Antifouling and Flux Enhancement of Reverse Osmosis Membrane by Grafting Poly (3-Sulfopropyl Methacrylate) Brushes

A commercial thin film composite (TFC) polyamide (PA) reverse osmosis membrane was grafted with 3-sulfopropyl methacrylate potassium (SPMK) to produce PA-g-SPMK by atom transfer radical polymerization (ATRP). The grafting of PA was done at varied concentrations of SPMK, and its effect on the surface composition and morphology was studied by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), optical profilometry, and contact angle analysis. The grafting of hydrophilic ionically charged PSPMK polymer brushes having acrylate and sulfonate groups resulted in enhanced hydrophilicity rendering a reduction of contact angle from 58° of pristine membrane sample labeled as MH0 to 10° for a modified membrane sample labeled as MH3. Due to the increased hydrophilicity, the flux rate rises from 57.1 L m−2 h−1 to 71.2 L m−2 h−1, and 99% resistance against microbial adhesion (Escherichia coli and Staphylococcus aureus) was obtained for MH3 after modification

The Study on the Effect of Wet and Dry Oxidation of Nickel Thin Film on Sensitivity of EGFET Based pH Sensor

The study is based on the use of NiO as an extended gate of field effect transistor (EGFET) using ITO/glass as a substrate for the sensitivity of pH sensor membrane. The NiO thin film was synthesis by wet and dry thermal oxidation method of Nickel metal thin film deposited by RF sputtering. The sensitivity of the NiO membrane was measured and comparatively analysed against the two different oxidation methods. Structural and morphological properties were investigated for both thin films. The sensitivities measurements of the two membranes were made as pH sensors. The results confirmed that NiO membrane grown by dry oxidation had much better sensitivity (87 μA/pH and 54 mV/pH) compared to wet oxidation membrane sample (52 μA/pH and 48 mV/pH).

Evaluation of novel hollow fibre membranes for NOM removal by advanced membrane autopsy

A full-scale inside out hollow fibre membrane module was operated in a pilot-scale water treatment plant in Sweden for a period of 12 months from August 2013 to July 2014. Liquid chromatography– organic carbon detection (LC-OCD) chromatogram indicated the membranes could effectively remove 86% of dissolved organic carbon and 92% of humic substances from the feedwater. Routine cleaning-in-place was conducted to remove any fouling material accumulated on the membranes. Autopsy of the aged membrane samples after 12 months’ operation suggested no significant changes were detected for the membrane samples obtained from the top, middle and bottom sections of the membrane module and were similar to the virgin membrane sample.

Characterization of polymer membranes by contact angle goniometer

The wider applications of all membrane separation processes have a main obstacle, namely the fouling phenomena, which have to be understood in more details. Surface properties, hydrophilic and hydrophobic characteristics of a polymer membrane can be determined by measuring the contact angle. The hydrophilicity of a membrane has an important influence on its performances, like permeate flux, membrane rejection or membrane fouling characteristics. In our work the contact angles of three kinds of typically commercial ultrafiltration (UF-PES-4), nanofiltration (NE-90) and reverse osmosis (LFC-30) membranes were firstly investigated and compared by contact angle goniometer measurements. The relationships between the contact angles were researched by well considering the effects of membrane sample pretreatments by distilled water prewetting and water droplet volume. Furthermore, the effects of prewetting, water droplet contact time on different molecular weight cut-off ultrafiltration membranes’ surface and droplet pH on the contact angle values were also investigated. Moreover, fresh, clean and dry, as well as pretreated, and fouled UF membranes were also measured and compared.

Influence of Ca2+ and Mg2+ Supplementation on In Vitro Biological Properties of Hydroxyapatite/Collagen Nanocomposite Membrane

Hydroxyapatite/collagen (HAp/Col) nanocomposites with bone-like self-organized nanostructure show excellent bioactivity in vivo. However, they show quite high absorbability for cationic ions and lower culture medium ionic concentrations which adversely affects bone cell proliferation and osteogenic differentiation in in vitro cell culture condition. To address this limitation, in this study we have supplemented Ca2+ and Mg2+ ions to the HAp/Col nanocomposite membrane sample prior to cell culture to improve it’s in vitro biological properties. The HAp/Col nanocomposite membrane samples were fabricated by the simultaneous titration method using Ca(OH)2, type-I atelocollagen and H3PO4 as starting precursor materials. Prior to in vitro cell culture experiments, the HAp/Col samples were pretreated with Ca2+ and/or Mg2+ ions by immersing in 10 ml of 20 mM CaCl2 solution, 20 mM MgCl2 solution, or a solution containing 20 mM CaCl2 and 20 mM MgCl2 for 7 days. In vitro bone cell-material interactions on the pretreated and untreated HAp/Col samples were studied by culturing MC3T3-E1 cells up to 7 days. Enhanced bone cell proliferation was found on all the pretreated HAp/col samples as confirmed by the CCK-8 assay. Interestingly, the HAp/Col samples pretreated with both Ca2+ and Mg2+ ions showed the maximum viable bone cell density.