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The long-term performance of three multilayered textured white conductive-backed geomembranes (GMBs) is compared to the comparable textured nonconductive GMBs and their smooth edge/equivalent to investigate the effect of the conductive layer on their longevity. Oven immersion in synthetic municipal solid waste leachate is used at a range of temperatures to accelerate the ageing during an incubation period of 50 months. It is shown that the conductive layer can antagonistically or synergistically affect the antioxidant depletion of conductive-backed GMBs relative to nonconductive GMBs produced by the same GMB manufacturer and formulated using the same nominal resin and antioxidant package. However, their relative degradation at 85 °C does not necessarily follow their relative antioxidant depletion times implying that the manufacturing process and the interaction between the additive packages of these GMBs can affect their relative degradation beyond the antioxidant depletion stage. Arrhenius modelling predicts the antioxidant depletion stage at field temperatures ranging between 180 and 1400 years at 20 °C for two different conductive-backed GMBs produced by two different manufacturers. With such variation in the long-term performance of conductive-backed GMBs currently available in the market, their durability should be investigated before their use in barrier systems to ensure they can meet the required design life of the desired geoenvironmental application. • First investigation into the degradation behaviour of conductive-backed geomembranes. • Examines the effect of texturing on the durability of conductive-backed geomembranes. • Estimates antioxidant depletion time of multilayered geomembranes at field temperatures. [ABSTRACT FROM AUTHOR]

Electrodialysis is an electrochemical separation process which is used for the removal of ionic species from aqueous solutions. In this study selectivity of an anion exchange membrane was tuned towards formate (CHOO-) anions compared to oxalates (C 2 O 4 2-) based on the characteristics of formate anions which show lower hydration energy. In order to enhance the removal efficiency of monovalent anions in electrodialysis, a hybrid surface modification on a heterogeneous anion exchange membrane was carried out. Surface modification consisted of three steps: plasma treatment (activation of the membrane surface), functionalization (acidification) and coupling with Polyethylenimine and Glutaraldehyde. Treatment of the membrane was verified using FTIR, Scanning Electron Microscopy, and Atomic Force Microscopy. The electrochemical properties of the membrane were measured before and after the modification. The results showed that due to the presence of the amide groups on the surface of the membrane upon modification, the water content of the membrane decreased by 8% while no other significant changes were observed in the membrane properties. Finally, the membrane selectivity towards CHOO-/ C 2 O 4 2- in electrodialysis process increased from 0.88 to 4.29 upon surface modification. [Display omitted] • Hybrid surface modification of a heterogenous anion exchange membrane through three steps. • Hybrid modification include: plasma treatment, functionalization, and coupling with Polyethylenimine and Glutaraldehyde. • Enhancing the selectivity toward monovalent anions (formate) against multivalent anions (oxalate) in the Electrodialysis. • Increasing the membrane selectivity towards anions with less hydration energy by changing the surface hydrophilicity. [ABSTRACT FROM AUTHOR]

In this study, an electrochemical sensor was fabricated based on gold nanoparticles/ ethylenediamine/ multi-wall carbon-nanotubes modified gold electrode (AuNPs/en/MWCNTs/AuE) for determination of valrubicin in biological samples. Valrubicin was effectively accumulated on the surface of AuNPs/en/MWCNTs/AuE and produced a pair of redox peaks at around 0.662 and 0.578 V (vs. Ag/AgCl) in citrate buffer (pH 4.0). The electrochemical parameters including pH, buffer, ionic strength, scan rate and size of AuNPs have been optimized. There was a good linear correlation between cathodic peak current and concentration of valrubicin in the range of 0.5 to 80.0 μmol L − 1 with the detection limit of 0.018 μmol L - 1 in citrate buffer (pH 4.0) and 0.1 mol L - 1 KCl. Finally, the constructed sensor was successfully applied for determination of valrubicin in human urine and blood serum. In further studies, the different sequences of single stranded DNA probes have been immobilized on the surface of AuNPs decorated on MWCNTs to study the interaction of oligonucleotides with valrubicin. [ABSTRACT FROM AUTHOR]