Comparison of the removal of hydrophobic trace organic contaminants by forward osmosis and reverse osmosis

We compared the rejection behaviours of three hydrophobic trace organic contaminants, bisphenol A, triclosan and diclofenac, in forward osmosis (FO) and reverse osmosis (RO). Using erythritol, xylose and glucose as inert reference organic solutes and the membrane pore transport model, the mean effective pore size of a commercial cellulose-based FO membrane was estimated to be 0.74 nm. When NaCl was used as the draw solute, at the same water permeate flux of 5.4 L/m² h (or 1.5 μm/s), the adsorption of all three compounds to the membrane in the FO mode was consistently lower than that in the RO mode. Rejection of bisphenol A and diclofenac were higher in the FO mode compared to that in the RO mode. Because the molecular width of triclosan was larger than the estimated mean effective membrane pore size, triclosan was completely rejected by the membrane and negligent difference between the FO and RO modes could be observed. The difference in the separation behaviour of these hydrophobic trace organics in the FO (using NaCl the draw solute) and RO modes could be explained by the phenomenon of retarded forward diffusion of solutes. The reverse salt flux of NaCl hinders the pore diffusion and subsequent adsorption of the trace organic compounds within the membrane. The retarded forward diffusion effect was not observed when MgSO₄ and glucose were used as the draw solutes. The reverse flux of both MgSO₄ and glucose was negligible and thus both adsorption and rejection of BPA in the FO mode were identical to those in the RO mode.     

Combinatorial materials research applied to the development of new surface coatings XII: Novel, environmentally friendly antimicrobial coatings derived from biocide-functional acrylic polyols and isocyanates

Novel, environmentally friendly antimicrobial coatings containing tethered biocide moieties derived from the ubiquitous biocide, triclosan, were synthesized and characterized using a high-throughput workflow. Triclosan was first modified with an acrylate functionality and, subsequently, copolymerized with hydroxyethyl acrylate and butyl acrylate using conventional free radical polymerization to form an array of acrylic polyol terpolymers. The polyols were characterized using nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and gel permeation chromatography. Arrays of urethane coatings were produced from the array of acrylic polyol terpolymers and, subsequently, characterized using parallel dynamic mechanical thermal analysis, surface energy measurements, and various biological assays. The results of the biological assays showed that the coatings were effective toward inhibiting Staphylococcus epidermidis biofilm retention without leaching triclosan or other toxic components from the coating. The level of antimicrobial activity was found to increase with the content of triclosan moieties incorporated into the coating matrix. These results indicate that triclosan moieties tethered to a polymer matrix can impart antimicrobial properties via a contact-active, nonleaching (i.e., environmentally friendly) mechanism. Since S. epidermidis is one of the primary microorganisms associated with infection and failure of implanted medical devices, such as prosthetic heart valves, urinary catheters, and a variety of orthopedic implants, these coatings may have good potential for commercialization in some of these applications. This paper was awarded First Place in the 2008 Roon Awards competition, held as part of the FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in Chicago, IL, on October 14–16, 2008.     

Identification of methyl triclosan and halogenated analogues in male common carp (Cyprinus carpio) from Las Vegas Bay and semipermeable membrane devices from Las Vegas Wash, Nevada

Methyl triclosan and four halogenated analogues have been identified in extracts of individual whole-body male carp (Cyprinus carpio) tissue that were collected from Las Vegas Bay, Nevada, and Semipermeable Membrane Devices (SPMD) that were deployed in Las Vegas Wash, Nevada. Methyl triclosan is believed to be the microbially methylated product of the antibacterial agent triclosan (2, 4, 4'-trichloro-4-hydroxydiphenyl ether, Chemical Abstract Service Registry Number 3380-34-5, Irgasan DP300). The presence of methyl triclosan and four halogenated analogues was confirmed in SPMD extracts by comparing low- and high-resolution mass spectral data and Kovats retention indices of methyl triclosan with commercially obtained triclosan that was derivatized to the methyl ether with ethereal diazomethane. The four halogenated analogues of methyl triclosan detected in both whole-body tissue and SPMD extracts were tentatively identified by high resolution mass spectrometry. Methyl triclosan was detected in all 29 male common carp from Las Vegas Bay with a mean concentration of 596 μg kg^− 1 wet weight (ww) which is more than an order of magnitude higher than previously reported concentrations in the literature. The halogenated analogs were detected less frequently (21%-76%) and at much lower concentrations (< 51 μg kg^− 1 ww). None of these compounds were detected in common carp from a Lake Mead reference site in Overton Arm, Nevada.     

GROWTH AND NUCLEATION KINETICS IN BATCH CRYSTALLIZATION OF TRICLOSAN

Batch crystallization of triclosan, a broad spectrum antibacterial agent, was carried out under isothermal conditions (at 10°C) with n-hexane as the solvent. Supersaturation was generated by cooling a seeded solution. Samples were collected at periodic intervals. Triclosan concentration in solution was determined by UV-spectrophotometry and particle size distribution by optical microscopy. Growth and nucleation kinetic parameters were obtained. The data indicated size independent growth. Growth kinetic parameters based on triclosan concentration in solution were in reasonable agreement with growth kinetic parameters obtained from cumulative size distribution data. Growth and nucleation kinetic orders were comparable to those reported in the literature.     

抗菌剂三氯生的生态毒性研究进展

三氯生作为广谱抗菌剂,30多年来在个人护理品中被广泛应用,长期与人体接触,并被排放到环境中。目前世界各地的各级生物体中均检测到三氯生的污染。三氯生已被证实对包括藻类、植物、低等动物、两栖类、鱼类、哺乳动物等在内的各级生物普遍具有毒性效应,主要表现为生长抑制、致死效应、内分泌干扰、生殖毒性、DNA毒性等方面。