Polyethylene separator supported thin-film composite forward osmosis membranes for concentrating lithium enriched brine

Superior forward osmosis cellulosic membrane for water desalination and brine concentration

Brine is an inevitable product of desalination plants and various industrial sectors. The appropriate disposal of brines and their highly concentrated salts and other diverse contaminants is a critical environmental challenge to most plants. Recently, the FO process is gaining attention as a viable alternative to conventional brine concentration methods, primarily due to its reduced energy consumption. This study aimed to fabricate a high-performance nonwoven FO membrane from cellulose acetate (CA) blended with polysulfone (PS) via the phase inversion technique. The prepared membrane was investigated in both saline water desalination and brine concentration. The FO membrane performance was tested for saline water desalination at different NaCl concentrations and applied in brine concentration using two kinds of draw solutions: ammonium bicarbonate (NH4HCO3) and a mixture of ammonium hydroxide/ammonium bicarbonate (NH4 OH)/(NH4HCO3) at different concentrations. It was observed that a high flux of 150 LMH was attained by using 2 M NaCl as a draw solution against distillate water as a feed solution. For brine concentration, by application of (NH4 OH)/(NH4HCO3) draw solution mixture at a 1:1 ratio, the modified cellulosic FO membrane exhibited the highest water flux of 113 LMH.

Study on the Changes in the Microcosmic Environment in Forward Osmosis Membranes to Reduce Membrane Resistance

Osmotic microbial fuel cells (OsMFCs) are an emerging wastewater treatment technology in bioelectricity generation, organic substrate removal, and wastewater reclamation. To address this issue, proton-conductive sites were strengthened after using the forward osmosis (FO) membrane by reducing the membrane resistance. The mechanism of improving electricity generation was attributed mainly to the unique characteristics of the membrane material and the water flux characteristics of the FO membrane. In particular, only when the concentration of catholyte was greater than 0.3 M was the membrane resistance the main contributor to the overall internal resistance. Meanwhile, through the simulation of the concentration inside the membrane, the changes in the membrane thickness direction and the phase transition of the internal structure of the membrane from the dry state (0% water content) to the expansion state (>50%water content) were analyzed, which were influenced by the water flux, further explaining the important role of the membrane’s microenvironment in reducing the membrane impedance. This further opens a novel avenue for the use of OsMFCs in practical engineering applications.