Preparing and analysis an innovative membrane based on polyethersulfone/sulfonated polyethersulfone/organically modified nanoclay: Ability to heavy metal removal

Abstract

A novel ternary mixed matrix membrane (MMM) was fabricated via a non-solvent induced phase separation method to effectively remove heavy metal from wastewater. The individual and combined addition of SPES and nanoclay with low loading (≤ 2 wt. %) was studied to determine if there was antagonistic, synergistic, or neutral impacts between the SPES and nanoclay on membrane properties and performance. SPES was synthesized via sulfonation reaction of PES and characterized by means of Fourier Transform Infrared Reflectance (FTIR), degree of sulfonation (DS), and Differential scanning calorimetry (DSC). SPES as an affordable additive provides an excellent hydrophilicity, morphology, and surface charge characteristics. Furthermore, the incorporation of nanoclay could remarkably alter the hydrophilicity, morphology, mechanical properties, charge characteristic, separation performance and fouling susceptibility of resultant membranes. First, PES membrane was modified via addition of different amounts of SPES (0−50 wt. %) and the optimal membrane (PES: SPES (1:1)) was determined based on permeate flux and ions rejection. It was shown that the permeate flux of optimal membrane (PES: SPES (1:1)) was dramatically increased (about 10.6 times) along with increase in rejection capability (by about 32 % for Ni and 34 % for Cr) compared to pristine PES membrane. In the next step, nanoclay was incorporated (0−2 wt. %) into PES: SPES (1:1) matrix to fabricate ternary MMM. The results indicated that the membrane containing 1.5 wt. % nanoclay possessed a higher permeate flux (118.3 L/m2 h) and mechanical strength with minimal loss in rejection. Accordingly, the high performance ternary MMMs display attractive features for application as NF membranes in the heavy metal (Chromium (Cr) and Nickel (Ni)) removal.