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A novel ion separation methodology using a cation-exchange membrane modified with iron oxide nanoparticles (Fe3O4 NPs) coated with polyhexamethylene guanidine (PHMG) is proposed. The separation is performed in an electrodialysis cell, where firstly phosphate is electro-adsorbed to the PHMG@Fe3O4 NP coating, followed by a desorption step by applying an electric current. [ABSTRACT FROM AUTHOR]

In this work commercially available Fe3O4 NPs were coated with polyallylamine hydrochloride (PAH) and PAH functionalized with guanidinium groups (PAH–Gu) for investigating the phosphate adsorption properties under alkaline conditions. The coating can be prepared easily and rapidly and results in Fe3O4 NPs with improved properties related to phosphate binding and colloidal stability. At a low initial phosphate concentration (2 mg L−1), the novel Fe3O4@PAH–Gu material was able to remove phosphate rather independently of the pH condition (4.0, 3.6 and 3.7 mg g−1 at pH = 5, 8 and 10, respectively), whereas for the uncoated Fe3O4 NPs the amount of adsorbed phosphate drops by ＞75% upon changing from acidic to alkaline conditions (0.84 mg g−1 at pH = 10). Under alkaline conditions, the fastest adsorption was observed for Fe3O4@PAH–Gu followed by Fe3O4@PAH and Fe3O4. This can be related to the additional interaction forces due to the presence of primary amine groups (in PAH and PAH–Gu) and Gu groups (in PAH–Gu only) in coatings. Over 80% of the phosphate adsorbed on the novel Fe3O4@PAH–Gu material was successfully desorbed and the coated NPs were re-used over three adsorption/desorption cycles. This work will stimulate the design and preparation of functionalized polyelectrolytes for an extended area of applications, especially for the selective removal of target compounds from wastewater. [ABSTRACT FROM AUTHOR]

The recovery of carboxylic acids from fermentation broth is one of the main bottlenecks for the industrial production of bio-based esters. This paper proposes an alternative for the recovery of carboxylates produced by fermentations at pH values above the pKa of the carboxylic acid. In this approach, the aqueous carboxylate anion is recovered using anion exchange, followed by desorption and esterification with CO2-expanded alcohols. Using CO2-expanded methanol, we achieved a high desorption yield at 10 bar of CO2 and 20 °C. An ester yield of 1.03 ± 0.07 mol methyl acetate/acetatein was obtained for the combined desorption–esterification at 5 bar of CO2 and 60 °C. The proposed process has low chemical consumption and low waste production. The proposed process works, with a lower yield, for other carboxylates (e.g. lactate and succinate) and alcohols (e.g. ethanol). [ABSTRACT FROM AUTHOR]

Novel bio-based and biodegradable electrospun membranes, containing bactericidal ricinoleic acid (RA) units either by copolymerization with butylene succinate (BS) units or by blending PRA and PBS homopolymers, are characterized in their chemical, thermal, mechanical and surface properties. In the blends E. coli and S. aureus mortality rate increases with PRA amount, while the copolymer shows lower bactericidal activity compared to the blend with similar composition. XPS demonstrates that in the blends an enrichment of RA units at the fiber surface occurs during electrospinning due to phase separation, while in the copolymer RA units are homogeneously dispersed along fiber cross-section. [ABSTRACT FROM AUTHOR]

We report an advanced treatment method for phosphoric acid recovery from leached sewage sludge ash. Layer-by-layer (LbL) polyelectrolyte deposition has been used as a tool to modify and convert a hollow ultrafiltration membrane into a nanofiltration (NF) LbL membrane for H 3 PO 4 recovery. To build the LbL membrane, poly(styrenesulfonate) PSS was chosen as polyanion, while three different polycations were used: a permanently charged polyelectrolyte, poly(diallyldimethylammonium chloride), PDADMAC; a pH-dependent charged polyelectrolyte poly(allylamine hydrochloride), PAH; and a PAH modified with guanidinium groups (PAH-Gu). Based on detailed surface characterizations (AFM, XPS and Zeta-potential) it was concluded that both charge density and pH-responsiveness of the polycations are key parameters to control the final membrane surface structure and transport properties. The surface properties of LbL-coated membranes were correlated with the membrane filtration performance, when exposed to the real leached sewage sludge ash solution. The highest permeability was recorded for (PDADMAC/PSS) 6 , a result that was rationalized on its loose, and possibly less interpenetrated, structure, followed by (PAH-Gu/PSS) 6 characterized by a more dense, compact layer. H 3 PO 4 recovery was the highest in the case of (PDADMAC/PSS) 6 , but the retention of multivalent metals (Fe3+ and Mg2+) was low, leading to a more contaminated permeate. The opposite trend was observed for (PAH-Gu/PSS) 6, resulting in a less metal-contaminated, but also a less H 3 PO 4 -concentrated permeate. Our LbL-modified membranes were found to improve the permeability and H 3 PO 4 recovery compared to a commercially available acid-resistant NF membrane. Image 1 • Layer-by-layer NF membranes recover H 3 PO 4 from leachate sewage sludge ash. • Permeability: LbL-coated membranes > commercial acid-resistant NF membranes. • Type of polycation in LbL coatings affects separation properties. • Largest H 3 PO 4 recovery for permanent polycation, but low Fe3+ and Mg2+ retention. • Weaker polycation with guanidinium moiety: less metal and less H 3 PO 4 in permeate. [ABSTRACT FROM AUTHOR]

A major challenge in nanotechnology is that of determining how to introduce green and sustainable principles when assembling individual nanoscale elements to create working devices. For instance, textile nanofinishing is restricted by the many constraints of traditional pad-dry-cure processes, such as the use of costly chemical precursors to produce nanoparticles (NPs), the high liquid and energy consumption, the production of harmful liquid wastes, and multistep batch operations. By integrating low-cost, scalable, and environmentally benign aerosol processes of the type proposed here into textile nanofinishing, these constraints can be circumvented while leading to a new class of fabrics. The proposed one-step textile nanofinishing process relies on the diffusional deposition of aerosol NPs onto textile fibers. As proof of this concept, we deposit Ag NPs onto a range of textiles and assess their antimicrobial properties for two strains of bacteria (i.e., Staphylococcus aureus and Klebsiella pneumoniae). The measurements show that the logarithmic reduction in bacterial count can get as high as ca. 5.5 (corresponding to a reduction efficiency of 99.96%) when the Ag loading is 1 order of magnitude less (10 ppm; i.e., 10 mg Ag NPs per kg of textile) than that of textiles treated by traditional wet-routes. The antimicrobial activity does not increase in proportion to the Ag content above 10 ppm as a consequence of a "saturation" effect. Such low NP loadings on antimicrobial textiles minimizes the risk to human health (during textile use) and to the ecosystem (after textile disposal), as well as it reduces potential changes in color and texture of the resulting textile products. After three washes, the release of Ag is in the order of 1 wt %, which is comparable to textiles nanofinished with wet routes using binders. Interestingly, the washed textiles exhibit almost no reduction in antimicrobial activity, much as those of as-deposited samples. Considering that a realm of functional textiles can be nanofinished by aerosol NP deposition, our results demonstrate that the proposed approach, which is universal and sustainable, can potentially lead to a wide number of applications.

The rotational spectra of three isotopologues, CH2(35)Cl2···(20)Ne, CH2(35)Cl(37)Cl···(20)Ne, and CH2(35)Cl2···(22)Ne, of the complex dichloromethane-neon have been assigned and measured by molecular beam Fourier transform microwave spectroscopy. The corresponding tunnelling splittings-due to the motion of Ne from above to below the ClCCl plane-have been determined as ΔE0+0- = 6.8900(5), 6.6630(4), and 6.3724(7) MHz, respectively. From these data the barrier to planarity has been obtained, B2 = 68.7 cm(-1). In addition, the structure and the (35)Cl (or (37)Cl) quadrupole coupling constants have been determined.