Optimization of Polysulfone Based Membranes Using Charged Graphite Nano Platelets for Separation of Manganese and Chromium (VI) From Water

Heavy metals are one of the major toxic pollutants affecting water quality. The higher concentrations of heavy metals in the environment cause water quality deterioration. As these metals are used for various purposes, they enter in the effluent streams of these processes. Their removal and recovery without further contamination would enhance their recyclability and usability in further applications. The use of graphite nanoplatelets (GNPs) with a polysulfone (PSF) based membrane is one potential solution to this issue. This will lead to rejection of heavy metals through the Donnan Exclusion Principle. At the same time, it offers the chemical and mechanical stability of PSF, and GNPs can be chemically modified to provide desired charge to membrane surface for optimum removal of heavy metals. Experiments using ultrafiltration membranes with GNPs anchored on them showed an increase in pore density, hydrophilicity, water flux and permeability transport properties. In addition, experiments involving Mn and Cr rejections revealed 96.97 and 93.07% rejections when 0.2% wt of GNP was included in the PSF based membrane. This highlights the importance of GNP treatment with suitable materials providing lower pore size and increased porosity and rejection of Mn and Cr. Such higher porosity would help to enhance transport rate and rejection properties which is necessity for successful industrial applications. Graphical Abstract