Enhanced boron rejection by NF/RO membranes by complexation with polyols: Measurement and mechanisms

Abstract

Boron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes in the presence of glycerol, mannitol and sorbitol was investigated as a function of feed solution pH and boron:polyol molar ratio. In the presence of polyols, significant boron rejection improvement was obtained and the extent of the impact was directly related to the stability constant of the boron-polyol complex. Polyols could complex with boron in either the boric acid or borate anion forms; however the complexation between polyol and boric acid appeared to be incomplete. With and without the presence of polyols, boron rejection was strongly pH dependent. The increase in boron rejection due to polyol addition was higher for the NF membrane compared to the RO membrane. A boron:polyol molar ratio of 1:1 appeared to be adequate. The presence of polyols did not cause any observable membrane fouling. Results reported here suggest that the addition of polyols could allow NF membranes to be effectively used for boron removal. AbstractBoron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes in the presence of glycerol, mannitol and sorbitol was investigated as a function of feed solution pH and boron:polyol molar ratio. In the presence of polyols, significant boron rejection improvement was obtained and the extent of the impact was directly related to the stability constant of the boron-polyol complex. Polyols could complex with boron in either the boric acid or borate anion forms; however the complexation between polyol and boric acid appeared to be incomplete.With and without the presence of polyols, boron rejection was strongly pH dependent. The increase in boron rejection due to polyol addition was higher for the NF membrane compared to the RO membrane. A boron:polyol molar ratio of 1:1 appeared to be adequate. The presence of polyols did not cause any observable membrane fouling. Results reported here suggest that the addition of polyols could allow NF membranes to be effectively used for boron removal.

Osmotic dilution for sustainable greenwall irrigation by liquid fertilizer: Performance and implications

“…Key characteristics of raw sewage are summarized in Table 2. concentration was determined by inductively coupled plasma mass spectrometry (ICP-MS) (Agilent 7500cs, Agilent Technologies, Wilmington, DE) using a method described elsewhere [30]. Solution pH and electrical conductivity were measured using an Orion 4-Star Plus pH/conductivity meter (Thermo Scientific, Waltham, MA).…”

Co-digestion of sewage sludge and crude glycerol for on-demand biogas production

“…The obtained samples were analysed using an Agilent 7500cs ICP-MS. A Merck ICP multi-element standard solution was used for calibration. The details of this analytical method are available elsewhere(Tu et al, 2013).…”

Nanoscale Surface Compositions and Structures Influence Boron Adsorption Properties of Anion Exchange Resins

“…Highly cross-linked polymers with surface-grafted acidic or basic functional groups are used to adsorb and exchange counterions from aqueous and organic solutions. The ion-exchange properties of such polymer resins can be adjusted by incorporating suitable surface functional groups for different technological applications including desalination, , chromatography-based separation and purification, and catalysis. − For example, naturally occurring chitosan polymers or synthetic styrene-divinylbenzene copolymers grafted with surface COO – or SO 3 – functional groups have been shown to exchange cations or anions − when surface-grafted with sorbitol, mannitol, and N -methyl- d -glucamine (NMDG) groups. , Ion-exchange resins have also been used to catalyze reactions, such as alkylation, isomerization, oligomerization, acylation, esterification, and nitration − and have long been recognized for their environmental remediation applications. ,,,, Of particular interest, ion-exchange resins have been used to reduce boron concentration levels in soil, surface, and wastewaters, including as part of decontamination efforts in Fukushima, Japan. Boron-containing materials are also used extensively in power generation applications and in the production and processing of diverse engineering materials, such as glasses, ceramics, fertilizers, detergents, catalysts, and semiconductors. − Despite their high technological importance, much remains unknown about the relationships between the compositions, structures, and properties of boron-containing materials, especially those involving dilute surface species.…”

“…The ionexchange properties of such polymer resins can be adjusted by incorporating suitable surface functional groups for different technological applications including desalination, 1,2 chromatography-based separation and purification, 3 and catalysis. 4−6 For example, naturally occurring chitosan polymers or synthetic styrene-divinylbenzene copolymers grafted with surface COO − or SO 3 − functional groups have been shown to exchange cations 1 or anions 7−9 when surface-grafted with sorbitol, 10 mannitol, 11 and N-methyl-D-glucamine (NMDG) groups. 12,13 Ion-exchange resins have also been used to catalyze reactions, such as alkylation, isomerization, oligomerization, acylation, esterification, and nitration 14−16 and have long been recognized for their environmental remediation applications.…”

“…36−39 In particular, interatomic proximities between dipole−dipole-coupled nuclei can be established by analyses of powerful 2D correlation NMR spectra. Recently, one-dimensional (1D) solid-state 11 B MAS NMR has been used to probe local boron environments in chelate complexes of ion-exchange resins and supramolecular hydrogels. 40,41 Similar analyses of solid-state 1D 1 H and 13 C MAS NMR spectra have yielded insights on surface compositions and structures of ion-exchange resins, though the signals are often poorly resolved, due to distributions of species associated with the polymer substrate (e.g., polystyrene) and surface-grafted NMDG functional groups.…”