Search results for "polymers"
showing 10 items of 3567 documents
Fabrication of zinc doped aluminium oxide/polysulfone mixed matrix membranes for enhanced antifouling property and heavy metal removal
2021
International audience; Heavy metal removal from water resources is essential for environmental protection and the production of safe drinking water. In this direction, Zinc doped Aluminium Oxide (Zn:Al2O3) nanoparticles were incorporated into Polysulfone (PSf) to prepare mixed matrix membranes for the efficient removal of heavy metals from water. These Zn:Al2O3 nanoparticles prepared by the solution combustion method have a very high surface area (261.44 m2/g) with an approximate size of 50 nm. X-ray Photoelectron Spectroscopy analysis showed that the Al and Zn were in +3 and + 2 oxidation states, respectively. Cross-sectional Scanning Electron Microscopy images revealed the finger-like mo…
Shear-thinning fluids for gravity and anisotropy mitigation during soil remediation in the vadose zone
2018
Abstract Surfactant foam has been proposed as an effective treatment fluid for in situ environmental remediation of soils. In the vadose zone, it could improve treatment homogeneity, but its use remains challenging. To better understand and predict foam formation and propagation in vadose zone, we studied them in 24 soils with wide range of properties (including permeability: 2 10−12 to 3.3 10−9 m2). Foam rheology showed to be complex and mostly influenced by soil permeability and grading. Below 2 10−11 m2, foam propagation velocity was not influenced by permeability. Conversely, slight shear thinning to Newtonian behavior was observed for higher permeabilities. Benefits for remediation in …
Pilot scale experiment with MBR operated in intermittent aeration condition: analysis of biological performance.
2014
The effect of intermittent aeration (IA) on a MBR system was investigated. The study was aimed at ana- lyzing different working conditions and the influence of different IA cycles on the biological performance of the MBR pilot plant, in terms of organic carbon and ammonium removal as well as extracellular poly- meric substances (EPSs) production. The membrane modules were placed in a separate compartment, continuously aerated. This configuration allowed to disconnect from the filtration stage the biological phenomena occurring into the IA bioreactor. The observed results highlighted good efficiencies, in terms of organic carbon and ammonium removal. It was noticed a significant soluble micr…
Degradation half-life times of PCDDs, PCDFs and PCBs for environmental fate modeling.
2000
Literature search of the knowledge on the degradation of persistent organic pollutants (POPs) in environmental compartments air, water, soil and sediment was done in purpose to find properties of POPs of interest for modeling. One degradation process, hydrolysis (chemical degradation), was omitted as negligibly slow for POPs studied. The other two, photolysis and biodegradation processes, were considered separately in purpose to develop estimation procedures. The estimates can be given as pseudo first-order rate constants kP for photolysis and kB for biodegradation. For each compartment, an overall degradation rate is k(tot) = kP + kB and lifetime t(1/2) = ln 2/k(tot). The latter values, li…
Degradation of Plasticised Poly(lactide) Composites with Nanofibrillated Cellulose in Different Hydrothermal Environments
2022
AbstractIn this study, bionanocomposite films based on poly(lactide) (PLA) plasticised with poly(ethylene glycol) (PEG) (7.5 wt%) and reinforced with various contents of nanofibrillated cellulose (NFC) (1, 3, 5 wt%) were prepared. The hydrothermal degradation was investigated through immersion in several aqueous environments at temperatures of 8, 23, 58, and 70 °C as a function of time (7, 15, 30, 60, 90 days). The effect of water immersion on the physicochemical properties of the materials was assessed by monitoring the changes in the morphology, thermo-oxidative stability, thermal properties, and molar mass through field emission scanning electron microscopy (FE-SEM), thermogravimetric an…
Preparation of fouling resistant and highly perm-selective novel PSf/GO-vanillin nanofiltration membrane for efficient water purification
2022
International audience; To meet the rising global demand for water, it is necessary to develop membranes capable of efficiently purifying contaminated water sources. Herein, we report a series of novel polysulfone (PSf)/GO-vanillin nanofiltration membranes highly permeable, selective, and fouling resistant. The membranes are composed of two-dimensional (2D) graphite oxide (GO) layers embedded with vanillin as porogen and PSf as the base polymer. There is a growing interest in addressing the synergistic effect of GO and vanillin on improving the permeability and antifouling characteristics of membranes. Various spectroscopic and microscopic techniques were used to perform detailed physicoche…
Microbial production and recovery of hybrid biopolymers from wastes for industrial applications- a review
2021
Abstract Agro-industrial wastes to be a global concern since agriculture and industrial processes are growing exponentially with the fast increase of the world population. Biopolymers are complex molecules produced by living organisms, but also found in many wastes or derived from wastes. The main drawbacks for the use of polymers are the high costs of the polymer purification processes from waste and the scale-up in the case of biopolymer production by microorganisms. However, the use of biopolymers at industrial scale for the development of products with high added value, such as food or biomedical products, not only can compensate the primary costs of biopolymer production, but also impr…
Strawberry fields forever: That is, how many grams of plastics are used to grow a strawberry?
2020
Abstract In important areas of the agricultural sector, plastic is one of the most important tools for improving the managerial and economic performance of companies. Horticultural production under protected cultivation, in particular, makes abundant use of plastic polymers—polymers that mostly turn into waste. This study aims to identify similar organisational models among farmers operating in the strawberry production sector in relation to their intention to recycle plastic material and which factors characterize these models (attitudes, subjective norms, perceived behavioural control, and socio-demographic characteristics) and to quantify the plastic used in relation to the different typ…
Effect of chemical and biological surfactants on activated sludge of MBR system: Microscopic analysis and foam test
2015
Abstract A bench-scale MBR unit was operated, under stressing condition, with the aim of stimulating the onset of foaming in the activated sludge. Possible synergies between synthetic surfactants in the wastewater and biological surfactants (Extra-Cellular Polymeric Substances, EPSs) were investigated by changing C/N ratio. The growth of filamentous bacteria was also discussed. The MBR unit provided satisfactory overall carbon removal overall efficiencies: in particular, synthetic surfactants were removed with efficiency higher than 90% and 95% for non-ionic and ionic surfactants, respectively. Lab investigation suggested also the importance to reduce synthetic surfactants presence entering…
The role of EPS in fouling and foaming phenomena for a membrane bioreactor
2013
In contraposition to conventional activated sludge processes, the foaming phenomenon in membrane bioreactor (MBR) is still in its infancy. On the other hand, although several studies have been carried out for better understanding the fouling phenomenon in MBR there are still some gaps in the up-to-date knowledge. The extracellular polymeric substances (EPSs) may have a primary role in fouling and foaming phenomena which in turn can be crucial for MBRs. The aim of this study is to detect a possible relationship that EPSs may have with fouling and foaming in an MBR for wastewater treatment. Foaming phenomenon is monitored by performing specific foam-tests: Foam Power, Scum Index, Foam Rating …