Interlayer-free silica–pectin membrane for sea-water desalination

Abstract

Water scarcity has become a serious problem worldwide. Research is now looking at the fabrication and use of interlayer-free silica–pectin membranes for sea-water desalination as one potential solution to this problem. This research work investigates the performance of interlayer-free silica–pectin membranes for artificial sea-water desalination. A dual acid–base catalyst process is applied during the sol–gel process used to prepare the membrane's thin layer structure. Membranes were prepared using tetraethyl orthosilicate as the silica precursor and various concentrations of pectin (0 wt%, 0.1 wt%, 0.5 wt% and 2.5 wt%) were used as the “templating” agent. The performance of membranes was evaluated using pervaporation (PV) processes at room temperature (~25°C). The results show that water flux for 0.1 wt% pectin was the highest (4.50 kg m−2 h−1 and 5.73 kg m−2 h−1, at calcination temperatures of 300°C and 400°C, respectively). The fluxes at 0.5 wt% and 2.5 wt% pectin concentration were much lower, compared with 0.1 wt% (3.12–0.51 kg m−2 h−1 for both, at calcination temperatures of 300°C and 400°C). In addition, the salt rejection for all membranes remained excellent, at ~99.9%. This clearly demonstrates that carbon chains in silica matrices may produce smaller and stronger pores.