Boron in seawater and methods for its separation — A review

The seawater reverse osmosis (SWRO) membrane desalination process is a relevant and reliable technology for desalination of seawater. However, some serious limitations had recently been discovered during field practice, among them the boron problem seems to have a critical meaning. According to the WHO regulations, the boron concentration should be reduced to less than 0.5 mg/L for drinking water. It was also reported that, this limit is rarely reached for conventional reverse osmosis desalination plants equipped with commercially available membranes. This paper reviews the extensive published literature on separation methods of boron removal from seawater.     

Enabling electrospinning of medium-chain length polyhydroxyalkanoates (PHAs) by blending with short-chain length PHAs

Polyhydroxyalkanoates (PHAs) have recently attracted significant attention in medical applications. Electrospinning of short chain-length (scl-)PHAs has been extensively investigated, while medium chain length (mcl-)PHAs are not suitable for electrospinning since they are elastomeric at room temperature. We improved the electrospinability of an mcl-PHA poly (3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHHx) by blending with a scl-PHA poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV25, with 25?mol% HV). Morphology of electrospun PHBV25/PHOHHx blends at various ratios was investigated. Effects of various processing parameters on nanofiber morphology were investigated, such as solution concentration, feeding rate and applied voltage. Crystallinity, chemical structure, and mechanical properties of the electrospun mats were also studied.     

ELECTRO-DEIONIZATION OF Cr (VI)-CONTAINING SOLUTION. PART II: CHROMIUM TRANSPORT THROUGH INORGANIC ION-EXCHANGER AND COMPOSITE CERAMIC MEMBRANE

Cr (VI) transport through a composite ceramic membrane containing an ion-exchange component, namely xerogel of hydrated zirconium dioxide, was investigated. The diffusion coefficient of Cr (VI) species through the membrane, which has been determined under open circuit conditions, is 1.80 × 10^?10 m² s^?1. The transport number of Cr (VI) species through the ceramic membrane was found to rise with increasing voltage and reached 0.17 under “over-limiting current” conditions. On the other hand, the transport of chromate ions through hydrogel of hydrated zirconium dioxide becomes more intensive with a decrease in potential drop through the system involving ion-exchanger bed and ceramic membrane due to decrease in the membrane resistance. The diffusion coefficient of Cr (VI) ions in hydrogel of the inorganic ion exchanger was estimated as 4.36 × 10^?12 m² s^?1. A possibility of Cr (VI) removal from a weakly acidic diluted solution using an electro-deionization method was shown: the degree of solution purification was found to reach 50%. The transport of species is realized through both the solution and the ion exchanger.     

Effects of fat reduction and fat replacer addition on some quality characteristics of frankfurter-type sausages

Some quality characteristics of frankfurters manufactured in three different fat levels (20%, 10% and 5%) and added citrus fibre (CF) and soy protein concentrate (SPC) were investigated. While moisture content of frankfurters increased with decreasing fat levels, protein contents increased. Lower fat levels resulted in lower water‐holding capacity (WHC), cooking losses and penetrometer values. Lower L* values and higher a* values were obtained in low fat frankfurters. SPC significantly increased the cooking losses in the sausages with 5% and 20% fat, but decreased in the sausages with 10% fat. The lower cooking loss values were obtained in sausages added CF for all fat levels. Addition of fat replacers decreased the L values but did not affect the a and b values. Addition of fat replacers increased hardness in case of low fat levels. The softer product was obtained with high‐fat formulation than low‐fat formulation. Lower taste scores were observed with addition of fat replacers.     

Polypropylene membranes modified with interpenetrating polymer networks for the removal of chromium ions

Polypropylene (PP) membranes incorporating poly[(ar‐vinylbenzyl) trimethylammonium chloride] P(ClVBTA), and poly[sodium (styrene sulfonate)] P(SSNa) were modified via an “in situ” radical polymerization synthesis. Two methods were used for impregnation of the reactive solution: pressure injection and plasma superficial activation with argon gas. The following conditions were varied: the monomer concentrations, number of injections, and cross‐linked concentration. The modified polypropylene membranes were then characterized using scanning electron microscopy/energy dispersive X‐ray spectroscopy, Fourier transform‐infrared spectroscopy, electrokinetic potential, and Donnan dialysis for the chromium ions transport. The modified membranes exhibited a hydrophilic character with a water uptake capacity between 15% and 20% and a percent modification between 2.5% and 4.0%. This was compared with the results of an unmodified polypropylene membrane as the blank and the mentioned polypropylene membrane has not the capacity to uptake water because this kind of material is highly hydrophobic. Hexavalent chromium ions were efficiently transported by the modified membranes containing P(ClVBTA) via a plasma method and it achieved 59.2% extraction at pH 9.0 using a 1‐mol L^?1 NaCl extraction agent. Therefore, unmodified polypropylene membrane shows an extraction percentage close to 10% from the hexavalent chromium ions at pH 9.0. In the same way, the trivalent chromium transport using membranes modified with P(SSNa) achieved 49.0% extraction at pH 2.0 using 1 × 10^?1 mol L^?1 HNO₃ and 1 mol L^?1 NaCl as the extraction agents. Moreover, the unmodified polypropylene membrane reached a value close to 10% from the trivalent chromium ions using 1 × 10^?1 mol L^?1 HNO₃ and 1 mol L^?1 NaCl. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41953.     

Water‐soluble polymer and photocatalysis for arsenic removal

In this study, the photocatalytic oxidation of hazardous arsenite (As(III)) to arsenate (As(V)) and the sequential removal of arsenate from aqueous solution by liquid‐phase polymer‐based retention (LPR) were investigated. The photocatalytic oxidation of arsenite was performed using TiO₂ (P25 Degussa, Germany) under UV‐A light. The optimal photocatalytic conditions to oxidize 10 mg L^?1 of arsenite solution were achieved using a 0.5 g L^?1 of catalyst at a pH value of 2. The As(III) oxidation reached 100% after 30 min of illumination with UV‐A light. A water‐soluble polymer containing quaternary ammonium groups, poly(3‐acrylamidopropyl)trimethylammonium chloride (P(ClAPTA)), was used as an extracting reagent in the LPR process. To obtain the optimized conditions, the removal experiments were performed at various polymer : As(V) molar ratios using 10 mg L^?1 of arsenate solutions. After the oxidation of As(III) to As(V), the removal of arsenate by P(ClAPTA) was obtained in a 99% yield using a 20 : 1 polymer : As(V) molar ratio at a pH value of 9. The results demonstrate that the combination of these methods is highly useful for potential applications related to the treatment of wastewater contaminated with As(III). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40871.