Synthesis of polymeric bismuth chlorido hydroxamato complexes; X-ray crystal structure and antibacterial activity of a novel Bi(lll) salicylhydroxamato complex

Reaction of salicylhydroxamic acid (Sha) and 2-aminophenyl hydroxamic acid (2-NH2-pha) with BiCl3 affords the corresponding novel polymeric bismuth chlorido hydroxamato complexes; [BiCl2(-Sha-1H)]∞ and [BiCl3(--Pha-1H)]∞ respectively. The X-ray crystal structure of the THF-solvated polymeric bismuth chlorido salicylhydroxamato complex, [BiCl2(-Sha-1H)(THF)]∞ was solved, confirming the polymeric structure of this class of compounds and the (O,μ-O’)-bidentate bridging coordination mode of the hydroxamato ligand. The antibacterial activity of the THF-free polymeric bismuth chlorido salicylhydroxamato complex, [BiCl2(-Sha-1H)]∞, was investigated against a broad panel of bacteria, further highlighting the antibacterial properties of Bi-based compounds against Gram-positive and Gram-negative pathogenic and environmental strains of bacteria

Controlled polymerisation and purification of branched poly(lactic acid) surfactants in supercritical carbon dioxide

Product degradability, sustainability and low-toxicity are driving demand for the synthesis of biobased polymers and surfactants. Here we report the synthesis of novel surface active polymers using cyclic esters (D,L-lactide) and temperature sensitive polyols (D-sorbitol) as renewable building blocks. We highlight the modification of chain length and degree of branching to provide a route to tailoring the properties and application performance of these new compounds. High processing temperatures (≥180 °C) and harsh post-reaction treatments are often needed to remove residual monomer and catalysts and these can become barriers to creating materials based on renewable resources. Here we exploit supercritical carbon dioxide (scCO2) as a green solvent to overcome these challenges; significantly reducing reaction temperatures, targeting controlled molecular weights with narrow dispersities and reducing sideproduct formation. Additionally in the same pot, we can use supercritical extraction to purify the compounds and to efficiently remove unreacted reagents, which could be recovered and recycled. We believe that our approach to the production and purification of these novel branched poly(lactides) is a significant step towards the development of the next generation of biopolymers and green surfactants, combining both the use of bio-sourced raw materials and the potential to use sustainable, low energy processes and techniques

Photophysical and electrochemical properties of meso-tetrathien-2′-yl porphyrins compared to meso-tetraphenylporphyrin

A series of novel tetra-meso-thien-2-yl porphyrins were synthesised, and the effect of the variation in the thienyl group on the photophysical properties were studied. Ground and excited state UV–vis absorption, steady-state and time-resolved emission, resonance Raman spectroscopy, and cyclic voltammetry, were used to establish the extent of electronic communication between the central Zn(II) porphyrin ring and the various meso-substituent groups. The properties of these novel thienyl porphyrins were compared to zinc tetraphenylporphyrin (ZnTPP), to elucidate the effect of the position and number of thienyl rings. The photochemically-driven antimicrobial activity of zinc(II)-5,10,15,20-tetra(thien-2′ -yl)porphyrin (ZnThPP) as a coating, was established against both Gram-positive and Gram-negative bacteria, and compared to ZnTPP. Visible irradiation of the porphyrins results in a significant antimicrobial response

First demonstration of hydrophobic membrane contactors for removal of ammonia from condensate wastewater

Hydrophobic membrane contactors represent a promising solution to the problem of recovering ammoniacal nitrogen from wastewater. The process has been shown to work best with wastewater streams that present high ammonia concentrations, low buffering capacities and low total suspended solids. The removal of ammonia from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene and polytetrafluoroethylene, at pilot scale and carry out process modification for ammonia removal. The results demonstrate that polypropylene membranes are not compatible with the condensate waste as it caused wetting. The polytetrafluoroethylene membranes showed potential and had a longer lifetime than the polypropylene membranes, removing up to 64% of ammonia from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater

Biodegradação de filmes de Polihidroxibutirato-co-hidroxivalerato (PHBV), polietileno de baixa densidade (PEBD) e blenda de PEBD/PHBV (70/30), com fungos específicos

O aumento do consumo de materiais plásticos, no mundo todo, tem sido objeto de grande preocupação e especial atenção por parte da comunidade científica, no sentido de promover o desenvolvimento de materiais que, ao serem descartados sejam biodegradados em tempo mais curto, no meio ambiente. Os plásticos sintéticos mais utilizados atualmente são de difícil degradação, por serem hidrofóbicos e resistentes à ação de enzimas microbianas. Entretanto, o uso de materiais alternativos, tais como as blendas de polímeros biodegradável e sintético, pode minimizar o efeito danoso do descarte desses materiais em lixões e aterros sanitários, por serem suscetíveis à ação de micro-organismo. Este trabalho visou investigar a biodegradação dos filmes de PHBV (biodegradável), PEBD (polietileno de baixa densidade) e da blenda de PEBD/PHBV (70/30), empregando fungos específicos em meios de cultura sólido e líquido, utilizando metodologias como: Microscopia óptica (MO), Microscopia Eletrônica de Varredura (MEV) e Espectroscopia de Absorção no Infravermelho com Transformada de Fourier (FTIR). Os fungos Penicillium funiculosum e Paecilomyces variotii degradam eficientemente o PHBV, sendo que o primeiro degradou o polímero com formação de ácidos insaturados, fortes indicadores da biodegradação deste tipo de material. Além disso, estes fungos aderem significativamente à superfície do PE, mudando expressivamente sua morfologia. A blenda de PE/PHBV (70/30), é um material suscetível à ação destes fungos, tendo sofrido mudanças, inclusive, na sua cristalinidade. Nesta blenda ficou evidente também a ação de proteção do PE, que inibiu o acesso do fungo à fase do PHBV contido na mesma. No meio mineral completo houve consumo da fase amorfa e...The increase in consumption of plastics in the world has been the subject of great concern and special attention from the scientific community, to promote the development of materials that are biodegradable in a shorter time when discarded in the environment. The most widely used synthetic plastics are hardly degraded, because they are hydrophobic and resistant to the action of microbial enzymes. However, the use of alternative materials, such as blends of biodegradable polymers and synthetic, can minimize the harmful effect of the disposal of these materials in dumps and landfills, because they are susceptible to the action of microorganisms. This work aims to investigate the biodegradation of PHBV films (biodegradable), LDPE (low density polyethylene) and blends of LDPE / PHBV (70/30), using specific fungi in culture media solid and liquid, employing methods such as optical microscopy (OM), scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR). Penicillium funiculosum and Paecilomyces variotii degrade PHBV efficiently and the first one degraded the polymer producing insaturated acids, strong indicators of the biodegradation of this type of material. Besides that, they adhere significantly on PE surface, changing meaningly the morphology of these materials. The PE / PHBV (70/30) blend, is a material susceptible to the fungi action, having undergone changes, including in its crystallinity. It was also evident the protective action of the PE, preventing the access of the fungus to the PHBV phase contained in the blend. In the complete mineral medium there was a consumption of amorphous and crystalline phases (decrease and increase of carbonyl indices, respectively – FTIR) and in the incomplete mineral medium, the amorphous and crystalline phases were consumed, showing the efficiency of P. funiculosum... (Complete abstract click electronic access below

Biodegradation of films of low density polyethylene (LDPE), poly(hydroxibutyrate-co-valerate) (PHBV), and LDPE/PHBV (70/30) blend with Paecilomyces variotii

The increased consumption of plastics in the world has been a subject of great concern and special attention by the scientific community. The aim is to promote development of materials that are biodegradable in a shorter time upon disposal in the environment. The most used synthetic plastics are difficult to biodegrade because they are made of long hydrocarbon chains, such as polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), which are hydrophobic and resistant to the action of microbial enzymes. The use of alternative materials (natural polyesters) can minimize the harm to dumps and landfills upon their disposal, because they are susceptible to the action of microorganisms. In this study we evaluated the biodegradation/biodeterioration of PHBV (poly(3-hydroxybutyrate-co-hydroxyvalerate) films, LDPE (low density polyethylene) and the blend of LDPE/PHBV (70/30) by the fungus Paecilomyces variotii, using different methods: optical microscopy (OM), scanning electronic microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR).Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES