oa Novel Nanoparticle Doped Nanofiltration (NF) Polymeric Membranes for Ions and Heavy Metal Removal for Drinking Water and Water Desalination

Availability of clean water is one of the most urgent challenges for our societies. Practically, all water sources around the world are polluted to some degree due to a heavy influx of industrial effluents and domestic and agricultural wastes discharged into water sources.

Membrane technology has gained significant attention in the water treatment, because of its advantages such as cost effective, no phase change, easy fabrication and high removal efficiency. One of the most important environmental issues today is water contamination with heavy metals, due to their strong toxicity even at low concentrations. Heavy metals exist in water in colloidal, particulate and dissolved phases, and their occurrence in water is either of natural origin (e.g. eroded minerals within sediments and leaching of ore deposits) or of human origin.

Polymeric membrane filtration such as Nanofiltration are commonly used membrane process in heavy metals removal and multivalent and monovalent ions.

Hence, we have developing a low cost and high efficiency polymeric NF membrane. The commercial/conventional NF polymeric membrane development is moving in the direction of improving the cross-linking chemical bonds, optimizing the effective porosity, and searching for better polymer groups.

Most NF membranes are charged, and hence, they have a higher rejection to multivalent ions (heavy metals) than to monovalent ions; therefore, selective partition of ions is possible through electrostatic interaction. However, for heavy metal removal to lower ppm values, the surface charge of the desired polymeric membrane has to be enhanced. Our new innovative idea is to increase the surface charge of the NF polymeric membrane; with this improvement we add a new dimension of enhancement to the NF polymers. We have doped NF polymeric membranes with selectively metallic nanoparticles, which will be actively driven and oriented with respect to the surface vector of the membrane and its pores and then therefore the surface charge of the membrane will be significantly enhanced, the effective surface area and the pores sizes will be increased due to hydrophopic interactions between the coated magnetic nanoparticles and the heavy metal ions removal through adsorption in addition to the traditional steric effect and Donnan exclusion. As a consequence consequently the overall process of heavy metal removal will be significantly improved in every direction, which will directly affect the filtration quality, efficiency and the cost.

We have prepared the NF polymer chemically, the doping process with the selective metallic nanoparticles performed with the help of a selective electromagnetic pulse sequence. Characterisation with dedicated analytics based on analytical tools such as X-ray photo-emission spectroscopy (XPS), scanning electron microscopy (SEM), attenuated total reflection infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM) showed an evidence of noticeable increase in surface charge, surface roughness and density of porosity. XPS measurements revealed that nanoparticles are bonded to the polymer strand forming vibrating polymeric nano-chains. As a sequence, the obtained NF polymeric membrane is a novel material with enhanced intrinsic properties for monovalent, multivalent ions and heavy metal removal, which is expected to have significant influence in developing filtration and treatment membrane for drinking and ultra-grade water as well as for water desalination.