Deposition of inorganic nanoparticles on the RO membrane surface via a simple and environmentally friendly approach based on surface mineralization

Abstract

Different modification techniques are employed by researchers to alter surface characteristics of thin film composite (TFC) membrane, but these techniques are typically associated with drawbacks such as multiple fabrication steps and requirement of organic solvents. In this work, a simple, rapid and environmentally friendly approach based on surface mineralization was employed, aiming to simultaneously improve membrane water flux and antifouling properties without compromising rejection. Lead sulphate (PbSO4) was deposited atop polyamide layer of reverse osmosis (RO) membrane via electrostatic interaction by varying concentration (0.05–0.2 M) of lead nitrate and sodium sulphate in aqueous solution. Our findings indicated that precipitation of PbSO4 nanoparticles from 0.05-M Pb source onto the membrane surface was sufficient to achieve desired characteristics including hydrophilicity, surface charge and homogenous nanoparticles distribution, leading to 48 % higher flux and 2.3 % higher NaCl rejection compared to the control membrane. Our results also revealed that the surface-mineralized membrane demonstrated extraordinary fouling resistances against sodium alginate and dyes. Most importantly, Pb ions leaching from the membrane could be negligible as it was below the detection limits of ICP-MS (<1.0 ppb). In conclusion, the PbSO4-mineralized membrane developed in this work is able to show great potential for RO application.