The effect of concentration of potassium hydrogen carbonate on the solubility of ammonium metavanadate in aqueous solutions

摘要

The soly.of NH_4VO_3 in aq.solns.was studied by isothermal satn.technique at 313 and 323 K.Soly.isotherms were detd.in the KHCO_3-NH_4VO_3-H_2O system and the d.of equ-il.solns was examd.in relation to NH_4VO_3concn.and temp.The data are essential for developing a low-waste prepn.of K_2CO_3 by carbonation of aq.-ammoniacal KVO_3 solns.Solid phases at equil.were identified by X-ray diffraction / /were x-rayed.In satd.KHCO_3NH_4VO_3 affected only slightly the soly of KHCO_3.The KHCO_3 salted-in NH_4VO_3 considerably.As temp,was raised,the solys.of KHCO_3 and NH_4VO_3 rose.The d.of satd.KHCO_3 rose to attain max.at the temp.-invariant(eutonic)p.,then fell to the ds.corresponding to satd.NH_4VO_3 solns.At each temp.,KHCO_3 and NH_4VO_3 were the solids at equil.with the soln.along the lower and the upper boundaries,resp.