Removal of Fluorine from RECl3 in Solution by Adsorption, Ion Exchange and Precipitation

In this paper, methods of effective removal of fluorine from rare earth chloride solution by adsorption, ion exchange and precipitation with lanthanum carbonate or CO2 gas as fluorine-removal agent, respectively, were studied. The relevant parameters studied for fluorine-removal percentage were the effects of the type and dosage of fluorine-removal agent, the injection flow and mode of CO2, the initial concentration of rare earth solution and initial pH value, contact time, temperature and stirring. XRD, SEM and EDS were used to analyze and characterize the filter slag obtained after fluorine removal. SEM and EDS results showed that RECO3(OH) with a porous structure was formed in rare earth chloride solution when lanthanum carbonate was used as fluorine-removal agent, and it had strong selective adsorption for F−. The XRD spectra showed that F− was removed in the form of REFCO3 precipitates, which indicates that the adsorbed F− replaced the OH- group on the surface of RECO3(OH) by ion exchange. The experimental results showed that a fluorine-removal percentage of 99.60% could be obtained under the following conditions: lanthanum carbonate dosage, 8%; initial conc. of rare earths, 240 g/L; initial pH, 1; reaction temperature, 90 °C; reaction time, 2 h. Simultaneously, a fluorine-removal process by CO2 precipitation was explored. In general, RE2(CO3)3 precipitation is generated when CO2 is injected into a rare earth chloride solution. Interestingly, the results of XRD, SEM and EDS showed that the sedimentation slag was composed of REFCO3 and RE2O2CO3. It was inferred that RE2(CO3)3 obtained at the initial reaction stage had a certain adsorption effect on F− in the solution, and then F− replaced CO32− on the surface of RE2(CO3)3 by ion exchange. Therefore, F− was finally removed by the high crystallization of REFCO3 precipitation, and excess RE2(CO3)3 was aged to precipitate RE2O2CO3. The fluorine-removal percentage can reach 98.92% with CO2 precipitation under the following conditions: venturi jet; CO2 injection flow, 1000 L/h; reaction temperature, 70 °C; initial pH, 1; reaction time, 1.5 h; initial conc. of rare earths, 240–300 g/L; without stirring. The above two methods achieve deep removal of fluorine in mixed fluorine-bearing rare earth chloride solution by exchanging different ionic groups. The negative influence of fluorine on subsequent rare earth extraction separation is eliminated. This technology is of great practical significance for the further development of the rare earth metallurgy industry and the protection of the environment.

The Effect of Phosphate Binders in Patients With End Stage Kidney Disease Undergoing Hemodialysis: a Prospective Observational Study

To compare the clinical efficacy of sevalamer carbonate and lanthanum carbonate in chronic hemodialysis patients. This prospective observational study included 80 patients randomly divided into two groups were followed from December 2019 to December 2020. After 12 months of maintenance hemodialysis treatment with sevalamer carbonate or lanthanum carbonate, serum phosphorus, serum calcium, alkaline phosphatase(ALP), parathyroid hormone (iPTH), low-density lipoprotein(LDL), hemoglobin(HGB), triglycerides(TG) and albumin(ALB) were evaluated. The adequacy of dialysis, the effective rate of treatment and the incidence of adverse reactions were compared as well. After treatment, In lanthanum carbonate group, serum phosphorus and iPTH decreased and albumin increased, the difference was significant(P < 0.05). In sevalamer carbonate group, serum phosphorus and LDL decreased and albumin increased after treatment, the difference was significant(P < 0.05). There was no significant difference in the dialysis adequacy and total effective rate between the two groups (P>0.05). However, the incidence of gastrointestinal adverse reactions in the sevalamer carbonate group was lower than in the lanthanum carbonate group and the difference was significant (P < 0.05). The two phosphate binders are safe and effective for the treatment of hyperphosphatemia in patients with ESKD undergoing maintenance hemodialysis. Nevertheless, sevalamer carbonate seems to be superior with lowering the incidence of gastrointestinal adverse reactions and improving lipid metabolism.

The Effect of Phosphate Binders in Patients With End Stage Kidney Disease Undergoing Hemodialysis: a Prospective Cohort Study

Background: To compare the clinical efficacy of sevalamer carbonate and lanthanum carbonate in chronic hemodialysis patients. Methods: This prospective observational study included 76 patients with follow-up from September 2019 to December 2020. After 15 months of maintenance hemodialysis treatment with sevalamer carbonate or lanthanum carbonate, serum phosphorus, serum calcium, alkaline phosphatase(ALP), parathyroid hormone (iPTH), low-density lipoprotein(LDL), hemoglobin(HGB), triglycerides(TG) and albumin(ALB) were evaluated. The adequacy of dialysis, the effective rate of treatment and the incidence of adverse reactions were compared as well. Results: After treatment, In lanthanum carbonate group, serum phosphorus and iPTH decreased and albumin increased, the difference was significant(P < 0.05). In sevalamer carbonate group, serum phosphorus and LDL decreased and albumin increased after treatment, the difference was significant(P < 0.05). There was no significant difference in the dialysis adequacy and total effective rate between the two groups (P>0.05). However, the incidence of adverse reactions in the sevalamer carbonate group was lower than in the lanthanum carbonate group and the difference was significant (P < 0.05). Conclusion: The two phosphate binders are safe and effective for the treatment of hyperphosphatemia in patients with ESKD undergoing maintenance hemodialysis. Nevertheless, sevalamer carbonate seems to be superior with lowering the incidence of gastrointestinal adverse reactions and improving lipid metabolism.

Gastric lanthanosis (lanthanum deposition) in an immunosuppressed patient that discontinued lanthanum carbonate seven years ago

A 72-year-old female used the oral phosphate binder lanthanum carbonate for 6 years, before discontinuing it after receiving a pancreas and kidney transplant. Now, 7 years after discontinuation, the patient developed bilious emesis. An upper gastrointestinal endoscopy showed an unspecific gastritis. Biopsies showed subepithelial crystalline deposits consistent with gastric lanthanosis.