Municipal effluent discharged from wastewater treatment works (WwTW) is suspected to be a significant contributor of microplastics (MP) to the environment as many personal care products contain plastic microbeads. A secondary WwTW (population equivalent 650 000) was sampled for microplastics at different stages of the treatment process to ascertain at what stage in the treatment process the MP are being removed. The influent contained on average 15.70 (±5.23) MP·L–1. This was reduced to 0.25 (±0.04) MP·L–1 in the final effluent, a decrease of 98.41%. Despite this large reduction we calculate that this WwTW is releasing 65 million microplastics into the receiving water every day. A significant proportion of the microplastic accumulated in and was removed during the grease removal stage (19.67 (±4.51) MP/2.5 g), it was only in the grease that the much publicised microbeads were found. This study shows that despite the efficient removal rates of MP achieved by this modern treatment plant when dealing with su...

https://myresearchspace.uws.ac.uk/ws/files/262183/160418_Waste_Water_Treatment_Works_WwTW_as_a_Source_of_Microplastics_in_the_Aquatic_Environment.pdf

Wastewater Treatment Works (WwTW) as a Source of Microplastics in the Aquatic Environment

Hydrogels for biomedical applications.

Each year vast amounts of plastic are produced worldwide. When released to the environment, plastics accumulate, and plastic debris in the world's oceans is of particular environmental concern. More than 60% of all floating debris in the oceans is plastic and amounts are increasing each year. Plastic polymers in the marine environment are exposed to sunlight, oxidants and physical stress, and over time they weather and degrade. The degradation processes and products must be understood to detect and evaluate potential environmental hazards. Some attention has been drawn to additives and persistent organic pollutants that sorb to the plastic surface, but so far the chemicals generated by degradation of the plastic polymers themselves have not been well studied from an environmental perspective. In this paper we review available information about the degradation pathways and chemicals that are formed by degradation of the six plastic types that are most widely used in Europe. We extrapolate that information to likely pathways and possible degradation products under environmental conditions found on the oceans' surface. The potential degradation pathways and products depend on the polymer type. UV-radiation and oxygen are the most important factors that initiate degradation of polymers with a carbon-carbon backbone, leading to chain scission. Smaller polymer fragments formed by chain scission are more susceptible to biodegradation and therefore abiotic degradation is expected to precede biodegradation. When heteroatoms are present in the main chain of a polymer, degradation proceeds by photo-oxidation, hydrolysis, and biodegradation. Degradation of plastic polymers can lead to low molecular weight polymer fragments, like monomers and oligomers, and formation of new end groups, especially carboxylic acids.

/pdf/pathways-for-degradation-of-plastic-polymers-floating-in-the-110uao8lbz.pdf

Pathways for degradation of plastic polymers floating in the marine environment

A review on polymeric hydrogel membranes for wound dressing applications: PVA-based hydrogel dressings

Mechanistic implications of plastic degradation

To introduce functional moieties into Tefzel® film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as methyl acrylate (MA) and ethyl acrylate (EA) was attempted by a pre-irradiation method in aqueous medium. Optimum conditions for obtaining the maximum grafting was evaluated for both monomers. Maximum grafting of MA (306.0%) and EA (462.1%) was obtained at a total dose of 25.4 and 31.9kGy respectively, using [MA] = 2.20 mol/L and [EA] 0.032 moles. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, n-butanol, 1-Pentanol and cyclohexanol on the percentage grafting of MA & EA was also studied. Characterization of Tefzel® and grafted Tefzel® films was carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel® film was found to have improved thermal resistance.

Radiation induced graft copolymerization of methyl acrylate and ethyl acrylate onto poly(tetrafluoroethylene-co-ethylene) film

A study on graft copolymerization of electron donor and electron acceptor monomer mixture onto Tefzel film

Keeping in view the advantages of hydrogel based wound dressing, the present work explore the potential of sterculia gum and psyllium polysaccharides to prepare the moxifloxacin loaded hydrogel wound dressings for better wound care. The polymers were characterized by cryo scanning electron microscopy (cryoSEM), atomic force microscopy, 13C nuclear magnetic resonance spectroscopy and swelling studies. Evaluation of drug release mechanism and kinetic model from the polymer matrix was performed along with some biomedical properties of hydrogel dressing including wound fluid absorption, blood-compatibility, antioxidant activity, oxygen permeability, muco-adhesion, and mechanical properties. CryoSEM showed porous nature of the polymer film. One gram of the hydrogel dressing absorbed 14.7 g simulated wound fluid. Release of drugs (moxifloxacin) from drug loaded hydrogel dressings, occurred through non-Fickian diffusion mechanism in simulated wound fluid without any burst effect. Hydrogel dressing showed porous structures with good degree of mechanical strength, antioxidant activity and biocompatibility.

Polysaccharides Sterculia Gum/Psyllium Based Hydrogel Dressings for Drug Delivery Applications

To introduce functional moieties to Tefzel film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as acrylonitrile (AN) and methacrylonitrile (MAN) was attempted by a preirradiation method in aqueous medium. Optimum conditions for obtaining the maximum percentage of grafting have been evaluated for both monomers. Maximum grafting of AN (52.2%) and MAN (77.7%) is obtained at a total dose of 3.14 and 2.69 × 10 4 Gy, respectively, using [AN] = 3.018 mol/L and [MAN] = 1.177 mol/L in 10 mL of water. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, isopropanol, n-butanol, and cyclohexanol, on percentage add-on of AN and MAN has also been studied. It has been found that all the alcohols decreased the percentage of grafting. Characterization of Tefzel and grafted Tefzel films has been carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel film has been found to have improved thermal resistance.

Functionalization of poly(tetrafluoroethylene‐co‐ethylene) film by radiation‐induced graft copolymerization

The present study deals with the modification of sterculia gum to develop the novel colon specific delivery system for use in colon cancer. The sterculia and acrylic acid based hydrogels were synthesized and characterized with FTIR, SEMs, TGA and swelling behavior. Swelling studies of the hydrogels were carried out as a function of reaction parameters such as monomer concentration, initiator concentration, amount of sterculia gum and crosslinker concentration and nature of swelling mediums. Swelling kinetics of the hydrogels and in vitro release dynamics of anticancer model drug methotrexate from the hydrogels were studied to evaluate the swelling mechanism and drug release mechanism from the drug-loaded hydrogels. The values of diffusion exponent for the release of drug were 0.883, 0.910 and 0.787 in distilled water, pH 2.2 buffer and pH 7.4 buffer, respectively. The release of drug from the polymer matrix occurred through a non -Fickian type diffusion mechanism.

Baljit Singh

Papers

Radiation induced graft copolymerization of methyl acrylate and ethyl acrylate onto poly(tetrafluoroethylene-co-ethylene) film

A study on graft copolymerization of electron donor and electron acceptor monomer mixture onto Tefzel film

Polysaccharides Sterculia Gum/Psyllium Based Hydrogel Dressings for Drug Delivery Applications

Functionalization of poly(tetrafluoroethylene‐co‐ethylene) film by radiation‐induced graft copolymerization

Synthesis and Characterization of Sterculia Gum Based pH Responsive Drug Delivery System for Use in Colon Cancer