Boric acid recovery using polymer filtration: Studies with alkyl monool, diol, and triol containing polyethylenimines

Abstract

Three water-soluble polymers containing linear alkyl monool, 1,2-diol, and 1,2,3-triol groups, mostly on the primary amines of polyethylenimine, were synthesized, characterized, and tested for their ability to recover boric acid. The boron-binding capacities of these polymers and the backbone polyethylenimine were determined by titration, ultrafiltration, and inductively coupled plasma/ atomic emission spectroscopy analysis. At low boron concentrations, the 1,2,3-triol polymer performed better than the 1,2-diol, whereas at high boron concentrations, the 1,2-diol outperformed the 1,2,3-triol.11 B-NMR spectroscopy and retention studies with various salt concentrations indicated that boron interacted with these two polymers by means of ion pairing with the protonated amines and by borate ester formation. For the monool and the polyethylenimine backbone, the mechanism for boron binding was ion pairing only. These polymers are under consideration for the selective recovery and recycling of enriched boric acid used in the primary coolant loop of pressurized water nuclear reactors.

Preparation of a chelating sorbent based on pyridylethylated polyethylenimine for recovering transition metal ions

“…High reactivity of PEI [17][18][19][20][21][22] is chiefl y due to primary amino groups [10]. However, no attempts of PEI modifi cation by the Michael reaction have been reported.…”

“…Sorbents can be jprepared both from unmodifi ed cross-linked PEI [3][4][5][6] and from the functionalized polymer [6][7][8][9][10][11][12]. PEI as a polyamine is highly active in sorption of Hg(II) (3.3 mmol g -1 [3]), Cu(II), Ni(II), Co(II), and Zn(II) ions (no less than 2 mmol g -1 [6]) and, in combination with chitosan, in sorption of Hg(II) [4], Pt(IV), and Pd(II) ions [5].…”

“…Such complexing properties of PEI allow preparation of structure-forming [13,14] and metal-containing catalytic [15] materials based on it. Additional N-functionalization of PEI, primarily occurring at the most reactive primary amino groups [10], signifi cantly alters the sorption characteristics. For example, at pH < 2, the sorption capacity of PEI-based sorbents containing carboxylic acid residues for Cu 2+ ions is 0.7 mmol g -1 [7,8].…”

“…For example, at pH < 2, the sorption capacity of PEI-based sorbents containing carboxylic acid residues for Cu 2+ ions is 0.7 mmol g -1 [7,8]. The sorbent prepared by introduction of the 2,3-dihydroxypropyl substituent exhibits high ability to sorb boric acid (>2 mmol g -1 ) [9,10].…”

Boric acid binding studies with diol containing polyethylenimines as determined by 11B NMR spectroscopy

“…1 The use of 10 B-enriched BA has been proposed as a way to (i) increase fuel cycles and fuel burn-ups, and (ii) to reduce the required concentration of BA, which is associated with stress corrosion cracking in the primary coolant loop and Zircaloy fuel-cladding corrosion. 2,3 Recent studies 4 performed by our group have shown that polyethylenimine (PEI) functionalized with 2,3-dihydroxy propyls are efficient polymer systems to recover BA because (i) they have a low average-repeat-unit (ARU) molecular weight (MW), (ii) they provide sufficiently stable boron adducts, and (iii) they are easy to synthesize.…”