Fig. 6: Filtration efficiency evaluation, ion exchange isotherms analysis, and pH-dependent membrane protonation/deprotonation. | npj Clean Water

Fig. 6: Filtration efficiency evaluation, ion exchange isotherms analysis, and pH-dependent membrane protonation/deprotonation.

From: Carboxylated wood membranes for selective capture and recovery of critical and commodity metal cations

Fig. 6: Filtration efficiency evaluation, ion exchange isotherms analysis, and pH-dependent membrane protonation/deprotonation.The alternative text for this image may have been generated using AI.

a Average Li+ filtration efficiency values for the SSp (blue) and MSp (green) wood membranes for the three consecutive filtration cycles. b Average Fe3+ filtration efficiency values for the SSp (blue) and MSp (green) wood membranes for the three consecutive filtration cycles. Error bars represent SD/√n across independent membranes (n = 3). c Li+ ion exchange isotherms and d) Fe3+ ion exchange sotherm in terms of change in number of moles (Δn) of available carboxylate sites –COO- (Δnmax) at retention time of 72 h under equilibrium. e Molar fraction for the protonated ϕRH (blue) and deprotonated ϕR- (black) species for maleic acid monoester (MH) and succinic acid monoester (SH) in a pH range from 0 to 7. Calculations were done using the Henderson-Hasselbach equation; pKa values are given in the plot. Individual membrane filtration efficiency values are reported in Table SI-1 and SI-2.

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