1 : 1. AAAc(1:1) was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to v_s of As—OH, As—O—Sb, Sb—OH and Sb—O—Sb in Raman spectra of AAAc(1:1) at 100 - 1 000 cm~(-1). The solution of AAAc(1:1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexa-basic acid with dissociation constants of k_1 = 3. 62 X 10~(-2), k_2 = 3. 05 X 10~(-3), k_3 = 6. 43 X 10~(-6), k_4 = 9. 78 X 10~(-8), k_5 = 1. 32X 10~(-11) , k_6 =3. 87X 10~(-12). AAAc(1:1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analysis show that the composition of AAAc(1:1) is As_2O_5 · Sb_2O_5 · 8H_2O in air at 25℃. AAAc(1:1) has the structure of AsO(OH)_2—OH—Sb(OH)_4—O—Sb(OH)_4—OH—AsO(OH)_2 or As (OH)_3—O—Sb(OH)_4—O— Sb(OH)_4—O—As(OH)_3(isomerism) through experimental determination and geometry optimization.