Beyerol triacetate

Background: In haemodialysis, maintaining patency of the extracorporeal circuit requires the use of anticoagulants. Although (low molecular weight) heparins are the mainstay, these are not well tolerated in all patients. Alternative approaches include saline infusion, citrate-containing dialysate, regional citrate anticoagulation or the use of heparin-coated membranes. Asymmetric cellulose triacetate (ATA) dialysers have a low degree of platelet contact activation and might be an alternative to heparin-coated dialysers. The aim of this study was to test the clotting propensity of ATA when used without systemic anticoagulation. Methods: We performed a Phase II pilot study in maintenance dialysis patients. The 'Strategies for Asymmetrical Triacetate dialyzer heparin-Free Effective hemodialysis' (SAFE) study was a two-arm open-label crossover study. In Arm A, patients were dialysed using 1.9 m2 ATA membranes in combination with a citrate-containing dialysate (1 mM). In Arm B, the ATA membrane was combined with high-volume predilution haemodiafiltration (HDF) without any other anticoagulation. The primary endpoint was the success rate to complete 4 h of haemodialysis without preterm clotting. Secondary endpoints included time to clotting and measures of dialysis adequacy. Results: We scheduled 240 dialysis sessions (120/arm) in 20 patients. Patients were randomized 1:1 to start with Arm A or B. All patients crossed to the other arm halfway through the study. A total of 232 (96.7%) study treatments were delivered. Overall, 23 clotting events occurred, 7 in Arm A and 16 in Arm B. The success rate in Arm A (ATA + citrate-containing dialysate) was 90.8/94.0% [intention to treat (ITT)/as treated]. The success rate in Arm B (ATA + predilution HDF) was 83.3/86.2% (ITT/as treated). Time to clotting was borderline significantly better in Arm A (Mantel-Cox log rank P = 0.05). Conclusion: ATA dialysers have a low clotting propensity and both predilution HDF and a citrate-containing dialysate resulted in high rates of completed dialysis sessions.

Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is one of the commercially successful semipermeable membranes that has had a long progress since the time the excellent semi-permeable feature of cellulose-based polymers was found in 1957. Because of the reliable and excellent performances, especially for drinking water production from seawater, CTA-HFs have been widely used as reverse osmosis (RO) membranes, especially in arid regions. In this review, recent developments and research trends on CTA-HF membranes for seawater reverse osmosis (SWRO) plants were presented. A flux analytical model, an optimization strategy for chlorine injection without losing salt rejection performance, and a module of current high performance CTA RO membranes along with its plant operation data were updated in this paper. Furthermore, a newly developed CTA-HF membrane for brine concentration (BC) application (called BC membrane) was also addressed. Finally, RO/BC hybrid operation was introduced as an effective SWRO desalination technique that enables minimizing the volume of brine disposal from the RO plant by increasing the recovery ratio and the subsequent amount of produced freshwater, without an additional energy input.

Cellulose triacetate (CTA) was successfully synthesized from corn stover cellulose (CSC) in the presence of [PyPS]3PW12O40 (IL-POM). The effects of IL-POM contents, reaction temperature, and reaction time on the yield and degree of substitution of CTA were investigated. The synthesized CTA was characterized by SEM, FTIR, and TGA, and the degree of polymerization and solubility in various organic solvents were evaluated. Results showed that the optimum reaction conditions were as follows: 0.04 g of IL-POM, reaction temperature of 140 °C, and reaction time of 45 min, for 0.4 g of CSC and 9 mL of glacial acetic acid. The yield of CTA under optimum reaction conditions was as high as 79.27%, and the degree of substitution was 2.95. SEM and FTIR results showed that the cellulose acetylation occurred, and CTA was synthesized. The TGA results revealed that the decomposition temperature of CTA increased by about 30 °C when compared with that of CSC. A simple, environment-friendly, and efficient process for the preparation of CTA from CSC was constructed, which provides a new pathway for the high-value utilization of corn stover.