Comparison of negatively and positively charged thin-film nanocomposite membranes for boron removal

The increasing demand for boron has resulted in its contamination of water supplies. Nanofiltration membranes, particularly thin-film nanocomposite (TFN) membranes, have shown promise in removing contaminants. This study evaluated the boron removal capabilities of negatively and positively charged TFN membranes alongside a control thin-film composite (TFC) membrane without nanoparticles. Piperazine (PIP, for negatively charged membrane) or polyethyleneimine (PEI, for positively charged membrane) aqueous monomer was reacted with trimesoyl chloride (TMC) in n-hexane solution via interfacial polymerization (IP) on the polyethersulfone (PES) membrane substrate to form the TFC membrane. During the TFN membrane preparation, titanium dioxide (TiO₂) and sulfocalix[4]arene (SCA4) were introduced as active nanoparticles to the aqueous monomer. Boron removal performance was evaluated using a 10 ppm aqueous boron solution. The PES substrate gave the highest water flux, which was 307.80 LMH. For the TFC membrane, TFC–PIP had a higher water flux at 113.71 LMH than TFC–PEI. Furthermore, the TFN membranes containing the PEI monomer had a lower water flux than those containing the PIP monomer. These findings highlight the potential of TFN membranes, particularly those incorporating nanoparticles, for effective boron removal. Further research and optimization of TFN membranes can contribute to addressing the challenge of boron contamination in water supplies.