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Abstract: The main objective of this work was to investigate boron removal from seawater using two commercial high rejection SWRO membranes. The impact of solution pH, feed concentration, pressure, and cross-flow velocity on boron rejection and permeate flux was determined. The membranes used were the Toray™ UTC-80-AB and Filmtec™ SW30HR. A lab-scale cross-flow flat-sheet configuration test unit was used for all RO experiments. Seawater sample was collected from the Mediterranean Sea, Alanya-Kızılot shores, south Turkey. For all experiments, mass balances were between 91% and 107%, suggesting relatively low loss of boron on membrane surfaces during 14 h of operation. Operation modes did not have any impact on boron rejection, indicating that boron rejection were independent of feedwater boron concentrations up to 6.6 mg/L. For both membranes, much higher boron rejection were obtained at pH of 10.5 (>98%) than those at original seawater pH of 8.2 (about 85–90%). Permeate boron concentrations less than 0.1 mg/L were easily achieved at pH 10.5 by both membranes. The dissociated boron species are dominant at this pH, thus both electrostatic repulsion and size exclusion mechanisms are responsible for the higher boron rejection. The rejection of salts in seawater did not correlate with boron rejection at constant conditions. For each membrane type, permeate fluxes at constant pressure were generally lower at pH of 10.5, which may be partially explained by membrane fouling and enhanced scale formation by Mg and Ca compounds from concentration polarization effect at higher pH values. While somewhat higher boron rejection was found for one membrane type as the pressure was increased from 600 to 800 psi, increasing pressure did not affect boron rejection for the other membrane. Feed flowrate thus the cross-flow velocity (0.5–1.0 m/s) did not exert any significant impact on boron rejection at constant conditions. [Copyright &y& Elsevier]

Abstract: The objective of this study is to explore the performance of the boron selective ion exchange resins for boron removal from seawater reverse osmosis (SWRO) permeate. A lab-scale cross-flow flat-sheet configuration test unit (SEPA CF II, Osmonics) and FilmTec RO membranes were used for batch-mode RO tests. Seawater samples containing 5.1 mg B/L were collected from the Mediterranean Sea. The chelating ion exchange resins containing N-methyl glucamine groups (Diaion CRB 02 and Dowex-XUS 43594.00 resins) were employed for batch and column-mode tests to remove boron from SWRO permeate. Optimum resin amount for boron removal from SWRO permeate was found as 1 g resin/L for both Diaion and Dowex resins. The equilibrium half-time for B removal was between 30 and 45 min for Dowex and 20–30 min for Diaion resins. Sorption kinetics for these resins fit to Ho pseudo-second-order kinetics model. Both resins exhibited large breakthrough capacities with boron leakage of less than 0.2 mg B/L. Breakthrough capacity was influenced by space velocity. Boron loaded onto the resins was quantitatively eluted with 5% H2SO4 solution. [Copyright &y& Elsevier]